EFI Bighorn

[Uniflow]

I have that frame ( Meagan's bike ) and have thought about it, the F9 gearbox has not been that good at changing gears. I decided it would be foolish to have such an old engine in a new frame with a gearbox that I had to fight with. As it happens when I had the gearbox apart to fix the bearing I found that reason for the problem. Now it changes smooth every time. No, I'm keen to finish this new 360 engine specially made for Meagan's YZF frame. I keep promising to do stuff for other people, I need to just lock the door to the workshop and tell every else to bugger off.

[citabjockey]

Incredibly good strategy!

I need to just lock the door to the workshop and tell every else to bugger off.

[Jeram]

nice work Neil.

[Uniflow]

There you go Racer X , I do get off the seat sometimes.
Click on the picture and it will take you to lot's of photos from the final VMX round in NZ.
Meagan is there riding the 175IT and the TT500.

[citabjockey]

You have some great pix there! What a great venue for a VMX race.

[Uniflow]

Any time, book that ticket.

[Turquine]

Hey, Uniflow, that Bighorn is really cool! Back in the late '70s, I bought a 1971 Kawasaki F81M from a friend of my Dad's, who raced it locally in El Paso, Texas in the early '70s. It was a 250, but he threw in the 350 Bighorn top end with it when I bought the bike. After about a month, I put the 350 head, piston and barrel on. Didn't really seem to gain much if any top-end, but it added a lot more midrange and low-end power. I left it that way from then on. It's interesting, that you also have a Yamaha TT 500 4stroke. My cousin bought the 1976 TT 500, and he was always smoking me on the 350 when we went out to the desert. I've been thinking as I read this thread, how it would have been had my 350 been set up like yours. Out of curiosity, how would your 350 Bighorn do against your or your daughter's TT 500 in a drag race through the gears?

[Uniflow]

The TT doesn't get a look in.
You still don't have that F81M do you?

[Turquine]

No, Uniflow, I sold it back in '79, to buy a 1974 Yamaha SC500 in cherry condition which I hoped would be able to beat that blasted TT 500, lol. It would on a long straight with a throttle roll-on race, but I never could get used to the SC. I found that although the SC 500 was more powerful and faster, it was peaky, and I was not able to do many things that I'd been previously able to on the old Kaw. I regretted selling it very soon. Now I can see that it had a ton of untapped potential which I never realized it had back then.

[Uniflow]

I had one ( 1971 F5 350 ) when I was 16, not the same one, with a Kawasaki Hot Kit. Supposed to produce 44HP.
 At 7000 it had about 15HP, at 7500 probably did about 30HP! Would go through to 9000. NOT a good trail bike. Either monstrously out of control or bogging.

[_X_]

There you go Racer X , I do get off the seat sometimes.
Click on the picture and it will take you to lot's of photos from the final VMX round in NZ.
Meagan is there riding the 175IT and the TT500.

HA! good show uni!

[Uniflow]

Ran the old girl on a dynajet dyno Sunday, not too bad, exhaust is only 186 degrees open time. Cut off is rev limiter cutting in, fueling is not too far off. This is rear wheel HP.

Did a run with the YZ 250 EFI as well.

[TMKIWI]

Thats a nice flat curve Neil.

[Uniflow]

It wasn't that good when it first went up on the dyno ( first run 42HP with a steep rough curve ), but after some fueling changes it's got good power spread. If I was to widen the exhaust and raise the exhaust to 190 degrees I might hit 46 ish HP. NO, just leave it alone and ride it!!

[TMKIWI]

Its a good base to aim for with your 360 motor.
Plus another 10hp on top.