Triumphrat

BadMouth · 09-04-2007

The "what jets do I need?" posts are pretty common. The only hope the person has of getting a real answer is if someone who has had the same exact setup happens to reply to the post. That only puts them in the ballpark, but it's better than no information at all.

What these members are really looking for is a proven setup that works with the modifications they've made (or are thinking about making).

As much as I'd hate making it that easy for others after all the work I've put in (....copying Saigon5), I think we need a proven setups sticky (preferrably dyno-proven).

Alternatively, we could list what setups we've had that were at least rideable. That would be useful as far getting in the ballpark and identifying consistencies.

Or.....we could just club Jimmy900 and steal his records.

So what setups have worked (no major issues, explain the minor ones)?

jimmyj900 · 09-05-2007

Model: 2000 Adventurer (standard)

Carbs: Keihin CVK
Airbox: K&N in Trophy/Sprint filter box w/ 2x1.5" holes at bottom inlets.
No snorkels.
Pipes: Aftermarket (?) 3:1 with conical collector.
Manufacturer unknown, from 1998 Speed 3.
Muffler: DIY high flow.
Cams: Triumph 'blue' Sprint/Trophy
Ignitor: Stock 8,750 rpm

Setup T-43 (43rd setup since January 2007)

Main Jets: #130 Keihin
Needle: Factory Pro Titanium, clip on bottom notch
Float Height: 17.5mm
Pilot Jets: #38
Mixture Screws: ~ 2.5 turns
Slide port drilled to 3.0mm from stock 2.5mm

Butt Dyno Results:
Small throttle operation excellent. Smooth to 7000 rpm, no bucking or audible misfire. (#40 pilots caused misfire/weakness throughout range)

WOT -- Hot and Cold -- no misfires or bucking. (#125 mains caused misfire @ 4K rpm.)

Notes: Could feel thrust surges between 4-5 K and at approximately 6.5K indicating a lean mixture at 4K, rich mixture from 5K - 6.5K, and lean mixture over 6.5K rpm.

Thrust has substantially increased over the entire operating range and the zero to redline time in first gear has decreased substantially -- I estimate 1 to 2 seconds improvement.

A 0-60 mph test with my digital speedo read 3.5 seconds but that is unverified -- I need to check the speedo calibration with the GPS and verify the reading.

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UPDATE: The wire from the speedo sender unit came loose and dropped onto the ignition wires. That resulted in ignition pulses being added semi-randomly to the speed sensor pulses. That made my miles a lot shorter and my 0-60 time a lot less. I'll update again after I cal the speedo and verify it's accurate and consistent. Sorry 'bout that.
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UPDATE: Mileage: 10 Oct 07: I did a group ride last weekend with multiple gas stops and the mileage varied from 34 to 40 mpg (US) depending on riding conditions and speed. The multiple fuel stops were necessary due to a Sportster with a peanut tank.
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It's going to take a dyno run to see what the ultimate results of this configuration are.

Jim -- Senior AMD

funhunter63 · 09-12-2007

Model: 1999 Thunderbird (standard)

Carbs: Keihin CVK
Airbox: K&N in standard filter box w/ 5 x 1.5" holes
Pipes: Stock
Muffler: TORs
Cams: Stock
Ignitor: Stock

Main Jets: #120 Keihin
Needle: 1 0.020" needle under stock needle
Float Height: 17.5mm
Pilot Jets: #40
Mixture Screws: ~ 2.5 turns
Plugs: DPR7EA-9

Butt Dyno Results:
Small throttle operation good. Smooth to 7000 rpm, no bucking or audible misfire.

WOT test:
Starting @ 2000 RPM in 2nd gear-then WOT. It stutters or bogs for an instant until about 2500-3000 RPM, then it takes off....yippee...until I hit the 6500 RPM pipe restriction spot that only slows it down a little. Doesn't appear to make much difference whether it is hot or cold for this test. But today was a cool day here...didn't even get to 60. This is not something I would do in normal riding anyway. I am almost always over 3000 RPM.

Future thoughts and questions:
If I put another shim or two under the stock needle I think it would help the accelleration @ 70MPH in high gear @ 4000 RPM??? If I put Thruxton needles in, would I need to shim them??? What RPM range do the shim affect? What RPM range does the difference in the tapers between the Thruxton needle and the stock needle affect?

Ronkeli · 09-14-2007

Bike: 1996 Adventurer

Carbs: Keihin CVK
Airbox: K&N filter in stock box, one 1.5" extra hole right side (secondary box removed)
Exhaust: Thunderbike 3-1
Cams: Stock
Ignitor: Stock
Spark Plugs: NGK Iridium DPR9EIX-9

Main Jets: #115
Pilot Jets: #40
Needle: Stock with one shim (0.5mm)
Float Height: Stock (17.5mm)
Air/Idle Screws: ~2 turns out

Notes: (only butt dyno results)
- pulls harder than stock all rpm, especially low rpm torque is much better
- better throttle response (or only feels like it ?)
- pretty simple and mild setup, no heavily engine modifications
all in all, everything works really fine

jimmyj900 · 09-15-2007

Quote:

Originally Posted by funhunter63

WOT test:
Starting @ 2000 RPM in 2nd gear-then WOT. It stutters or bogs for an instant until about 2500-3000 RPM, then it takes off....yippee...until I hit the 6500 RPM pipe restriction spot that only slows it down a little. Doesn't appear to make much difference whether it is hot or cold for this test. But today was a cool day here...didn't even get to 60. This is not something I would do in normal riding anyway. I am almost always over 3000 RPM.

Future thoughts and questions:
If I put another shim or two under the stock needle I think it would help the accelleration @ 70MPH in high gear @ 4000 RPM??? If I put Thruxton needles in, would I need to shim them??? What RPM range do the shim affect? What RPM range does the difference in the tapers between the Thruxton needle and the stock needle affect?

The needles/needle jets supply a small amount of fuel at low rpms/small thottle from the straight section of the needles. The difference between needle straight diameter and needle jet inside diameter forms an annulus which is essentially a small orifice -- like a pilot or main jet. The velocity of the airflow determines how much fuel is 'drawn' into the airstream.

As the slide rises and the needle lifts, the tapered diameter of the needle starts interacting with the needle jet inside diameter and increases the area of the annulus which allows more fuel to be 'drawn' into the airstream. More lift on the slide means a decrease in needle diameter due to the taper and more fuel flows.

So.... If the slide isn't lifting enough or the needle taper starts too late (straight section too long) then you're going to experience a lean WOT mixture at low rpms.

At part throttle the lean operation can be masked (swamped) by oversize pilot jets and large mixture screw openings, but at WOT those options are essentially bypassed (due to low airflow velocity) and the needle taper effects become dominant.

The Thruxton needles are virtually identical in configuration to the FP needles with the clip on the bottom notch. In this configuration the needle head to taper distance is around 2mm shorter than the stock needles, so the tapers start acting with 2mm less slide lift than the stock needles -- much sooner.

I've found that it's the needle taper distance (from the head to the start of taper) that is critical to WOT operation in the 3000-4000 rpm range and that the effect is most pronounced at 4000 rpm with a modified air intake. Longer cams exacerbate the problem because the increased duration of the cam generates a lower velocity through the carb and doesn't open the slide as far -- spreading the cylinder fill over a greater time period means the cylinder doesn't have to fill as fast.

Shimming the needle effectively shortens the distance from the needle head to the start of the taper, but stacking 2mm of shims under the stock needle is not a good idea. The needle tends to 'wobble' more and will contact the needle jet and that may cause it to jam and bounce. Stuck or bouncing needles don't run well...

The Thruxton needles are less expensive than the FP needles, so that makes them worth a try, but be sure to check the pricing on both. With the value of the dollar down against the Euro, the FP needles might be a good value in terms of adjustability and price differential.

Shimming the Thruxton needles should be unnecessary. I tried a 0.5mm shim with the FPs and it was way too rich at low rpm to the point of misfire and bucking. When that didn't work I opened up the slide vacuum port from 2.5mm to 3.0mm. I don't recommend that except as a last resort with the bigger cams, but it is reversable with a judicious application of expoxy and re-drilling.

Does all this make sense?

Jim

crosstie · 09-16-2007

Bike: 1999 Legend
Carbs: Keihin CVK

I've been through a bunch of set-ups (long-time AMD

)... starting with the oldest:
August 2004
Mains: 120
Pilots: 40
Factory Pro needles 3rd clip
4x 1-1/2" holes in the airbox
Triumph 'Off-Road' Pipes

Max RWHP: 74.1*
View dyno chart

January 2007
Mains: 130
Pilots: 40
Factory Pro Needles 4th clip
Pod filters**
Custom 3-1 pipe

Max RWHP: 74.87
Max Torque: 51.96
First run with Pod filters replacing the modified airbox, and the new 3-1 custom pipe. Slight HP improvement, but look at the big lean spot at 4K
View dyno chart

June 2007
Mains: 130
Pilots: 40
Factory Pro Needles 5th clip (highest position)
Pod filters
T509 speed triple cams
Custom 3-1 pipe

Max RWHP: 86.98
Max Torque: 56.95
First try with the T509 cams. BIG top-end horsepower boost, but also a BIG lean spot at 4K RPM, leading to a BIG hole in the power band, and an actual HP decrease from previous between 5.5-6.5K RPM
View dyno chart

August 2007
Mains: 126
Pilots: 40
Factory Pro Needles 5th clip (highest position)
Pod filters
T509 speed triple cams
Custom 3-1 pipe

Max RWHP: 84.7
Max Torque: 55.63
This was where I had the bike professionally dyno-tuned. In addition to the jetting tweaks, the mechanic modifed the pipe to get better backpressure, which really helped the huge lean spot you can see at 4K RPM. He lengthened slightly one of the collector pipes, and added a small second baffle to another. Made a huge improvement in the way the bike runs. It still runs a bit lean at 4K, probably on account of the needles (see Jimmy's post above) but overall it feels great - no bogging, no stuttering, and major improvements in acceleration and top-end... feels much better on the highway now, almost like having a 6th gear

View dyno chart

HTH somebody...

*Note: all HP & Torque numbers are uncorrected... since I don't have the corrected #s for each run, figured I'd stick with an apples-to-apples comparison.

**Pod Filters... there are lots of opinions out there, I can only speak to my experience. I've never had any trouble with them in the rain, and I've ridden through some downpours (though I've never ridden them for more then 2-3 hours in the rain). I do have DIY carb brace (pics) and i wouldn't trust just the carb rubbers to keep everything together, personally. Jetting with them wasn't any harder then jetting for a drilled-out airbox. Others have had more issues, maybe I just got lucky. The filters I'm using are K&Ns with Jack Lilley aluminum adapters to attach them.

BadMouth · 09-17-2007

Great info Crosstie.

Thanks for sharing it with us.

Here's my FINAL

setup. No dyno, but I put about 700 miles on it this weekend and I'm completely satisfied with everything except the small throttle/low RPM operation.

Model: 2000 Thunderbird (standard)

Carbs: Keihin CVK
Airbox: K&N in stock airbox w/ almost the entire back hacked out (will add photo later)
Exhaust: Thunderbike 3 into 1
Cams: 955 Sprint
Ignitor: 95 Speed Triple, 9,700 redline IIRC
Advance: Factory Pro Ignition Advance Rotor +4 degrees

Main Jets: 140
Needle: Factory Pro, center notch
Float Height: 17.5mm
Pilot Jets: 40
Air/Idle Screws: 2 turns (plan on experimenting more when I buy the tool)

Notes: It was dyno'd a few days earlier at 84.6 rwhp with the following differences: 142.5 mains & needles on 4th notch down. With that setup, it was slightly rich across the board with a big, very rich spot at 5.5k.

ShikePoke · 10-11-2007

I do not have a dyno run to post yet, but inspecting the plugs, and the thrill of the ride is enough proof for me, I have a 2001 Legend TT.

Keihin carbs:
128 Mains.
Stock Needles with one shim each.
38 Pilots @ 3.25 turns, got the 40's on the way, but idles fine, not much pop on decel.
Emgo pod filters.
Speed Triple rubbers, open.
Slip on aftermarket with baffle removed. Stock headers.

The intake note and exhaust note make music on WOT. Never heard a bike before or since like the triple opened up!

Poke

funhunter63 · 11-05-2007

Model: 1999 Thunderbird (standard)

Carbs: Keihin CVK
Airbox: K&N in standard filter box w/ 5 x 1.5" holes
Pipes: Stock
Muffler: TORs
Cams: Stock
Ignitor: Stock

Main Jets: #120 Keihin
Needle: Thruxton needles
Float Height: 17.5mm
Pilot Jets: #40
Mixture Screws: ~ 3.0 turns
Plugs: DPR7EA-9

Butt Dyno Results:
Small throttle operation good. Smooth to 7000 rpm, no bucking or audible misfire.

WOT test:
Better WOT operation with Thuxton needles at low and mid RPM. Thanks Jimmy!

BigVinny · 11-17-2007

Model 97 Thunderbird

1 Mikuni carbs taken off and replaced with Keihin CVK carbs off a 2001 model

2 Airbox in the bin - fitted pod filters S&B maxi-flow 125-RC-T conical (2.25x3.5x2x4) onto the Keihin CVK's. These are totally "free flow" and would give the same air flow as no filters at all. Air inlet (bellmouth) size is 57mm (CVK's only, Mikuni are different size)

3 Restrictive intake rubbers (with dimple) replaced with unrestricted (smooth) intake rubbers. The unrestricted rubbers should be standard with Keihin CVK carbs

4 Standard spark plugs changed for NGK Irirdium DPR8EIX-9

5 Main #98 jets replaced with #120 jets - This works perfectly the plugs are just the right colour (I live at sea level). Jimmy reckons it might be worth trying #125's but the risk is it might run rich at 5000 rpm to 7000 rpm

6 Copper washer under each carb needle - didnt seem to make any noticable difference but did it anyway. The needles on CVK carbs are not adjustable.

7 Mixture screw taken another full turn out

Everything else is stock ! Fuel is standard 95 RON.

Picture at:

http://www.triumphrat.net/hinckley-c...120-mains.html

Im so pleased with the result I havnt bothered fiddling around anymore, The bike really smooths out at 4000 rpm to 5000 rpm and the iduction roar is fantastic bearing in mind the exhaust is standard. The economy as well as the power has noticably improved, I get about 20 more miles per tank. Recommended !