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View Full Version : Lean Bog Fixed



Bones
08-14-2006, 10:04 AM
Ok, I have a new 06 450er that I have had a lean bog in on the bottom end since day one. I purchased the HRC kit thinking that I could gain power and eliminate the bog all in one shot. I installed all the components just to find out that the bog was way worst with the kit than stock. So I started doing a lot of research and found out a few key things. Most guys really like going with bigger pilot jets to fix a lean bog but I found out in a quick hurry that you definatly are waisting your time going with a much bigger pilot jet. the biggest pilot a guy should need in this quad with the HRC is a 45. I actually ended up with a 40 pilot in it because it was hard to get a good smooth idle without having my fuel screw being less than one turn out from bottomed.

Ok, here is the thing that cured my lean bog COMPLETELY. First I adjusted the accelerator pump screw till I got my squirt to shoot as soon as possible without hitting the back of the slide. The setting ended up being 1/4 turn clockwise from the stock setting. The HRC kit manual has you turning it 1-1/8 turn counter clockwise from the stock setting and that is the wrong way to turn it if you are trying to get rid of a lean bog. I think the honda engineers messed up on that setting spec when they produced the manual. You are better off just leaving it at the stock setting rather than turning it counter clockwise. Ok, next I took out the HRC 55 leak jet and made my own leak jet plug. I completely plugged off the leak jet hole. The squirt on mine is about 2 seconds in duration. I now have absolutaly NO bog at any rpm in any gear. I am planning on ordering a 35 leak jet and installing that for the following reasons. By plugging off the leak jet circuit you are not allowing any fuel to bypass the squirter so in the situation where you want to roll on the throttle instead of stabbing the trottle you end up throwing extra fuel into the engine that is not neaded in a roll on throttle situation. I had to lean out the needle to compensate for the rich mid range that the plugged leak jet caused. I could ramble on about this fix for hours but I dont want to bore you guys so If you have questions dont be afraid to ask. I have done many hours of research and testing on this problem to fix it and now I have good knowledge about it, so I hope this helps any of you with a lean bog on the bottom end........:)

4ABURN
08-14-2006, 05:53 PM
Right on thanks for the writeup sounds like you have put some time into this, Mine only does this if I get lazy and nail the throttle at a very low RPM. After the HRC kit goes in then I will try this fix.:D

chad502ex
08-14-2006, 06:21 PM
i've been doing this for a long time now- this info is correct. Install a small 35 leak jet into the float bowl and remove the lean bog. All my taper bored carbs get this mod.

BLACKMX440
08-15-2006, 04:01 PM
where can i buy leak jets at?

08-15-2006, 04:03 PM
i got mine from magic racing...i had ordered some other stuff too...if i hadn't an 8 dollar jet would have cost me $16 because of shipping. see if you local dealer can get one for you...

GPracer2500
08-15-2006, 05:01 PM
Sudco should have them. Their website kinda sucks so I'd just call them.

Bones
08-16-2006, 01:43 PM
yeah, I just ordered from Sudco and they have a minimum order of $15, so i ordered 2 leak jets. The jets are like $8.88 per jet and then $10 on shipping. Pretty spendy for 2 tiny little pieces of brass. I ordered 35 and 40 leak jets.

RayWilt
08-17-2006, 07:52 AM
Here is the part number from honda for a 40 couldnt find one for a 35 99108-krn-0400 any honda dealer should be able to get it for you they sell for $7.70. Its a optinal jet on a crf250. Ill keep looking for a 35

brandon837
08-22-2006, 10:05 PM
where can I find diagrams for the adjustment I am having the same problem as most I took it to the shops and had jetting done there I still cant get it dialed in the did not charg me because it was a learning experience for them I started tuning got it close it feels good on the top end smell of unburnt fuel running a 165 main they changed my start jet to a 75 that supose to help out with easy starts that did not help I talked to honda dealers in my area they want to use a dj set and run with airbox lid I seen this post someware else but had step by step instructins how to adjust the accelerator pump but could not find where I am at sea level any thing helps running full dmc afterburner and k&N with HRC air lid