My 700 just got back 50cc

[Guest]

Picked this up off of Ebay today, http://cgi.ebay.com/ebaymotors/ws/eB...tem=7900475547. That's one of the last few things I've been after before doing some serious tweaking on the engine.

[lhanscom]

Congrats!!! That's awesome. What else are you planning on doing to the engine?

[Billy Ricks]

Cosworth 12:1 pistons, V&H modified grind cams, head has already had a mild port job done with intake runners matched to the manifolds. All new valves in the head probably less than 6,000 miles ago. I already run RS flatslides and a Duplex exhaust. I'll rebuild the clutch using a billet basket. I'm going to have APE lighten and balance the crank. About all I have left to do is rockers then I'm set for the rebuild.

[Anonymous]

What sort of gains do you expect? A faster reving engine and more HP across the RPM range? I heard your bike doesn't need any more added to the top speed.

Steve

[Billy Ricks]

Steve,
I should have more power across the rpm range though the bottom end will feel weak compared to the rest of the rpm range. It will likely still make more power down low than it does now but compared to the topend rush it will feel weak. I would think it will be putting out somewhere around 100 rear wheel hp when all is said and done, maybe more. I'll go up another tooth or two on the front sprocket when it's done.

[moto_dan]

Steve,
I should have more power across the rpm range though the bottom end will feel weak compared to the rest of the rpm range. It will likely still make more power down low than it does now but compared to the topend rush it will feel weak. I would think it will be putting out somewhere around 100 rear wheel hp when all is said and done, maybe more. I'll go up another tooth or two on the front sprocket when it's done.

Do I smell a dyno run in the fall at the museum? 8O

[Billy Ricks]

Do I smell a dyno run in the fall at the museum?

I doubt if I'll tear into before then. Too many other things on my plate this summer. My wife took a job in SA so we'll be busy finding a home and getting moved. Maybe over the winter I'll do the rebuild and be ready for a dyno run next spring.

[Bolder Biker]

Cosworth 12:1 pistons, V&H modified grind cams, head has already had a mild port job done with intake runners matched to the manifolds. All new valves in the head probably less than 6,000 miles ago. I already run RS flatslides and a Duplex exhaust. I'll rebuild the clutch using a billet basket. I'm going to have APE lighten and balance the crank. About all I have left to do is rockers then I'm set for the rebuild.

Let me know when it's done, Billy, so I can have Claude come down and "borrow" it to drop into my 83 GS750ES!

Seriously, although I know it will be some time before all the work is done, please give us your comments and reports as the work progresses and is completed. We will be fascinated to learn how the new "wild beast" performs.

Simon

[Billy Ricks]

Will do Simon. This has only be in the works for ten years since I got the pistons so another year isn't going to kill me. It should be a wicked ride when it's done. If I'm ever up your way with the bike I'll bring it by for you and Claude to ride.

[lhanscom]

I think a detail documentary, with lots of photos is in order for this project. Do you have a dyno chart on the bike now? It would be good to have a baseline run first.

[Billy Ricks]

Luke,
No dyno chart. I thought I'd run it on the dyno when we do our fall ride. The museum we stop at has a dyno on premises. It would be interesting to have before and after figures. I will do a thread on the rebuild when I get around to it.

[oldschoolGS]

I will be interested to see if you have good luck at running 12-1 on the street., I had my 83' 750ED at 11.25-1 and 802cc but I had to run a 50/50 mixture of 112/93 octane fuel to prevent detonation. During hot summer months and after several high rpm runs dissapating heat and preventing pinging was a serious problem. The motor was set up with a 2.4mm overbore (210psi per cylinder) with a Megacycle head (valves,springs and rockers) and Cammotion cams (350 lift at 252 duration-110 lobe centers). Accell ignition with a 5 degree advance and 34 flatslides with V+H pods and exhaust. The bike was a real screamer-it would lift the front wheel in third at about 7500 rpm, but disapating heat was always a problem during summer. Cam and ignition timing was varied but without luck. The second motor I have is set up the same but at 750cc and 10.25-1. This setup has been much more streetable and able to run on 93 octane alone. Just a side note- your domed 700cc pistons along with the 750 crank and rods will give you 10.25-1 instead of the stock 9.6-1 (the 700cc motor had domed pistons to make up the compression loss of being destroked)Good luck and keep us posted, Ed.

[Billy Ricks]

Ed,

I'm going to use a huge GSXR cooler and I'm thinking about adding a fan over the top of the head to blow air across it. If heat proves to be too much of a problem I'll go back to the 700 pistons. I have a couple of spare blocks so I can keep the stock block and pistons in case I need them and send one of the spares out to be done for the Cosworths. The Cosworths are only .05mm over, barely anything. The cylinders shouldn't need much more than a clean up hone.

[oldschoolGS]

The large cooler will certainly help-if you are able to get a GSXR cooler mounted in that space, please send me a photo-I did not think one would fit and was planning on using a twin-row Earl's cooler on my current build in the works. I have also wanted to try a heat shield barrier between the carbs and motor like they used to use on the early GSXR Superbikes. Another idea is to use the front half of the stock airbox as a barrier and run ram air intakes from under the steering head to feed cool fresh air into the carb area. All just ideas for now. Keep us posted, Ed.

[Billy Ricks]

Ed,

I have a carb heat shield on the bike now. It's from an airhead Gixxer. If I can find space for a couple of computer case fans between the tank and the head I plan on mounting them so I can switch them on and off in traffic. I may keep an eye out for one of the fresh air intakes like Yosh used to make for the Gixxers.