Does anyone know how to open the engine block. And how hard would it be to swap old crankcase (lower and upper)with new crankcase. I have rebuilt car engines but never a motorcycle.

Thanks.

 

Why do you need to swap a crankcase? I've done that kind of work on dirt bike motors but not a CBR. I suspect it could be done, and even think that the transmission can be completely separated from the engine case if need be. Obviously the whole top end (head and cylinders) could be separated from the bottom end. From there I'm guessing the engine case is all a one piece solid cast. But then again I've never looked at it so I'm not sure. I guess the bottom line is that by the time you pull the engine and do all the work, its probably a lot more practical for you to just get a different engine and throw it in instead. Now might be a good time to upgrade if you can't find an F2 engine. An F3 engine will work but you'll need to get the carbs and airbox with it as well as the electric fuel pump as the F2 is not equipped. There may be some other things but it is quite nearly a direct bolt in. There's people on here that have done it so you have plenty of knowledge willing to be shared. There's also more than one user that has dropped in a 900rr engine I believe into the F2 frame, I assume with relatively little trouble.
Good luck!

 

Sorry elmer,wrong.

The cases can be split.The engine case is made from an upper and a lower.But remember,the upper and lower case must be a match,due to how they are cut from Honda.You cannot mis-match them.

You can put in an F3 engine,but you will not require an F3 airbox and carbs.Plus,you will not need a fuel pump.A fuel pump is only needed if you useram air.You will however need F3 carb boots,as the F3 head intakes are larger than F2s.

I'll be back.Got a meeting to go to

 

The reason i need to swap the crankscase is because the guy i got the bike from fell and cracked the stator cover, ruin the flywheel and parts of the crankcase where the stator cover mounts have been ripped of. I found the whole crankcase for $50 but did not want to buy until i had confidence to do it myself. I found a manual and it does not seem to be that hard. I dont want to be cheap with my bike, but i cannot afford the whole motor. One question. Can i take the cylinder head off and put it on the new crankcase without taking the lifter out?

 

Taking the lifter out? What do you mean by that?

The head comes off easy and will go on your new engine assembly with no worries.

Make sure you use all new gaskets in your motor.If you don't you will have trouble soon.

While it's apart,put in new bottom end bearings.Might as well.

Holla back

 

I just want to swap the crankcase without taking alot apart. What about the clutch, does the clutch need to be taken apart? Also, can i pull the crankshaft out with the pistons and everything attached?

 

Ah, KJohnson thank you for the correction. I had just made an assumption that things would have been similar to a car engine block at that point, just one solid piece. But thats not the way the dirt bike engines I've worked on are so it would stand to reason that I should have assumed the CBR would be similar.

rray, swapping the crankcase probably isn't going to be done without taking a lot apart, arguably, without taking EVERYTHING apart. And if you can handle swapping crankcases, then a clutch shouldn't be much of a problem for you. But yes, the clutch will have to come out. It doesn't necessarily have to come apart, you can leave all the clutch springs in and everything and just take the center nut that holds the outer basket in with an impact gun and it'll come out as a complete unit.

From the sounds of things though I would just keep my eyes out for a cheap replacement engine because you're going to have to put in quite a bit of work and I just wonder if it'll actually pay off in the end. In the grand scheme of things it might even make more financial sense to just part the whole machine out and start over with a different bike. Just my opinion though.

 

The bike it self is in GREAT SHAPE the only problem is the engine. I assumed that it would be a cheap fix the just swap the crankcase. Once the motor is together again, it is good to go. I still think it will be cheaper to replace the crankcase and a few gaskets.

 

You would have to take the gears out, and everything else in the lower crankcase (clutch, shift linkage, starter + gears, etc).

You should take the engine to a welding shop and ask if it can be welded, and get a quote on welding it, and machining it flat/fixing any broken screw holes, etc... I would imagine it might cost 300 bucks or more, but that's better than swapping an engine if you've got a low mileage engine with a verifed history... otherwise buy a new engine and part out this one.

 

Does not matter now. Just found out it is seized!