Ok, another (possible) piston replacement thread '90/90hp

[Jiggz]

Re: Ok, another (possible) piston replacement thread '90/90hp

A shop press is the best way to push out the old wrist pin. And yes it is pressed fit. The new Wiseco is not pressed fit so that should be easy to put together. I used a small dremel with a conical grind stone to chamfer the ports. No need to grind more than 32nd of an inch. I think as long as they do not feel sharp when you run your fingers should be good. Of course, if you can do 16th of an inch it will be better.

 

[Bigprairie1]

Re: Ok, another (possible) piston replacement thread '90/90hp

Thanks Jiggz, good info!!
That said I got the piston pin out of the damaged piston...so the rod is ready for a remount with the Wiseco stuff. With any luck I'll take that on tomorrow.
Question: How did you clean out the filings/debris etc from the dremel operation? was the head completely dismantled and easy to clean?
My engine is still pretty much intact except for this piston the intake system on the other side. So I'm trying to be careful about what I 'leave behind' in that bore if I hone etc and if I have to chamfer those ports.
all Good
BP

 

[Jiggz]

Re: Ok, another (possible) piston replacement thread '90/90hp

It takes a firm and solid hand. First place a rag to prevent the filings going into the crankcase section. Not a whole lot of worries for the exhaust ports but for the intake ports, you will have to vacuum it thoroughly afterwards. A speed adjustable dremel is what you need and make sure you only use the lowest speed. You can try using masking tape to protect the adjacent areas if you have problem controlling the dremel.