350x motor question on rebuilding

[Escanabajosh]

I picked up a 1985 350x this summer that needed a little work but ran good when I bought it,no smoke.

I get all the little things done and it's ready for a test run. No back breaks but it ran good,kinda pulled to the one side. Come to find out the tripples and the forks were bent so I changed them and that fixed the pull.

My fiance and I were going camping so we took along my 250sx and the new 350x. Took them out for a short ride and on the way back I opened it up, I take off like a bat outta hell big grin on my face. I turn around to see how far back my fiance is and she is right on my ass! I'm pinned yet she is still keeping up. We got back and the bike went on the trailer.

So I dont see smoke out the pipe but figure it must be rings that are bad? any other ideas?

I am looking at getting the ebay kit with new jug and piston and stuff for a little over $200 and was also wondering if I should do cam chain and oil pump while in there?

if the bike didn't "blow" could I get away with pulling the jug off and using a bore hone and putting new rings on?

Thanks for any advice/help

[matt22895]

Did you check the gearing and the tire size because if the previous owner put smaller tires on and did not gear up you will lose speed.

[dougspcs]

A bit of gun jumping going on I think there!!!

Compression test perhaps to start to see where the motor health is..before you start tearing into the motor.

Carb and gearing would be a good start point maybe!

[RIDE-RED 250r]

A 350x in stock form with it's 22" round-profile rear rubber would top out around 60-65mph.

If you swap those 22's in the rear out for flat profile 20"s that will reduce speed fairly significantly, quite possibly down in the range of a 250sx.

Check tire size and gearing before assuming your engine is toast. From what you have posted I seriously doubt your engine is shot.

[blkstangman88]

if looking for speed pop a 14 tooth up front. i did that and stock rear sprocket. my woman's yfz450 was clocked at 72 on the radar gun and on the long shot i pulled away lol short track i just spin like no other!! though i have a 430 build too....good times

[userj8670]

If you took off like a bat outta hell and then she was keeping up with you and there was no smoke i would assume gearing like others have said. Do a compression test as suggested and see where she stands. You might be fine other than gearing which is a easy fix. Good luck!

[Escanabajosh]

Thanks for the tips guys,I'll check it out and see what size tire/gears and I think my father inlaw has a comp tester I could use.

[Dirtcrasher]

You need to do a leak down test (plenty of threads on here that explain it to you. . And like Raffa said, not even the slightest amount of play up-down , or left to right or it's time to split the cases.

Don't do it if you feel uncomfortable with it of find a good buddy who is familiar with it to help. Even tearing it down requires brains and special tools; Good luck!!