I had a suspicion that my bike was running too lean. Since I know nothing about jetting a carburetor, I took it to a local guy known for his tuning abilities. He worked on it most of the day, going up to a #200 main jet, PMS out 3 1/2, and its still too lean. Does anyone else out there have a main jet larger than a 200 in their carb? I don't want to grenade this engine.

I haven't done any jetting but I've been reading alot of jetting posts because I might someday. Those numbers seem pretty high. (200 and 3 1/2 turns.) Not sure how you could still be lean. Have you checked for air leaks on the carb and exhaust? I'm sure Doc or Gram can help you. If not I would go to the Road Star riders site and ask Odo. He helps everyone with their jetting problems. He seems to be pretty good based on all the happy people he's helped. Just out of curiousity, what's wrong to make you think your lean?

Musky,

My first indicator was the popping I get when I let off the throttle above 2000 RPM. I was told that removing the AIS would fix it. So I removed it, but nothing changed. So I talked to this mechanic and he told me the pilot jet was too lean. The one clue that sealed the deal was when he pulled the spark plugs and they were white. Doesn't that signal a lean condition?

Pilot jet - 200? That has to be the main jet size. Is it the center electrode that is white or the outside ring of the plug? Are all the plugs the same color? Exhaust leaks can cause popping on decel. Had it on mine till I remembered to re tighten my flange nuts after putting on new pipes. I read alot about leaks from slip ons where they connect to the heder pipe too. I sure hope someone with experience shows up to give you some more concretre answers. I just can't see you being lean with that set up but I'm still learning too.

Need more info: what kind of modifications have you made? what year is your bike? what kind of needle are you using? what kind of gas milage are you getting?

I'd also suggest you go to the delphi site and talk to the carb guru "ODO".. He knows his stuff...

Looking from a general point of view, if you don't have High compression pistons I would think you're to rich, these bikes run great rich, until you get to much carbon built up and develop the sticky valve syndrome...

yes, a lean pilot jet will make you pop, but thats not the only thing, exhaust leaks are a major cause, some exhaust pipes will also do this just because of how they are designed... you can ask if anyone here or at delphi has the same pipes and has the same symptoms...

checking the spark plugs are a guide but not the end all and begin all of jetting, spark plugs will generally tell you how the bike is running when you shut it off... but even then, if you've run the bike hard just recently you would have burnt off any carbon build up... I look at my plugs when I change them... but I wouldn't change my jetting because of how they looked...

the current theory about jetting is to run these bikes lean... they have ceramic cylinder walls and can take the heat of running lean... most guys will set their carbs to just lean enough not to have symptoms of being lean.. I say theory because we learn as we go along how our bikes run and how to set them up.. and any mechanic who says otherwise is lying to you.. I guess the only way to really be scientific is to measure the CO in your exhaust... and you can buy one of these over the internet... and then adjust the mix to proper burn ratios... ~Guido

ps, I won't be able to respond til friday (work... sigh)

Guido,

My bike is set up as follows:

Samson Rolling Thunder slip-on mufflers
Speedstar air filter kit with K&N open filter
AIS removed
#200 main jet, PMS out 3 1/2 (don't know the size of the pilot jet)

I used to have Cobra slip-on mufflers on it and I had no problems with backfiring at all. Once I took those off and put the Samsons on, thats when it started. I figured it was due to the Samsons being a bigger and much more open pipe. I've checked for exhaust leaks around the mid section where the muffler clamps are and everything is tight. My fuel mileage is always in the 40-50 MPG range. When I get home, I will check the torque on the bolts of the head pipe to be totally sure it isn't exhaust related. I'm relieved to hear they can take the heat of being run lean. It's been over 100 here and I was riding it and panicked when I was told how lean it was......Thought I was gonna cook the motor.

Does any of that help?

Matt

borchdp:

You will get a better response if you start a new post. This one is old enough that folks who have already read it, and may not be able address the issues of the original poster aren't going to read it again. Since your question is slightly different than the original post some of thos folks who aren't going to read it again might be able to help you. Just FYI...

BlkCherryBomb:

200 is too large for these bikes (brand of jet does not matter, its too big in all brands). I have seen a few that required one or two steps higher than standard for thier accessories, but never that large unless they were either running the stock needle, or had their needle clip position set way too high.

If you are running the stock needle with aftermarket air kit and pipes, it will never balance out right. Its too thick to flow the proper amount of fuel, and no main can really fix it (the main attaches to the bottom of the needle jet, so the needle meters the main jet). You can try sanding it down to make it narrower, but best option is to replace it. If the guy working on it is not familiar with the carb, the stock needle has only one c-clip rung. The aftermarket needles have several.

If your needle is aftermarket, you need to try raising it up (moving the c-clip down toward the point of the needle).

This assumes you have no vacuum leaks, so check for that too (as posted by others).

GRAM

I did not see what air kit you are using but if it's a Baron's BAK you can log into the Baron's forum and their guy, Bulldog, is an expert on jetting, especially with their kit and by either reading the MANY posts or asking specifically about your ride he can probably get you settled. The only issue is that they get a little testy if you are not using their products.....Good luck!

I think Gram hit it.If there using the stock needle it could be runnimg to lean.When I had the dealer do mine (they did a shit job by the way it ran way lean).
Had 200 main plus a 40 pilot jet.I bought a dyno jet kit and rejetted myself.
Now I have dyno190main,dyno needle 3rd clip.Stock 37 pilot,PMS 2 1/2 turns.
42 to 44 miles per gallon .