Cracked Crankcase. Now what?

98superhawk · Feb 4, 2016

Hi guys,

I am new to the forum and the Vmax as well.
I got a hold of an 85 Vmax with 24K miles that had been sitting for at least 6 years.
I spent the last two months rebuilding the carbs, brake cylinders, clutch cylinders and fuel system.
I finally got it running again, and on the maiden voyage the crankcase cracked at the mount by the number 4 cylinder.
I obviously need a new crank case and I am assuming the number 4 piston is toast.
What other damage should I look for?
Should I look for a new motor all together or just a case and pistons?

Thanks in advance. This site has been a great help to me so far!

tothemax93 · Feb 4, 2016

Welcome superhawk. Sad way to get here, but you couldn't be in a better place for a vmax. To your question, depends on your mechanical abilities. You might like the project. Personally, I would get a different motor. Few guys on here with complete motors, or can help you with parts to rebuild it.

blaxmax · Feb 4, 2016

Sounds like you are mechanically inclined-take it apart and see exactly how it looks.

95spfldmax · Feb 4, 2016

I bought a Craigslist '94 motor for $600 going on three years ago now & put about 15,000 miles or so on it now (claimed to have 6K on it when I got it and do believe it after going thru it prior to installation). Was an easy swap. Probably your easiest/cheapest way out. I believe you'll have to get a '92 or older one to work with your harnesses and ignitor box.

Traumahawk · Feb 4, 2016

I would say the CHEAPEST route is another motor.

sdt354 · Feb 4, 2016

Can you post up a pic of the crack? maybe all is not lost.
I always think fix it first, and have been screwed by that train of thought a few times.But I'm stubborn as hell. If it is through the cylinder wall the guys are right to suggest a used motor. Our motors are sleeved, and sleeve bores & water jackets, can sometimes be repaired if time is on your side. An 85 with matching numbers makes it worth a try. Like Blaxmax said, take it apart either way, you'll learn a ton about your motor. Get Damon's video and you'll be confident after watching it that you can repair it. I took apart an 85 case that had been running on a welded oil filter case tab. I didn't use the case, but someone extended it's life for quite a while.
Steve-o

blaxmax · Feb 4, 2016

+1 Steve-o I jb welded a friends case on a gsxr1100 after he came home crying.
He ran from the cops and bypassed the electric gate into the apartments thinking he had lost them. When he hit the post with the case it left and oil trail straight to the culprit.:ummm:
It held up longer than he did.

Damon · Feb 4, 2016

98Superhawk,
I have inventory of Vmax engines & parts etc. & live in South Lyon MI 20 mile from Royal Oak. My direct E-Mail is [email protected] Drop me a line if you feel I can help.
Thanks! Damon

98superhawk · Feb 4, 2016

I took a better look and I am definitely missing a piece of the crankcase.
Looks like no more matching vin #'s.

98superhawk · Feb 4, 2016

Thanks Damon.
I'd love to see what you've got.

Traumahawk · Feb 4, 2016

98superhawk said:
Thanks Damon.
I'd love to see what you've got.

Damon also has VERY good videos on engines, carb rebuilding, the whole nine yards.

blaxmax · Feb 4, 2016

98superhawk said:
I took a better look and I am definitely missing a piece of the crankcase.
Looks like no more matching vin #'s.

I would think that case is gone.

mabdcmb@yahoo.com · Feb 4, 2016

I'd say that is a candidate for replacement. Looks like the block flexed enough to pop out the oil level window too.

one2dmax · Feb 4, 2016

I've not seen one quite like that. I suspect that the rod broke and vacated the premises. You're going to likely need a "short block" assembly at the very least. I also have plenty of good options from used shortblocks, to long blocks, to big bore engines. Just depends on your budget and how much work you want to go.

Before you commited to needing anything I would suggest to get it apart and see what you're dealing with.

We also have all the gaskets/seals and misc including optional stuff like HD oiling, solid mounts and more.

Sean

98superhawk · Feb 4, 2016

Thanks for the replies everyone.
Thanks Sean for offering parts.
There is what looks like a rod poking out of the front of the case.
How would that have happened?
I will have to pull everything apart and find out what's going on inside.
Once I figure out what I broke I can figure out what I need.
It will be a good learning experience I guess.

one2dmax · Feb 4, 2016

I would say oiling problem which led to spun bearing which then lead to locking up and the sudden stop in reciprocating mass overcame the strength of the parts and bang! Did you not hear a knocking sound before it went? It could have been an assembly issue though rarely does a rod cap come loose.

I forgot I had one here that broke that same location but higher on the case. This one let loose around 11k rpm or so after being tortured in a mini sprint car for many laps.

blaxmax · Feb 4, 2016

98superhawk said:
Thanks for the replies everyone.
Thanks Sean for offering parts.
There is what looks like a rod poking out of the front of the case.
How would that have happened?
I will have to pull everything apart and find out what's going on inside.
Once I figure out what I broke I can figure out what I need.
It will be a good learning experience I guess.

Superhawk, that is the way to go about it. Tear it down and then tell us what you learned about it. Info is priceless here--well almost---well not really----well you know. Get back to us and everyone here will appreciate it--------except dave.

98superhawk · Feb 4, 2016

Yes Sean,
I did hear a faint knocking up front there, but I had just got the engine running for the first time and I had no "normal" to go by.
I haven't gone into the guts of the motor (aside from the clutch), so I doubt it was anything miss assembled.
It sounds like there were some other underlying issues.
Do you think I will be better off with an entire motor or is it still to soon to tell?

one2dmax · Feb 4, 2016

Likely the trans and heads/cams are going to be ok. But, unless you're really in a rush I'd say to yank that one apart. Depending on what's good in that engine would make your options different from me. Of course I stick behind and warranty everything I sell.

98superhawk · Feb 4, 2016

Thanks again everyone!
I am kicking myself for not pulling everything apart when I had the carbs off.
I considered it, but didn't want to get in over my head and mostly just wan't to get the bike running asap.
I will tear it down and let you guys know what I find...

Cracked Crankcase. Now what?

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