Piston Slap Help

quadsrus1

quadsrus1

New Member
Oct 4, 2011
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Red Lion'PA
OK well i just got my new top end put on yesterday new piston rings gaskets everything OK so i put a new plug in this morning it wouldn't start so i unplug the tors it starts but is making a weird noise that i believe is piston slap so in a case like this what do i do i am uploading a video to YouTube with the noise maybe that will help a little more. PLEASE HELP
 
I couldnt' hear it run much but I wouldn't be worried about piston slap....I would be worried about getting the jetting right so that it starts up!! You should be able to start the bike in a kick or two.

I would jet that thing rich for now and do some break in heat cycles....just heat it up and let it idle - give it a tiny bit of throttle but not much, then let it cool. Half hour to an hour later (depending on outside temps) drive it around the yard a tad in at very low speed, just putt around for 5 minutes, then let it cool again.

Is your air filter clean? You dont' want a fresh top end and a dirty air filter!! That will kill the fresh top end quickly!! Get some fresh gas in the carb and make sure everything is tight, no air leaks, and there should be no reason at all that you can't get it started on the second kick.
 
Yes clean filter new plug everything is tight and i don't see why i would jet it with it being all stock i think i might just sell it these 2 strokes are killing my wallet
 
Its not like a rattle or nothing its like a slapping noise like pa pa pa pa pa pa pa pa pa ive never heard it but ive also never did a top end on a blaster it has a lot more compression then before though and if i was to tear it apart again and bore it what should i bore it to
 
if it needed to be bored you just go to the next size up, generally 0.020" larger, unless there are some gouges deeper than that you keep going until the gouges are gone....or the cylinder is too thin to bore any more!

see if you can get a better vid outside maybe? two strokes, especially blasters, are noisey. I really didn't hear anything out of the ordinary but it could be my speakers??

you should have a larger main jet in there for sure. sorry, but 2strokes require a little maintenance to keep them in tip top shape!

you put new rings in there too, right? and used new gaskets?
 
xjma said:
if it needed to be bored you just go to the next size up, generally 0.020" larger, unless there are some gouges deeper than that you keep going until the gouges are gone....or the cylinder is too thin to bore any more!

see if you can get a better vid outside maybe? two strokes, especially blasters, are noisey. I really didn't hear anything out of the ordinary but it could be my speakers??

you should have a larger main jet in there for sure. sorry, but 2strokes require a little maintenance to keep them in tip top shape!

you put new rings in there too, right? and used new gaskets?
Click to expand...

I put in new everything bearings gaskets wristpin cir clips everything rings piston here is my next problem someone told me its the bottom end lower end bearing would this be what i need to fix the problem Wiseco Complete Bottom End Rebuild Kit - Dirt Bike Motocross 1998 Yamaha Blaster 200 - Motorcycle Superstore My local shop said 500 for the rebuild if i bring them the parts so is that reasonable
 
if your bottom end needs replacing those would be the parts that you would need. look around for pricing, I haven't had it done in a long time so I don't know what to pay.

Have someone familiar with 2strokes some listen to the bike before just throwing parts at it...it's easier to diagnose in person rather than over the interweb!

also, are you using br8es plug?? i have no idea what the bike with do with a b10es...
 
xjma said:
if your bottom end needs replacing those would be the parts that you would need. look around for pricing, I haven't had it done in a long time so I don't know what to pay.

Have someone familiar with 2strokes some listen to the bike before just throwing parts at it...it's easier to diagnose in person rather than over the interweb!

also, are you using br8es plug?? i have no idea what the bike with do with a b10es...
Click to expand...

I don't believe it has anything to do with the plug if you heard it in person you would be like wtf lol to split a crank case on a blaster do you need anything special to do it or would i be better off taking it to a shop i am fairly good with working on small engines but i have never done a bottom end only top
 
there are case splitter tools but you can do it with just rubber mallet and wooden wedges, carefully.

It's really up to you if you want to do it or not, if you've got a manual and are confident I'm sure you'll be able to do it.

I would just throw the proper plug in there and see how it is...if you really think the bottom end needs a rebuild than go ahead. Was there any play on the connecting rod when you had it apart?? Did you rotate the crank at all?? was it smoking more than usual before the top end rebuild? was the stock piston even bad? you had someone measure the cylinder before throwing in a new piston, correct?
 
xjma said:
there are case splitter tools but you can do it with just rubber mallet and wooden wedges, carefully.

It's really up to you if you want to do it or not, if you've got a manual and are confident I'm sure you'll be able to do it.

I would just throw the proper plug in there and see how it is...if you really think the bottom end needs a rebuild than go ahead. Was there any play on the connecting rod when you had it apart?? Did you rotate the crank at all?? was it smoking more than usual before the top end rebuild? was the stock piston even bad? you had someone measure the cylinder before throwing in a new piston, correct?
Click to expand...

Yes the stock piston was bad the ring had melted into the piston also i think i may just go with getting a bore done before i go ahead and replace the bottom end so i should bore over .020 correct
 
Quick Google search for you:

"The classic term is used to describe a piston who's skirt clearence is excessive.
As the piston rocks in it's bore a low frquency dead type bang is heard between the piston and the block bore up near top dead center on the compression/firing stroke.
If the piston expands with warm-up, the noise often goes away or reduces in extreme cases."

"Extreme spark knock on one cylinder under heavy load will often be mistaken for piston slap but the sound is easy to relate to driving conditions only." <--- Not sure exactly what that means.

My advice would be to put in the correct plug and not order ANY parts until you know what's needed.
 
Jammies said:
Quick Google search for you:

"The classic term is used to describe a piston who's skirt clearence is excessive.
As the piston rocks in it's bore a low frquency dead type bang is heard between the piston and the block bore up near top dead center on the compression/firing stroke.
If the piston expands with warm-up, the noise often goes away or reduces in extreme cases."

"Extreme spark knock on one cylinder under heavy load will often be mistaken for piston slap but the sound is easy to relate to driving conditions only." <--- Not sure exactly what that means.

My advice would be to put in the correct plug and not order ANY parts until you know what's needed.
Click to expand...

Ok thank you very much i appreciate that i will give that a shot then let you know
 
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