Triumphrat

mn9130s · 07-31-2007

Just had a run on the dyno. Engine mods: AI removed, NARK, 150 mains, 42 pilots, 3 turns out, K&Ns & Sprint mufflers. Can't post the charts unfortunately, their printer is down. Got 63.39 max HP @ 7200 RPM, top speed 106 @ 7400 RPM. The tech said it was still pulling but he didn't want to hit the rev limiter. I did the mods to remove the midrange flat spot & the curves were nice & linear so I'm very pleased. Seat-of-the-pants dyno said the mods made a huge difference. Although I expected a much higher top end, not like I'll ever hit it or need it.

The techs were young guys who'd never heard of a Bonneville & really liked it. Grins from ear-to-ear

Bonnie1000th · 07-31-2007

Quote:

Originally Posted by mn9130s

Just had a run on the dyno. Engine mods: AI removed, NARK, 150 mains, 42 pilots, 3 turns out, K&Ns & Sprint mufflers. Can't post the charts unfortunately, their printer is down. Got 63.39 max HP @ 7200 RPM, top speed 106 @ 7400 RPM. The tech said it was still pulling but he didn't want to hit the rev limiter. I did the mods to remove the midrange flat spot & the curves were nice & linear so I'm very pleased. Seat-of-the-pants dyno said the mods made a huge difference. Although I expected a much higher top end, not like I'll ever hit it or need it.

The techs were young guys who'd never heard of a Bonneville & really liked it. Grins from ear-to-ear

Those numbers are good, you are in the ball park for your 790 mods, different mufflers can up the RWHP, but you are in good shape with the Sprints.
When you said much higher top end I assume your dyno run was done in 4th gear.

mn9130s · 07-31-2007

Thanks, good to know I'm in the ballpark. Top speed - the 1st 2 runs were in 4th, the last for top end supposedly was in 5th. I'll admit i didn't pay close attention to see if he really had it in 5th but I'd assume so. I expected at least 120. Like I said, I'll never go that fast but 106 seemed slow to me.

Those Sprints sound fantastic at 7K rpms !

cdk80gs · 07-31-2007

Hi, well thats better than my 04 790 put out, 1st run with std filter, AI removed, std carb settings but 115 mains and TOR's gave
60.3BHP, 41NM Torque, max speed 86.2 @ 8,045RPM
Then fitted K&N filter, Bellmouth,Mototwin megas, Dynojet needles, 120 Mains (Dynojet kit came with 112's) slides drilled and rather dissapointingly got the following
60.4BHP 42.6NM, 95.7MPH @ 8,442 RPM
All runs in 4th gear, however the 1st one was with a 17T sprocket and the later one with an 18T sprocket, Dyno guy said this could account for lack of rise in power figures.
To say I was dissapointed in the figures in an understatement but on the road the bike feels much better, much more mid range
Have attached a pic of the graph showing the best of run 1 and the best of run 2

mn9130s · 07-31-2007

Thanks cdk. Hmm, maybe 106 is fine for the RPMs but i could have gone up another grand or so without hitting the rev limiter ? That would seem to make more sense.

bendavanza · 07-31-2007

I don't know why the dyno operator did not want to hit the rev limiter, it's there to prevent damage, and it's where your sweet spot could be
-Ben

Bonnie1000th · 07-31-2007

Here is a a perfect jetting dyno run for a 790 motor with AEK and Predators.
Graph 1 and 2 is RWHP, and RWTQ, graph 3 and 4 is A/F ratio.
That was when I had a stock 790 motor.