Jetting problem

[JD450Rider]

So I installed my HRC jet kit on my 06 today. Everything seemed to go well. Runs stronger, idles good. But if I quickly stab the throttle it bogs and almost stalls. I know this has to do with the acc pump. It now has the smaller leak jet and I adjusted the acc pump screw out 1-1/8 turn per the HRC instructions. So I'm really not sure what the deal is. Any advice would be greatly appreciated.

[DnB_racing]

it all depends on were your throtle is positioned it could be:

If your engine is bogging when you dump the clutch on a holeshot or you are riding at a constant 1/2 throttle and you engine is bogging then you need to move the c-clip up one notch.


or: Pilot jet: Controls 0 to 1/4 throttle. This jet requires the least amount of adjusting over the rest. If your engine cuts out when you rev it up then you need to make this richer (higher number) if it bogs when you rev it up you need to make this leaner (lower number).

[Ruf Racing]

It sounds like it is the ACC pump. These R&D pumps are badass!
Adjustable on the fly!

http://i532.photobucket.com/albums/ee328/RideRed187/450R%20Pics%20Parts/RDAccellatorPump.jpg

[DnB_racing]

the adjustable ones are nice Ive got one, but after I got it dialed in Ive never touched it since and Ive rode mountains and low lands.if you get the right size leak jet its a lot cheaper get a few different sizes for 15 bucks and fine tune it or the adjustable for 120. I wish i saved the money and got the separate jets, money is tight

[JD450Rider]

Well, I was under the impression from the previous owner that my carb had never been rejetted. But when I looked at the main jet it was a size bigger. So I took the carb apart again to see if the slow jet was bigger as well. And lo and behold it was a 52(stock is 42). So I went ahead and ordered some 42 and 45 slow jets and a 35 leak jet too. Hopefully I'll be able to get it sorted out just by changing the slow jet.

[Fast470r]

I instaled a 55 leakjet stoped mine.

[eastside 400]

safety wire the accel pump linkage to the throttle linkage and adjust it so they are touching, then take out the accel pump diaphram and grind down half of the rivet/nipple, this will allow more fuel to go threw the circuit, got rid of the bog on every bike ive done it to... you can just get a different diaphram, yami, ktm and all them use different size rivet lengths but grinding it down works easier and is free

[quad71]

First check to see if you have fuel squirting out of the accp nozzle in the throat of the carb. 2 did you get a adjustable fuel screw if not get one. my jetting fuel screw 1 3/4 turn out 42 piolt hrc neddle 162 main 55 leak and turned the accp timing screw out to hrc spec same thing as grinding down rivet. 09 with hot cam stg2 motoworks slip on uni filter no lid green wire mod no bog here.

[400cc]

Originally posted by eastside 400
safety wire the accel pump linkage to the throttle linkage and adjust it so they are touching, then take out the accel pump diaphram and grind down half of the rivet/nipple, this will allow more fuel to go threw the circuit, got rid of the bog on every bike ive done it to... you can just get a different diaphram, yami, ktm and all them use different size rivet lengths but grinding it down works easier and is free

would you happen to have any pictures before and after when you did this mod? i would like to do it to mine to get rid of the bog

i wouldn't mind ordering the part but i hate waiting on parts when i order them

any idea where to order the parts from? are they stock parts or aftermarket parts for the different size diaphram that youre talking about

[eastside 400]

they are OEM diaphrams, just OE for yamaha or KTM, i forget what one you need to use. I would just grind the rivet down though because it does the same thing and is free. i cant seem to find anything but google or youtube the FCR o-ring mod, its the same thing but they use O-rings to tie the two together, i perfer safety wire though

[Jonas]

Originally posted by JD450Rider
Well, I was under the impression from the previous owner that my carb had never been rejetted. But when I looked at the main jet it was a size bigger. So I took the carb apart again to see if the slow jet was bigger as well. And lo and behold it was a 52(stock is 42). So I went ahead and ordered some 42 and 45 slow jets and a 35 leak jet too. Hopefully I'll be able to get it sorted out just by changing the slow jet.

The R&D pump bowl won't necessarily take away the bog completely. I have ridden quite a few 06-09 450's and heard some complains from people, but the bogging does not effect me when I am riding at all. I guess my riding style is different that some others. Most people do not carry near enough RPM's into the gear they are riding in. Additionally, some people are bothered by it because they can't snap the throttle in neutral while they are sitting. Not very important in my book. The carb mod discussed previously does seem to help a great deal with the bog. It won't make you go any faster as under a load you motor can only rev up so fast and most people are turning/depressing the throttle in this case way faster that the motor can rev up under a load. Don't forget, these motors perform best when they are reved up a bit and do well with a little clutch work.

[DnB_racing]

I disagree that the mod doesn't help,
with out the mod there is a definite problem when riding in slow technical trails when its impossible to carrier high rpms,the only way to avoid the "bog"is to ride your clutch, and Id rather do the mod and cure the problem and save my clutch! and Jonas he did say he did jet with hrc jets! It seems the more you mod your motor the more its noticable, most people that run stock motors have less problems with throttle response

[JD450Rider]

Well, I managed to get my jetting sorted out pretty well. Putting the right size pilot jet in there helped a lot. It has almost no bog now. The only time I notice it is snapping the throttle in neutral. Even then it's not nearly as bad as it was. Not noticeable at all while riding. Oh yeah, I got an aftermarket fuel screw also. That made tuning it 10 times easier. Thanks for all the advice guys.