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AM I getting close on the jetting?


lt1bird

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Still working on a off idle studder.......

I keep going down on pilot jets. It will idle ok for a minute then slowly want to die. My air screws are 3 turns out to max the rpm....

I had larger jets in it and thought it was running better but I really think its super important to get the bike very hot before doing the idle...I think I was getting close with the pilot jets but when it got real wamrned up it ran diffrent seems to make sense.

 

If i put the choke on it runs a bit worste.....

 

So you think im getting closer by lowering the pilot jets more....Im at a 52 right now.... 38mm PWK carbs on a 535

 

Thanks!

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Still working on a off idle studder.......

I keep going down on pilot jets. It will idle ok for a minute then slowly want to die. My air screws are 3 turns out to max the rpm....

I had larger jets in it and thought it was running better but I really think its super important to get the bike very hot before doing the idle...I think I was getting close with the pilot jets but when it got real wamrned up it ran diffrent seems to make sense.

 

If i put the choke on it runs a bit worste.....

 

So you think im getting closer by lowering the pilot jets more....Im at a 52 right now.... 38mm PWK carbs on a 535

 

Thanks!

 

 

if you don't need the choke to start a cold motor, you're too rich. if you need the choke to start a warm motor, then you're too lean. 52 sounds a tad high to me.

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Ok, It was rich at idle.... ive gone down from 60 pilots and now at 45 pilots. Seems to run a bit better with these pilot jets. Warmed it up, adjust the mixture screws to get the highest rpms....Still seems like the screws are out a bit to far at almost 3 turns. After adjustment I put new plugs in it....ran it for 10 minutes at idle only....The plugs looked perfect..... Rode it...still has a studder at 1/8 to 1/4 throttle..... it did not seem to fix that...... I put a larger diameter needle in and it seemed to clear up 80% of the studder... It almost seems a bit lean now....because i get a little booowwwaaahhhhhhh now and its not as snappy..... but when I pull the plugs they are black again.... What should I do now? How do I get that needle tuned in properly? I was at a DEG needle and went to a DEL Needle...(about 3 needles leaner in the 1/8 to 1/4 throttle...)

 

I think I can try some smaller pilots still..... do they have them in the 30's? what about the main jets being to large? Im running 172 right now. Other seem to run 148 mains...this is on a 535.......If my mains are so large maybe its effecting the pilot circuit more than normal?

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  • 1 month later...
yea, might be rich.... opening the throttle is like letting more air through leaning it a little.

 

Wouldnt opening the throttle let more fuel in, both through your main and pilot? How does it lean it out? or are you talking just the first kick? im sure you know alot more than i do thats why im asking...

 

I have the same carbs on my 421 cub, and last i rode with 58 pilots and 180 main...starts with first kick usually, and dont have to use the choke, but its also around 70 deg right now, im sure that when it hits 40 deg thats gotta make a big difference right?

 

tommorow im gonna try 56 pilots, and 185 mains, when i went from 175 mains to 180 it seems to pull harder, and longer, also rev faster....

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as long as it keep pulling harder keep going up on the mains.... at some point it should start to feel flat... I find it to be weird on jeting the 421...... I have same carbs....535 engine and my mains want to be so much smaller(140). All I can think of is that i have a much stronger suction on the carb do to the larger stroke and displament so smaller mains work ok(185), where your engine is a shorter stroke, maybe alot less suction with the porting so the mains need to be large to supply the proper amount of fuel. anyone want to chime in?

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I just got my 535 dialed in today. She screams. I'm at 55/178 CGK, 3rd clip, 1 turn out. I don't think it's gonna get much better than that. It really makes your hands shake when you get off it, from the adrenaline rush. This motor is extremely fast. This is the video for the last plug chop run that we did. Fast forward to 1:00. I moved it to the 3rd clip after this, and it's right.

 

http://www.bansheehq.com/forums/index.php?showtopic=116390

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