Triumphrat

Saigon5

The run was made today, it is from a TBS with off road pipes, stock jetting and stock airbox and Speed Triple cams. No other change was made in order to see the difference in the cams.

The bottom part is quite equal to what it was, there is no loss in the bottom part, the jetting problem is creating a dip at 4200 RPM and goes off from there. Even with the wrong jetting, the cams still managed to give an extra 6HP and 4 pound of torque.

All the new found ponies and torque are located above 5500 RPM all the way to the red line. I did ask the dyno operator to be nice and not bring it to the cutt off this time which is at 9500 on mine.

At this point I could just bother jetting for what I have but I will see if I can get further a bit. Since it is starving for air from 4200, I will fit a trophy airbox and go back to the dyno.

More to come but don't know when.



[ This message was edited by: Saigon5 on 2005-04-14 19:02 ]

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In doubt, crank the throttle.

johnyC

Saigon,
I don't think that saggy bit in the middle is down to lack of air but lack of gas, other folks on here suggest raising the needles or fitting Dyno jet or similar.
I've already done a minor airbox mod' having removed the auxiliary box from my TBS and now have the TBS TOR's fitted.
I intend to do the needle job and possibly the mains too, but not until I have the airbox off next to fit the K&N filter I got. I have the pilot screws at 2 1/2 turns out as others suggest.

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johny. the boy's happy, leave him alone.

MickMaguire

Interesting - so these cams are actually out of a 2000 Speed triple - T509?

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Mick...

Just remember; an awful lot of the free advice you will get on forums is worth exactly what you paid for it. There will always be somebody trying to convince you to do something really stupid, just because they did it or want to do it.

fbird

Hey Saigon, Looks like it definately needs some more fuel. Nice increase without any jetting. Should make a big increase once dialed in. Good Luck with it! Shawn

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99TBS and 2000 Sprint ST

Saigon5

Yes they are. Same cmas as older engine.

While I am here, other post are suggesting that I put more gas, it is too rich now, it seems that everyone is reading the dyno chart upside down. In a perfect world the aim is for
14.7 to 1 less than that is rich more than that is lean. Now the carbs are in bad need of air.

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In doubt, crank the throttle.

fbird

Oops! quess that would make alot more sense wouldnt it.[quote]
On 2005-04-06 15:59, Saigon5 wrote:

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99TBS and 2000 Sprint ST

TBSstunta

When I was researching this I was tyold that while the 1997+ cams would fit they weren't as compatible with the Thunderbirds as the 95 & 96 S3 cams.

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2000 TBS Cafe Racer :: 2000 Frankenmille

Bushwhacker

Right. Even without the gas analysis at the bottom of the page. A lean fuel mixture will not give you the dip you have in the power curve. You may not have quite as much power running lean and the engine may run a little hotter, but you would have a smooth power curve.

My Valk ran anywhere from 14-20 to 1 and had a perfectly smooth power curve on the dyno. It ran so great I did not touch it but left it lean. In this condition it was putting 93 hp to the rear wheel.

Your dyno chart looks like one I would expect to see if it were run with the choke full on.

I just put "Green" Sprint cams in my 2k TBS and had the carb rejetted and the airbox opened at the same time. I have not yet had it dyno'd, but seat of the pants it has a bit of low end hesitation up to about 2500 rpm's but after that it runs like a scalded dog! :-D

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When you look like a rude, crude, scum sucking cretin people tend not to ask you stupid questions!

Saigon5

Today I took the carbs out and fitted a trophy air filter. Now my feeling is that it is way too lean. I can harly accelerate past 5000 RPM, lot's of hesitation and clean popping if I let go. I will know more soon since I am going back to the dyno.

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In doubt, crank the throttle.

jimmyj900

Saigon5,

You'll find after a couple of dyno runs that the engine is much less sensitive to mixture ratios than it is to airflow capacity. The mixture can be way off and only produce minor variations in the torque curve.

For maximum power you want your fuel mixture at about 13:1. A 14.7:1 mixture is the "optimal" stochiometric ratio but not the best "performance" ratio.

What pilot and main jets are you currently running? With the Trophy airbox your main jets would be about #130 with Keihin carbs and close to that with Mikuni carbs.

How many turns do you have on the mixture screws? If your mixture screws are at around 3 to 3.5 turns, it's time to go up one size on the pilot jets. Trying to compensate for a small pilot jet and opening the mixture screws will cause lean operation at small throttle settings.

Jim

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