wrist pin bearing

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
Typically they "rattle" in "no-load" situations.
Wristpins rattle, big ends rumble, as you let off the throttle and take load off the engine.

Steve
 

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
Ahhh, so how would you describe that noise for those interested?
"A tinny rattle getting louder as you give it more throttle"?

Some of us are like wine connoisseurs, but to the automotive industry...

Steve
 

mike carter 2

Member
Nov 23, 2011
253
13
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west virgina
i have a steep driveway i have to hit it speed to make it to the top rite at the top the motor has lost rpms to the point its pulling as hard as it can mabey 100 rpms a tinny rattling sound comes frome the top of the motor
 

mike carter 2

Member
Nov 23, 2011
253
13
18
west virgina
it also happens when i lug it around at real low rpms under 10 miles an hour like around in a parking lot im also looking at my exaust i just installded a cr machine header kit on my chamber there are 2 springs that hold the chamber to the jug mabey rattling there? it didnt do it before
 

crassius

Well-Known Member
Sep 30, 2012
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USA
stop lugging it in parking lots - roll up a bit of speed, then pull clutch and coast a bit, lather and repeat

when going up hills, try to adjust throttle for the power peak (where it sounds nice & 2-strokey) - help out by pedaling a bit if revs get too low
 

mike carter 2

Member
Nov 23, 2011
253
13
18
west virgina
its a gasbike gt 80 kit on shwinn blackwell cruser bike high c head reed valves ported jug ported piston tranfers matched to cases 1979 rm 60 x chamber i sanded about a gasket and 1/2 off head to raise compression running reg gas at about 40 to 1 oil mix gets to over 35ish mph pulls fairly hard from about 7 or 8 all the way to top end almost forgot 40 tooth cog trying to build some tork into it
 

sbest

Member
Nov 3, 2015
343
2
18
Nova Scotia
I'd suggest cutting some squish area into your present head and gap it to 0.020 to0.035".

Cut a 4" radius out to 40 or 47mm and set the gap by filing and sanding down the cylinder, or leaving off the head gasket and sealing it with Teflon tape.

Steve
 

salorr33cc

Member
Apr 30, 2016
49
0
6
pennsylvania
speaking of wristpin bearings, i was wondering same thing,, i heard they were having trouble with earlier wristpin bearings falling apart,,, i have a 09/09/2015 gt5 38mm stroke engine,,,i have looked at wristpins and it seems like there are three types,,, here are pictures of two,, the one is what came in my engine,, the other style is sold by JNM motors,,, should i change to different style,,, the third type has smaller length needles and more solid cage material,,,, and what size drill bit do you use to drill out wrist pin for less vibration ???
 

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mike carter 2

Member
Nov 23, 2011
253
13
18
west virgina
well i do belive i fixed it it was the header vibrateing when the ingine hit hard while pulling a load the cr machine header has 2 springs that hold the header onto the exaust mount i think the springs are letting the exaust bounce on the mount i made a new brace for the x chamber noise is gone thanks for all the info i learn new things every day