View Full Version : My disappointing dyno

21st June 2006, 15:18
Page 2 is the final. I was (still am) looking for a lot closer to 90 RWHP.

All comments appreciated. Sorry there's no AFR...I working on getting that.

21st June 2006, 15:27
Looking at the parts list the only thing I see that might be hurting you is maybe the pipes or an inexperienced tuner.:dunno
I would have expected a bit more out of that build,not sure about the cam choice as I've been away from Sportster builds since back in my iron days but I'll be paying attention now that I have one to play with.

21st June 2006, 15:31
Y2K -

I agree with BOTH. I'm taking it somewhere next week, and there's been quite a bit of discussion about this situation here:


It seems I'm not the only one having trouble with those pipes.

21st June 2006, 15:44
Why the shut off at 6200 rpm? You should have more HP going to 6.8 -7.0K.

21st June 2006, 15:53
That goes directly to point #2 above...Inexperience. I asked him how it did at higher reves and he said nothing more up there...probably because he's taken my main down from 165 to 152.5!

I'll have the next guy take it to 6,700. I don't want to blow it up and if 10 HP isn't up there, it wont be at 7K.

19th October 2006, 01:50
Ok...I'm back at this. I got an RB LSR 2-1 pipe and the bike is at Black Hills Customs for a real dyno-tune after they install the pipe.

But, before he does anything, he did a baseline run with my old V&H Straight Shots on and guess what he came up with?

88 HP!!!!! I forgot the torque number as he gave me this over the phone. I'll get the bike back with the before and after sheets this weekend, but I just thought I'd give you all a heads up.

19th October 2006, 01:59
That goes directly to point #2 above...Inexperience. I asked him how it did at higher reves and he said nothing more up there...probably because he's taken my main down from 165 to 152.5!

I'll have the next guy take it to 6,700. I don't want to blow it up and if 10 HP isn't up there, it wont be at 7K.

That really sounds *way* lean for the amount of mods you've done. I'm at 48/180 after a basic bread and butter upgrade. Mine's just pistons - stock cams or head work.

19th October 2006, 02:07
you may be able to get a bit more torque if you weld a washer to the inside of the straight shot baffles. My dyno guy did that and I gained about 5lbs of torque. Since your putting the 2-1 system I guess that doesn't really matter anymore just figured I would tell what they did to mine.

19th October 2006, 02:14
162.5 does sound pretty damn lean to me.

19th October 2006, 02:18
162.5 does sound pretty damn lean to me.

hes got a mikuni. his type speak a different language and probably use the metric system too.

19th October 2006, 15:44
hes got a mikuni. his type speak a different language and probably use the metric system too.

Right, because Mikuni's are Jap carbs and Kehins are ..... :doh

But yeah different jet #'s apply.

NRHS Sales
19th October 2006, 16:11
Yes us mikuni users definately do speak a different language. We use wrenches to get to our main jet, not a phillips screwdriver which inevitably will strip the heads off those stupid screws too!! ;)

19th October 2006, 17:07
I would say your original run is defineitly weak in terms of what you have on the bike. Remember all the discussions here about differences between dynos. How does it feel. I know that with the mods you have you should have had way more power than me and that was not the case. Let the other guys tune and see what happens. I would suspect that 90 is a lot closer to what you have.

20th October 2006, 02:44
Right, because Mikuni's are Jap carbs and Kehins are ..... :doh


yeah, was just being sarcastic. i guess it wasnt obvious enough

11th November 2006, 13:29
Just a quick update.

I took my bike to a different dyno and they had it at 88RWHP. That sounds more like what I expected with the V&H pipes. Still had that huge reversion/torque dip between 2,500 and 3,500 rpm, though.

I just put the RB LSR pipe on and it's soooooo much better. Pulls hard through the whole curve. I'll post final dyno charts when I get them.

12th November 2006, 05:56
do you know what this new dyno guy did differently than the last to give you the correct numbers?
I just realized that the first dyno results you posted(run006) you are pushing only .62 more torque than I got with just my stage 1 with the modded baffles in my straight shots wear your HP is 13.29 more than me so they obviously did something wrong with the first dyno because there is no way my right now stock bike with stage1 will or could push the same torque as your bike can with all the mods you have unless there is something wrong with the bike I think. I don't even think I'll come that close with the mods I'm about to do with my bike.
Maybee ask the first guy what he did to get those numbers and tell him he messed up and see if he will give you a free run to make up for it or something. I know that temp, humidity and other factors play a role in a dyno but could it really be that much of a difference for him to be that far off?

12th November 2006, 06:10
Mikeli, if he has one part limiting his performance it could actually yield those results. Torqe and h.p are not on a linear curve. My bike made 74 h.p. and 78.4 ft/lbs. I had ported 883 heads this time and the torque increased 12% compared to 5% h.p. increase over my unported milled 1200 heads which was 70/70 on the dyno. The cams responded better to the extra compression. I expect the addition of jet heads coming soon will flip the scale and get me 90 h.p. with 80 foot lbs. It is all in how the components relate and work together. Some exhausts limit production as well and shamdog most likely has that happening right now shown in the significant reversion. Not good to assume anything here as stated to me earlier this week by STEVO.

12th November 2006, 06:33
I understand that but he said he just took it to another dyno. Didn't say they did any changes to the bike from the result of the first dyno to the most recent one so shouldn't that show that something was not right with the first one that was done or it was not done correctly?

12th November 2006, 19:26
Mike -

The short answer is no, I have no idea what #2 did differently. There were no substantial mods to the bike.

Unfortunatly, this is where this story is going to end for now. I took the bike out for a 100 mile test run (I had to back the initial timing off just a tad due to pinging at WOT) and the bike runs so damn good, I can't justify the time or expense to have it redone. Maybe, if I get a chance, I'll have someone do a cheap pull just to see the AFR. It was so close before except for the huge rich spot because of the reversion from the V&H pipes. Now, the reversion is gone, so I'm expecting that the richness is gone, too. This bike is now wicked fast and runs like a top so I'm going to leave it alone.

12th November 2006, 20:00
that's good. Glad it's running good for you and you got what you wanted out of it.

28th November 2006, 02:44
Ok...Finally got the dyno sheet scanned

Can't get it to show up in this post, though.

Anyway, you can see the huge reversion (and richness) from 2,700 to 3,500 RPMs. That made the bike a real pain in the ass to ride.

Other than that, the AFR was real close. Now, with the LSR pipe, there's no more reversion and it pulls hard all through the curve.I have left the jeting alone since I changed pipes as I see no need to tinker...It runs that good.

PS - he had it wrong on the sheet. I changed it to show 170 as my main jet.

28th November 2006, 02:53
Damn that's right at 90hp, maybe a little more fine tuning and who knows? Sorry i read it worng i thought it was closer to 90

28th November 2006, 04:21
I hope I have as much luck. Really expecting 90/90 this time around. Spring will tell the tale.

13th December 2006, 07:18
you should have a quite a bit more with that head/cam/carb setup... Mine put down 89.XX rwhp at MMI in my screamin eagle class with just a set of box stock thunderstorm heads, n4 cams, thunder header(really made a big difference), and a mikuni with hi-4 single fire. Jetted stock from mikuni, one clip up on the needle afr was at 13.5:1!