I just rebuilt my blaster, I got a new left side case and replaced the crank and all the bearings and seals and put a wiseco piston .2 over. I started it up and the jetting was lean, my friend bumped the jets up and it still wasn't running good so I took it to the shop and got it tuned. when I get it back from the shop the guy says my top end is going soon because its noisy, I told him what I did and he said I could have killed the top end starting it with the lean jets or he said it might just work out. I got it home and started it up and it wasn't slapping at first then I let it warm up and it started it doing it then I rode it up my street real quick to see if it was just idle and it started slapping louder as I went so I turned it off. I started it again hf hour later and it was still slapping when I revved it a little and I just turned it off. What do you guys think I should take off the cylinder and check the piston??
Rebuilt Blaster Knocking Noise HELP PLEASE
- Thread starter 03redblaster
- Start date
I sent the cylinder out to a place summit offrode and they shipped it back with the piston kit bored but I did not measure
a reputable shops work shouldnt produce piston slap like it sounds you're describing
pull the pipe off and look up in there with a flashlight while rotating the engine to look for marks/scratches on the piston
if it's slapping that bad, it should leave some clearly seen evidence on the piston skirt.
if you find scoring on the piston, it's time to pull the cylinder and measure the piston to cylinder clearence, and call that shop for an explanation if out of spec.
here's how to measure it...........
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okay I'm gona check that out and get back on here, but I find it weird that it didn't do it the first few times I started it and then I got it back from action yamaha today it started slapping
A few questions.
Did you heat cycle after rebuild.?
Did you leak test after rebuild? Was the jetting lean or the motor leaking.
Why did you need to rebuild in the first place?
Are you aware that a forged piston require a perfect warm up to avoid four point wear/seizure?
Running lean on a fresh rebuild can harm the motor drastically.
Pull the pipe of and geek up the exhaust port for signs of piston damage.
You forgot to tell him to leak test it
And OP, you really should leak test it I:I
Edit: Blaater said to as i wrote this post lol (Good man)
the first time I started it the jetting was very lean I had a 38 pilot jet and a 135 main jet, I have v force 3 reeds fmf gold series 30 mm carb and a intake. we had it on 5 min maybe giving little revs. put a 40 pilot and a 155 main started it again for like 5 min reving it a little and turned it off. the next time I started it I let it warm up and I just putted around my yard but when I would rev it up it wouldn't come back down so I took it to the shop told them the work I did and asked them to tune it when I got it back he said the top end was going.
I did not do a leak test and did not do the heat cycles properly and no I was not aware about the warm up, this is my first build and I've just had help from friends.
I did the bottom end rebuild because my left side case was cracked and while I had it off I noticed the crank had very bad pitting from the key snapping multiple time from the previous owner not righting the flywheel correctly
I did the top end previous to this and it only ran a few times and I killed the piston from being lean I believe so I'm thinking I killed this one to just from starting it the first time.
I did look up in the exhaust and there is minor scratches on the piston and if I push on it it does move a little bit
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I took the top off and there was oil on the head gasget only on one side is it possible that it was just loss or a stud wasn't all the way down
I put the top back on it still makes the noise I made sure they were all tight I guess I need another new piston
where do you ride around spotswood? i used to live in spotswood when i was a kid, and grew up in south river.
there is a machine shop in south river, right off jackson street, the owners name is nick, im not sure the name of his shop, but he wont do you wrong with any machine work
I ride right in crescent woods and a place in monroe we call the moonpit off Spotswood-englishtown road and thanks I'm probably going to stop by that shop
but I hope it's just the top end it does show the signs the piston is a little scratch but when I took the top off the walls looked pretty clean I could still see the hone cross hatchings, I'm not sure what to do
take it to nick, hes an old guy, his prices are cheap and his work is second to none.
im betting they didnt match the bore to the piston, or you revved it up too much before warming it up. either way, it needs to be fixed lol.
alright thanks man I'm gona try to find him, it just has me thinking cuz I just did the bottom end also
if you see scratches on the piston sides, then i would bet the sound is piston slap. if your crank had no play when you had it apart, and you properly installed new crank bearings in the case, they shouldnt make any noise at all
yeah It's got to be the top end when it's on I could almost feel the slap when I hold the fins and the crank was brand new oem and I got oem bearings too I've heard always stick with oem
yamaha blaster piston slap? - YouTube that's the video I took after I put the top back on and that's the noise it makes
Without heat cycling and retorquing the head and jug, that could have caused a leak.
Combine that with a possibility of an air leak, because the crancase and intake tract was not leak tested.
The hanging revs point to an air leak.
After your mate swapped the jets did you ride the bike hard or did you just rev it up?
Was the motor making any noise before you took it to the shop?
If is was not noisy my question is is the shop a reputabe 2 stroke repairer?
Did they leak test it, or did they just dump in some larger jets and fang the motor to test it.
If the motor was not making noise before they took control of tuning, I would suspect that their actions could have caused it to start knocking.
Undoubtably your lack of knowledge and poor practices would have presented a problem, but did the shop add the final straw that broke the Blasters back.
Did they leak test and also give you results of a plug chop?
Combine that with a possibility of an air leak, because the crancase and intake tract was not leak tested.
The hanging revs point to an air leak.
After your mate swapped the jets did you ride the bike hard or did you just rev it up?
Was the motor making any noise before you took it to the shop?
If is was not noisy my question is is the shop a reputabe 2 stroke repairer?
Did they leak test it, or did they just dump in some larger jets and fang the motor to test it.
If the motor was not making noise before they took control of tuning, I would suspect that their actions could have caused it to start knocking.
Undoubtably your lack of knowledge and poor practices would have presented a problem, but did the shop add the final straw that broke the Blasters back.
Did they leak test and also give you results of a plug chop?
I'm not sure if it was a good 2 stroke shop the place is a yamaha dealer so I assume they know what there doing it's action yamaha in metuchen, nj. They did not give me the result of the plug chop, I also did give it to them with no gas. I don't believe they leak tested it all they said to me is the top end was going I said no way I replaced it he said it will either just settle or u will need a new top end.
action yamaha? yea i know who's at fault lmao, that place sucks, plus they have no machine shop in house. so they are ASSEMBLERS. i know extreme machines has a machine shop, but i can't speak for their work at all.
