Wow this was fun!These are some really slick motors.Alot of neat little things I have never seen before.I got this motor from a member here just to do some experimenting on the head.Turns out even the head is useable along with many other parts including crank,rods,pump and more.Kind of like a bonus finding all that!
Took me about 1.5hrs to completely tear it down.Broke a socket on the Headbolts so could of been done quicker.Putting it back together would probably take days!
Here is the flywheel and the One-way bearing is behind it.When starters were failing worries about this bearing came up.Dont.Its a very good size oneway.See that wire in the end of the bolt that holds flywheel on.It flings oil out the crank hole and into the oneway.Pretty slick idea.That bolt and counterbalancer nut are lefthand threads.Took awhile to figure that out!This would not be that difficult to get at since motor could stay in sled.Bulkhead would have to be removed on that side though.
Flywheel is easily removed with a 3 bolt puller.No need for special puller like YFZ has.
Also shown is the waterpump.Its completely seperate and it and oilpump are driven by that small chain you see there.
Took me about 1.5hrs to completely tear it down.Broke a socket on the Headbolts so could of been done quicker.Putting it back together would probably take days!
Here is the flywheel and the One-way bearing is behind it.When starters were failing worries about this bearing came up.Dont.Its a very good size oneway.See that wire in the end of the bolt that holds flywheel on.It flings oil out the crank hole and into the oneway.Pretty slick idea.That bolt and counterbalancer nut are lefthand threads.Took awhile to figure that out!This would not be that difficult to get at since motor could stay in sled.Bulkhead would have to be removed on that side though.
Flywheel is easily removed with a 3 bolt puller.No need for special puller like YFZ has.
Also shown is the waterpump.Its completely seperate and it and oilpump are driven by that small chain you see there.
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Do you have someone lined up to do some bench flowing the head and do some porting after?
otter
otter
Once case is split then you can remove the rodcaps and pop the pistons out the top.The caps are pinned and bolted.Very nice.
Pistons are tiny!Absolutely minimal skirt and noticed piston skirt is much larger dia than the ring area.Two big oil holes each side also.Never saw a piston like this.
Counterbalancer can slide right out without splitting case.Both ends are splined and wieght can only be put on one way since one of the splines is shaped different than others.
Pistons are tiny!Absolutely minimal skirt and noticed piston skirt is much larger dia than the ring area.Two big oil holes each side also.Never saw a piston like this.
Counterbalancer can slide right out without splitting case.Both ends are splined and wieght can only be put on one way since one of the splines is shaped different than others.
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Otter said:
Yes.Matczak Machine in PA.
Engine surelooks beefy for 80hp Weak spot would probably be rods and pistons
Otter
Otter
Now for the bad news.This is what happens when Gear Reduction goes.Its ugly.Found big pieces of gear in sump.Gear was burned to a crisp.If it could be looked at easier it would be very easy to see a set that was going to fail.Also the output where clutch is mounted to wieghs over 5lbs!I dont know if its like a harmonic balancer or what but will cut it apart in Lathe to see.Really has me wondering thought behind this.Must be a strain on gears.
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Otter said:
Pistons maybe.I really think the rods are beefy for such a small stroke.
Ruckus
TY 4 Stroke Master
Nice work!
snomaniac
Expert
Cannondale27, simply an awesome post. People that take the time to post these things are why.... 
Keep us posted as you do your mods. I have renewed confidence in my motor now that I see some of those components.
Keep us posted as you do your mods. I have renewed confidence in my motor now that I see some of those components.Jeremy
Expert
X2
Very nice job! Thanks for documenting evrything and then posting! AWSOME! 
No problem.It was fun!Putting it all back together is whole different game.
Here is cylinders.Notice oil squirter in each.Thats a good thing.Also is a hole going right through center which would give access to the wristpins without splitting the case.Not sure how a guy would get the piston out of bore once pins are out?Maybe a piece of rod pushed up through hole.
Here is cylinders.Notice oil squirter in each.Thats a good thing.Also is a hole going right through center which would give access to the wristpins without splitting the case.Not sure how a guy would get the piston out of bore once pins are out?Maybe a piece of rod pushed up through hole.
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