rattle

[FileStyle]

Ive always noticed since day one of having my motor , that it has a slight rattle. it sounds like its either in the upper part of the motor (jug) or down in the bottom , its hard to tell , but it is there! as far as performance , I havent had any problems it seems to run fine. at top end you dont hear it , at mid range ,yeah its there , at idle you know its there! the motor was sold as a "80cc". Ive rode with Hookwormrider1 last weekend and his motor seems to sound a lot tighter than mine. any solutions or just the nature of the beast.

 

[Dave31]

Could be a wrist pin

 

[FileStyle]

please dont say that! lets just pray

 

[misteright1_99]

Put your hand on the clutch cover and see if it goes away. Mine had a sound coming from there. I covered it with an old mouse pad, and it cuts down the rattle...Cheap cover amplifies the sound of the clutch I guess.....

 

[Mopedamauter79]

Did you try a new gasket or tightening the bolts ?

 

[thatsdax]

wrist pin bearing most likely. I'll bet it has a little slop in it.. Also..There is no such thing as an 80cc kit from Asia. Enjoy the ride...

 

[FileStyle]

well Iam still hoping not a wrist pin , as for the clutch cover I have applied a 1/4" thick piece of rubber on it to deaden the sound. last night , I did remove some additional noise from my system, and that is the way the motor mounts to the down tube. according to the "instructions" to drill through the frame , so I did ! , which after getting into this forum and finding diff. mounting techniques I fabbed up a new front mounting plate to have a 2" u-bolt be used instead. I've also had been using thin rubber between the motor and frame anyway , but that u-bolt did the trick ! this morning was a really good ride. that trick took all vibrations out! I wouldnt recommend anyone drilling through their frame (downtube) if they didnt have to ! I learned the hard way and now have a weak spot in the frame!

 

[MrLarkins]

what is a wrist pin?

 

[Dave31]

what is a wrist pin?

The wrist pin connects the piston to the connecting rod. It could be the bearing between the connecting rod and pin or the pin could have slope in the piston. Also in some case's it is possible that the pin will bounce back in forth in the cyclinder wall.

 

[MrLarkins]

ah, is there a solution to keep it from bouncing?

 

[Dave31]

ah, is there a solution to keep it from bouncing?

New top end (replacement)

 

[Mopedamauter79]

The wrist pin connects the piston to the connecting rod. It could be the bearing between the connecting rod and pin or the pin could have slope in the piston. Also in some case's it is possible that the pin will bounce back in forth in the cyclinder wall.

If that's the case would a small thin piece of rubber not prevent it from bouncing around?

Sorry, I really have no idea what I'm talking about but I thought I'd throw that out there....

-Mopedamater79's gf

 

[Bikeguy Joe]

Rubber would burn or melt there. Also, the amount of free play is thousanths of an inch.

These engines have a very bad "acceptable" amount of play in the wrist pin. I have had one engine for awhile and it never gets any louder, just rattles along.

EXELLENT diagram Mr. Fair!

 

[Mopedamauter79]

Rubber would burn or melt there. Also, the amount of free play is thousanths of an inch.

These engines have a very bad "acceptable" amount of play in the wrist pin. I have had one engine for awhile and it never gets any louder, just rattles along.

EXELLENT diagram Mr. Fair!

well, it was worth it to ask, and by doing so i learned why it wouldnt work

-Mopedamauter79's gf

 

[Bikeguy Joe]

Right on. .