What Cam Do I Have?

[gene xs]

New to me 78 XS650. The PO's dad put a 750 kit into it (80 mm bore). The cylinders need at least a honing, but I cannot find new rings to fit the vintage 80 mm pistons.

I would like to take it back to stock. I think the cam is stock, but thought I'd ask the group if it truly is.

Is my cam stock?

The only marking on the cam is an "A".

 

[TwoManyXS1Bs]

Gene, count the teeth on the sprocket, 34 or 36.
The lobes look a bit wide to me.
Don't recognize the rings near the "A".
Measure the base circle and lobe lift
There's a manual extract showing the stock measurements in this thread:

http://www.xs650.com/forum/showthread.php?t=40042

 

[TwoManyXS1Bs]

On the piston rings, found another potential candidate.
The top and 2nd rings from:
Hastings# 4691 - used on Ford CVH engine, '80s Escort, 80mm
Hastings# 4918 - used on 99-02 Mazda 2.3L KJ engine, 80.3mm
Hastings# 5300 - used on 86 Toyota 1.5L 5K engine, 80.5mm
Hastings# 4367 - used on 83-94 Mitsubishi Eclipse 1.8L, 80.51mm

I have a set of those last rings, 4367, coming here. Will see how they fit.

The oil rings are still a challenge. Closest so far is:
Hastings# 6180 - used on 83-89.Toyota Corolla, 81mm, 2.8mm thick

I have an eBay alert set for when CruzinImage offers the TX750 2nd over rings.
Then I can get those measurements.

Gary Hoos Racing also offers 447 piston kits in 80mm.
But, you'd have to coordinate with him about your bore diameters and clearances...

 

[XSLeo]

Mike's has a one over piston and rings for their 750 kit. I don't know if the rings would fit your pistons but they might be the right size to bore your cylinders to fit.
Leo

 

[Jack]

New to me 78 XS650. The PO's dad put a 750 kit into it (80 mm bore). The cylinders need at least a honing, but I cannot find new rings to fit the vintage 80 mm pistons.

I would like to take it back to stock. I think the cam is stock, but thought I'd ask the group if it truly is.

Is my cam stock?

The only marking on the cam is an "A".

The lobe differences between the 477 and 256 cam are visually obvious and you have the 256 cam.

 

[gene xs]

The cam has 36 teeth and measures up as stock in terms of lobe height. I have a new used cam on the way. So, either I will have two stock cams or a stock cam and a lumpy cam (which is my suspicion).

Thanks!

 

[gene xs]

I'm going back to stock on the bike. Original bore cylinders and pistons are on the way. With luck, It'll just need a honing and re-ringing.

No need to keep searching for the white whale of rings to fit my 80 mm vintage (??) pistons. Thanks for your help.

 

[TwoManyXS1Bs]

The cam has 36 teeth...

That would make it some sort of 447 cam, unless that sprocket had been refitted to it.
Be sure your next cam has 36 teeth.

I'm going back to stock on the bike.

No need to keep searching for the white whale of rings to fit my 80 mm vintage (??) pistons...

Good, you found the easy way out.

Me, I'm still searching...