SD1026 Posted May 6, 2009 Report Posted May 6, 2009 How would one know if they have piston slapp?? What causes it how do u fix it and what happens if u run a bike with piston slapp. I just redid everything in the clutch case due to a nocking sound and it is still there. Bike is 80 over I honed the cylinders a very little bit the way it should be done with continuous motion and new rings both cylinders have 180 psi. So where does this leave me?? Quote
2strokesmoker Posted May 6, 2009 Report Posted May 6, 2009 How would one know if they have piston slapp?? What causes it how do u fix it and what happens if u run a bike with piston slapp. I just redid everything in the clutch case due to a nocking sound and it is still there. Bike is 80 over I honed the cylinders a very little bit the way it should be done with continuous motion and new rings both cylinders have 180 psi. So where does this leave me?? Do you have a high compression head? 180psi seems like a lot for stock. I could be wrong though. Quote
SD1026 Posted May 6, 2009 Author Report Posted May 6, 2009 (edited) Do you have a high compression head? 180psi seems like a lot for stock. I could be wrong though. have ported jugs the kid thinks it is a duncain port for mx but it isnt aggressive port . plus 5 timming vitos hemi head with 18cc domes.stock crank i think it said 27L in the rod. bike is fast and has monster bottom end. i just put procurcuit platinums on it with bored stock carbs. Edited May 6, 2009 by SD1026 Quote
2strokesmoker Posted May 6, 2009 Report Posted May 6, 2009 have ported jugs the kid thinks it is a duncain port for mx but it isnt aggressive port . plus 5 timming vitos hemi head with 18cc domes.stock crank i think it said 27L in the rod. bike is fast and has monster bottom end. i just put procurcuit platinums on it with bored stock carbs. well if you honed out the jugs I don't see why the rings would't be seated. hmmmm im not to sure. Did you buy the pistons ans rings as a set? Maybe wrong ring size??? Quote
wacko2000 Posted May 6, 2009 Report Posted May 6, 2009 well if you honed out the jugs I don't see why the rings would't be seated. hmmmm im not to sure. Did you buy the pistons ans rings as a set? Maybe wrong ring size??? No the pistons where in the bike when he got it. Just decided to freshen her up a bit so he got some new rings and what not. New rings/old rings still 180psi. It didnt change What else would case a knocking noise? The bike runs strong, I say rock that bitch till it blows up and then start fresh with something bigger and badder Quote
AWR Posted May 6, 2009 Report Posted May 6, 2009 knocking could be a rod.did you check them when the cylinders were off. Quote
mopar1rules Posted May 7, 2009 Report Posted May 7, 2009 piston slap is caused by too much piston/cylinder clearance. the only way to fix it is to have it bored out to the next size (freshen and true up the bore), and then having the smallest piston/cylinder clearance that's allowed. for ex...if the piston/cylinder clearance tolerance is .0030-.0045", then you would want to pick .003". see what i mean? smaller bore will yeild less piston/cylinder clearance, so there will be less piston slop and it will be quieter. could have rod or wristpin bearings going south too. Quote
lt1bird Posted May 7, 2009 Report Posted May 7, 2009 piston slap ususally is only heard while cold and when your reving it a bit but not putting a load on the engine... kinda like 1/2 throttle then backing off so the engine unloads the pistons so the slap side to side a bit....use to get that in my performance cars.... not a real problem...if its knocking at idle it could be something else... Quote
captainhowdie Posted May 7, 2009 Report Posted May 7, 2009 Mine does the same thing. Run that bitch till it blows Quote
sheefreak Posted May 7, 2009 Report Posted May 7, 2009 I have seen broken teeth on the primary and clutch basket gears make a knocking sound. Also seen broken teeth on tranny gears make this noise also, but in this situation you would only have it in one gear while moving. If you have 180 lbs of compression, especially on a ported jug, the chances of it being piston slap are slim to none. Quote
grizzly700 Posted May 7, 2009 Report Posted May 7, 2009 i vote rod or wrist pin bearings. maybe crank bearing. mine just started this also. im gonna tear down and tru weld crank and raplace all bearings and bore and hone, pistons all that. and ill bet mine stops. lol Quote
SD1026 Posted May 8, 2009 Author Report Posted May 8, 2009 Wow the out come of this topic is great!!!! I installed a billet basket and idler gear rebuild kit. I think after this forum its a rod.I'm building a 4mil motor anyway so just gonna rock the sit out of this one and see what damage I can cause. I am going to punish this bike for making noises that annoy me lol. Quote
swrbansheeboy Posted May 8, 2009 Report Posted May 8, 2009 if you think it's piston slap you can pull the intakes and exhaust then look at the piston skirts to make sure they dont have an excessive amount of scoring... Quote
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