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ATTN: Plug Chop Pro's


jbooker82

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Hey I am in the process of jetting my banshee's new carbs. I went from Keihin PJ34's (152 main jet, CEK needle 3rd middle clip) to Keihin PWK33's (155 Main jet, CEL needle middle clip postion).

 

My banshee ran great with the PJ's and 152 mains in around 60 to 80 deg weather. I never did a plug chop with the 152 mains in there. I did one with 155's in the PJ's and it had a dark brown ring.

 

 

I just took the banshee out and did a plug chop with the PWK33's (155 main, CEL Middle Clip Position). It seem to run ok on the top end. It was 30 deg out tonight when I did it. I think that it might be lean though. Here are the pics of the Plug chop I did tonight.

 

I just ran WOT through the gears all the way up to 6th and held it at WOT for probably 10 to 20 sec. Is that why the pics look like it is lean. Not enough time to color the plugs? Let me know what you think.

 

josh

 

RH33mm-155MJ5.jpg

RH33mm-155MJ4.jpg

RH33mm-155MJ3.jpg

RH33mm-155MJ2.jpg

RH33mm-155MJ1.jpg

LH33mm-155MJ4.jpg

LH33mm-155MJ3.jpg

LH33mm-155MJ2.jpg

LH33mm-155MJ1.jpg

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smoke ring looks a little shallow, a size up should put ya in the right spot!

 

 

I will try the next size up (158) too. It was pretty cold today, about the coldest i would ride in.

 

I just didnt know if a quick accereration through the gears and being at wot for 20 sec or so would be long engough to get a good reading.

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I would agree...1 or two sizes up on the main. A tad thin on that ring for my tastes, too.

 

A lean condition on the needle normally would make the bike rev but not want to pull, or miss/pop/ping.

You might be rich on the needle to be honest...bog is usually rich.

Go up one or two on the main, then dial that needle in. Try the old choke trick...if you can. (yeah, I know....a bitch on twin aftermarket carbs.)

 

If you pull the choke out a little and it gets better, than richen up the needle. Worse, lean it out.

Make sure the bike is fully warmed up of course, Josh.

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Josh, i would say go up prolly 2 sizes if your running it hard like that in 30 degree weather. Looks real close for 80-90 degree though. When you say jab it to 1/2 throttle or so and it bogs might try turning the air screws in richer a 1/2 turn and see if that helps. Does it start good cold?

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Josh, i would say go up prolly 2 sizes if your running it hard like that in 30 degree weather. Looks real close for 80-90 degree though. When you say jab it to 1/2 throttle or so and it bogs might try turning the air screws in richer a 1/2 turn and see if that helps. Does it start good cold?

 

Well i will be rolling along at just above an idle and jab it to 1/2 throttle and it boggs. Sounds like you turn the ignition off and are holding the carbs opean. No cough or sneez or back fire.

 

It starts on the 3rd kick when cold. It is better now that I put 48 Pilots in vs. the 52's that they come with. My air screws are around 2 turns out.

 

I will probably up the main one size. I really dont like riding when it is that cold out. I just thought I would go do a plug chop and see. 50 deg or so is about the coldest i would like to ride at. I will up the main 1 more size and do a plug chop when it is a little warmer. Might be a little while before I can get around to it. The nebraska winter weather, it could be sunny and nice out one minute and it could be snowing the next. :yelrotflmao:

 

I really apprecat you guys help.

 

josh

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Hey Josh, try 1 turn out on the air screws and see if that helps it on the bog. Hey it could be worse, you could have a foot of snow like Rippen has now. lol Give us a holler if you need help.

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Hey Josh, try 1 turn out on the air screws and see if that helps it on the bog. Hey it could be worse, you could have a foot of snow like Rippen has now. lol Give us a holler if you need help.

 

I will try the one turn out. If is is more than 3 truns out I need a size smaller pilot jet and re adjust the air screw right?

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I will try the one turn out. If is is more than 3 truns out I need a size smaller pilot jet and re adjust the air screw right?

Yes, it has been said that 1-3 turns is the working limits of the pilot jet. Anymore or any less they should be changed. I have ran them at 1/2 turn out for years on stock carbs with no problems but prolly should have richened the pilot.

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I will try the one turn out. If is is more than 3 truns out I need a size smaller pilot jet and re adjust the air screw right?

 

Yep, 3 turns or more out, smaller pilot. Less than 1.0 turn out, bigger pilot.

 

Really, nothing wrong with running it .5 turns out, but...you're really limited to adjustability then, not much room...that's all!!

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Hay just wanted to say thanks for you guys's help. I know what it is like to not hear back on what you said. Wondering if the person you gave advice helped or not.

 

One turn out on the screws and moved the needle down from the 3rd to the 4th did the trick. Now i just have to get the main changed for this cold weather. I will probably go up 2 sizes and do a chop.

 

Can you do a plug chop at 1/2 throttle to see how the midrange is tuned. Do the same thing as a WOT Chop only use 1/2 throttle?

 

josh

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