Unable to balance carbs

05-12-2003, 05:58 PM

I'm having probs trying to balance my carbs. The balance adjustment screw seems to have no effect (I hope it's the balance screw, next to the idle adjustment screw.)
In addition, I can't get the bike to idle correctly. It'll either idle 3000 revs plus or not at all. Regardless of weather, Or fuel type, or giving it a hand full when stationary.
The bike is one of the early models (No.617) and at only 8000 miles when I bought her, I guess that she'd been stood idle for some time previously. The bikes never really idled all that well. But general running has deteriorated of late.
Could the butterflies be gummed?
Could the jets do with a clean?
Replaced Choke, open and close cables of late and lubed them well (no sticking apparent)
Any general pointers greatly appreciated.

Gil

gary tompkins · 05-12-2003, 06:47 PM

Sounds like you could have a blocked idle jet, so the carbs might have to come off for a good clean. The other thing to try is draining off the carbs and tank, and refilling with fresh fuel. If the bikes been standing a while the petrol can go off, and water/crap tends to collect in the float bowls which flushing through should purge.

05-12-2003, 07:23 PM

Gaz
your a star gadgie! I'll try it before attempting to balance again.
Regards
Gil

spacemonkey · 05-12-2003, 10:21 PM

After draining, put Motorex ...(****, forgotten what it's called! Motorplus I think??) It's a wee blue botle and it absorbs any water into the fuel, and also dissolves gum residue in the carb. Blast around inside the carb first in every tube you can find internally and if you're lucky you might not have to strip. But don't bank on it...

NattyBoy · 05-12-2003, 11:21 PM

My bikes a similar age & capacity to yours and I had similar problems when I got it. Mate gave it a strip down but one of the screws was seized. Much better but still not 100%. Blasted it with Wynns carb cleaner aerosol though and it seemed to like that for a while..

Nat

06-12-2003, 12:08 AM

Thanks for all replies boys.

06-12-2003, 08:23 AM

Gil,
before you do anything drastic, just check that you don't have an air leak because a small leak will produce these symptoms

good luck

SimonH

06-12-2003, 09:08 AM

Nice One.
Are you talking about the area in and around the air box mounting to the carbs or elsewhere on the fuel/air delivery system. Any specifics would be great as I'm gonna go through this as thoroughly as poss using yours and all the above tips.
Cheers Si.
Gil

06-12-2003, 02:02 PM

Gil

The leak (if any) would be on the engine side of the carbs.

Identical symptoms can be obtained if one of your air screws is loose or if the blanking screw(s) for the carb balancer is either out or missing;

Or there is a leak on the inlet manifold either at the carb mounting rubber or where it joins the cylinder head

The choices are endless I'm afraid!

Simon

06-12-2003, 07:42 PM

Finding an air leak between the carbs and the engine isn't so difficult. With the engine running spray carb cleaner or easy start around the area you might expect could be letting in air, just stay well clear of the air filter. If the revs rise there is a leak.
Mick.

05-12-2003, 05:58 PM	#1
Gil1696 Guest Posts: n/a	Unable to balance carbs I'm having probs trying to balance my carbs. The balance adjustment screw seems to have no effect (I hope it's the balance screw, next to the idle adjustment screw.) In addition, I can't get the bike to idle correctly. It'll either idle 3000 revs plus or not at all. Regardless of weather, Or fuel type, or giving it a hand full when stationary. The bike is one of the early models (No.617) and at only 8000 miles when I bought her, I guess that she'd been stood idle for some time previously. The bikes never really idled all that well. But general running has deteriorated of late. Could the butterflies be gummed? Could the jets do with a clean? Replaced Choke, open and close cables of late and lubed them well (no sticking apparent) Any general pointers greatly appreciated. Gil

05-12-2003, 06:47 PM	#2
gary tompkins 1/2 man - 1/2 pogo-stick Join Date: Aug 2002 Location: Dartford, Kent Bike: M900ie Posts: 7,241	Sounds like you could have a blocked idle jet, so the carbs might have to come off for a good clean. The other thing to try is draining off the carbs and tank, and refilling with fresh fuel. If the bikes been standing a while the petrol can go off, and water/crap tends to collect in the float bowls which flushing through should purge. __________________ GT Fully paid up member of the S.A.S. (Scottoiler Appreciation Society) 27,000 miles on original chain - and still going strong!

05-12-2003, 07:23 PM	#3
Gil1696 Guest Posts: n/a	Unbalanced carbs Gaz your a star gadgie! I'll try it before attempting to balance again. Regards Gil

05-12-2003, 10:21 PM	#4
spacemonkey I see dead people. Join Date: May 2003 Location: Carving a slice thru the braindead masses..(pun intended) Bike: M900 Posts: 1,464	After draining, put Motorex ...(****, forgotten what it's called! Motorplus I think??) It's a wee blue botle and it absorbs any water into the fuel, and also dissolves gum residue in the carb. Blast around inside the carb first in every tube you can find internally and if you're lucky you might not have to strip. But don't bank on it... __________________ http://www.jasperfforde.com/swindon/7wonders.html

05-12-2003, 11:21 PM	#5
NattyBoy Monsterless again for now Join Date: Sep 2002 Location: Wiltshire Bike: M900 Posts: 3,189	My bikes a similar age & capacity to yours and I had similar problems when I got it. Mate gave it a strip down but one of the screws was seized. Much better but still not 100%. Blasted it with Wynns carb cleaner aerosol though and it seemed to like that for a while.. Nat

06-12-2003, 12:08 AM	#6
Gil1696 Guest Posts: n/a	Thanks for all replies boys.

06-12-2003, 08:23 AM	#7
SimonH Guest Posts: n/a	Gil, before you do anything drastic, just check that you don't have an air leak because a small leak will produce these symptoms good luck SimonH

06-12-2003, 09:08 AM	#8
Gil1696 Guest Posts: n/a	Nice One. Are you talking about the area in and around the air box mounting to the carbs or elsewhere on the fuel/air delivery system. Any specifics would be great as I'm gonna go through this as thoroughly as poss using yours and all the above tips. Cheers Si. Gil

06-12-2003, 02:02 PM	#9
SimonH Guest Posts: n/a	Gil The leak (if any) would be on the engine side of the carbs. Identical symptoms can be obtained if one of your air screws is loose or if the blanking screw(s) for the carb balancer is either out or missing; Or there is a leak on the inlet manifold either at the carb mounting rubber or where it joins the cylinder head The choices are endless I'm afraid! Simon

06-12-2003, 07:42 PM	#10
Mick Shaw Guest Posts: n/a	Finding an air leak between the carbs and the engine isn't so difficult. With the engine running spray carb cleaner or easy start around the area you might expect could be letting in air, just stay well clear of the air filter. If the revs rise there is a leak. Mick.