256 vs 447? Here we go...

[grizld1]

Yep, you can do that. Just be aware that the 22 mm. wristpin doesn't leave much meat at the small end of the stock rods, and if you wind that motor up very tight they're likely to stretch. If you're doing a performance build on a 256 motor, you might think about heavy duty rods and a welded crank.

 

[Rabbidmk1]

Awesome thanks for the info!

 

[Quilty]

I know this post is a bit old but I've come across it whilst looking for info on my xs2 crank. I've seen on eBay a few decent looking cranks mostly 447 type with low ish mileage. From what I've read here ive a 306 type with the longer conrods. I'm pretty sure my 5th gear has been chewed and has destroyed my bearings. My question is that if I put a 447 type crank with the shorter conrods. A. Can I use the same Pistons ect and B. What will it do performance wise to my bike. These cranks are available for about $100 + or am I better off spending $300 for new bearings ect

 

[TwoManyXS1Bs]

Quilty, this can get complicated, and expensive. If you leave the 18 tooth camchain sprocket in the 447 crank, then you have to go 447 with the entire camdrive system, including tensioner (xs1/xs2 tensioner sprocket is different pitch). And, that later tensioner needs the wider camchain tunnel found in the later cylinders. The 447 crank with 447 rods also uses 447 pistons. I don't think there's a comprehensive cross-compatability checklist in here. Myself, I'm still learning about this.

Here's a thread discussing the tensioners:

http://www.xs650.com/forum/showthread.php?t=38674

 

[bikermike035]

Subscribed

 

[Quilty]

well since 306 cranks are rarer than a yellow bellied wood pecker I'll stick with the one I have looking at 400 buck for a set of bearings. If anyone knows of anywhere that sells them cheaper than Mike s pls let me know

 

[weaselbeak]

I never, ever buy expensive bearings from a final source such as a dealer unless I have to. Their markups are tremendous. Any bearing outlet can get me what I want almost overnight at a fraction of the cost. They care not the application, they cross reference the measurements & type. I have purchased some weird looking bearings over the years, some costing 30 bucks that were listed for Italian bike trans as high as 160 bucks. I'd almost bet those 400 dollar bearings are used in other applications (bike makers don't just create new dimensions for everything) and can be found at Motion outlets & such.

 

[Quilty]

Ok that's fantastic news so if I wanted a set of crankshaft bearings (3 needle and 1 ball bearing) would I have to give the OEM koyo part number and see what they can match them with??

 

[weaselbeak]

Numbers are great if you have them, but I like to carry the old ones in and let them play with their calipers. You also get some helpful advise from those guys often.

 

[grizld1]

Don't waste your time looking, Quilty; you're not going to find generic bearings drilled for XS650 crankcase pins. Those main bearings are expensive at least in part because they're specialized items produced in small volume.

 

[Quilty]

Found them at a price far far cheaper than mikes xs or Heiden tuning. I made a phone call to koyo in England who in turn gave me a phone number of another company in Ireland. 16 euro for the ball bearing anyway but I have a question regarding the others. The guy on the end of the phone says that the 74 xs650 onwards have a set of main bearings that have a locking pin. I know that mikes and Heiden supply main needle bearings that cover all models but did the original bearings do the same and cover the early models aswell

 

[mrriggs]

Don't waste your time looking, Quilty; you're not going to find generic bearings drilled for XS650 crankcase pins. Those main bearings are expensive at least in part because they're specialized items produced in small volume.

If you could find the right size bearings then it wouldn't be too hard to EDM the holes. All you need for a basic EDM is a car battery, resistor and capacitor. It would be slow so if you had to pay yourself for your time then it would be cheaper to buy the bearings from Yamaha.

 

[dozen dts]

- the numbers are cast into the conrod
256...136mm conrod, 22mm wrist pin, 26mm crank pin, no starter cog...306...same with a starter cog
447...130mm rod, 20mm wrist pin, 26mm crank pin, starter cog
533...140mm rod, 20mm wrist pin, 29mm crank pin...mostly sold in europe

- because the bores and strokes are the same each crank type has its own pistons...the cranks can be swapped complete with their rods and pistons...there are other differences in the motors-compression ratios, clutches, cam timing, gearbox etc

If the cranks are the same stroke, Do the cylinders interchange? Deck heights come out the same with a different pin height?

 

[GLJ]

Cylinders interchange if you use the correct piston for the rod in the crank. Deck height will also be the same.