99 Indy 500 Fuji 488

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vic_junior

Member
Doing a top end job for a friend and just have some questions. Sled has 5800 miles and compression in both cylinders was right at 95. Should I reuse the wrist pin bearings or get new ones? Also, the intake boots had small cracks in them. Would it be risking too much to keep them on? I told him to buy new bearings and boots, but that is just me, just trying to get other opinions. He plans on keeping the sled for a long time yet and it's in great shape.

Is there anything I should be checking while I have the motor halfway apart?

I know "Indy 500" has worked on these sleds, maybe he can chime in if anyone knows where he is at!

Will post some pics when I get the pistons out. I saw and felt some scuff marks on the intake sides of the pto piston.
 
indy_500

indy_500

Well-known member
I don't see why you couldn't reuse the wrist pin bearings. I've never really heard of one failing before, but they don't cost all that much to replace. You could put a few coats of Elmer's rubber cement all over the boots. Did that to a buddies 700 Doo and it lasted all last season without any problems. He bought Vforce reeds and boots this summer to try and gain an "edge" on my 700 and a buddies F6 LOL I don't think that's going to happen :) I had small cracks on my 99 indy 500 carb boots, never did anything about them and never had a problem, but I'm not saying your friend won't. If he plans on keeping it for a while, it would be a wise decision to replace them, I don't believe they're too costy for that motor, $40 a piece from a dealer, could possibly get them cheaper aftermarket. There should be an O-ring between the carb boot and the motor. Hold the rods up and tap on them with your finger and listen for a clunk. My PTO bearing went at 8200 miles. Still not sure if the bearing went due to the crank seal, or if the crank seal went because of the bearing. Depending on how hot the motor got, wouldn't be a bad idea to split the cases, replace crank seals and h20 pump belt. I believe that h20 pump belt is a v-belt and rather cheap compared to water pump belts on Poo big blocks.
 
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trailshredder

Member
Before ordering pistons and rings make sure to check clearences in the cylinders. With that many miles they could be "egged" and just replacing pistons and rings would be a waste of time.
 
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vic_junior

Member
All right Gents, what do you think is going on. This is the PTO piston, intake side showing. The scuff marks were getting pretty bad. All other sides of the pistons are perfect except this one. View attachment 28693
 
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tealracing16

Member
The key to scratches is if you can feel it with your fingernail then it's to big. Scuffs in the piston that don't catch a nail don't count. That's how we did it at the piston ring plant (it was for diesel engines so the tolerances were a little tighter).
 
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snowbuff

New member
Definetley replace wrist pins and wrist pin bearings. When you get the new pistons, send a piston and cylinder to get matched (may need to be re nickacilled) or honed. The scuff marks could be the result of the cracks in the boot(s), replace them too. If your goig thru the trouble of diong the job, you may as well do it right.
 
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vic_junior

Member
xcr440 said:
What was the problem before you started the rebuild?
Click to expand...

No problem... Had 5800 miles and low compression and he wanted a top end done. He is prior military with deployments to Afghanistan and is going to school now. So I told him I could do the job since he isn't bringing in a lot of dough. I thought I wasn't going to have any problems with the compression being exactly the same in both cylinders.
 
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vic_junior

Member
snowbuff said:
Definetley replace wrist pins and wrist pin bearings. When you get the new pistons, send a piston and cylinder to get matched (may need to be re nickacilled) or honed. The scuff marks could be the result of the cracks in the boot(s), replace them too. If your goig thru the trouble of diong the job, you may as well do it right.
Click to expand...

Will definitely replace all of that. I told him before we started he will probably need to get it bored out a little.
 
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vic_junior

Member
Talked with dealer today and they said, it looked like the piston was just getting a little loose due to wear. He sounded pretty confident with being able to read the scuff marks and what color they were. They also said, the wrist pin bearings looks like they were getting hot due to their color. The helps me a little because I had a hard time getting the wrist pins out. Sound legit???
 
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vic_junior

Member
Going to change the crank seals too. Noticed a fare share of oil splash between clutch and case. For only $40, can't go wrong.
 
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