Crankshaft decisions

[707trx250r]

I am rebuilding my whole R motor. I have a ct 350pv for a top end. But I don't know what to do for a crank. I have a oem one that is in good shape. Should I rebuild it or just buy a new one. I can get a deal on rebuilding it at ct since I bought a cylinder from them.

[georgedoggy]

i have a duncan 300 cylinder and i rebuild by whole motor every year. for the extra few dollars do the bottom end. i use hotrod rod kits and havent had a problem. its worth it for piece of mind...

[wilkin250r]

What does CT recommend?

[707trx250r]

I am rebuilding the bottom end. I just don't know wat to do for the crank. Allen at ct said to rebuild it. I guess that is what I will do

[wilkin250r]

In some situations, I think rebuilding might actually be a better option.

I don't know all that is involved in the rebuild, but I think they weld a little on the journals if they are out-of-round. The weld material will be harder than the original, and thus won't wear out as easily. A rebuilt crank may (in some situations) last longer than a brand new one.

I'd like to get a crank specialist on the website and learn a thing or two from him...

[C-LEIGH RACING]

Allens right, you need a fresh crank to go along with that 350 top end.
Rebuilding the cranks ok if its the first time being rebuilt.
A crank will have a life span just like any other part of the engine, amount of use & age plays a big part.
Things to think about before a rebuild,
has the crank gone through a main bearing lock up at any time,
ever had a busted piston or anything ever gotten on top of the piston & ended up destoring the piston, ever ran the engine hot & locked it up, bad wear marks on the shaft from the seal. Any of these things listed shorten the lifespan of the crank. Any nicks, gouge, or scrapes on the tins at all, best not to reuse any part of that crank.
When a tin comes apart on an old crank, its just like busting a trans gear, it takes the cases with it.
Inspect the crank your taking out real close for any wear on the flywheel side from the seal rubbing, if it bad, the crank needs replacing. Check the crank sleeve on the clutch side, if the seal has worn into it, replace it as well.
Neil

[707trx250r]

Thanks neil, I should have asked you when I called. The crank has some wear from the seals, also I bought the bike used so I don't know if it ever broke a piston. I think considering the top end it will be supporting I am going to buy a new OEM crank.

Thanks all

Adam

[beerock]

just buy a new oem 88 crank and be done with it

[atvmxr]

if you search around ebay there is a company selling new wiseco hot rod crank assemblies. I've only had it a couple months, but didnt have any problems with it fitting, installation etc. And it was cheaper than OEM like $170 compared to $230. just an idea

[707trx250r]

I am just going to go with a OEM crank. I have been told the hot rods are fine but I am not taking a chance with the new ct 350 pv top end:D
thanks
Adam

[86 Quad R]

Originally posted by 707trx250r
I am just going to go with a OEM crank. I have been told the hot rods are fine but I am not taking a chance with the new ct 350 pv top end:D
thanks
Adam

wise decision :cool:

[beerock]

Originally posted by 707trx250r
I am just going to go with a OEM crank. I have been told the hot rods are fine but I am not taking a chance with the new ct 350 pv top end:D
thanks
Adam

very wise, theres a reason people nicknamed wiseco wiseblow

there cranks are notorius for either working for a long time or blowing up right away.