I am seriously thinking of fuel injection, I can make ny own ECM and all I need is a fuel pump, injectors, and throttle body of some kind!! I think in the last month I have changed the jets, moved the needles, and adjusted the air fuel at least 50 times. I've been from 155/160 to 170/175, every clip on the needles at least twice, and three set of pilots. And the damn thing still is not perfect (and yes I checked the float level) I got it really close now but it still wants to bog and stall if you lug it too much, but the top is a little on the lean side, but if I go up on the mains it makes the bottom worse, it is amazing how much all the jests work together. I thought they worked seperatly for the most part but have found that the pilots and A/F affect it every where!! Anyway I think my main problem is not enough back pressure, but I already ordered a new baffle and a spark arrestor to replace the one that shot out into where ever last year. Once that is done I think I will be able to get the bottom perfect and get the top richened up. I'll let you know once I get it all set.

 

I feel your pain and actually am glad I dont have to mess with two carb set-ups often.

The idea of the various carb circuits working together and how one effects the other would make a great topic for discussion. I never really found any printed or other info on this but know its true just from experience alone.

Even on my own machine I dont always have the needle and main perfect simultaniously all the time. Its just not possible without having a large amount of not just main jets but different taper and size needles.

There were some ugly times while trying to get the jetting 100% before I just accepted that its not always possible with a handfull of jets and needles and its easier for those of us working on our own engines to just work with having one circuit (either the main or needle) a little on the rich side so the other can be where were happy.

Then the problem is which to jet "closer" and which fatter [img]i/expressions/face-icon-small-smile.gif[/img] and that can change a lot depending on your preference for performance in a particular range, willingness to add stress and heat to the engine (from running a little lean) and what kind of riding you will be doing next or most.

Not sure how many will reply to this but I bet we will hear from those who have wanted to have more precise needle adjustments (more grooves between the top and bottom) to get it just right.

Anyhow good luck and let us know how you make out and what you did.

 

Just get some new carbs, thats what I did.[img]i/expressions/face-icon-small-smile.gif[/img]

If you are having that bad of time with jetting I have 3 solutions for you. 1. Take it to a dyno and get it jetted right, 2. Get an A/F meter and O2 sensor and do it yourself, 3. Get new carbs or carb.

While it doesnt produce quite the feed and hp I would want on a big bore build, the Edelbrock is much easier to tune. Its just getting to to run right at WOT that is the problem. None of them I've ever seen have liked to run wide open in 5th gear, you have to back off the throttle just a little and it runs great.

A lectron or a single mikuni would work as well if the FCRs are out of range.

 

Maddog holy #$@#$ your pushing 6300 posts, damn do you ever sleep [img]i/expressions/face-icon-small-happy.gif[/img]

Great suggestion on the AF meter etc!!

 

Come to think of it I dont sleep as much as I should, and posting and browsing here is the only thing that keeps me sane since I barely ever get to ride my machine.[img]i/expressions/face-icon-small-smile.gif[/img][img]i/expressions/face-icon-small-wink.gif[/img]

Jet4power is the company that makes the kit for atvs I believe. They run around 185 bucks or so and work great.

 

The edel works great in the top end for me, top of 5th really punches. What needle did you throw in it out of curiosity? A big factor in getting the punch is setting the accelerator pump dead on, since its effect is much greater in the high gears, and also drilling the sh*t out of the crappy stock airbox on the lower left side and on the bottom back areas. You really have to get the air going to make the carb work to it's fullest, gave me a 2 click change in jetting just by drilling the box up, even with the lid already off.

 

You need back pressure in your exhaust system for the jetting of the motor to be right.....Exhaust Pulse timing/back pressure makes allot of difference in a "near perfectly tuned motor". You will SEE and notice the difference when you reinstall the baffle & spark arrestor.....JMO [img]i/expressions/face-icon-small-smile.gif[/img]