 Stalling out
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Joined: Jan 2005
Posts: 228
Adjunct
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OP
Adjunct
Joined: Jan 2005
Posts: 228 |
Here's one that has me baffled. I have BB, freak, cams and put in 145s with Truxton needles, stock pilots and about 4 turns out. Had 160s with stock needles one shim and never had the problem. Now when I lay into it hard from a start it stalls like it's out of fuel before I even get close to the limiter. I have checked both filter and strainer and they are clean. The rest of the time while running even if I downshift and hit it hard it appears ok. I wondered if maybe the pet cock is not allowing enough fuel. Or maybe I need to go to bigger jets?? Any of you gurus have any thoughts on this?
"They don't call it a SPEEDMASTER for nothin"
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Re: Stalling out
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Joined: Jan 2005
Posts: 3,753
Loquacious
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Loquacious
Joined: Jan 2005
Posts: 3,753 |
goin to 145 is a pretty big jump down isnt it? i say try the bigger main and maybe spring for the pingle just to have it
Frank
(Former)05 BA tbike pipes, ai removed, Freak, mikuni hsr 42's, 904, ported/polished head, 1mm oversized valves
NOW-2010 silver and black tbird
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Re: Stalling out
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Joined: Jan 2005
Posts: 1,018
Learned Hand
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Learned Hand
Joined: Jan 2005
Posts: 1,018 |
It's not likely the petcock. I had a simalar experience when i went from 160's back down and was using tbs needles.
I eventually after trying different things went back to the stock needles with one shim and back to 160 mains. Appartently tbs and truxton needles dont work the same for everyone.
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Re: Stalling out
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Joined: Jan 2005
Posts: 9,223
Big Bore
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Big Bore
Joined: Jan 2005
Posts: 9,223 |
Quote:
Had 160s with stock needles one shim
never had the problem
Quote:
put in 145s with Thruxton needles
it stalls like it's out of fuel
Getting the balance between jets, needles, & shims on these carbs is like walking a tightrope. Stray too far one way or the other and you lose it.
Why did you change jets and needles from the 160s/stock, one shim?
My suggestion is to go back to the 160s and stock needles with the one shim. Then add a shim or change to TBS needles and 150/155 jets. The main thing is, not too radical of a change. The smaller changes will let you see the edges of the rope....
"Never underestimate the power of human stupidity" - Robert Heinlein
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Re: Stalling out
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Joined: Jan 2005
Posts: 694
Adjunct
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Adjunct
Joined: Jan 2005
Posts: 694 |
Jango,
My guess is that it's the Thruxton needles.
I'd try canning those.
-BT
"Speedmaster" is a title not a name, - and the title is not plural.
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Re: Stalling out
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Joined: Jan 2005
Posts: 6,308 Likes: 4
Worn Saddle
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Worn Saddle
Joined: Jan 2005
Posts: 6,308 Likes: 4 |
That sounds like you have it set up nicely, are you sure you don't have a plugged main jet?
If not it's already been said; back to the TBS needles and the 160 jets.
Mines been running fine with the 150s and Thruxton needles. Some seem to like the Thrux needles, some don't. They are a lot richer in the mid throttle, and maybe the 145s aren't getting enough gas to them bigger cylinders at full throttle.
You could play with the float levels, the higher the floats the fuller the bowls the more available gas for the carbs to suck out.
A plug check will tell you what's going on in there. When it stalls, pull the plugs and see what's happenin in the cylinders.
A word to the wise is not necessary. It is the stupid ones who need the advice.
Pat
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Re: Stalling out
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Joined: Jul 2005
Posts: 1,378
Learned Hand
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Learned Hand
Joined: Jul 2005
Posts: 1,378 |
Quote:
Now when I lay into it hard from a start it stalls like it's out of fuel before I even get close to the limiter.
Are you at wot? If so i'd suspect the mains and if it's only like 3/4 or lower then maybe the needles. Not sure why no one has mentioned that, but the mains come in to play in the last little bit of throttle range and the needles cover the mid ground up to that point. Actually there is overlap, so what i'd do is try winding it out real good in 1st without going past 3/4 throttle, then shift thru the gears never going past 3/4 throttle but winding it out to as high as it'll go in each gear RPM wise. if it does it than it's gotta be the needles. If it only does it wot or close it's probably the mains.
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Re: Stalling out
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Joined: Jan 2005
Posts: 8,639 Likes: 3
Old Hand
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Old Hand
Joined: Jan 2005
Posts: 8,639 Likes: 3 |
I'm thinking that it probably runs fine up to around 3000 - 3200 and gets worse from there up. Try putting the 160 jets back first and see how it runs. If it's better, take a nice long ride keeping the engine at 4000 or better (use a lower gear if you have to). Then shut the engine down and grab the clutch, stop andtake a look at the sparkplugs. If they have some carbon on them, try maybe 150 jets and see what happens.
Let's hope there's intelligent life somewhere in space 'cause it's buggar all down here. -- Monte Python
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Re: Stalling out
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Joined: Jan 2005
Posts: 228
Adjunct
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OP
Adjunct
Joined: Jan 2005
Posts: 228 |
Thank you all for your thoughts. iknowjohnny you may be onto something. At 3/4 I am on the verge. This only happens when I run up to near full rpm. There are times I'll shift in 1st at 3/4 then hit second to near full and it'll quit. You know though I need to get through to full RPM when schooling these Harley's. I'll go back to 160s since I have them to start and go from there. Thanks again all.
"They don't call it a SPEEDMASTER for nothin"
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