Car Tire Bike on Dyno

[OB_c.dolan]

Tried to run on dyno, last night. Did
burnout in parking lot, to warm up
motor, and tire. On dyno, back tire
would break loose on roller, when tech
cracked throttle. Print out would show
graph going almost straight up, skip
printing, then resume printing, when
throttle shut down. Bike has 10.5"
Goodyear..............................
..Some of you guys that have run major
power, did you have to strap rear, down
on dyno ? Will that enable rear roller
to stay with the tire ? ..........................(Sorry about double post, hit wrong button, couldn't delete)

[This message has been edited by c.dolan (edited 20 January 2000).]

 

[OB_GSXRTURBO1]

Try dragbike.com, I'm SURE someone there has had this problem.

 

[OB_turbo1300]

One of my local mech. has a couple of turbo/alcohol street bikes that even strapped on each side with two straps and two people on the bike the tire still would brake a lose around 385 hp. They have already ate 2 dynos. Good luck and they where using motorcycle slicks.

[This message has been edited by turbo1300 (edited 20 January 2000).]

 

[OB_c.dolan]

To Turbo 1300: Bike is Hillborn injected, alky, or 90 % nitro. GS 1150 based motor. Was just running alky, last night. Have run alky, or nitro, on track, depending on occasion. Originally intended to run alky, turbo. Had bike since 1985. Haven't been on track since '92. Want to put on turbo, this year. May have to run on car dyno ? Dyna jet 200 may not hang.

 

[OB_Jamie]

Strap the back end down, I think shops that don't are half-*** . I ran my bike unstraped and it lost 10hp. I've seen little 25cc kids dirt bikes break traction unstraped at 7hp.

 

[OB_c.dolan]

To Jamie: Will strap, if we do it again, Just wasn't expecting a square tire, with only 4psi, would break loose on a roller, that was making that much contact. Also the alky only makes about half the hp as nitro would. We only ran alky........... ...Your mention of the dirt bike brings to mind a stock YZ 80 we set up to run alky. It turned 15.30 @ 80 mph in quarter. I weighed more than the bike.

 

[OB_THE MOTORHEAD]

also make sure the front forks are pulled down tight because when you get the traction that baby will want to push the front end down and that will make the rear wheel move forward on the roller.and and can scrape on dyno base eatin up the tire.

 

[OB_c.dolan]

To Motorhead: Good call on the forward movement. You've done this before. That's part of what was going on last night. Forks have only 2" travel, and very stiff. We also noticed the front stop on dyno was flexing more than forks. We set it up 1" toward rear of roller, so we wouldn't rub table. Our major problem was, still, the rear tire outrunning the roller. When the tech hit throttle, it looked, and sounded like a burnout.

 

[OB_THE MOTORHEAD]

maybe strap bike down in back then add a little air pressure to rear tire creating evan more force on tire while shortening contact patch.also as pull is underway you may have to move bike rearward slightly it will probably creap up some maybe front end straps.we did this on an old kz street bike w/266rwl hp then we were able to put it to it and got 325=

 

[OB_THE MOTORHEAD]

let me know if it works for the car tire I have a pro mod w/11/29 tire to do when i get my new d.j.250 dyno

 

[OB_c.dolan]

Will strap, and adjust rearward. Tire is 10.5"w. x 30" od. It "grows" 1 ~ 1 1/2" on radius. That would certainly tighten it up, some. Dyna model 200 was used, last night.