different needles for 04-05 carb

[boosted3g]

I have a slight hesitation when i am at lower engine speeds and stab the throttle hard. I have richened the pilot and dropped the clip to the needle to the bottom spot. My pilot is perfect and my main is spot on but i have this dead spot that can be cured with more fuel at the start of full throttle. I have read that some guys run an HRC needle would this benifit me at all. I need something that will either give a bigger shot of fuel out of the pump or a needle that will taper sooner. I know its a 400ex but you guys know the 450r carb. My mods are in the sig. Can anyone offer some help.

[pro-rider46]

that may work, did you try leaning it more, the hrc will deffinatly let it more fuel

[86250rrider]

you adjusted the air/fuel mixture screw correctly first ...didnt you ?the 04/05 i know have a mix screw ,i just adjusted mine tonight. its like right now throttle response right from idle . its nice!let me know if you need help with it.

[86250rrider]

if the air/fuel screw isnt right...it will stumble because its lean and the big smack of fuel bogs it down.that will only fix a stumble right off idle or just above .at like half throttle snapped open wide it will do nothing for that circuit. its free and takes about 5 minutes to do.

[boosted3g]

I know it goes lean but im out of adjustments to fix it. I had no problems on straight gas but with the ethanol mix its getting to be a problem that i cant fix without replacing parts. I have been tuning it as i increase the amount of ethanol and after this hesitation it will pull hard to the limiter with no hickups. I stoped the tuning session to think about this and correct the problem before i head back to finish up. The quad will run absolutly flawless other than this hesitation but i want to get it on 85% ethanol but that will make me leaner at this hesitation point. I see on the microfiche that there is a jet in the pump. Can this be changed?

[pro-rider46]

hey just otta curiosity whats your jetting, i was thinking of converting my quad to e85

[86250rrider]

this may be a dumb question ,but why are you using ethanol in an 11:1 ratio bike? ethanol requires jetting approximately 45-50 % larger than a equivalent gasoling engine. by using ethanol ...you are massively leaning out your jetting.its highly corrosive and a pain in the butt ! pretty cheap but you use soo much of it. did you ever touch the screw im speaking of ?if so i cant help much as im not sure what your doing mixing alcohol and gasoline. i personally would run race fuel instead. good luck

[boosted3g]

The jetting in my sig are up to date. I run 50-50 e85 and 93 ocatane. With the ethanol content in the 93 it works out to almost 50-50 ethanol to gas. I have e85 right down the road from me and so far it has made horsepower and torque everywhere and it is enough to feel. Those jets are keihin jets, they seem larger but thats what it needs. Any leaner on the pilot or any higher on the needle it will run lean. My first pull i had the needle on the middle clip and at my hesitation point it popped and then woke up and pulled hard to the limiter. Dropping the needle helps but i im at the 5th clip and need more. If you have access to e85 id say do it its easy power, and cheap.

[boosted3g]

e85 is only 105 octane and will make more power than race gas and i can get it locally for 2.00 a gallon. The 400ex is aircooled and e85 does help with keeping the engine cooler. It is also not uncommon for an 11:1 400ex to have detonation problems. E85 is an easy solution, ive been using it for years with nothing but good results. Just a little time in tuning and your good to go.

[GPracer2500]

You may have to dig into the AP and look for a way to get more squirt. Try taking a look at the AP diaphragm. See if there's any material (height) you can remove from the diaphragm's center rivet. Maybe you can get some additional stroke out of the AP that way. I know on FCR's there are a whole variety of AP diaphragms with different center rivet heights. The change is similar in effect to changing a leak jet (an option not available on a 04/05 450r carb). Also, examine the linkage carefully. Look for areas that might be creating a lag between slide movement and AP activation. If any changes are made in that regard, just make sure the slide can clear the squirt.

Examples of three different FCR diaphragms just to give a sense of what I'm talking about. I think the 04/05 450r carb's diaphragm has the pump rod attached to it.

http://k53.pbase.com/g4/20/347520/3/64625104.9Fzfm5Ay.jpg

[pro-rider46]

Originally posted by GPracer2500
I think the 04/05 450r carb's diaphragm has the pump rod attached to it.



yeah they do

[boosted3g]

thanks GPracer2500 that is some info that might help. I think if i can more from the pump it will solve the problem.