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Discussion Starter · #1 ·
I posted a couple of days ago but got no replies...just trying again. After coming off of WOT I often end up on the "fast idle" (about 1500 RPMs) which makes braking a little more difficult and certainly annoying. It comes down to normal idle RPMs as soon as I bump the throttle but have any of you had this happen or know how to fix it? At that particular time (after a WOT tire smoker) I have enough issues to deal with without that. Lock the choke open maybe so it cannot fall on the fast idle cam?

Thanks,
Conrad
 

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I would check the choke operation.... Make sure it has 12 volts going to it. On my bike I found that with the electric choke it would close even with warm engine temps since the coil is not heated with exhaust. I cut the lock out tang off on thr right side of the carb because after a short sit I had no secondaries. Also my fast idle would come on when warm after sitting for a few minutes. For this I adjusted my choke down to where it barely closes when cold and backed off the fast idle screw to where it idles at 750 -800 cold. Now I have just enough choke to help cold drivebility and never notice it otherwise.
 

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Hi Conrad, I have noticed this also with the Q-Jets. It doesn't do it all the time, but every once in a while after a good twist I have had it happen.

I have not checked it with a vacuum gauge, But am willing to bet it is caused by a high intake manifold vacuum, created by shutting the throttle closed at a high RPM.

This leave the engine pulling hard for air, but the only place that it can quickly relieve this high vacuum, is through the idle mixture ports which feeds in an air/fuel mixture, which makes the engine idle faster. But after a few seconds the vacuum drops back to normal as the high vacuum bleeds off from around the throttle plates or any other place it can find.

Try closeing the throttle a little slower. Or just bring it off idle a little and it should settle right down to it's normal idle.
 

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Hi Conrad, Just reread your post and wanted to reply about the choke. Mine is tiewraped open. So I'm not getting onto the fast idle cam.

But I have seen carbs start to close the choke when you open them up. This may be what is causeing you to get on the fast idle cam. I would lock the choke wide open and then try it again to see if it helped.

If not then it's just a high vacuum issue.
 

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Discussion Starter · #5 ·
Thanks. I suspect you are right as it doesn't happen most of the time. In fact, it usually happens when I get WOT and off quickly...usually due to running out of room ahead or a red light.
Conrad
 

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Conrad,
When I tightened my throttle cable, I had exactly the same problem as you. I lubed my cable and backed the cable adjustment off another 1/2 turn and it went away.

Dave In Columbus
 

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Conrad, mine does the same and only when I back out if it quickly. I now roll out of it slower and that solved it.

But that's not the reason I started backing out of it slower. I've noticed that at WOT there is a lot of torque being produced, and by backing out quickly you have a lot of torque suddenly being "not produced". This has nearly thrown the bike into a wobble more that once at 120MPH and I hate wobbles. So I started backing out slower and that ended the wobbles.

Just my observations :shock:

Bryan
 

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I am curious as to what carb the Bosses used over the years. I remember the old Thermo-Quads and Quadrajets years ago on big blocks. Do any of your bkes have Holleys on them? What size ? 650 single, 750, 850 double pumpers? -Greg
 

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To the best of my knowledge, they have used the Edelbrock Q-Jet, which
is made by Weber since the Rochester Division of GM sold the rights years
ago to Weber.

Just recently, Elderbrock quit selling the Q-Jet, I was told by a Edelbrock
employee because of low sales.

I assume in 2005, BH purchased directly from Weber, and now we hear
the rumor that Demon's will be installed on the 2006.

Time will tell.

Geezer
 

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Geezer said:
To the best of my knowledge, they have used the Edelbrock Q-Jet, which
is made by Weber since the Rochester Division of GM sold the rights years
ago to Weber.

Just recently, Elderbrock quit selling the Q-Jet, I was told by a Edelbrock
employee because of low sales.

I assume in 2005, BH purchased directly from Weber, and now we hear
the rumor that Demon's will be installed on the 2006.

Time will tell.

Geezer

Demons are a fact for 2006---if you like Performance toss the Q-Jet is junk in that respect. If you want a reliable carburetor, it usually serves that purpose well. I use a 950 Race Demon and love it! Made a huge difference on my bike but I did have the Q-Jet worked over by Shafiroff Racing (Redtro has it now) and that did help but the mechanically actuated carburetors are the way to go for performance and that is all I care about—may be one reason mine is always torn apart!!! :D
 

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Dave...Do you have the Sanderson headers? With your incredible engine they might wake it up even more. The difference for me has been unbelievable..Joe
 

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I have seen the Demons at the local Hot Rod Shop. They are nice looking carbs. But in its day, so was the Stromberg. What kind of CFM's are we talking about? Auto or manual choke?
 

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zenbiker said:
Dave...Do you have the Sanderson headers? With your incredible engine they might wake it up even more. The difference for me has been unbelievable..Joe
I have the 1800.00 :shock: big headers sold by Mountain. When building the engine Scott Shafiroff estimated that the factory headers (if you want to call them that) would have cost me 40 to 60 hp and the same in tq. The large header decision is one of the first things you should do after getting rid of the Q-Jet.
 
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