idle screw (air/fuel mix) - Honda Shadow Forums : Shadow Motorcycle Forum

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Old 04-14-2011, 12:29 PM   #1 (permalink)
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Default idle screw (air/fuel mix)

ok, since i have never heard of this adjustment before.. is this the same thing as the "pilot screw"? i know, its a silly question.. but its the only thing i can find in the manual that says anything about altitude adjustments...

They give turns to put the screw at, but they also say to adjust the idle speed to 1000 +/- 100 rpms... how can i do that if my bike doesn't have an RPM gauge?

Sorry, i did a search, but could find one post that would answer my questions... (that and there were over 20 pages for air/fuel mix).

Also, my rear cylinder doesn't seem to be running right at idle, but when i give any throttle, it seems to start working right. at idle, the exhaust sucks in. open the throttle, it pushes out. This is only on the rear cylinder. Is this a sync issue or a fuel/air mixture issue?


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Old 04-14-2011, 01:42 PM   #2 (permalink)
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Someone can correct me if I am wrong since I only have experiences with my VLX.

There is an idle screw that you can be adjusted easily and on my bike looks like a little black knob near the choke. Someone mentioned in another thread how to check rpm's for adjusting it, but I think most people just listen to how the bike sounds when adjusting it.

The pilot screw is for the air/fuel mixture where you need to drill out the caps and then worry about the number of turns of the screw.

Does your bike have a dual carb? This is just from stuff that I have read on this forum, but could the idle jet for the rear cylinder be partially plugged?
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Old 04-14-2011, 01:50 PM   #3 (permalink)
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Originally Posted by Endy View Post
Someone can correct me if I am wrong since I only have experiences with my VLX.

There is an idle screw that you can be adjusted easily and on my bike looks like a little black knob near the choke. Someone mentioned in another thread how to check rpm's for adjusting it, but I think most people just listen to how the bike sounds when adjusting it.

The pilot screw is for the air/fuel mixture where you need to drill out the caps and then worry about the number of turns of the screw.

Does your bike have a dual carb? This is just from stuff that I have read on this forum, but could the idle jet for the rear cylinder be partially plugged?
The idle on the front cylinder is good (sounds good at least)... its the rear cylinder that bothers me and has my mechanic stumped (unless he opens the bike up)... I didn't want to take the carb apart cause its a pain in the backside.... but, i may have to this weekend. should probably sync them as well..
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Old 04-14-2011, 03:54 PM   #4 (permalink)
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Idle screw and idle mixture screws are not the same thing. The Idle screw adjust the thottle plate(s) to increase or decrease engine speed at Idle. The Idle mixture screw or pilot screws adjust the air/fuel mixture from Idle rpm to about 1/8th throttle. Adjusting the mixture screw can affect idle speed, thus requiring adjustment of the Idle screw. BUT, adjusting the Idle screw shouldn't affect the mixture setting enough to casue the need to adjust the mixture.
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Old 04-15-2011, 04:43 AM   #5 (permalink)
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So i took it for a short ride yesterday (30 mins)... there seems to be nothing wrong anymore (or so i thought)..... I was up around 55mph, let off the throttle, then re-engaged the throttle.... slight bog then the engine would catch up... The mechanic said i have only a fuel issue to figure out then i should be A-OK. He also said it would be a waste of money to sync the carbs right now. He recommended adjustment of the rear carb air/fuel mix screw and maybe tearing the carbs apart to make sure nothing is stuck.

opinions?
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Old 04-15-2011, 09:53 AM   #6 (permalink)
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For once I agree with a mechanic.. Wait on syncing the carbs, till it is running correctly and ALL other service issues are resolved. Carb syncing is easy and can be done at home for less than $10. Plenty of write-ups. Home sync using a Homemade gauge is going to be more accurate than a shop sync and save $50-$100.
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Old 04-15-2011, 09:59 AM   #7 (permalink)
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Originally Posted by 93gc40 View Post
For once I agree with a mechanic.. Wait on syncing the carbs, till it is running correctly and ALL other service issues are resolved. Carb syncing is easy and can be done at home for less than $10. Plenty of write-ups. Home sync using a Homemade gauge is going to be more accurate than a shop sync and save $50-$100.
yeah, i read the write-ups like 3 times.. just not sure how comfortable i am with it.. going to try and adjust the air/fuel screw on the rear carb today when i get home.... maybe get my shopping list together for the sync materials, give it a try... worst case, i have to take it to the shop right?
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Old 04-15-2011, 10:58 AM   #8 (permalink)
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Worst case you take it to a shop. The most difficult part of the home sychronization is Getting the fluid into the tubing and establishing a fuel supply. Fuel supply issue, is not a problem for those bikes with the auxilory tank. A/F mixture is alot more difficult to get right than carb syncing..
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Old 04-15-2011, 11:26 AM   #9 (permalink)
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Originally Posted by 93gc40 View Post
Worst case you take it to a shop. The most difficult part of the home sychronization is Getting the fluid into the tubing and establishing a fuel supply. Fuel supply issue, is not a problem for those bikes with the auxilory tank. A/F mixture is alot more difficult to get right than carb syncing..
greeaat..... way to boost my confidence...

I don't have a garage.. i keep tools/bikes in a rubbermaid type storage shed.. 10'x8'.... sucks when i want to do big work.... living in a rental townhome sucks.
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Old 04-15-2011, 11:51 AM   #10 (permalink)
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greeaat..... way to boost my confidence...

I don't have a garage.. i keep tools/bikes in a rubbermaid type storage shed.. 10'x8'.... sucks when i want to do big work.... living in a rental townhome sucks.
I don't have a garage either, I do have a driveway, but its dirt. I lay a tarp down when I work on the bike or Jeep so i don't have to lay/sit in the dirt. My tools are stored in the back of my Jeep. Bike is stored under a cover. 2 sheds are full of crap from the wife and 2 daughters.
I have been known to roll the bike into the kitchen to do work, on rainy days. Try explaining to your wife, why there is a motor leaking oil all over her brand new Glass dining table and the house smells of solvent for a month.
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