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Buell Motorcycle Forum » Old School Buell » M2 Cyclone » Archive through December 23, 2009 » CV Adjusting Idle mixture « Previous Next »

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Daveswan
Posted on Monday, September 28, 2009 - 09:55 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I have a 2000 M2 stock engine with SuperTrap and Race Kit K&N oval filter.
Carb is essentially stock, but I replaced the slow speed jet with a 45 and have backed out the mixture screw 2 1/2 turns at first, then another 1/4 turn since it popped out the carb very slightly when I stabbed the throttle.
Now it's better but still seems like I could screw out the needle another 1/4.
Now, how far can I screw out the mixture screw before I just go up to a 48 pilot jet - 3 or 3 1/2 turns? And if I do exceed the amount I can unscrew it and just go up to a 48 where's a good point to begin with unscrewing the mixture jet?
Or how about putting a washer under the needle to raise it to enrich the slow speed mixture and keep the 45 and start with it screwed out 2 1/2 turns again?
thanks for your time

(Message edited by Daveswan on September 28, 2009)
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Littlebuggles
Posted on Monday, September 28, 2009 - 05:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Dave, several guys including those that know stuff have mentioned shimming the needle to clear up what is called by Buellistic the "Kehein(sp?)Cough" so if you are of the mind to try it, it's probably the right way to go and will be a bit cheaper than replacing your jet again
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Daveswan
Posted on Monday, September 28, 2009 - 05:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thank you sir... I'm leaning in that direction from the info I'm trying to dig up.
I'm also thinking about perhaps getting the 88 sportster needle as it's slimmer nearer the end to overcome the lack of accelerator pump on the early carb. I might not even need to shim that one?
That way I think I can leave the main jet as-is at least for now.
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Blake
Posted on Tuesday, September 29, 2009 - 09:03 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Adjustments involving main jet won't affect the low speed performance.

Try a #48 with 2 turns out on idle air mixture; adjust further to optimize.
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Daveswan
Posted on Tuesday, September 29, 2009 - 09:42 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thanks Blake... will give it a shot.

I know the main doesn't effect low speed performance, but if I we're to raise the needle to help low/mid would that impact the top end?

I may not have been completely clear in that I think that the midrange might be a bit lean.

at slow idle if I crack the throttle I might get a pop from the carb. Mid range cruise isn't popping back but it almost seems like it's on the verge. I was going to put some more miles on it and pull the plugs to see how they're burning.

In any gear, if I do a hard roll-on it pulls like a train and there's no popping. I think I'm very close.

thanks!
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Bluzm2
Posted on Tuesday, September 29, 2009 - 09:56 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

First make sure you don't have an intake leak.
If you didn't change the carb seal it's probably time. They only last a couple of years anyway. That includes the 2 manifold seals.
Once you are certain about that part and it it still pops, go to a 48 as Blake suggested.
The Sportster NC65 needle (If memory serves..)might make a small difference. Also as Blake suggested, try shimming the stock needle about .050".

Do you get any popping on decelleration?

Brad
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Daveswan
Posted on Tuesday, September 29, 2009 - 11:00 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Brad, I'm revising this - I sprayed all of the intake areas while idling with WD40 with no change in engine speed.
I just came back from a 45 minute drive so things are fresh in my head. Plus, I have moved the slow speed screw out to 3 turns now and when it's completely warm and I crack the throttle hard it doesn't pop out the carb. If I get up to speed in a hurry and back off the throttle quick, it pops just a little. When I'm cruising along at maybe 1/4 throttle or thereabouts and keep the speed steady it seems like it's a little rough. I don't know how to describe it, it's my first Harley engine. If I keep the revs up a bit more it's smooth as butter. I don't have a tach YET. I didn't think not having a tach would bother me but it does so that's on my list.

thanks!

(Message edited by daveswan on September 29, 2009)
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Outdoors
Posted on Friday, October 02, 2009 - 12:22 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'm running the same muffler and intake and also have a #45 slow jet. A fellow I know that is a HArley/Buell tech and runs a S3T and M2 gave me a washer for under my jet as well. Seems to run great and the screw is out just over 2.5 turns.

The thunderstorm motor likes to be turning up more than a sportster. Keep her about 3000 and it will run smooth.

You are close.
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Daveswan
Posted on Friday, October 02, 2009 - 05:24 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

It definitely feels good with the rpm up a bit. like to know exactly what it is, so a tach is on my list after the speedo sensor. Right now I don't know anything and I don't like flying blind.
I have the screw out 3 turns at the moment and am going to leave it alone until I get the gauges up and running.
thanks!
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Jrams28
Posted on Friday, October 30, 2009 - 02:04 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I am new to posting,but have been looking for a while. I have a 2002 M2 with buell pro-series exhaust and intake,and i re-jetted to 195-45-3 turns out and drilled slide hole.(this is what the kit said to start with)It has a slight hesitation when you blip the throttle and i wondered if this could be a needle that needs raised another notch? I put the needle where the kit said (4th notch).It is not popping through carb.and seems to run fine otherwise.
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Daveswan
Posted on Friday, October 30, 2009 - 06:36 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I actually raised my stock needle yesterday .050" using 2 #4 brass washers. and that cured my lean spot. i did drill the slide this time since I had it apart.
I'm leaving he #45 jet - 3 turns out and I didn't touch the stock #200 main. I did run it at full throttle and it seemed fine to me.
No popping, nice smooth cruise.

(Message edited by daveswan on November 02, 2009)
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