TT500 motor in a 78 CR250 frame

[edgo897]

This is my attempt to do it. I think it is going to work. The frame has plenty of room but it was a little narrow so I had to spread the bottom rear of the frame out an inch to avoid chain rub on the side tube. I added the bottom rear cross-brace and the rear square tube which is the oil tank. The YZ490 swingarm fits well so I'll weld some shock mounts to it. The motor mounts in five places to I added a bit of metal to hold it.

Ed

 

[Motosportz]

interesting project. please keep us updated and post more pix as it progresses.

 

[Michel Dufayard]

This is my attempt to do it. I think it is going to work. The frame has plenty of room but it was a little narrow so I had to spread the bottom rear of the frame out an inch to avoid chain rub on the side tube. I added the bottom rear cross-brace and the rear square tube which is the oil tank. The YZ490 swingarm fits well so I'll weld some shock mounts to it. The motor mounts in five places to I added a bit of metal to hold it.

Ed

Humm, nice project. I've seen a 78 HVA frame with a 370 sp suzuki motor.

 

[MOTORHEAD]

Those style frames are great for project bikes, there's so much acreage in there. I think that was also the basis for the Hallman TT500's when they were conceived.

Yeah, keep us posted. I'd love to see how it turns out.

 

[edgo897]

I kind of bolted all my parts together and everything fits. It has a 1978 Suzuki PE250 front end, and a 1982 YZ490 rear arm and wheel. I'm trying to keep it an EVO1 class bike, that's under FLVMX rules. So I'll keep it at about 9 inches of suspension which is about what the frame was made for. I got those Works shocks for $10.00 and they cleaned up really well.

 

[Motosportz]

I think you might have an issue with the CS sprocket being that far from the swing arm pivot. It will have a lot of leverage over the rear suspension and you will have major chain slack to get past the tightest point. I know you already welded stuff up but I think you need to get the CS sprocket as close to the swing arm pivot as possible.

those frames are HUGE. That think swallows that engine with ease.

 

[edgo897]

I have the CS sprocket as close to the pivot as I can get it. It is about a five inch gap between the CS shaft and the pivot bolt. I have both a 1977 and a 1978 Yamaha YZ 400 and they both have this same issue. Yamaha didn't relocate the CS to the rear of the engine case in their motors until 1980. I'll make some guides and I'll use the largest front and rear sprockets I can find. That is another reason I'm keeping suspension travel to about nine inches rather than twelve.

The front of the swingarm on the right side is about 1/4 inch from the rear of the case. It is a tight fit. Before I decided where to mount the motor I placed it in every position possible within the frame with all kinds of supports. Where it is now is the best spot, all thing considered.

Good eye Motosportz.

Ed

 

[Michel Dufayard]

A HVA frame with a non-hva motor !

 

[schimmelaw]

Michel,
Love the engineering, fabrication and outcome. Where is the cable operated rear brake? Left side? Hand lever?

 

[Leftcoast leftkicker]

Michel- what's in the water in France??? These 4s are the bomb! I've NEVER seen anything like them here in the US.

 

[Michel Dufayard]

Michel,
Love the engineering, fabrication and outcome. Where is the cable operated rear brake? Left side? Hand lever?

One of my friend sent me these pics .
Not sure the owner is in France !
Surely in Europe. I think the motor is a JAWA.( not sure).
The gear lever is right side, we see a cable for rear brake, so I think there's a left brake pedal.

 

[Michel Dufayard]

Michel- what's in the water in France??? These 4s are the bomb! I've NEVER seen anything like them here in the US.

Water ????

 

[Michel Dufayard]

I've been heard that the first YAMAHA HL was made from a HVA Frame.

http://www.leguidevert.com/_V5/visu_sujet-forum-159449-159449-0-500-hl-yamaha.html