Triumph Rat Motorcycle Forums banner

Jets / Carbs / Pipes / Dyno - Pt 453 in a series

1825 Views 11 Replies 7 Participants Last post by  crosstie
<deactivates lurking device>

Back when I did this to my bike, a few people were curious how much power difference it made from my previous set up. Short answer, not much :???:

I was running:
40 pilots
120 mains
Factory Pro needles (4th clip I think)
Airbox w/ 5x 1.5" holes

Dyno said 74.1 RWHP - a nice jump from stock

Now running:
same pilots & needles
130 mains
pod filters (no airbox)
custom 3-1 pipe

Dyno says: 74.87 RWHP - gaining a whopping .76 over the previous set up. Sigh.

However, I am no longer too rich at low throttle, and I have a significant lean spot between 4-5k rpm... which I *think* means the needles need to come up a notch - more gas earlier.

On the upside, the pod filters do just fine in pouring rain... as I found out on the ride home

I still have some s3 cams to drop in as well. I'll let you all know when the next dyno run comes around...

[ This message was edited by: crosstie on 2007-03-12 12:48 ]
See less See more
1 - 4 of 12 Posts
Don't you think you're overdoing the pilot size a little? :-D
No way! Those huge pilot jets are the secret to my power! :razz:

OK, how about 40 pilots, up from the stock 38s... I blame cut-&-paste for the error.

Jim, you're absolutely right - as are all the people who keep pointing out the bike has more than enough power already. :wink: It was more just surprise that there was so little difference between a drilled airbox and 120s, and pod filters w/ 130s. It just goes to show I guess that there's only so much extra hp to be coaxed from jetting and airbox mods.

On 2007-02-10 08:26, TBSstunta wrote:
Did you notice an increase, decrease, or relocation of the flat spot with the bigger mains? Did you put the pods on and run with the smaller mains before rejetting? How did that feel?
The flat spot got bigger (leaner) - from about 15 to about 16.5... and it moved lower on the powerband - it now peaks at 4600rpm instead of 5500. Remember though that I also added pod filters and a new exhaust to the equation.

The air/fuel ratio is pretty even everywhere else, right at 13.5, though it climbs back to 15 at wide-open throttle. I could maybe use 132s or something, but I'm not sure it's worth the hassle.

I hope to eliminate (or at least reduce) the flat spot by raising the needles one notch - hopefully that won't make me too rich at 6000rpm.

So I've been reading up on the green cam swap, and I'm feeling a bit intimidated. It looks like there may be some valve adjustment involved, and a gasket or two to replace. As far as adjusting the valves, it looks like I might need new shims... where does one find such a thing? Anybody? Are they universal, or bike-specific? Where do people go for gaskets these days?

I'm afraid of getting the engine apart and then having to wait 6 weeks while the dealer tracks down the bits I need...
See less See more
The problem is that peak horsepower is calculated at high rpm, so opening up the airbox has the potential for high horsepower but the reality is that you run afoul of the airflow restrictions in the exhaust system.
So what you're saying is, if I just removed the exhaust altogether... :-D

Denny, BadMouth, thanks for the info! Very helpful. BM, did you re-use the spark plug tower seals as well?

Rhinoe, I did get torque #s this time, but I didn't the first time so I have no baseline comparison. It was pretty well flat: It jumped between 45-50 ft-lbs up to 4800K, and then it's at 52 ft-lbs the rest of the way out. I don't know what stock is offhand, but since hp is just torque x rpm, I expect it's up by the same %.

Cheers all.
Cool cool. Thanks again for the info and the links. Good luck w/ the 3->3...
1 - 4 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.