aren't the gb500 and ascot very similar machines? If so there is a bunch of info on racing/ prepping them over at: http://www.thumperpage.com/articles/GBprep.html
and a cool article on racing the thing: http://www.thumperpage.com/articles/rzgb500.html
with a quote like this you know it'll be awesome:
"Someday, perhaps it will again roar to life and terrorize competitors while women protectively draw small children closer as its thundering voice of doom reverberates through the hills."
I have built and raced several. They are easy to do. Here is the formula I came up with and a few differences I would do now.
Stock frame, XR500 swing arm (not necessary), VF500 front end ( I would use cbr600F1), CBR600F1 wheels, Nighthawk S shocks (they work), Jemco pipe, XR500 carb, Wiseco 12:1 stock bore piston, Megacycle cam valve Springs and refaced rockers, ported head. Keep an eye on the cam chain tension and the counter balancer tensioner, and oil. It will scuff pistons and cams if not careful. The Wiseco will break if not run on race gas. I don't like the bigger bore Wiseco (540) since it doesn't seem to rev out as fast or as well for me. I sold that one and built another with stock bore.
I still have a new megacycle cam in my tool box so I am looking for another one for the right price. I will build another one.
I definitely recommend building one.
I would reccomend a falicon knife or carrillo H rod with the 12:1 piston. I have seen alot of these with stock rods sticking through the cases. At least on the flattracks. I flattracked one for 3 years set up pretty much like Kens motor, only difference I had a carrilo rod and falicon did the crank($$$$$), but I was able to through away the counter balancer. It reved and pulled real nice.
The GB is an entirely different motor. It is the RFVC top end. I have never broken a rod on an Ascot motor. I have always run the counterbalancer, too. I suspect that roadracing engine demands are enough different from dirt track to make the difference. All that being said, If I had the money I would love a Falicon crank and Carillo rod.
Hmmmmm, might be the counterbalancer that saves it. I know they asked if I wanted to keep it or not and what rpm I would be running when they balanced it. I'm in no way questioning or disbelieving you, but before this point, I honestly would have never considered building one up with out an aftermarket rod. I do love these motors, I have 4 of these in the xr/xl version. I think the FT's have a bigger sump and hold a little more oil, and they have the ring gear on the flyweel for the starter. Otherwise pretty much the same as the 79-81 XR/XL500's. Maybe I should......Ah damn, so many projects and not enough time and money. - Dan
I think your right in that Falicon must rebalance the crank differently depending on whether you are running a counter balancer or not. I suspect they have a lot more experience and knowledge than me about rod failure and crank life. I have run an XR or XL flywheel and left side cover on an FT motor. It bolts right up and eliminates the entire starter set-up. I was surprised to discover that the 6v output from the XL stator was compatible with the FT ignition. I didn't have to change anything in the ignition setup. Are you interested in parting with any of your motors? I have a couple of project ideas for the future. I am interested in putting one in a VF500F interceptor frame. It is almost a straight bolt in operation. I test fitted one once and it requires only rear motor mounting plates for 1 of the rear motor mounts and a brace for the top motor mount that will bolt straight onto the VF500 frame in existing holes.
Yeh, I would probably get rid of one or two. Are you in hurry for one? The reason I ask is I have a lot going on right now and the only one that is a runner(I never heard it run, but I got it from a friend that said it did) is in a rolling chassis, actually they are all in rollers except one that's taken apart. I have a couple spare cylinders and heads also. Send me an e-mail, we can work something out.- Dan
I am not in any hurry at all since I am still in Alaska and we have feet of snow still on the ground. I had to take the snowmobile and sled to the post office yesterday to mail some moving boxes. However, the road is plowed now, but the school's truck still has about 30 ft of 4 foot deep snow to get melted or moved before I can get it to the road.
I wouldn't mind having one in a roller for now just to make things easier and to get it running before a transplant.
There is only one road racing track up here. It is an old air field over by Fairbanks. It is probably 1000 miles from here. I am in the village of Hooper Bay which is due west of Anchorage on the Bering Sea. I have been working up here for the last 10 years or so. I am a school principal and my wife is the school counselor. This is our last year here. We are looking at MN or WI for jobs for next year. We have a place just north of Menomonie.
I am hoping to see you at Road America in June. Maybe we can do a bike deal then or I am going to be in Waukesha the weekend before so maybe we can do something then. Want to come to a pig roast in Waukesha?