Sounds like marbles

[dirtydeezl]

Only about 20 hours on top end and now it's making weird noises, like there's marble rolling around in the there.
Any opinions? Gotta leak down test it, and then possibly tear it down. Figured I'd ask you guys first.

 

[blasterboy91]

Any chance of a video?

Does it sound like it's in the expansion chamber or the cylinder?

Top end or bottom end?

 

[82cutty]

That sucks...you have the right plan of attack . Sounds like a bearing . Get in there and check it out before it blows up

 

[joeak47]

When you rebuilt it, did you re-bore your stock cylinder, or did you pick up a top end kit from ebay?

 

[dirtydeezl]

I don't have the means to compress video small enough to post, I did try, sorry.
It's definitely in the cylinder.
I bored a stock cylinder over by 1.5mm and used a Wiseco piston, rings, pin and wrist pin bearing.
I didn't test compression but it doesn't seem to be suffering from low compression, it starts pretty easily hot or cold and runs strong.

 

[Blaaster]

What was the size of the piston you put in...and did you allow for the forged Pistons tolerances.

 

[dirtydeezl]

It started out at 66mm bore bit she was pretty beat up. I was told that by the shop that he wanted to go out a minimum of 1mm to true the bore, but I needed to order the set so he could Mic it up and then bore it to fit. I ordered a 67.5mm. I suspect (and hoping) that it's a wrist pin bearing, but I'm coming here first before I go about making assumptions. Here are few other details, maybe they're relevant:
32:1 premix- maxima/premium Sunoco pump gas.
Appears to be one of them ridiculous EBay Mikuni pwk type carbs but has correct stock main jet.
Replaced float and needle valve because it was overflowing.
Smokes like a steam locomotive.
Has holes drilled in airbox lid.
Stock pipe with type II silencer
doesn't burn case oil
Wet fouls plugs religiously
Falls flat on top
Doesn't rev clean
Will be replacing reeds soon

 

[99blasterzach]

after i rebuilt my blaster ( and all the heat cycles) with a bore and hone at 67mm and wisco piston) i had done a lot of riding in one day ( hours on hours of 1/2-3/4 throttle and full on open roads) and it made a sound like there was a piece of a gear or something in the transmission. it made a terrible sound as if there was marbles in a blender.... need else to say i wasn't having any of that so i sold it.
thats the day i believe i overheated my transmission. There was the correct about of just under 3/4 of a quart of oil in it and i was riding 6th gear 3/4 throttle for 10 plus miles and then when i went to stop my blaster wouldn't go into any other gear. ( the hole engine was real hot like even the plastic cases and the lower engine of the trans was relay hot!) then we went to a restaurant and waited it out for about an hour and it was able to shift just fine. i believe that that was the day that the trans started making the noise because the oil go to hot and couldn't provide enough lucubration.

 

[82cutty]

Try to upload a short video on youtube so we can take a listen .

 

[dirtydeezl]

Good. Call 82cutty.

 

[dirtydeezl]

How do we feel about this free play?

 

[dirtydeezl]

 

[dirtydeezl]

 

[dirtydeezl]

 

[joeak47]

Thank you for posting the video and photos. It helps a ton...
It sounds like a loose piston in the bore to me.
When I look at the photos of the piston skirt on the exhaust side, there is a BUNCH of scuffing. That in turn, reduced the diameter of the piston at the skirt area, which in turn has increased the clearance in the bore between the piston and cylinder.

The rocking of the piston in your second video is very normal. The pistons are actually tapered slightly, to compensate for expansion when warmed up.

I see NO CHAMFERING at the edges of any of the port windows... anywhere. That's a total no no.

You mention about 20 hours on that top end. I would still see "cross hatching" from the honing in the cylinder walls if that was true. This to me looks like a piston was put in a used un-trued bore. I'm not saying that's what happened...just saying that is what it looks like.

With that amount of scuffing on the piston skirt, It looks to me like that cylinder was installed dirty and un-cleaned when assembled, or no air filter was used, or a damaged air filter with a hole in it was used, letting in excessive debris.

All of this is repairable. You need a ROUND, STRAIT bore with NO TAPER and .003 clearance for that forged piston, and PROPER CHAMFERING of ALL PORTS in that cylinder.

Not yelling, just saying.

 

[joeak47]

After looking at the photos again, I still stand by my review. There is no way that cylinder has 20 hours on it.

 

[dirtydeezl]

I appreciate your input, I'm not under the impression that you're yelling at me. There is a hole in my air filter. I assure you that it was a stock bore, he measured the piston in front of me. I ordered a 67.5mm and that's what went in. I used degreaser and soapy hot water to wash the cylinder and piston when I got it back, let them dry thoroughly and used a very slight amount of 2 stroke oil in the wrist pin bearing and rings to assemble it. It might be up to a maximum of 30 hours since I don't ride daily and it's usually less than 2 hours at a time. I even warm the machine for 10 minutes prior to riding. I'm not the most experienced mechanic but I never had issues with my other machines. I'll never use this shop again for engine work, especially since Ken OConner is only an hour from me. Lessons learned are ggood, even if they are hard. I appreciate your input, I thank you heartily.

 

[dirtydeezl]

So , I guess this means I need to get my cylinder Mic'd up, true and order another piston kit, air filter and gaskets....... Such is 2 stroke life.

 

[82cutty]

No good on that bore job...they should refund your money . Good luck with that though . Send it to Ken and get it done right .

 

[dirtydeezl]

I guess it serves me right for trying to support local business...No good deed goes unpunished, lol.