Rattly top end!

[Rossco]

I have just rebuilt my engine to CY GP290 specs, 36mm bore, 28mm stroke, (cylinder,crank,piston,pin,pin bearing&washers,ring,case bearings,seals,gaskets etc etc, all brand new CY!!!)

It screams like a banshee in heat up top & has mobs of grunt down low, as one would expect,,,,BUT,, it has a metalic rattle when I shut down.

I suspect it may be the pin washers.

Anyone else had this with their engines?

 

[zouz10]

Rossco,
The simplest thing I could think of is that it might be something rattling in the flywheel. Maybe see about taking it off and checking for debris.
If its not that, it might also be your clutch bell. Mine used to do that a while back. I can't remember why though.

finally, it might be something internal, maybe even a shot bearing in your crank case (that might be a far fetched idea since its a new motor though).


Chris

 

[Timmahh]

the pin washers or bearing would be my likley choice. they are cheap enough to replace. i would install a new set and see if the noise is still there. ofcourse, check everything else out to see if you can better locate the rattle.

 

[voo2doo]

Both of the above are good answers but If its metalic it sounds like the bell housing.If not take your plug out,put a pencil or pen down the plug hole and turn the crank via the flywheel.There should be no play in the wrist pin and crank bearings,I.E the pencil should move with the movement of the flywheel with no freeplay whatsoever.
Have you made sure the pin bearings are CY? I have done numerous head replacement on the two stroke engines and If the bottom end is CY and the top is Zen then you will need the CY wrist pin washers.If both are Zenoahs(head/crank case) then you can use Zen washers.
J.
iF THAT doesn't HELP THEN THROW IT AWAY AND BUY A NEW ONE!!! (KIDDING)

 

[Bigger the Better]

Any chance you could show us a video of it?:helpsmilie:

 

[Rossco]

I fixed it!:celebrate:

It was the pin washers.

Some sirry iriot put the old washers in it instead of the new ones?:innocent:

I wonder WHO that could have been,,

Sorry BTB no video, as I am but a poor man with no video camera coz every time I have the money for one I blow it on RC stuff!!

 

[zouz10]

Good to hear you fixed the issue with minimal money spent.




Chris

 

[Timmahh]

heh, ya old pin washers can do that.

for the zen topend on a cy bottom. yes you must use the Zen pin washers and bearing. the cy bearing and washers will not even let the Zen piston get to the crank to install it.

 

[pipeous]

Don't you hate it when the other personality takes over the brain while doing intricate work?

 

[Rossco]

Yeah, the missus & kids daily catfight can be quite distracting !