XR200 piston hits crank.
- Thread starter divot02
- Start date
If the crank is clearing the skirt, the only place (that I can picture at the moment) that it would be contacting on the piston would be the wrist pin. You can't take any metal from there.
That leaves the crankshaft counterweights, which are not an uncommon place to trim metal anyway. A machinist should be able to help you with that. Balancing and knifing-edging the crank should come in at less than $200.
This isn't a job I'd tackle at home.
That leaves the crankshaft counterweights, which are not an uncommon place to trim metal anyway. A machinist should be able to help you with that. Balancing and knifing-edging the crank should come in at less than $200.
This isn't a job I'd tackle at home.
Either that or for some reason the con rod is connecting the piston for some reason, but that shouldn't be happening at BDC. Seems like something wonky is going on. Powroll is renowned for good machine work out of the box. What piston do the spec out for their cranks as a recommendation?
well the powroll stroked crank use a shortened rod as well so it is really getting the piston far down at bdc
deciding how much clearance you need and if is safe to remove any at all from the pin boss area is the issue, pics will be needed of the piston
did you have it assembled when you found this out ?
the crank would not need to be turned only remove some material in the correct spot,of course this will change balance rpm's,( a single is not anything like in perfect "balance" only has design "balance" for minimal shaking that is practical at a certain rpm narrow range)it may even be a better spot in the rpm range,that occurs removing the needed metal,may be worse
it may be only a matter of drilling/grinding some material out the opposite side
grinder,drill and scales would be all you need
weigh the assembly,remove needed matrerial on crank under piston at btc
re-weigh crank
remove mo material opposite
its not rocket science,but should be left to somebody with a grip on the entire concept
deciding how much clearance you need and if is safe to remove any at all from the pin boss area is the issue, pics will be needed of the piston
did you have it assembled when you found this out ?
the crank would not need to be turned only remove some material in the correct spot,of course this will change balance rpm's,( a single is not anything like in perfect "balance" only has design "balance" for minimal shaking that is practical at a certain rpm narrow range)it may even be a better spot in the rpm range,that occurs removing the needed metal,may be worse
it may be only a matter of drilling/grinding some material out the opposite side
grinder,drill and scales would be all you need
weigh the assembly,remove needed matrerial on crank under piston at btc
re-weigh crank
remove mo material opposite
its not rocket science,but should be left to somebody with a grip on the entire concept
looking close now at that piston it does have some amount of material sticking up right there where it is hitting,right at the oil hole
that is my bet where it hits,anyway
good thing being a forged piston,she has stronger graine strukcher in that area than a cast slug wood
that is my bet where it hits,anyway
good thing being a forged piston,she has stronger graine strukcher in that area than a cast slug wood
divot02 said:
the rod is shortened half the increase in stroke of the stroked crankshaft,in other words the SAME amount of measure as the crank pin is moved from center,double-ing this value yeilds the increase in stroke
this away the assembly retains standard piston heght at tdc no need for a spacer at base or longer cam chain etc
crazypj
Split personality, I fake being smart
I would fit a stock rod to crank and a spacer under cylinder.
I was never impressed with the Powerol stoker kits
That piston looks like it has already had material removed from pin area.
You could remove material from flywheels but that will have a pretty drastic effect on balance
The other thing you could try is contact Wiseco for piston with pin 2~3mm higher
I was never impressed with the Powerol stoker kits
That piston looks like it has already had material removed from pin area.
You could remove material from flywheels but that will have a pretty drastic effect on balance
The other thing you could try is contact Wiseco for piston with pin 2~3mm higher
crazypj
Split personality, I fake being smart
The sides will be half the needed thickness or less as they share the stresses.
The main stress on piston is at TDC overlap, if it's going to break that's when it will happen. Forged pistons will stretch a bit before they break, maybe you would hear it hitting the cylinder head?
AS I said, I would replace the rod with stock and fit a cylinder spacer, the only reason not to is for a 'cheater' motor that looks stock
Single cylinder cranks are real easy to take apart and true up, I have no idea how many hundreds of them I've done
It is the pin boss touching flywheels and not skirt either side?
I have machined pistons to 1mm larger than flywheel radius but never into the pin boss
The main stress on piston is at TDC overlap, if it's going to break that's when it will happen. Forged pistons will stretch a bit before they break, maybe you would hear it hitting the cylinder head?
AS I said, I would replace the rod with stock and fit a cylinder spacer, the only reason not to is for a 'cheater' motor that looks stock
Single cylinder cranks are real easy to take apart and true up, I have no idea how many hundreds of them I've done
It is the pin boss touching flywheels and not skirt either side?
I have machined pistons to 1mm larger than flywheel radius but never into the pin boss
kopcicle
antidisestablishmentarian
Stock rod ? May run into cam chain length issues . It wouldn't be the first time I've had to take a bit off the crank wheels opposite the crank pin on a Powroll stroker . Balance ? really ? it's a fsckn single . Just take off the amount you need to .
however ...
If you can get the cam chain up and over the cam sprocket there is nothing wrong with a spacer other than the upper motor mount . If the cam chain won't make it you end up adding length to the chain and it ends up at the end of the tensioner travel .
Just wondering what Powroll has to say .
~kop
however ...
If you can get the cam chain up and over the cam sprocket there is nothing wrong with a spacer other than the upper motor mount . If the cam chain won't make it you end up adding length to the chain and it ends up at the end of the tensioner travel .
Just wondering what Powroll has to say .
~kop
