Carb setting Fear of lean condition. 98 gp1200

[novo64]

I just finish rebuilding my carb. on my 98 gp1200 135 mains 100 pilots 1.5 N&S 115 gram spring. Have aftermarket head 145 psi all 3 cylinders R&D intake grate R&D ride plate Solas 13 -17 x-prop. Riva CDI. I started tuning the carbs got the low speed screws good about one turn out started tuning the highs I couldn't get the RPMs over 6200 tuning the highs in didn't seem to change any thing. Got to about 1/2 turn and decided to stop before I went to lean. Got back checked the plugs the seemed black and wet. So I decide to get rid of the oil injectors and go premix just incase this was the problem now I haven't ran it sence I went premix. do you guy have any idea what this may be. if any one else is running close to the same carb setup can you tellme wat you screw are set to.

[cwehse]

Re: Carb setting Fear of lean condition. 98 gp1200

I'm rebuilding the carbs on my '98 GP1200s...My low speed jet is at 1.25 turn out and the high speed is at 1.125 turn out.

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

are you running the same carb setup I am?

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

I sure somebody else is running the same carb set-up I got it from the GURU of 65u motors.

[1200ks]

Re: Carb setting Fear of lean condition. 98 gp1200

are you seeing the 6200 rpm on the "dream-o-meter" tach or do you have a tiny tach? The D-O-M's are notoriously inaccurate.

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

it's a tiny tack. wired to the first plug.

[anapg77]

Re: Carb setting Fear of lean condition. 98 gp1200

Err. Something has to be wrong. It should be able to hit 67-6800 with the carbs being rich. I have seen people with that setup on an unported engine at 3/4 to 1 turn on highs and lows.

What is your altitude? Is it ported?

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

well the last time I tuned the I had carb dribble. which come to think of it may have been causing this problem. I was running a 95g spring and I went up to a 115g spring to stop the dribble, it worked. I'm a dumb@$$ to forget this point I haven't tried to tune the highs since I changed the springs out. Not ported and I am at sea level. East coast Florida air

[dav_dman]

Re: Carb setting Fear of lean condition. 98 gp1200

5/8 to 3/4 on the highs.. 6900 rpm no problem. Double ck comp. No way you should be at 6200.

[Mpeavler1]

Re: Carb setting Fear of lean condition. 98 gp1200

Here is a quick test.....if you go from a 50% throttle and ride for 1 min and nail it to full throttle does it jump really fast to the peak rpm and then drop off ? Does it hesitate and slowly climb up? You should be able to get peak rpm and if your turning your needles in and in and still running same rpm without it dropping then your to rich on the Main jet if you get no response from turning in the high needles. First you need to ensure that you have a PET2100 tach or better. A tiny tach does not refresh fast enough to get good results for tunning a 2 stroke. The high speed needle only effects 90- 100% throttle....

Mike

[Bill O'Neal2]

Re: Carb setting Fear of lean condition. 98 gp1200

Mike, The high speed needles effect EVERYTHING above 15% of throttle plate opening in Mikuni carbs, not just the last 10%.

If his motor is way too rich, turning needles in to 1/2 turn out may not be enough. He may start seeing an increase in rpm if he went further in. Bottomline is he needs the sparkplugs to start taking some brownish color, not black and wet. He should try his new springs, as he may be getting a dribble from the too light springs, if that is his problem. If his main jets are too large, he may still see black wet sparkplugs at zero turns out. That would mean he needs to decrease the main jet size.

[dav_dman]

Re: Carb setting Fear of lean condition. 98 gp1200

cwehse, pls correct your typo.. add a 1 to your turns, man.

novo, you can trust your plug chop at 6200rpm but what about higher.. 1/2 turn is min for everybody with a GP but you?..

go back to square one. Check your rev limit settingon the cdi.. did it work before the carb rebuild? turn your screws in all the way to verify position and then back em back out to where you wanna pick up. Chk comp again..takes 5 mins and one bad cyl at 50 pounds will put you at 6000 rpms. . Did you mess with the exhaust..water in the rubber boot area can affect the sonic wave length and rob rpms.

I've tuned with a tiny tach and it works okay for now.. fine tuning with a pet is best, no doubt. Does the stock tach read close to the tiny..to verify the tiny is not screwed cuz sometimes they do get messed up (put 4 coils on the plug wire and try it. What does your gps say? If you're gettin 60mph at 6200 rpm then the tach is wrong.

of course Bill is right about the jetting tests, but this jetting is tested and proven on a lotta gp's, so it would be odd for yours to wanna run so lean i think.

[Mpeavler1]

Re: Carb setting Fear of lean condition. 98 gp1200

Bill,

Um I think we were saying the same thing in our posts?

Mike

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

Sorry guys, I have been out of the country for the last two week. (fighting for our freedom, Air Force) Hopefully I can get out this weekend and get everything straight.

[novo64]

Re: Carb setting Fear of lean condition. 98 gp1200

Well I just got back from being out today, Some good news some bad. Well I set my carbs to 1 1/8 Low 3/4 highs. There was 2-3 foot chop at some time but I was still hitting 6900-7000 So I am super happy about that thank you. Heres the bad news. I noticed a bog or hesataion on the the bottom end coming off of idel. Giving it gas noting the it would take off with no ploblem. Went to shore Turned it off checked plugs and cooling lines everything seemed fine. Started back up ideled finegave it gas wouldn't go about 2400 RPms. Thought I had sucked something up so I jumped in the water and it was clear.Started back up turned tward shore gave it some gas it stalled. hit start button started right up no problems. Gave it gas wouldn't go over 2400. Put it on the trailer went home. got in the driveway hooked it up to the hose Ideled fine flushed it gave it gas and everything seemed fine rpms up to where they should be. Another thing I noticed when starting it did back fire. It also back fired once on the hose when I gave it so gas. I am thinking my lows are too rich. but would like some of your expert opinions. Thanks in advance.