Topic: CB750K4 contradictory chain length info...

[Holden]

I've read that the stock chain length for a 750K4 is 100 links, but then there have been people with K4 bikes who posted that the proper size is 102 links with stock gearing.  I don't know if I counted links correctly, but my bike appears to have 100 links.  I'm going to order a new chain.  Why do some people post that they use 102 link chains?

[MCRider]

The motogrid.com microfishy for K4 says 100L. I think 102 will work, (don't quote me on that.) it justs puts the wheel back near the end of its adjustment range. This may actually provide a nicer ride for those who can appreciate such things, but not much chain adjustment.

Otherwise, they are either wrong (possible) or don't have stock gearing (not likely as they would have been going up on front or rear which from stock is very rare.).

[Holden]

I would imagine then that putting a 102 link chain on would lengthen the wheelbase, or effective swing arm length, with the result being slightly better straight line stability at the expensive of turning agility.

[MCRider]

I would imagine then that putting a 102 link chain on would lengthen the wheelbase, or effective swing arm length, with the result being slightly better straight line stability at the expensive of turning agility.

That's what I think. Assuming the 102 is not too long altogether. I've never done it personally.

I do know using a 100L on a 18/48 gearing will put the wheel as far forward as nearly possible. On a 17/48 gear, it's starts comfortably back a bit.

[754]

 I am TRYING a lightly used 102 today.
 100 may be a bit on the tight side but should go on..with the 102, I am thinking you will run out of adjustment before chain wers out and have to remove a link.

 Actualy I think the adusters were pincehed on mine when I put the 100 on so it was hard to slide all the way forward.
 Either should work

[Holden]

I ordered a 100 length chain.  Now I'm looking at sprockets.  The stock front sprocket is 18, which is what I'll probably get.  If I go to a 17, it should improve acceleration, but I think it might make it rev too high on the freeway.  Does anyone know what the rpm difference would be at about 75 mph? 

[MCRider]

I ordered a 100 length chain.  Now I'm looking at sprockets.  The stock front sprocket is 18, which is what I'll probably get.  If I go to a 17, it should improve acceleration, but I think it might make it rev too high on the freeway.  Does anyone know what the rpm difference would be at about 75 mph?

I run/ran 17/48 with the 888 kit. Its not that it revs too high, but it does rev higher. I used to know exact, but memory says about 350 rpm higher. Maybe not that much. With a ported head it breathes nicer a little higher and as said, its just overall more pleasant, IMO.

 The 18/48 is too doggy especially with a stocker, but you aren't stock, so you might like it. Heck, get both and switch em up.

[andy750]

I just replaced the chain on my STOCK 1972 Honda CB750 with 17/48. 102 links was too long and I am at 2/3 adjustment already - I used a Tsubaki Omega o-ring chain. Ill be ordering a 100 link chain next time. Previously I have used a 102 link chain on my 1974 Honda CB750K4 with no issues - this bike also has 17/48 set up and rides much better than using 18/48. RPMS at 75 mph are not much greater than 18/48.

cheers
Andy