Can I build a motor with these parts

[DRedel]

If my franken bike was not bad enough I have three bad motors. Can I build one? I have good top ends on a 80 and 81. Both have bad pistons and cylinders. Both have good lower ends. Can I used the pistons and cylinders off a bike that the vin starts with 2h7-020767. If I used this do I have to used the ignition system or will it not work at all. This is my last option.

[crazy steve]

The only real internal differences between the different year motors is the head, pistons, and cams, with the break coming in 1980. The heads and pistons are the important bits, cams less so, but the ignition system needs to follow the cams.

The 2H7 is the early motor, so best results would be to use the head, pistons, cams, and ignition advances off that motor. The lower ends/transmissions are all the same....

[DRedel]

Off that 2h7 all I have is the pistons and cylinders. I would have to use the head and cams off the 80 or 81

[crazy steve]

That will work, but you'll take a hit on power as that combo will lower compression. Also make sure the valve reliefs in the pistons are large enough to clear the larger late valves. They should be, but you might want to 'clay' the combination before final assembly to make sure.

[crazy steve]

There is one more possible option; if between your two sets if you have four good cylinders, it is supposedly possible to swap liners between the cast aluminum cylinders. Put the cylinder set in an over and heat to 400 degrees and they can be pushed out. You'll probably need new rings, but this may be less trouble.

[DRedel]

I thought that new rings are impossible? That they can not be found. So I would need to file down oversized rings

[crazy steve]

Rings show up on eBay, but I haven't looked lately. Yes, you'll likely be filing down an oversize set to fit. But it's an option....

[DRedel]

Ok I might be liking that option. I'll see if I have 4 good ones.

[Courtney]

There are 4 different auctions right now on Ebay for standard size piston rings. Check it out!

[DRedel]

I was looking but I don't know how to tell if they are standard or oversized

[CRXSi90]

Question from the gallery....

When you talk about filing down the rings, is this to get the right end gap?

[Courtney]

http://www.ebay.com/itm/YAMAHA-XJ110...94106b&vxp=mtr

These are standard size, there are 3 more auctions with standard; that is the size you are looking for.

[Courtney]

When you talk about filing down the rings, is this to get the right end gap?

Yes, you can file the ends down to allow the rings to make a smaller "ring" as the circumference is now smaller due to filing.

[CRXSi90]

Cool, thanks! That's kind of what I figured.

[DRedel]

Great thanks.