300ex jetting

[brettg]

i ahve posted a previous question aobut my jetting bnut i wasnt sure if i cood acess the feul air mixture screw without disammbling it...if i cood n turned it ouit 2 and 3/4 a turn do u tihnk i wood b able to fix my problem......again... i put a 118 main jet in and cna only run fine when the choke is fully open....wen i close the choke it starts to sputter and eventually dies out....anyone have a clue wuts going on ....somene else said tiw as too lean and needed to b richened by the screw or adding a larger jet......any replies wood b helpful

[300exOH]

Are you using dynojet jets or keihen? If they are keihen then 118 is WAY too lean.

[brettg]

nooo its the dynojettt...they recommneded tha for the main for my elevation n stuff

[300exOH]

Then it sounds like you just need to adjust the fuel screw. There is a good article in the how to section that explains the proper way to adjust your pilot screw. There really isn't a set number of turns you will need to use. Basically you can adjust the screw out about 2.5 turns from lightly seated(all the way in) and adjust out until you reach the highest idle possible and then back off about a quarter turn. It helps to turn you idle up a bit to make th adjustment so it will be easier to hear for any RPM changes. Also make sure the engine is good and warm and the choke is off before making any changes. You may even want to write down how many turns it was at to begin with in case you need to start over again.

[brettg]

alright thankkkksss...do u think i wood b bale to adjust it without dismanteling the hole bike........i hope it fixes the problem becuz ripin it aprt is a pain

[300exOH]

Originally posted by brettg
alright thankkkksss...do u think i wood b bale to adjust it without dismanteling the hole bike........i hope it fixes the problem becuz ripin it aprt is a pain

Yeah. The fuel screw is tricky to get to but it can be done without taking anything apart. The fuel screw is a brass screw just in front of the carb bowl and it faces the ground. You will need a carb tool or a VERY short flat screwdriver to get at it. I actually used a flathead bit from my cordless drill and my fingers to adjust mine but it still is not easy especially with a hot engine. Gloves help.

[brettg]

alright no mroe questions for now thanks for ur help tho

[bwamos]

Originally posted by 300exOH
Yeah. The fuel screw is tricky to get to but it can be done without taking anything apart. The fuel screw is a brass screw just in front of the carb bowl and it faces the ground. You will need a carb tool or a VERY short flat screwdriver to get at it. I actually used a flathead bit from my cordless drill and my fingers to adjust mine but it still is not easy especially with a hot engine. Gloves help.

Aye it's pretty tight in there. I cant even get a special carb tool in there. My hands are too fat.. lol. The tool will fit.. but my hands wont. When jacking with jetting I got a longer hose to go from the tank to the carb w/ another petcock at the carb end. and set the tank up on the bars so I can quickly remove, and reattach the carb for adjustments.

[300exOH]

Originally posted by bwamos
Aye it's pretty tight in there. I cant even get a special carb tool in there. My hands are too fat.. lol. The tool will fit.. but my hands wont. When jacking with jetting I got a longer hose to go from the tank to the carb w/ another petcock at the carb end. and set the tank up on the bars so I can quickly remove, and reattach the carb for adjustments.

Not a bad idea...

Is the extra petcock just to keep from losing all the fuel in the line?

I thought about using epoxy to attach a thumb screw to the fuel screw so it can be turned with 2 fingers but I'm not even sure theres room for that.

[bwamos]

Yea I just added an inline petcock at the bottom of the 2ft hose so I didn't have to drain as much fuel when draining the carb, or pulling the hose off.

The problem I see with adding a thumb screw is there's not way to secure it in place once you've set it (no set screw). I would think vibrations with the extra leverage would cause it to vibrate the whole airscrew out. Just like any other bolt/screw that wasn't tightened all the way down.

[300exOH]

Originally posted by bwamos
Yea I just added an inline petcock at the bottom of the 2ft hose so I didn't have to drain as much fuel when draining the carb, or pulling the hose off.

The problem I see with adding a thumb screw is there's not way to tighten/fix it in place once you've set it (no set screw). I would think vibrations with the extra leverage would cause it to vibrate it's way out. Just like any other bolt/screw that wasn't tightened all the way down.

That's what I thought. A pair of vice grips would work in place of the extra petcock then.

You may be right about vibration being a problem. I know I've seen where others have done this type of mod but I haven't heard if there have been any problems with it working it's way out. Would be nice to find an easier way to make adjustments though.