Putting a 79' Honda CB750K on the track?

Went to Daytona for Bike Week and met my cousin that I hadn't seen in a while. He tells me that he has a 1979 Honda CB750K (10th Anniversary Edition) and that he's started getting it ready to possibly do a track day or two. He said he's already had someone put a big bore kit in it, has some aftermarket exhaust, pod filters etc ...
I told him that he probably should have spent the money on suspension stuff first but that's water under the bridge at this point.

I have a few questions for the guys that might have some experience with these or similar machines. Are there any inherent problems with this model that would suggest he should stop this project? If not, what improvements can be made for the suspension? What tires are available (18" rear, 19" front)?

I took a quick look at the rule book and it looks like this would fit in V5 (and bump up) ... correct me if I'm wrong. I don't think he would ever actually race it but made remarks that if I wanted to come out of "retirement" that I could use it.

Thanks in advance for your help!

 

How's it's going Steve.
Hit Facebook and look up Scott Ward.
He has lots of experience with these bikes.
He has a 5 or 6 time Championship winning bike from way back.
You can look on my friends page to find him. Just tell him i sent you.
Drop on buy Nola when Wera gets there and say Hello.
Take care.

Steven Isenhower #52

 

I have never looked but V5 seems pretty far up the ladder so to speak for a bike that debuted in 69, going off memory but I believe a 79 750K should still be single overhead cam and would be like design to the original. Regardless Avon's are probably the most popular/readily available tire in those sizes although Continental and Hidenua(sp) both offered something in those sizes last I knew. Most people would probably recommend lacing a 18" to the front hub but if you/him are just getting started don't let that stop you from getting on the track.

Suspension wise, the rear is easy, if it still has the original shocks throw them in the trash or Ebay and replace with anything, at this point wooden struts might even perform better Joking aside most any new shocks are going to be better, good options from cheap to expensive off the top of my head are Hagon, Progressive, YSS, Works, and Race-Tech. I personally have used Hagon and YSS, if I was to buy another set I would go with Works the next time. Hagon and Works will assemble a shock with input from the user, in this case important info would be if he sheds a lot of weight from the stock bike, he might want lower spring rate than if the bike was stock.

On the front a swap is always possible but it sounds like simple due to cost/complexity is what you are looking for information on. Minimum would be to get the proper springs, fresh oil, and seals if needed and then play with spacer/oil level. Next step would be emulators assuming someone makes them for those forks. Race-Tech is of course the original, I would assume someone is making knock offs for the Honda forks by now. What the extra cost of the Race-Techs would get you is more/better information and support on setup. With a bike that heavy and forks that small diameter I would want some type of fork brace even if it was still the stock heavy metal fender there. A front end with the right springs, emulators, and braced would be good match for a stockish frame/brake/wheel combo I think.

 

1979 is first year DOHC, not the single cam. V5.

 

The K is not the same as the F. It has a single disk with narrow wire wheels and I believe the frame has more flex. I would upgrade the whole front suspension, brakes and wheels to CBR1000F. I don't think that frame can handle any more tire or brake than that.

 

Actually I've dissuaded him from trying to make this a track/race bike for a host of reasons. I think he's going to get it together and sell it then choose a better starting point. Thanks for everyone's input.

 

Good call Steve. As someone that's built a few race bikes from scratch, the 750K would be at the bottom end of bikes I'd choose to build (as a race bike anyway).