88 YZ250 flared thread on Crankshaft bolt

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9/23/2018 3:47 AM

I have a 88 YZ250 I picked up for a project a few months back and have just started to go over it to get an idea of the extent of work ahead.

One of the first issues I’d like to fix before going any further is that I have noticed the crankshaft bolt thread on the flywheel side is flared quite badly. Is there anyway to repair this or something I can do to make the crank still useable? otherwise can anyone advise what compatibility the crank has with other year models? Searching for a 88 crank hasn’t been very successful so far



9/23/2018 5:19 AM

I think at that point all you can really do is cut that section off if there’s enough material...I wouldn’t though, I’d look into a replacement.


RPM Performance

9/23/2018 6:20 AM

I would get the crank out & have a reputable crank rebuilder inspect the assembly, they will tell you if it's junk or not.


9/23/2018 12:34 PM

Yeah that was my thought, if there was no other option could I get away with cutting of the first 3-4 threads by the looks and what effect this would have.

I will be keeping my eyes peeled for a replacement crank as I think that’s the best option.


9/25/2018 9:36 AM

Looks like someone screwed the puller directly into the crank without using the cap...


9/25/2018 1:17 PM

I have used a thread chase ( flat style) to fix these in the past. It takes some time and does not always work, but it would be worth a try before trashing the crank. A good machine shop can also fix it if the threaded section is still running true to the crank.

Paw Paw


9/25/2018 1:44 PM

File it down to the same size as the rest of it and run a die on it to cut new threads. Like Paw Paw said you may have to use a thread file to cut some threads to get the die started.


Take it to the limit, one more time!

9/25/2018 3:17 PM

88 yz 250 is an orphan model and there aint a lot of parts around for them


9/28/2018 2:25 AM

Thanks guys for the suggestions. I think I will be giving the thread file and die a try first before going much further with the project


9/28/2018 7:31 PM

There is an 88 crank in eBay.


vomiting equals disqualification.