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Discussion Starter #1
ktm dyno runs 1 & 2: 185 main jet, 45 pilot jet, jd jetting red needle clipped 5th from top

ktm dyno runs 3 -6: 205 main jet, 48 pilot jet, jd jetting blue needle clipped 5th from top

ktm dyno runs 7-11: 215 main jet, 45 pilot jet, jd jetting blue needle clipped 5th from top

ktm dyno run 12: 225 main jet, 45 pilot jet, jd jetting blue needle clipped 5th from top

ltr dyno run 8: kbr porting, kbr 13.75:1 piston, crower gen 1 intake cam, full rossier exhaust, fuel atv intake, atp injector, power commander 3 usb & sunoco purple 110 gas

To show just how far off my 540 jetting really is; I put up one of my LTR run's from the same dyno. Also the tires used on the 540 dyno runs most likely have a significant impact on the numbers... There is no doubt in my 540 should have made hp & tq than my LTR did. I have a sneaking suspicion that this dyno is very stingy!

I will have my new full exhaust by wednesday or thursday next week and plan to head back to the dyno a few days after that!
 

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Bronson,

Did you have it on performance curve?
I thought the Blue Needle was for above 3000ft elevation?
Looks like the it was starving for air? I left a rag over my K&N Filter one time and when I got my wifes Z400 started finally it would only run with half throttle no air to pull fuel into chamber and man did her exhaust get cherry red just after the cylinder!!!
 

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Not to Dis anything Bronson, I don't got any knowledge in the dyno area but it really seems odd to me that on the ct racing site they can take a 400ex with a 440 big bore kit and get close to the same hp that you was getting. I'm just stumped at the numbers.
-Voodoo
 

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Discussion Starter #5
Not to Dis anything Bronson, I don't got any knowledge in the dyno area but it really seems odd to me that on the ct racing site they can take a 400ex with a 440 big bore kit and get close to the same hp that you was getting. I'm just stumped at the numbers.
-Voodoo
no that just further shows how something it just not right... heck just look at the AF for all the runs. when i got to run 12 with the 225 main jet, the power was still climbing and it was richening up, but i would have needed a dang 250 main jet to get the AF near 13 or 14. the biggest main jet is 230, i almost wish i would have run it without a jet at all and see what it did...

i should have some needles from james dean any day now as well as allan knowles is sending me his titanium needles to use with his pipe. he has a 540 at his shop right now that is nearly identical to my build and he will have it up on the dyno sometime mid next week with his pipe and needles.
 

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Discussion Starter #6
also i am not going to use the dyno to jet from anymore, i am going to jet each area of the throttle (i.e. idle - 1/4, 1/4-3/4 and 3/4 - wot) and then just use the dyno to sligtly modify the fuel screw and leak jet to get the maximum numbers...
 

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check the fuel bowl inlet needle size............. looks / sounds like the float needle is regulating the whole fuel curve

saw exactly the same deal years ago with a dellorto side draft pinto buggy, we jetted until we where blue in the face, lean lean lean........... float needle valve was to small.............. soon as we upped that the jetting all feel into place nicely !!!

otherwiase allot thinner needle is needed.

The 2 wheeler guys seem to be able to jet really easy / make big numbers on the 39 / 41mm carbs
 

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also i am not going to use the dyno to jet from anymore, i am going to jet each area of the throttle (i.e. idle - 1/4, 1/4-3/4 and 3/4 - wot) and then just use the dyno to sligtly modify the fuel screw and leak jet to get the maximum numbers...

Bronson just a thought but could the fuel filter you have on there be causeing the lean problem? It is a pressure less system and I would think any drag would cause a lean situation. Like I said just a thought.

s/f
Brian
 

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good spot, biff that damn fuel filter ASAP

similarly the dyno A/F is simply telling what it is reading, a universally accepted good tool for tuning.
 

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go over to ktm talk and check out the RFS page an d the jetting page, there are several 540 gurus over there.
 

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Discussion Starter #11
fuel filter is gone already. it was a visu-filter designed for gravity/vaccum fed setup like the ktm and is highly recommended on ktmtalk.

i have spoken to many of the guys over on ktmtalk and they have offered up some good suggestions that i will try.
 

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For a test if you don't mind .... toss the powerbowl and run stock bowl for a run. If your set on keeping the powerbowl try a 55 pilot.
-Voodoo
 

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Discussion Starter #13
For a test if you don't mind .... toss the powerbowl and run stock bowl for a run. If your set on keeping the powerbowl try a 55 pilot.
-Voodoo
I just need to try a 100% stock carb and see what happens... I took the carb off tonight and took it all apart again. I tested the tps and it seemed okay, but the coil didn't test out like manual suggested. So who know's?
 

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Didn't want to come off sounding stupid on the starving for air...what I was getting at was the air velocity in the 43mm Carb is not enough to pull the right amount of fuel through the Main Jet and this would cause a lean condition as you were seeing and going up on the MJ would help some...I just don't know alot about these bigger bore carbs and I do know you need air velocity across the throat of the carb to "pull" the fuel into the intake and mix with the incoming air so it looked as if there was not enough air velocity across the carb or it was being restricted on the intake side like when i had the rag over the K&N so at low throttle it couldn't even pull enough velocity to run but at half throttle it was pulling enough fuel in but was LEAN!!!!
 

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Didn't want to come off sounding stupid on the starving for air...what I was getting at was the air velocity in the 43mm Carb is not enough to pull the right amount of fuel through the Main Jet and this would cause a lean condition as you were seeing and going up on the MJ would help some...I just don't know alot about these bigger bore carbs and I do know you need air velocity across the throat of the carb to "pull" the fuel into the intake and mix with the incoming air so it looked as if there was not enough air velocity across the carb or it was being restricted on the intake side like when i had the rag over the K&N so at low throttle it couldn't even pull enough velocity to run but at half throttle it was pulling enough fuel in but was LEAN!!!!
That's why on my 540 build I am staying with the stock carb until more data is received on what the motor really likes as far as carburation is concerned. Like they always say bigger is not always better. I have had some tell me not to touch the head also, but I couldn't let the port job that I won in the raffle go. I also went with the bigger valves to help with the 806 cam.

s/f
Brian
 

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I just need to try a 100% stock carb and see what happens... I took the carb off tonight and took it all apart again. I tested the tps and it seemed okay, but the coil didn't test out like manual suggested. So who know's?
I know it would be a pain, but the 41mm FCR off a 520SX with Hot Start and TPS is sitting on the bench in my garage...or you can get the one off the Katoom in the Toyhauler garage...
 

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Discussion Starter #19
went back to the dyno today to see where i stood now that everything is fixed... he hasn't emailed me the graphs yet, but i will post them as soon as i get them.

today it made a little over 54hp, which is a far cry from 47hp that it struggled to make a few weeks ago... he is going to send me some other dyno runs from a bone stock yfz & 450r that made 34hp and 32hp respectively.

i am going to have to buy some better tires to use in the future. i need to find some used american racers to use...
 

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