carb tuning question... kinda simple

ok... so I've been tinkering with main jets lately cause my bike has 4 open pipes and stacks w no filters on the carbs... bike cranks, runs great all over town... awesome power, no weirdness, but get in the highway and she starts sputtering and falling off at higher speeds... pull the choke up about 3/4 the way and she pulls hard and rolls along. I'm assuming this means it's runnin lean at high rpms? what is the fix? any help is much appreciated. thanks

Your running lean, main jets need to be increased, especially with 4 open pipes and wide open carbs.

anyone with a ballpark idea of what size mains I should be running?

Kingcobra wrote:

anyone with a ballpark idea of what size mains I should be running?

You did not say what mains you are running now. I would guess you need to go up about 2 or 3 sizes if it is running as lean as you say it is.

it has 102's in it now... it HAD 98's in it stock. pulled a plug the other day to get a reading and they are black and sooty with tan insulator if this helps.

Post edited by: Kingcobra, at: 2008/02/19 18:24

If we're talking about a 650 I'de be tempted to think of about 110's as a good starting point?, along with 17.5 pilots. Also with black sooty plugs I would recommened the WG coil mod.

Post edited by: Bluemeanie, at: 2008/02/19 18:28

coil mod? whats that?

It is an addition of a simple Shuck's/Napa automotive relay to your existing ignition system. WG refers to wiredgeorge, a very knowledgeable KZrider member.

A more apt member will be able to get you a link to the post which has the schematic that will show you how to easily add the relay to your bike. It boosts the spark plug power which tends to help solve weak spark problems.

well my bike already has accel coils, 8.8 wires and I just added the dyna ignition last weekend... do I still need this mod?

I added Andrews coils, Acell wires, and a Dyna s ign also. I did the WG coil mod and noticed no real difference but many other people have noticed a huge difference. But I know now that I have a very healthy 12 volts to my coils so with my current ign system I could melt spark plugs! I provided a link below but basically it costs about $20 (unless your a mech and have acess to "free" stuff) read the article and see what you think, almost all of us have done it.

P.S. If you used the blue connector with the Dyna, get rid of it and solder that connection! A few people here including my self started haveing a bad misfire after installing the Dyns S, WG tracked it down to a bad connection with the blue connector. Remove it and solder that connection! No problems since.


WG's Coil Mod

Post edited by: Bluemeanie, at: 2008/02/19 20:14

I hardwired and soldered all of mine thx for the tip tho! I'll check into the mod

I just checked it out... I don't think mine has a problem w coil power... I made an all new custom wiring harness for this bike... I'm good to go there