Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

Is there a simple way to disconnect the governor arm from the carborator? I've removed the bolts that hold the carb on but it won't slide off (It needs cleaned big time) because the of the linkage to the governor arm (wire rod and spring).  The shop manual says to remove one of the two screws that hold it on, but I'm not sure which one should be removed or what will happen to the governor if I do remove them.  I have heard that governors are really hard to adjust and I was trying to avoid that agrevation.  I've labels the two screws "A" and "B"  (one of them is really a bolt).

Unscrew the 2 bolts of the carburator that goes to the intake and disconnect fuel line lift up the crab you will easely get the rod of the governor hole without bent it. that how I do

good luck

Denis, the carb is held on a pair of long rods (arms) and carb's linkage to the governor arm will not let me slide it off  (thank you Yamaha).  I could bend the long governor arm (I suppose) but there's no guarante that I'll ever get it stranght again.  I am not very familiar with the two screws.  I think that screw "A" is acually the shaft to the governor but I'm not sure.  I have no clue what the other screw "B" (really a bolt) does.  I keep spraying both down with BP Blaster.  I love that stuff.

"B" is the clamp FOr the Governor rod "A"

I would take both the nuts from the intake manifold and tighten them against  each other  on one of the carb studs "double nut",   then unscrew the stud from the engine case.

Friiy

friiy wrote:
No, not on this carb.  The rods are just long enough to get one small nut on there. No hope in getting two nuts on there. But thanks

I see what you mean, it's yamaha carb okay I understand, I use to work on walbro or tecumseh well let me try to find some documentation for those carb I'll be back soon.

At this point I would say bend the arm of the governor,  about 45 degrees.

Hold the it with two pairs of needle nose,  bend it just below the link holes, use the 2nd to below the first about an inch below to stablize the rest of the arm so the whole thing does not twist..

You aren't putting this thing in a classic Yamaha show are you?  :)

Is this a "TK" carb?

Good Luck,

Friiy

If you use rubber hose over the plyers,  you won't put any teeth marks on the arm,   those arms should bend easy,   and bend back with no problems.

Or you could just mark the Govorner shaft and take it off,   They are not hard to set,  just like any other govenor..

Good Luck

Friiy

friiy wrote: The motor must have been made in Japan so I just assumed it was a Mikuni carb.  But maybe you are right.  I'll have to  take a closer look.  Would a TK carb have the letters "TK" imprinted on it?

Yeah,  Funny round little circle with "TK" in it,  (rounded edged letters)....I thought I saw the logo in the photo..

What model of engine is this? what is it on...  I can see it is gummed up in the photo.   and has not run for sometime.

....Brown fuel gum deposits under the choke butterfly..

Friiy

Is the carburetor's model number also printed ?  I'd like to find a rebuild kit or a direct replacement. 

Kits are not really needed ,  There is only about 3 or 4 things that may need to be replaced at worst case....

1) float inlet needle

2) Bowl  seal (large o-ring goes around the bowl and seals to the carb body)

3) bowl bolt seal

4) float and pin

Unless the carb is Rotted out with water and full of powdery residue...   I would only change the the parts that are un-serviceable after cleaning.

The float is un-ajustable, the needle is only thing that is hard to tell it it is bad without a trained eye...  But  if It leaks after being put back together then needle is suspect..

About everthing can be reused unless the carb is rotted out or full of green and white powder..

as for a carb model it Should  be printed on it,  But who knows... What modle of Yamaha is this and what type of thrower (model)?

Thats most likely about $85 for that carb.

Good Luck,

Friiy

I've got it apart and now I'm trying to free the jets and nozzles. There's quite a bit of corrosion, we'll see how it goes.

#9   7KF1434221 JET. PILOT (#42)
#10 7KF1434345 JET. MAIN (#90)
#11 7KF1434100 NOZZLE. MAIN
#13 14T1439202 VALVE. NEEDLE

Ref # Part number
1 7KF1450100 CARBURETOR ASSY superseded by 7KF1450101.
2 7KF1422700 WASHER
3 7KF1416200 BOLT. HOLDING
4 7KF1419100 PLUG. DRAIN
5 6461421201 SPRING. PILOT ADJUSTI (3 needed)
6 7KF1421100 SCREW. PILOT ADJUSTIN
7 7KF1421600 SCREW
8 7KF1438400 GASKET. FLOAT CHAMBER
9 7KF1434221 JET. PILOT (#42)
10 7KF1434345 JET. MAIN (#90)
11 7KF1434100 NOZZLE. MAIN
12 3671438600 PIN. FLOAT
13 14T1439202 VALVE. NEEDLE
14 7KF1438500 FLOAT
15 7KF135550000 MANIFOLD,INTAKE
16 7KF1355710 GASKET

It doesn't look that bad from what I see ( no heavy pitting),   It looks as though you cleaned of the corrosion...

When I take out the main jet to get to the nozzel,  I get a good stubby screwdriver with  the right size blade width for the main jet slot,  then I grind the shaft of the screwdriver to fit in the well hole of the main jet/ nozzel tower. I grind the shaft to so i don't screw up the threads for the bowl nut.  I take the carb body and put it in a vise with soft faced grip ( so I do not tear up the carb)..... If the Main jet is going to be difficult, I tap it with the screw driver and hammer lightly.   If that does not work I may heat the main jet with a small pencil torche for a moment to break it loose (brass heats up quick and expands alot).   Sometimes "Mouse's Milk" or " Aero-kroll"  penetrating oil may  help. 

Good Luck,

Friiy

I wonder if there is some special tool they use for this.

This is good advice.  I can do this.  I'll get busy grinding down my screwdrivers.

I don't know why the jets and nozzle woul be critical to the carb getting gas into the bowl.  The fact that the bowl remains dry seems strange to me.     When I removed the carb the bowl it is still empty. I know for a fact that the float is working and that the little needle valve on the spring is dropping down (to open and let fuel in) but no gas is dropping into the bowl.  The carb is fed by a small diaphram fuel pump and that is working (there's gas under pressure when I remove the fuel line connection to the carb).  So why is the gas not dropping into the bowl?  I don't think its the jets, their job is to mix the air and fuel.  Am I right about this.  This has me baffled.

You must have something stuck in the fuel inlet for the carb,  try blowing compredded air through the the fuel inlet and see if somethin falls out...

Is the fuel line rotted at all internally,  I have seen the inside of black fuel line turn to mush and get rolled into the inlet when the fuel line is reattached..(like a ball of chewing gum)..

Good Luck

Friiy

Sure I have compressed air. I flushed out the gas lines and they did not seem bad at all.   I'm guessing I should blow the compressed air with a nozzle through the line from the end where the needle seats above the bowl.  so I don't further cram whatever is in there down the line. Problem now is that the bowl pin does not slide. The pin is really tight.

Is there any way to loosen the pin?  I've been told by others that the TK carbs have very fragile arms that hold the pin.  Any ideas?

Put the carb back in the vice and tap it out lightly with a small punch (like 3/32 or so)    it"s gotta come out>>

friiy

friiy wrote:

 I have not been able to get the screw of the main jet  to budge. I did take a lighter and try to heat up the brass jet. I will try tapping with a hammer if I can find a way to hold the carb in a vise.  I have never seen a "soft sided vise" but I will look around for one of those.  I didn't have any "Mouse's Milk" or " Aero-kroll"  penetrating oil may but I did have some liquid wrench  so I put some of that on the brass of the jet.  i'm going to cross my fingers that the next time I get this carb on the bowl will fill with fuel. 

You can make the faces of the vice non-marring by putting something soft on the faces to grip the carb.

I use a small peice of aluminum sheet cut to go over the grip of the vice(for a smooth soft grip) .   This is used for cast parts...

I put a piece oif rubber over the vice face for hard plastics,   or a piece of linoleum flooring over the vice face for delicate machined parts (it has good grip)..

Sometimes I will use soft side of velcro for some small parts that slide around in the vice...

Or you can use some paint sticks,  once.... 

Ohhh.  I hold all this to the vice face with double sided carpet tape..

Keep us up-to-date

Friiy

I got the pin out (finally), got the float and needle off. I squirted some carb cleaner in the fuel intake but nothing would come out the needle valve hole. Then I hooked up a compressor and with a nozzle I blew compressed air through the intake. It took a while (3 or 4 tries) but the air came through. There did not seem to be an object clogging the line. It seemed more like fuel deposits built up on the walls of the small orifice of the carburetor. I still have not been able to free the jets. I ground down a custom screwdriver and carefully wrapped the shaft in tape to keep from damaging the threaded walls of the shaft. I let the carb soak overnight in penetrating oil. I borrowed a pencil torch but I'm really nervous about heating this thing up. What if I melt it or crack it? I have had all sorts of interesting adventures with the propane torch. Any thoughts?

I would not use that torch, you are going to catch yourself on fire.... Try a torch like this.

These torchs are cheep and run on butane,    with this you can heat only the jet can keep the carb cool.  ( as long as you don't go crazy)...

If you can't get that jet / nozzle out,  I would try to run the carb with with out pulling it out...  ( If the carb fails to run, take it back apart and  keep working at it)

Remember to only heat the brass jet, It will (may) swell with heat and break it's bond with the carb body.  I would keep a wet shop towel around the carb body to keep it form getting hot. it should only take a few seconds..

I think alot of places sell these small pencil torches or similar,  I bought one at harbour Freight and one at Lowes made by Weller...

Good Luck,          

Friiy

OK, that was a close one, glad I didn't go crazy with the extra large sized pencil torch.  Instead I went out to the garage and got the lighter I use to start the grill. Seems to have done the job because the jet screw finally let go. I  held the carb body with a damp cloth and only heated the jet screw for three seconds. Then gave the screw a four nice taps with the screwdriver and small hammer.  It worked.  Thanks for the image of the small pencil torch, like they say; " a picture is worth a thousand words."     The custom ground screwdriver was a life saver.  Only about a third of the jets were clogged when I spayed carb cleaner through them to clean them out.

Cool,   Is the throttle shaft and choke shaft turning free?    If you shoot carb cleaner through the adjustment needle on the side of the carb, can you see spray on the inside of the carb venturi next to the throttle shaft (it should come out small holes there..  On that carb there is 2 or 3 holes ).

I would start by flushing the fuel tankand check for gummy brown deposits on the bottom... check your fuel lines for rot,  inside and out (The inside gets gummy like wet bread).

You may want to get a small fuel filter for the fuel line,  I like the cheap small paper ones that VW bugs used,  they are see through and you can spot water and dirt in them..

Does this have a fuel pump?,   If so you may need to flush or replace the diaphrams and gaskets..

If so put it back together ans see if it starts.    See if it leaks when it sits, you may need to replace the fuel inlet needle...

Good luck,

Friiy

friiy wrote:

Is the adjustment needle that  you are refering to identified as #6 in the diagram above?  Sure, I can try to spray carb cleaner in there. I do not know where the venturi is or where its small holes might be. 

I did clean out the gas tank and flushed out the gas lines.  I could not locate replacement diaphrams for the (Mikuni?) fuel pump so I chickened out on the idea of opening it up. I just soaked it an flushed it out a few times. It does seem to be working.  I would agree with your recommendation for a fuel filter. I think this is the weak link in the fuel delivery system.  There's a small sediment bowl under the gas tank and a filter screen on top of the tank for large particulates. But there is nothing to filter the finer particles.  That said, I would not want a fuel filter that would interrupt the function and flow of the fuel pump.  

Sorry,  The venturi is the narrowest part of the carb throat...   The holes I am talking about are where the throttle butterfly wipes past the inside wall of the carb as the butterfly opens from fully closed postion.. on the same side of course as the needle adjustment screw.

Have you tried to start that thing up yet?  Or check for leaks?....   It  should start/run,  you just need to find out if you need to replace the inlet needle at this point.

Friiy

I have been dying to go get the carb back on and try it out. But family stuff got in the way all weekend.  The needle valve looks good to me but I would like to polish the small channel that it slides up in to. I noticed before that it would sometimes stick or hesitate when it moved up or down.  The snowblower has not run in a long time and I thought I would put some fresh oil in the crank case. Here's an image of the needle's  tip . 

 

You can polish the channel it rides in,  but do not polish the area that the rubber tip seats at...  

Friiy

friiy wrote:
The carb is completely back together..  Maybe I should have assembled the main jet using anti- seize.  It was so tough to get out. But I didn't .  I'll be amazed if the the large O-ring gasket around the top of the bowl doesn't   leak.  A new one is close to $20, so I take my chances for now.  

The large bowl rubber  ring is not nuch of a seal,   fuel only reaches that point when the engine is tipped. or if the inlet needle is leaking past overfilling the carb...

Friiy...

besides.... that ring is most likly cheeper from a aftermarket company like Rotory, Arnold , Billues.... or so on.....

Plus,   that ring may be the same as a Honda bowl or a Kawasaki...

Friiy

Did you start the Yamaha yet?

Friiy

friiy wrote:

No, I have not started it  yet. Its on the docket for Sunday. I have to put the fuel tank back on. It was full of gummy stuff in the bottom that had to be cleaned out (done). I did find the original owner's manual and the correct spark plug cheap online. Those arrived.  The manual helped me set the gap on the plug and describes the correct choke and throttle settings for starting the YAMAHA.

Here it is running (see link).  It started right up.  What a difference with a clean carb.  I do think that the old fuel line is pumping rubber residue into the carb.  The oil was clear when it started but after about 30 minutes it was really gross.  The engine runs fine at idle. And it runs fine at a higher RPM.  The only issue I have (with the motor) is that when the snowblower is running with a heavy load the governor kicks in and raises the rpms way up. Far higher that I think the engine should be running.  Is this screw (on a part connecting the governor to the throttle) supposed to control high rpms called for by the governor?   This screw does not appear to be doing anyting. If not this screw is there a control elsewhere  for how high a governor is allowed to take the rpms? Note: you can see the screw in the photo below in the yellow box with a pink check mark

 

Here's the video:

http://vimeo.com/2411425

Screw A and B are you should not have to adjust....  unless someone has taken it apart... It looks as though no one has touched it..

The screw with the check mark is the high speed throttle plate limit,  if you tighten that down it will ( if I remember right) / should limit the no load top speed..

The unit,,as far as I  can tell from the video,  is running too fast at idle.  It should just put aglong about 500-700 rmp (I think).  and should run at about 3250 rpm at high speed.  ( I think)... Check the manual.  It should tell you...  Do you have a tach to see how fast it is going?

Just a note.... The checked screw and the screw on top of the  throttle shaft plate (low idle speed set screw) are screws that people try to adjust when the carb starts to clog up..

When the carbs start to clog up, they hunt and surge in rpm,  and will not sustain low speed rpm (idle)...  they adjust the screw so the carb is out of the idle range and continues to run...   But of coarse this is not right...

Good to hear it running,  does all the drive/ snow auger work ?

From the Desert,

Friiy

Your choke arm lever seems to bounce around alot, is it borken or just comming loose?

You may want to  peen the shaft back on the arm, and straighten it out. it will keep you from looseing the arm lever.

take a picture of the top of it, and I will tell you what I think should be done...

Friiy

friiy wrote:

I have no tach.  Sometimes auto parts stores will loan you things.  The manual says high rpm is 4000 and low rpm is 2000 (is "low" the same as "idle?").  There's also a horsepower rating but that is at a lower rpm like 3200 or so (under load?)  Wow 2000 rpm at idle. That might be about right. What do you think?

The engine RPMs   sound too fast to me too, its not you imagination.  That's why I'd like to adjust that limiting screw.  The screw does not look right the way it is. Its backed out so far that the little spring has no tension. But I don't know my way around those parts.  I do think that the rubber in the fuel line is breaking down and dissolving into the fuel.  I can see some black stuff in the carb when I look in past the choke plate. Not a lot, just a trace.  Where else would that be coming from?  The valve cover has a vent tube that feeds back into the air intake.  Maybe there's oil blowing by those valves. Hard to say.

You can imagine how great it was to hear it start.  The blower is a real beast.  I want to be able to snowblow the sidewalks in my neighborhood and so I will rarely have to turn it.  Until we get a snow I won't know if  was worth the effort.  It turns easier than some wheeled blowers that I have used but it is very heavy.  The blower part sounds like it needs a few new bearings (those are cheap) and I guess I'm going to have to open up the drive system to see why the shifting is sometimes "hit or miss."   In fourth gear it really moves along.  The belts need checked, I always worry that someone puts the wrong belt on.  It was used on a gravel drive so there are some paint issues.  I don't want to spend a lot of time on it until I know that I like how it blows snow.  

Are you sure the RMP (4000,2000) is that auger rpm?

Friiy

Can you send me the link on the manual? or post it..

Thanks,

Friiy

friiy wrote: Yes it shakes. You cannot balance a quarter on this one.  Apparently Yamaha engines are known for vibration issues  when carbon builds up someplace (the cylinder head?) .  The engine is mounted on big rubber bumpers and the fuel tank has its own set of rubber bumpers. I was thinking of wrapping some fine wire around the vibrating arm. I worried I'd wreck something if I started hammering away.  But if you have any ideas I'm game.  The shaking does not send vibration down to the choke plate (not yet anyway.)  If I find a tach, what do I point it at? The shaft coming out out to the pulleys and belts?

http://www.tinytach.com/tinytach/gasoline.php

This is the kind I have used for years, It has a induction pickup wire  you wrap around the spark plug wire ( around the insulation, you dont want to send engien spark down the pick-up wire)

Friiy

friiy wrote: This is from the manual to my snowblower's smaller 6hp twin.  The two engins are very similiar.

What you do with the choke is:

    With a small punch (with the diameter about the size of the float pin) tap the top of the brass shaft of the carb.  Tap just tap hard enough to start denting and moving/ flareing out he brass over the steel choke plate and arm...  After that I would clean the area  with contact cleaner and ruff it up with some heavy Scotch bright  (maroon color).   Clean it again with contack cleaner and put a drop of epoxy  ( like JB weld) on the shaft and plate-arm area.  Just to reinforce the shaft to arm area and to prevent fretting and wear.

   Friiy

Wow,   seems high.. your's is a 8hp?    Where do you see full speed?

You said you saw something on the motor rated at  ##hp @ 3200 rpm or so?

.Friiy

friiy wrote:

Yes mine is 8hp.  Nobody can find the service manual for the 8hp, but the specs for the 6hp is often very close.  The maximum torque (HP?)  for the 6hp is rated at 2800 rpms.  The max RPM is 4000 rpm.

 

My first big splurge on the Yamaha.  (it's earned a little pampering after all these years).  I found a see-thru filter at Volkswagen shop $2, a piece of 1/4 fuel line (not sure what size I needed) $3 and some BJ weld (they give you a black tube and a red tube to mix together) $4. .  Oh, and I picked up a multimeter with a clamp for a spark plug.  I'm storing the snowblower outside until I know it does not leak gas. I have started storing my plastic gas tanks outside too.  Just a little piece of mind. 

 

I hooked up the mutimeter's tach clamp and  got a  reading on the rpms.  The multimeter did not give me just one number, it was more like a range of numbers so I just took the average. The idle RPM has been adjusted and is now running at 2000 and sounds much quieter and calmer that it did before.  I cannot reach the limiting (high) screw with my short screwdriver so I could not adjust it. But I did get a sense of where 4000 rpm is on the throtte.  I was running it higher that that for a few intermitten moments before, I hope I didn't wreck anything.  The motor does still shake more that I think it should at idle but at idle it is now quiet enough to easily talk over.

The snowblower started right up without and issue (electric start) and it was cool out tonight (34 F).  The oil was changed and has remained clear ( the engine has a viewing window for the oil reservoir that is really interesting to watch)  Should tachs give a range or just one number?

Not sure if I'm reading the spec sheet correctly but the snow thrower is a Yamaha with a side valve engine?  Honestly, I've never heard of nor seen a Japanese side valve engine.  Not that they don't exist.  I just haven't seen one in all of my years.   Japanese have been techno leaders in engine design.  I'm curious how old the snow thrower is?  

Borat,  The old Colman generators back in the early to mid 80's were all Kawasaki l head engines ( the first Powermate's) ,  John Deer had on all its large mowing tractors a separate 5 hp L head Kawasaki vaccum/ blower motor to drive clippings up the bag chute...   Also the first Honda mowers I worked on were L head on the HR215..

honda made for a time a 2.5 hp motor (L head ) that went on the Mclane edgers which was real sweet.  My dad has a EM3000 honda generator with the first CDI ignition that is L head.

The stuff really flurished out west back in the early 80's and stayed until California started enacting smog and noise requirements,   That's when the OHV started to take off for us. 

The L head stuff that was made was great,   It was like they took all the features the mechanics liked and placed it in a Aluminum block,   Big ball bearings,  unboltable rewind,  quite muffler,  chrome sheilds over the muffler,  float carb, CDI ignition standard. oil alert / shutoff.  IT was like they took motorcycle engineering and put it lawn mowers with high gloss paint...

I think you were able to get so much more because the doller was worth so much over in Japan.

Things I miss :

Kawasaki TD24d motor (2 cycle)

Echo CS280   saw

Echo PB210E blower

Echo 2 stroke mower (4 hp) .  Borat,  thats what you have right?

Toro 2 stroke commerical lawn mower with the Suzuki engine

Wisconsin Robin 5 hp (L head)

Oh well,  

Friiy

borat wrote:

Yes, those valves are on the side.  They are covered with small tin plate and are easy to get to. I opened it up to look in there not knowing what I would find.  There are two of them.  I think that this Yamaha snowblower was manufactured in the mid 1980's.  Isn't "overhead valve" considered a far advanced/improved  design over the side valve or L-head?  While trying to find parts for this snowblower I met a Yamaha snowmobile dealer that used to sell the Yamaha snowblowers in his store.  He said they were really nice but pricey and hard to sell for that reason. 

Note: I also found this very useful information on the web (the high throttle position on the "adjust bolt" leads me to believe mine is way out of adjustment) :

You are correct.  Over head valve design is more efficient than  L  head (flat head).  It provides superior gas flow and head cooling.  Which in turn extends the life of moving parts in the head and has better opportunity for generating more power for the same displacement and runs smoother.  I'm just surprised to see a Japanese engine manufacturer actually building L head engines that recently.   In  1981, I owned a 750 cc Yamaha Seca.  It was very sophisticated for the day.  The engine on that thing was dual over head cams with four carburetors, four into two exhaust.  It's hard to imagine that they'd be building state of the art engines on bikes yet building near stone age engines on other equipment. 

Actually, I find it unusual that many Japanese manufacturers are building any kind of push rod engines (ohv).  Their specialty in small ATV, scooter, and motorcycles is generally single overhead cam engines which are stone axe reliable but technologically  more advanced than push rod engines.  Could be some cost savings with the push rod design.  I don't know.  It's very unusual to find overhead cam engines in OPE.  I know that Honda does provide a few engines for that purpose.   I bought a Craftsman lawn tractor for my camp in 2005.  It has a V-twin single overhead cam engine in it.  However, almost everything else I looked at  when I was shopping was push rod.    The Husqvarna machine I have at home has a push rod V-twin Kawasaki engine in it.  Can't say that there is any noticeable difference between the two. 

The problem with going to a overhead cam  on a smaller engine is the need for a chain of smilar size,  the cam gear would have to be twice the size of the engine crank gear,   The crank gear would be at LEAST the size of the PTO shaft,   The head would have to hold the cam gear and it's bearings + cam .  plus a chain tensioner- maybe a ajustment setup or a spring loaded mechanism... Then you would have to seal it all up... That is a lot of gasket / o-ring surface..   Now that lawnmowers are price shopped items and the rpms between  the diffrent power equipment needs are pretty standard.   There really is no need to go crazy with a small engine lawnmower arms race..  That is what the Honda rep told me back in 93,   That's why he said you don't see tuned mufflers , ohv cams and timing advance on most small engines...

Borat, Bikes have always had a arms race going on,  look at the rpms  they run at and the HP and torque they produce.   All that and small CC's.

Borat.... When you gonna post some pics of your bikes?  What sweet projects have you got going on now?

With grease under the nails,

Friiy

Do motorcycle engines ever end up on OPE?

I'm presently doing the brakes on a '74 RD350.  It has front disk and rear hub brakes.  I pulled the calipers off, separated them and blew out the pistons with compressed air.  That was a bit of a chore.  The brake piston look as though they'd never been removed in 34 years.  Internals are good.  No rust or pitting.  I'm waiting for a shipment of parts.  Lots of parts for the entire project.  I need to re-seal the calipers, put on an new stainless steel front brake line (with built in micro-switch - sweet), and install new brake shoes in the rear wheel.  I spent a good week re-doing the wiring.  The way the bike arrived, it looked as though a colour blind chimpanzee with set of wire cutters and a roll of tape did some "repair" work.  It was a major mess.  Thank God for schematics.  I still have the headlight & gauges all apart.  That's where the wiring lives.   My next job is to take the forks off and refurbish them with new seals, oil and whatever else looks like needing replacement.  I have numerous parts in getting powder coated and my engine apart as well.  I need to get the new pistons before I can take the cylinders in for re-bore and honing.  I also have the heads going in to get the squish step reduced.   I could go on all day, the list of things to do is sooooo long.  Fortunately so is the winter.  So I'm taking my  time, doing a few hours a day. 

Despite the condition of the wiring on this bike, the machine is fairly fresh for it's age.  Just over 9000 miles on the bike and the engine (not original) looks even fresher.  Before I pulled it apart,  I did a compression test.  It had 120 lbs. on each side.  That's freaking remarkable because the engine has it's original pistons!   The heads had virtually no carbon build up.  This engine appears to have never been apart.  That's a good thing.  There are signs of blow-by on the pistons but that's the norm for those old two strokes.   I'm completely rebuilding the top end so new pistons and rings will be installed in the fresh cylinders.

My '76 RD400 that I built earlier this year turned out to be a lovely little rocket.  Just an amazing machine.  Even by today's standards, that bike hauls serious ass and is a delightful handler.  It does have a number of go-fast goodies on it though.  The '74 RD350 will be as fast if not faster.   It will be making similar power but the bike will be around 40 lbs. lighter.  I'll post some pics when it's done.  Here's a couple pics of the RD400 (red) in finished condition and the 350 I'm working on.    

Friiy:

You got me all wound up talking about bikes that I forgot to tell you that the ohc engine in my V-twin Honda powered lawn tractor has belts to run the cams not chains.  Also, the belts are designed to bring oil from the crank case up to the engine heads to augment valve gear lubrication.  It has a pressurized lubrication system so I don't know why they'd need the belt to pull oil up the the heads??? 

Borat, The bikes look great,  it is nice to see someone going though them like they deserve,   instead of watching them decay on the side of someones house...

 On your Honda tractor, Does the pressurized oil make it to the head via some sort of porting?   Or does it strickly use the belts for lube and scavange?

The Honda's I've had apartper pressurized only to the cam, crank and rod.   The head was still oiled from slinged / splashed from the cam gear. up the pushrod well.

Friiy

Yeah, saving the old bikes (cars & other historical stuff) is a rewarding thing for me.  Those old RDs were the orignal sport bike.  All the high tech crotch rockets of today are riding on the coat tails of the RDs.   They changed motorcyling as we know it.

I don't have my manual here.  It's at camp.   I'm under the impression that the belt fed lubrication is in addition to the oil galleries that push oil to the head/valve area.  Could possibly be redundancy  to protect components if a gallery gets blocked.  Who knows?  Maybe just a sales hook.  Worked on me!

These are some nice bikes.  When you find them are they is mint shape like this?  Do their owners share an appreciation for their technological accomplishment or do you see something that they don't?

I saw a motor like the brown one you have shown posted on craigslist recently.  The guy selling it said it would be a good go-cart power plant.  But I wasn't buying.  

Underdog wrote:

Q: "When you find them are they is mint shape like this?"

A:  No.  The red RD400 is the one that I fully restored.  It was shamefully abused and in terrible condition.  Spent several grand and hundreds of hours of work to make it look like that.   The purple RD350 is a very well kept example but hardly mint.  It's all in pieces right now as I begin it's restoration.  I'll post some pics as I go along...

Q:  "Do their owners share an appreciation for their technological accomplishment or do you see something that they don't?"

A:  Hard to say for sure.  Can't really speak for the previous owners.  Some would like to restore the bikes but don't have the money or wherewithal to do it.  Others don't have a clue of what they  have.  Just an  old  motorcycle getting in the way in the shed.  There are a many however who fully appreciate these machines for the true icons they are.  Guys who have either owned one in the past or just plain motorcycle enthusiasts with a knowledge of their history  covet these machines.  I've seen examples of restoration and modification of some of these old rockets that is truly impressive and worthy of praise.  Some guys just keep riding them with little or no attention to restoration.  Basic maintenance and that's it. 

Re the go cart power plant.   If it's from either an RD350 or RD400, it would make an excellent go cart engine.  In stock form they make around 40 h.p. at the rear wheel.   With a little massaging and a few bucks,  somewhere around 60 h.p. can be realized.   In the hands of a skilled racer, it would be a great engine.   If one is not familiar with the "light switch" power delivery of a pipey two stroke, it would be a handful to say the least.  

When you are restoring a bike like this how do you clean up the corrossion that forms on the aluminun cylinder head?  The aluminum sometimes gets a white film and bumps on it.  Is there a chemical that can clean this corrosion up? Or do you just live with it?

The guy I bought my Yamaha snowblower  owner's manual from had this bike that he was trying to get rid of.  

When I have air cooled cylinders that look like that (oxidized),  I usually get them bead blasted then paint them with black engine (heat resistant) paint.  Painting the cylinders black actually improves heat dissipation.  However, do not have them powder coated.  That method leaves too thick of a layer of paint and will actually inhibit cooling. 

Is that an RD200?  Sweet.  That baby looks mint.  With the front disk brake I'd guess it's probably a '76 to '78 I have one of those too in very good condition.  If you can get that bike cheap ($1000.00 or less),  and you're into bikes, I'd scoop it up.  What was the owner asking?   Here's a pic of my '74  RD200:

Is that a Magnesium jug or Aluminum....That pitting looks like Magnesium..

Friiy

The cylinders are alway aluminum.  Occasionally you'll find a magnesium ignition cover or other component cover but not cylinders.  At least none that I've seen.

This Yamaha is blowing snow. It still needs some fine tuning and adjustments.  The skids/shoes and scaper bar are not correctly adjusted.  The governor will sometimes over-rev the engine. I'd like to test the compression to see if that's an issue.  But overall I can see why these swowblowers have developed somewhat of a cult following.  Very easy to turn the tracks on snow (one hand). 4th speed in forward is a nice walking pace and the 2nd reverse gear partially makes up for the fact that you cannot roll this blower backwards in neutral.  I'm running it in a low-mid throttle setting (in 2nd gear) in the video in a heavy windblown snow/sleet mix that sat for 2 days. You can tell by the spotlight that I need to increase the throttle.  But its at high throttle that I get the over reving governor.  If I go into a big snowbank it revs up just fine but then when i clear the snowbank the rpms don't automatically drop back down. 

Is it hard to test for compression?

http://www.vimeo.com/2604216

Testing compression is very easy as long as you have the tester.  Canadian Tire sell a decent unit for around $50.00.  If you don't have plans to use it much, they might loan you one to use. 

Always test with a cold engine.  Take out spark plug, put in the proper sized fitting for the tester into the spark plug hole.  Using your electric start, crank the engine.  On each compression stroke the gauge needle will jump to the next reading.  Watch the needle until it no longer responds (increases).  Once it is at it's highest reading, that's what your compression is.  Make sure your compression tester connections are good and tight and try to use as few in line adapters as possible. That will reduce opportunities for leaks.   

Can I just assume that the reason the governor over-revs the engine rpms is because of a compression issue (pistons/rings/cylinders)?.  Does " changing the rings" entail a great deal of effort/work/experience?