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Need help Jetting Keihin PJ carbs


Bvid74

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I do not own the carbs yet.

 

I am looking to buy 2 34mm Keihin Carbs and I wondering what size jets and what to have them turned to so I can order them with the carbs.

 

I have T5 exhaust and I'm going to try to run foam air filters on the carbs with no airbox. I want to trail ride and drag.

I live in south Louisiana so I'll be riding between 0 and 100ft elevations. My bike has a good porting job on it so it does some inhaling.

 

This is all I can think of. I am looking to get some more quiet pipes so that may affect the jet sizing.

 

Thank you for the help.

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In the end i think its personal preference. The Pjs Idle is adjusted with the choke knob which is the most common complaint.  Some claim that the PWK offers better response due to their D shaped Slide design.

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Ever since you told me about your preference I've been doing a little research and am finding pwk looking a little better. My only question is that I want to drag and trail ride so would it be better to get a 33mm pwk or would a 35mm pwk work just a well? The main reason I wanted a 34mm is so that I was able to do both and that was the size that I researched to give me the best of both worlds. Thank you both for the help.

 

 

Pj choke and idle circuit are one. I always knocked them out of adjustment. I also couldn't get them tuned in well. I felt they were to sensitive to weather change. 
But other people like them and have good luck


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Edited by Bvid74
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How many HP is your engine?

 

Stock carbs are good in to the 70 hp range.. Are you sure you want new carbs when stockers will do just fine? no benefit really if your under 70hpish

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I have never dynoed so I am not sure but the person who built my motor builds drag boats and has made this bike to drag in the sand, The motor has been worked on quite extensively so I wouldn't be sure unless I rolled it on a dyno.

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what is your compression?

 

what type of domes in your cool head?

 

With toomey pipes its very doubtful its 70 hp or more not unheard of but they are not really Drag pipes.

 

Also if its stock cylinder on pump gas stock stroke then its probably well under 70

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stock cylinders? if not what kind?

 

What size stroke?

 

If it falls on its face then its probably jetting not pipes. Have you looked into what jets it has?

 

pipes wont make it cut out they just wont give you the gains you could have with other pipes.

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If you don't have the PJ's yet, don't buy em. Save a few more bucks and grab the PWK's. The idle on a PJ is easy. 6 1/2 to 7 1/2 turns out and they are good. People just need to mark them with paint pen so they can tell where they are at as far as adjustment. The PWK adjusts with a screw on the side of the carb wich is a cunt, but a 90 degree flat head of some fashion gets the job done. Waiting on some one to make an idle screw with the Knob for the bigger PWK's that are readily available. The Slide/needle combo are way easier on the PJ as well needing only a 1/4 turn on the spring lock to access the needle. PWK needle adjustments require you to actually unscrew the lock and remove the goofy plastic spacer. Work in the bowl area is about the same as far as access and location of jets, but this is where the PJ gets sloppy. The float pin set up IMO always seems to just flop apart wich then drops the small pin, needle &seat, and float. There is also the plastic baffle that clips in to that needs removal for some work. I mean, the PJ seems to come apart way faster then the PWK in general. So it sounds like it's a better set up? Definitely not! I swear that the reason they are so easy to work on is because they are always needing attention if you ride regardless of weather and temp changes. The air screw is always wrong from one weekend to the next, the needle is more sensitive then your bi polar ex girl friend, and the main needs changing what seems like every 10 degrees. The PWK really is a dial it in one time kinda deal though. So it makes up for the extra minute or two when making changes. It's slide design seems far superior to and it shows in performance. The 35 PWK IMO can be just as responsive as the smaller 34 PJ. Plus it always feels so much more crisp through the mid and in to the top. It is far less finicky in the humidity as well.

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I have been looking at some 33mm pwks, because we are wanting to trail ride and still be able to drag a little. Our compression is too high and its only 370cc bore on the stock cylinder with some heavy porting so I was wondering if 33mm pwks would be sufficient air/fuel flow. Its not too big for the work that has been done on it and we are looking to do some more major upgrades so we will be able to use them in the future. 

Edited by Bvid74
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