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Discussion Starter #1
Hi,
New to this,
This is the dyno run on my 06 865cc T00.
Moto Twin "pea shooter" silencers,
39mm FCR Flat slides,
K&N's
AI removed.

Carb kit was delivered with 155 main jets, this was very rich so reduced them to 140 and got results as shown.
Hope to crack the 70bhp with re map of ignition and will leave it there. Bike is very usable and big improvement over standard.

BR
Dave.
 

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Nice!

Welcome to the forum.

Do you plan to do anything to improve the lean condition at the low end? Are you going to change the main jets at all - maybe try 145s to see if that ups things a bit more!

Pretty good run! Thanks for posting!
 

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the mains dont look lean if anything a tad rich that lean at the low end was more then likely the guy doing the dyno dumping the throttle up to fast .He needs to roll on it slower with flat slide carbs.Your at around 12.8 mix some put out there best power there some like just a tad leaner I would go down 1 size and see if it makes more power .But you are about where you should be on power.
 

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Duh yeah really what was I thinking? Upping the mains richens it. I need to think more before posting. :eek: :D
 

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Discussion Starter #5
T100 Dyno

Hi,
Sorry for confusion, the dyno run first posted was with 140 main jets and yes it was a little lean at the lower end this was cleaned up by moving the needles up, ( sorry no graph with this done) .
The graph attatched to this post shows the same set up but with 155 main jets........ very rich. I have tried 138 and 145 mains with no real improvements.
I am hoping a re map of the ignition timing might give me the 70bhp I am looking for, the bike has done less than 1000 miles so it might make a bit more power once it has loosened up a bit more.

BR.
Dave.
 

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the mains look better in the first run did you dyno it with the 138 mains and the niddle where it is in the 155 main run? if so post that
 

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Discussion Starter #7
I did run it with the 138 main in and the needles in same position as 1st posted run, power was very slightly up but as i intend to run with a more advanced ignition map I decided that it would probebly be best to run it a little richer than Ideal accross the range just in case I get into a detenation situation.
I always start with a slightly rich set up prior to making changes to the advance curves, this way I do not buy too many pistons.

With a 145 main jet power was down 1.5 hp so that came right back out.

The best run I have had is with the 140 mains and the needle in the 2nd from top clip, this gave me 66.69 bhp and 52.31 ft/lbs of Torque.

I am currently running no modifacations to the ignition so rev limiter is at 7600 ( it looks a little higher on the graphs but it is 7600).
I am not sure if increasing the limit will give me more as the curve is deminishing slightly, although with some more advance if the curve is still "growing" I may well try another 500 rpm on the limit.

I have more graphs in the dyno pc but will have to retreve them another day.

Does anyone know if there is any significant differences in the down pipes on the standard bike and the Thruxton? are the Thruxton pipes larger diameter?

Has anyone noticed any significant power gains from NOT running a balance pipe?

BR.
Dave.
 

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I don't think the thrux headers are any different diameter to the Bonnie, but they are just shaped and bent differently, such that I don't think thrux silencers will fit bonnie headers.

Something like that anyway!
 

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thrux headers are the same size but the way they are bent make them flow better but you will have to run mufflers made to fit them.You dont need to high of limit on a stock motor they put out max hp before 8000 rpm. If you add 3 deg. total advance you will be safe going a little leaner it wont ping heck stock bikes run 14.7 to 1 from triumph.You have only got 9.2 to1 comp. it wont ping easy.I have 10.5 to 1 on my bike and over 3 deg advanced timing.
 

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FCR Pumps/Slow air jet

Just a check. Were these runs done with the pumps disconnected? From the lean condition it would seem so, but I thought the information was worth the question.

If your FCR's have the adjustable slow air jet, you show be able to clear the lean condition by turning in about 1/4 turn.
 

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when the guys dyno it its all done at wot so would the slow air jet even be in play?Once you go wot are you not 100%on the main jet? I dont know much about the fcr carbs but thats how my flat slides work .The low air works before the slide opens enough.
 

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with flat slide carbs when you open them fast vac falls way off .That is where the pumps have to give it a shot of gas to make it take off.On a dyno sheet alot of times you will see a/f mix do some crazy dips when the pumps shoot but if the hp and ft/lb lines dont dip it wont hurt a thing.Jetting can fool you with flat slides because of this.You can get the main jet way to rich for max hp at high rpm but it might take off better when you wack the throttle at low speeds ,thats not how you want it .Find the main that makes the most hp ,Then play with the pump to get it to take off when you wack it.I dont know what you can change on the pumps on the fcr pumps on the 42mm carbs i run you can change where the pump starts and stops and go up and down on nozzle size.It took me alot of playing around but i got mine so i can wack it open at any rpm now and it just plan wants to pull you off the seat when you do and pulls to red line very fast.I started out playing with niddles niddle setting pilots pilot settings and so on .Once i knew none of that has a thing to do with wot it was simple.The other things afect part throttle you got to test and adj them at the throttle pos that they are in play.
 

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Mike, According to this man http://www.factorypro.com/tech/carbkei.html
the slow jet affects the carbs performance up to and including WOT (It surprised me) the reading is a bit long winded but informative

sidseismic
I have almost the same set up as you but 904cc, with advanced ignition and a main jet of 140 is to small, the bike will not pull up the top end as good. I hope over the holiday period to put in some 142 or 145 jets to see how much it changes, i'll keep you posted
 

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In looking closer at the graphs, the area that is lean, is beyond
where I thought it was, 3000 RPM and above, so the slow air
adjustment probably wouldn't be able to offset the situation.


Mike, the FCR and HSR are very much the same in the slow/low speed jetting. Both use a combination of a pilot/low speed jet coupled with a fuel adjustment screw and and an air jet. Both carbs fuel delivery is dominated from idle to about 1/8 throttle by the low speed circuit. These throttle positions are steady state positions,
etc.


While in a dyno run your are at WOT for nearly all the run,
your airflow thru the carb/carbs is of course directly rpm
related and the attendant vacumm level determining fuel
delivered to the intake manifold/engine. For some
small part of the run, the low speed circuit will be delivering
a significant portion of the overall fuel delivery mechanism
results.

The low speed circuits contribute fuel through out the entire
run and the entire RPM spectrum, as the rpm rises above the value
that would correspond to 1/8 throttle (steady state), the amount
of influence the low speed circuits have on mixture diminishes to the point it becomes nearly moot, with the main jet and needle combination dominating until at full throttle/high RPM, with the
needle at max extraction, the main jet/main air jet are
the dominating factor.

This is how FCR are documented to function, and I would think this is
true for the HSR as well, just in differing degrees.

On the FCR pumps, Keihin didn't provide much in the way of adjustment as to start and stop points, no variable nozzle sizes (that I can find), etc. And disconnecting them while on the bike is a real pain, Mukini did a much better job in designing the pumps on the HSR series.

To call Kehins adjustments in this area a design is being very kind.
 

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Mike, According to this man http://www.factorypro.com/tech/carbkei.html
the slow jet affects the carbs performance up to and including WOT (It surprised me) the reading is a bit long winded but informative

sidseismic
I have almost the same set up as you but 904cc, with advanced ignition and a main jet of 140 is to small, the bike will not pull up the top end as good. I hope over the holiday period to put in some 142 or 145 jets to see how much it changes, i'll keep you posted
After looking at that I dont want any parts of the 39mm carbs thats way more to adj then is needed.thats plan crazy.
 

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On the hsr the low speed has very little if any afect at wot.After reading the fcr quide i can see where it might have more afect on them. on the hrs it is the mains and pumps that have to be right at wot. BUT ON THE FCR it looks like everything counts.That why they are harder to tune.
With the 42mm HSR carbs on a motor thats right I can get the main dang close useing the old roll off test.When they get to rich they will spit at high rpms .when there to lean there lazy and will pick up when you roll off from wot to 7/8 throttle.
As far as the pump set it to come in at 1/4 throttle and go out at 3/4 throttle.Use a #50 nozzle set to spray dead center of the niddle.
Start with a #97 niddle in the middle slot if it surges at cruse speed about 1/8 throttle go to a #96 niddle if not leave the #97 in there .I have played with niddle clip but it seams to work out the best on my motor stock or now with the stroker motor in the middle slot.I have found the small pilot jet works best and gives the best mpg for me .screws set at 3/4to 7/8 out.
 

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FCR39's
Going up one size on the main (now #142) has made an excellent improvement, I am out for a longer run tomorrow so will let you know
 
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