72 rebuild option's please

[CalsXS2]

I knew better to buy a bike that was not running. But,,,this XS2 really made me want it. So after cleaning the point's, changing tanks, and going through all the basic's, I was able to get this thing to breath again. Come to find out, it has the ol' wrist pin slap and tickle going on. It's really too bad to ride. So I pulled it apart and verified that it needs a rebuild.

So. What are my option's. The 256 rod's are hard to find, and pricey. Can I swap the crank out for a late model and save any money. I thought about a used engine, but I always end up with one just as bad as I started with. So that's why I'm really considering a rebuild. I thought about a big bore kit, but it won't work on the 72.

This thing only has 13,000 mile's on it. If I rebuild it stock, is it just going to need rebuilt again in no time.

What are you guy's doing for the early model's. Thanks.

 

[azman857]

I've wondered if a 256 crank could use a later model rod reuild kits and pistons and keep the 256 cam sproket.

 

[sreimer]

Yes you can use late model pistons and rods on an early crank. If you swap the crank and pistons you also need to swap the cam.

 

[CalsXS2]

Are the 72's so problematic that I would actually want to swap to the newer style part's. What I really would prefer is saving the head ache's of switching over. But I don't want to have to do another rebuild in a short time with the 72 stuff. Is there any truth to the 72's wearing out prematurely. Thanks.

 

[yamasarus]

The 256 engines are just as reliable, all things being equal. If you properly maintain it life will be good. I put 50,000 on a 70 back in the day. It is faster but not as pleasant to ride......vibration. If you want more comfort go with a 447 engine. And if you hunt long enough you can find a 750 kit for the 256 engine.

 

[XSLeo]

There are several options on rebuilding your engine.
#1 swapping in a complete 447 crank, easy and not to costly. Only thing is the 256 uses a different cam chain and sprockets. So if you use the 447 crank use the 447 cam and chain.
#2 Rebuilding your crank with 447 rods, cost more but keeps the 256 cam and chain.
#3 Find new 256 rods and rebuild as stock.
I might get a 447 crank, split it between the halfs. Split the 256 crank the same, swap the crank sprocket from the 256 to the 447. This I think is less problematic with cam timing than swapping the cam sprockets.
Mike's sells 750 sleeves. Take you cylinders, pull the stock sleeves, rebore the cylinders to fit the 750 sleeves.
Now you can rebuild it as a 750 with the look of the 72 engine and using the slightly hotter cam of the 72 but with the power of the 750.
A strong reliable engine. And if it works like my 75 it will vibrate less at the higher rpms than it did as a 650.
Good luck on it how ever you choose.
Leo

 

[sreimer]

Very well said xsleo! But as for removing the sprocket from the crank, it would be more likely to be destroyed then removed. I wouldn't suggest that as an option

 

[650Skull]

Mikes sells a 256 piston and pin and rings set. If your rods a ok then mikes would be the cheapest way out

 

[XSLeo]

I have rebuilt a couple cranks. When you replace the inside bearings you press apart the crank parts and the two center flywheels are splined together. The sprocket is part of the spacer between the flywheels and is splined to the crank an has a notch the unsure your using the correct splines.
You have to remove the sprocket to replace the bearings. It won't hurt the sprocket at all.
Leo

 

[XSLeo]

You could just send it to Hugh and let him do the 750 kit and rephase. He might like the challenge. His work is great and the 750 rephase will perform.
Leo

 

[Okie dokie]

Is there enough meat in the 650 cylinders to bore them out to accept 750 sleeves?

 

[CalsXS2]

Mikes sells a 256 piston and pin and rings set. If your rods a ok then mikes would be the cheapest way out

My rod's are wobbled out at the wrist pin. Hopefully you can see the wear in the pic below.

The 256 piston's that Mikes sell are second over size. I guess that really doesn't matter at this point.

I really like the sound of making it a 750, but I can see the dollar's adding up quick. I was hoping to keep this on the cheap side, but I can all ready tell that's not going to happen. I'm going to give the 750 route some serious thought.

 

[650Skull]

After rereading your post i realized your little ends were shot and mikes pistons would not work. As for the 13,000 miles, a well maintained XS will go a lot further than that and can have a couple of top end rebuilds before the bottom is touched. the PO probably done a lot of red lining to cause the little ends to go so fast.

There is always a risk, but buying a good crank and rods off ebay would be a way to go. make sure to ask all relevant questions and getting the answers you want before committing to a bid. If they cant or wont give you the crank tolerances then don't bother.

The crank from the 256 is worth money so can be sold to help pay for the rebuild

 

[CalsXS2]

After rereading your post i realized your little ends were shot and mikes pistons would not work.

Actually, they would work,,,wouldn't they. I'd just have to skip one re-bore,,,right?? For the price of everything bought separately, Mike's would be a lot better deal as long as I skip right to a second over size.

 

[CalsXS2]

There are several options on rebuilding your engine.
#1 swapping in a complete 447 crank, easy and not to costly. Only thing is the 256 uses a different cam chain and sprockets. So if you use the 447 crank use the 447 cam and chain.
#2 Rebuilding your crank with 447 rods, cost more but keeps the 256 cam and chain.
#3 Find new 256 rods and rebuild as stock.
I might get a 447 crank, split it between the halfs. Split the 256 crank the same, swap the crank sprocket from the 256 to the 447. This I think is less problematic with cam timing than swapping the cam sprockets.
Mike's sells 750 sleeves. Take you cylinders, pull the stock sleeves, rebore the cylinders to fit the 750 sleeves.
Now you can rebuild it as a 750 with the look of the 72 engine and using the slightly hotter cam of the 72 but with the power of the 750.
A strong reliable engine. And if it works like my 75 it will vibrate less at the higher rpms than it did as a 650.
Good luck on it how ever you choose.
Leo

Would I be able to use my original 650 head with out any issue's?

 

[Allroy1967]

You could just send it to Hugh and let him do the 750 kit and rephase. He might like the challenge. His work is great and the 750 rephase will perform.
Leo

Do you have contact info on that? I am getting ready to rebuild the motor in my bike and I like the thought of a 750.

 

[Okie]

Do you have contact info on that? I am getting ready to rebuild the motor in my bike and I like the thought of a 750.

Look in the shops section.Here http://www.xs650.com/forum/showthread.php?t=3157

Like XSLeo said, I believe if you use a 447 crank, you must use a 447 cam. Sprockets on the 256 and 447 are different, so crank sprocket and cam sprocket must match. Other than the cam & sprocket I don't think there are any differences in the head aside from the decompressor, so yes you could use your head and rebore your current cylinder for oversize 447 pistons. It would mean splitting the cases to swap cranks, but they are relatively cheap on here or on ebay. You could save your 256 crank, and perhaps restore it at a later date or resell to compensate for the rebuild.

 

[Punkskalar]

HughsHandBuilt@gmail.com

And I have lots of 256 crank parts if you need to stay on the cheap.... Rephasing them is completely possible... Ya'll are too kind over here, thanks XSLeo!!

No need to swap cams, you can run what you got!!

 

[angus67]

what of the cam chain tensioner? my pal's 71 has a rod knock, and was releived we can just put in 447 rods and cam, but what about the tensioner? his 71 motor has the four bolt tensioner, which I belive has the gear instead of the slider?

 

[Punkskalar]

If you use a 447 crank, you'll need a late model style tensioner, as well as a late style cam gear.