Mixture question...
Thread Starter
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Stellar HDF Member
Joined: Nov 2005
Posts: 2,272
Likes: 10
From: Orange VA
Mixture question...
Installed SE AC and rejetted from 42/180 to 45/190. Stock mufflers right now. Cycle Shack slipons in the mail.
Got it started and running. I'm at the point where I am trying to get the mix right. I'm doing that thing where you start lean and go to rich and then set the mixture screw beteen the 2 points.
Started with mixture out 2 turns. Then kept backing out, engine speeds up as mix richens. How many turns is it supposed to take before its too rich and the engine slows again? I feel like I'm going to back the mixture screw out of the carb. Gone maybe 3 additional turns and doesn't sound any different. But the front pipe sure is glowing right at the head.
UPDATE: Backed out 2 turns to start, plus another 3. Blipping the throttle, it will backfire through the carb maybe once every 3-4 times.
UPDATE2: Took it for a spin. Sporadic, single carb backfires decelerating in gear.
Got it started and running. I'm at the point where I am trying to get the mix right. I'm doing that thing where you start lean and go to rich and then set the mixture screw beteen the 2 points.
Started with mixture out 2 turns. Then kept backing out, engine speeds up as mix richens. How many turns is it supposed to take before its too rich and the engine slows again? I feel like I'm going to back the mixture screw out of the carb. Gone maybe 3 additional turns and doesn't sound any different. But the front pipe sure is glowing right at the head.
UPDATE: Backed out 2 turns to start, plus another 3. Blipping the throttle, it will backfire through the carb maybe once every 3-4 times.
UPDATE2: Took it for a spin. Sporadic, single carb backfires decelerating in gear.
Road Captain
Joined: Nov 2005
Posts: 720
Likes: 6
RE: Mixture question...
Generally speaking, if the mixture is open too far you need a bigger jet on the bottom end, but the 45 you have in there is more than enough to do the job.
You always adjust the mixture screw to the highest and smoothest setting , not a pre determined amount. Again if you are 5 open you need other points richened like the needle itself to get the taper out of the jet quicker.
You always adjust the mixture screw to the highest and smoothest setting , not a pre determined amount. Again if you are 5 open you need other points richened like the needle itself to get the taper out of the jet quicker.
Road Warrior
Joined: Jun 2005
Posts: 1,334
Likes: 2
RE: Mixture question...
bensonjv,
Here is a nice guide that should help you out.
http://xlforum.net/vbportal/forums/s...ead.php?t=4465
Here is a nice guide that should help you out.
http://xlforum.net/vbportal/forums/s...ead.php?t=4465
Thread Starter
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Stellar HDF Member
Joined: Nov 2005
Posts: 2,272
Likes: 10
From: Orange VA
RE: Mixture question...
Reading everything I can get my hands on. On one hand I'm wondering if I should have done the main jet. On the other hand, all my woes seem to be where the pilot is running things.
Carb pops (more forceful than a fart)....pops and hesitation when trying to clutch 1st gear from a stop - requires more throttle than before the rejet.
My guess is jets are fine. I'm just not where I need to be on the mixture.
Carb pops (more forceful than a fart)....pops and hesitation when trying to clutch 1st gear from a stop - requires more throttle than before the rejet.
My guess is jets are fine. I'm just not where I need to be on the mixture.
Banned
Joined: Jul 2005
Posts: 14,082
Likes: 8
RE: Mixture question...
I don't understand all I need to I admit that. Clear some of this up for me or tell me where I'm thinking/learned wrong. The 45 is the slow jet right, which is the idle jet. When changing the A/C the rejet itself sets the mixture back to where it should be, more fuel for the A/C allowing more air. If this is true then I fail to see why you would need to mess with/adjust the mixture screw. Right? If this is the case, could this be why you can't find the sweet spot? The rejet put your mixture where it needed to be and any adjustment from that point doesn't do much? Dumb questions I know, but dumber if I don't ask and get it straight in my head. Have you looked at the plugs? If so what do they tell you?
Thread Starter
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Stellar HDF Member
Joined: Nov 2005
Posts: 2,272
Likes: 10
From: Orange VA
RE: Mixture question...
I blindly followed the instructions.[sm=badidea.gif]
Didn't want to do the AC without the rejet; figured that would compound the problem. I used the guide HERE. I didn't even try to start it up prior to turning the mixture screw all the way in. DUH....I know.[sm=headbang.gif] Makes sense the combo of the AC and the jet should have resulted in a fairly close balance. Like you said - might not have needed to tweak the mix at all.
Alas, not leaving well enough alone, I'm left with the mix gooned up. Its acting super lean - off idle popping and backfiring at slow engine speeds, all out of the carb.
My main stumbling block is not knowing if I will back the mixture screw out too far. How many turns does it have and what happens if I back it all the way out? Can I just pop it back in?
Didn't want to do the AC without the rejet; figured that would compound the problem. I used the guide HERE. I didn't even try to start it up prior to turning the mixture screw all the way in. DUH....I know.[sm=headbang.gif] Makes sense the combo of the AC and the jet should have resulted in a fairly close balance. Like you said - might not have needed to tweak the mix at all.
Alas, not leaving well enough alone, I'm left with the mix gooned up. Its acting super lean - off idle popping and backfiring at slow engine speeds, all out of the carb.
My main stumbling block is not knowing if I will back the mixture screw out too far. How many turns does it have and what happens if I back it all the way out? Can I just pop it back in?
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Elite HDF Member
Joined: Mar 2005
Posts: 4,092
Likes: 1
From: St. Petersburg Florida
RE: Mixture question...
I think you might have an intake leak. Happened to me after doing some carb work. The pipe was glowing red hot and look like it was on the verge of melting by the time I noticed it and shut it down. Good thing my heads are made of Iron.
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Thread Starter
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Stellar HDF Member
Joined: Nov 2005
Posts: 2,272
Likes: 10
From: Orange VA
RE: Mixture question...
Yikes. If that's it how'd I do that? I'll get a look at it in the light tomorrow. I'm already too many beers from effectively troubleshooting anyway.
Thanks for your help everyone. Keep it coming.
Thanks for your help everyone. Keep it coming.
Elite HDF Member
Joined: Mar 2005
Posts: 4,092
Likes: 1
From: St. Petersburg Florida
RE: Mixture question...
Quite easily if you removed the manifold or carburator for any reason. If there is a small break in the seal where the manifold connects to the head or the carb, air will get in and lean out the mixture causing a dangerous over temp condition if not caught right away. When it happened to me, I was amazed at how bright a pipe can glow when it gets hot enough LOL.