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).

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.