New crankcases for my 2005 RC51 SP2?

9Hondas · 12-09-2007, 5:51 PM

I've searched a bit and haven't found anything that totally answers my questions, thus a new thread.

I have a recently purchased 2005 RC51 with 3500 miles but I just discovered the previous owner used a clip type master link (I know!!!) and evidently the bike threw the chain sometime before I bought it, because most of the countershaft cover mounts are broken.

I rode it only a few miles before discovering the problem. I didn't notice it during the pre-purchase inspection because it was mostly hidden by the plastic, and he had the CS cover on with the threads left and the busted castings were only visible after disassembling the cover and getting all the hoses out of the way. The bike otherwise runs great and appears perfect in every way, not a smudge. I'm also exploring legal remedies, but that's another story.

I'm looking for opinions here about how to best proceed on the mechanical side of this. The bike is otherwise in showroom condition. I know the motor will have to come out, I guess the only question is what goes back in, this one with a new crankcase set or a used motor off ebay. Regarding welding, I do a decent job with my TIG welder on aluminum but I don't think the cases can be welded becase so much is missing already. I'd basically be building case back up out of rod then have to re-machine it somehow. Probably ending up weak and ugly.

I'd like to put new cases on this motor since its such low miles, but aside from the obvious cost of cases and gaskets, what other parts will I need?

Would it be possible to swap the guts between cases without pulling the flywheel and alternator rotors? Would I need new rings etc on the pistons too?

I'm somewhat experienced as a mechanic and have an FAA Airframe & Powerplant Mechanics ratings, but the last time I split cases on a motorcycle was on my 1976 Kawasaki KX125!

Sorry about all the questions, but I hope there is somebody here online that has some experience that I may benefit from. Any advice would be appreciated, thanks in advance!

Motophoria · 12-11-2007, 7:25 AM

Dang,
Sorry to hear about that...I bought a SV650 from a guy who was tracking it...when I got it home and looked it over real well I found out he was also using a clip master link...BUT THE CLIP WAS MISSING!

I told him about it and he had been at the track with it that way...as he never inspected it himself....yikes! Think of what could have happened there...

I've never gone that far into the motor...but wish you luck.

I do have a perfect right side case cover with water pump from an SP2 if you get into it and find you need that as well. It should fit SP1 as well...

Good luck and post up your progress...

9Hondas · 12-11-2007, 10:49 AM

Thanks, this story will take some time to be told no doubt. I'm still weighing my options at this point.

KDA · 12-11-2007, 2:09 PM

Call me crazy, but I would just ride it. Unless I'm missing something, the cover doesn't really serve that large of a purpose. Most MX bikes (including everyone I've ever had and currently own) have a thin plastic cover that is usually removed since it only serves to pack mud.

You are talking about spending a lot of $$ on swapping out cases. I would think 20 hours labor or more (just a guess) plus the parts. Just my opinion.

DVIII · 12-11-2007, 4:01 PM

Quote:

Originally Posted by KDA

Call me crazy, but I would just ride it. Unless I'm missing something, the cover doesn't really serve that large of a purpose. Most MX bikes (including everyone I've ever had and currently own) have a thin plastic cover that is usually removed since it only serves to pack mud.

You are talking about spending a lot of $$ on swapping out cases. I would think 20 hours labor or more (just a guess) plus the parts. Just my opinion.

playwme · 12-12-2007, 5:38 AM

I'd have to agree with the 2 above. Just ride it. As for legal rights, I don't see how that will hep you any. Surely it's your responsibility to check the bike over. Dealers may have some sort of code of conduct but buying privately comes down to buyer beware and sold as is.

9Hondas · 12-18-2007, 12:28 PM

Quote:

Originally Posted by KDA

Call me crazy, but I would just ride it. Unless I'm missing something, the cover doesn't really serve that large of a purpose. Most MX bikes (including everyone I've ever had and currently own) have a thin plastic cover that is usually removed since it only serves to pack mud.

You are talking about spending a lot of $$ on swapping out cases. I would think 20 hours labor or more (just a guess) plus the parts. Just my opinion.

You're not crazy - just uninformed about the bike.

Most streetbike engines are quite different than dirtbike engines. For example most dirtbike engines split their cases vertically while this one is split horizontally.

The countershaft cover serves as the mounting case for the clutch slave cylinder. That little rod sticking out of the case ahead of the CS sprocket is the clutch rod which gets pushed in when operating the clutch.

Thus, no countershaft cover - no clutch.

msalser1000 · 12-18-2007, 1:26 PM

There is a huge difference between a streebike motor and a dirt bike motor, i just rebuilt my 05 1Krr motor. There are just a few gaskets but the big things are making sure you know what bearing you need to go with and you have. Youwill need to look at the numbers stamped in the cases on the crank and the con rods. The best route would be to find a used engine off ebay, I have saw rc51 motor on there as cheap as 500 bucks.

KDA · 12-18-2007, 1:44 PM

Good point. That is the clutch push rod sticking out. Although the original poster did say the cover was threaded on with what was left and the bike rode fine before he took it apart. If (a big if) there's enough there to keep the cover on and the clutch working properly, I would still just ride it. If not, go ahead and repair it via a new case or second hand motor. Good luck either way.

9Hondas · 12-18-2007, 2:20 PM

Quote:

Originally Posted by KDA

If (a big if) there's enough there to keep the cover on and the clutch working properly, I would still just ride it.

Normally the CS/Clutch Slave cylinder cover is held on with 4 bolts into the two crankcase halves. This one was held in with only three, using the bolts pictured below.

Notice the one already bent from the stress of clutch operation. Obviously you can see why I wouldn't want to ride the bike much further away than I could walk back!