Topic: 77/78 750 530 conversion

[eldar]

Ok so this is not really new but it might be a help.
I just switched to a 530 set up from the old 630.
Now there is a big thing about the chain length with no direct answer.

Now my bike is stock when it comes to the chassis. The old setup was 15/41 with a 88 link chain.
I went with the standard 17/48 set up. I wanted 16/45 which would have been slightly closer to the original set up but it is hard to find either a 16 or 45 tooth sprocket.
The chain I got was an RK o-ring which will fit fine as the 77/78 came with oring chains.
I got a 112 link length and finally took it down to 108 links. Chain fits very well. You may be able to go to 106 but with riding season almost over in my area and not wanting to fork out 65 buck, yes my chain was under 70 at mawonline.com but their shipping is a bit slow,  I decided not to experiment.

no special tricks or anything but the rk chain I got was a rivet link and I decided to go to clip which was still a #$%* to get on so I know it will not come off!

Install went smooth aside from the link and seems to work goo.
The old ratio was a bit doggish off the line and so the new ration is a bit of a change. At 70 before I did about 5000 rpm and now it is about 5800 rpm or so. Only had a chance to ride once cause of crappy weather. Once off the line, the accel is not a whole lot different, slightly quicker but requiring an earlier shift..

Was the change worth it? I don't know. I will have to test a bit more, we should have good weather this weekend. Currently I would only suggest a 530 as the chain is a bit cheaper by about $20. The sprockets were not much different. The gearing will make the K bike accel more like the F bikes.

I will add more thoughts to this after the weekend probably but at least it is a definite start for those looking at the conversion.

[tinyrobot]

nice write up, I have been on the fence about this conversion for replacement costs down the road.

can you tell the difference in weight?   

[eldar]

Well I doubt that the sprockets will be much different. The chain is probably a little lighter. I suppose if you add the chain and sprockets the weight diff would probably be 1 pound. This is with standard stuff though. If you forked over cash for more expensive stuff, then the diff would be more. 

So 1 - 1.5 pounds lighter on the new set up. Just a guess though.

[frostypuck]

Why such a long chain? When I did my swap about 5 years ago, I just used stock pre-77 sprockets and the stock length chain, which I think was 102 links. I did find it slightly tight, so when it wore out, I went with one link set more than stock for a '76. It did take me a while to get the spacers I made up on there correctly to keep the front and rear sprocks in line. Didn't use an o-ring, because the swap was experimental and I didn't want to drop the money on an o-ring. Stuck with an Heavy Duty chain ever after.
Later,
Chris in Boston

[jtb]

Eldar,  This must be about saving money, right?  Because, we all know that you cannot improve upon a K8.
Ride safe, man.

[eldar]

Well I would not call it an improvement. More like an expansion. The 630 is not as common as the 530. There are also more sprocket choices too. With the 630 you pretty much have 14 or 15 tooth front and 41 back, sometimes 43.

As for chain length, this is a K8 and has a longer swingarm than the 76 and earlier bikes. I can only assume the 77 is the same. I may have been able to whack out one more link set but what if it was too short then? Then the chain is wasted. with 108 links, it fits perfectly and has plenty of room for adjustment.

[kghost]

630 chains are 3/4 inch pitch where as 530 is 5/8.

Course the teeth and link count will be different.

What ya did by retaining the stock 630 tooth count on a 530 was gear it down.

 

[nteek754]

Hey all, On the gearing,  I have been running the 530 oring for years  now, and have stayed with the 18 48 stock set up for the 73 750K years ago played with the 17 48 combo and younger brother  had that set up and after 25 or 27 years of rideing he finnally beat me. and we discovered for 1/8th mile thats the way to go 17 48 but 1/4 mile 18 48 and when I did it  some 20 years ago just for #$%*s and giggles I didnt like the higher revs.. yup great for blasting around town but going out for a 200 mile jont gets a bit too rattley if you  know what I mean. have fun Craig in Maine

[eldar]

Well i knew it was all going to be different. It is quite a bit different too. numbers-wise anyways.
The 15/41 had a ratio of 2.73 or so and the 17/48 is 2.83 about. So I knew things were going to change.

[eldar]

Well after a bit more riding and after lubing up the speedo so it stops giving me dead spots, I was able to get a comparison for the 70 mph mark. At 70, I am now doing around 5200 rpm. Before it was about 4800 or so. So the higher ratio brings the rpms up by about 400. Not so bad as I first thought. I will double check it on the way home tonight to be sure. Then my final thoughts on it.