Wrist pin cap question
03-13-2013, 03:23 AM
#1
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Wrist pin cap question
I am putting a new piston and sleeve in my engine, and I was going to use the old wrist pin. But the wrist pin has some kind of teflon caps on the end and one side looks wore off. I also noticed that this wrist pin does not have clips to hold it in. Does this wrist pin just float from end to end rubbing on those caps with no clips? and how do I know if I need a new one?
03-13-2013, 04:55 AM
#2
RE: Wrist pin cap question
Some side exhaust engines may still use those nylon type of end pads which stops the wrist pin scoring the liner but they may be hard to find. Rear exhaust engines can't use them because the wristpin ends pass across both the exhaust and boost ports. On RE engines, which need circlips, one end of the wristpin has to be blanked off to stop crankcase compression escaping through the exhaust port. I know, more info than you needed 
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03-13-2013, 06:02 AM
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RE: Wrist pin cap question
All good info to know, It is a Dynamite .12 SPD side exaust. I just bought a wrist pin with the caps on it, it does not come with clips so I am assuming it does not need them. The part number for the wrist pin is the same for both the one with clips and one without clips, and seeing as theworn one that came out of there had caps and no clips, I think I will be alright. let me know if I am wrong.
03-13-2013, 08:15 AM
#4
RE: Wrist pin cap question
Chances are the pistons are different for the two different wristpins.
If you wore out the piston and liner and consequently the Teflon pads on the wristpin, the conrod should be replaced too.
If you wore out the piston and liner and consequently the Teflon pads on the wristpin, the conrod should be replaced too.
03-13-2013, 05:49 PM
#5
RE: Wrist pin cap question
The end pads on the wristpin do the same job as circlips of keeping the wristpin from contacting the liner so there'd be no point in having both pads and circlips. Some engines used brass pads instead of the nylon type. It's possible your new piston may have the grooves to accept circlips so you've got a choice. Either fit the new wristpin and pads or get some circlips. Whichever way you go, make sure the rod is fitted the right way round to the crankshaft. If you didn't mark the back of the rod then have a careful look at both ends of the lower rod bush. One end will have a very slight chamfer in the bush and that must go up against the crank web.
