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post #1 of 29 (permalink) Old 06-26-2006, 11:21 PM Thread Starter
Grand Prix 125
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After removing my AI, I started to notice one pipe bluing a bit more than the other. Pulled the spark plugs and one side's burned a bit hotter than the other too. Decided to sync the carbs.

I've got a California bike, so it's got an evaporative loss system. General instruction (for all bikes) in the tech manual says to take the rubber caps off at the take-off points on top of the intake manifolds. My bike (2006 Bonnie, purchased new) has vacuum hoses here, not rubber caps.

lt also says (in bold) that for California bikes, I should disconnect the evap loss system hoses from the *carb* take off points and plug the hose ends.

So, two questions:

1. The *carb* take off points - are these located on the carbs, facing up, about three inches behind the intake manifold take-off points? (I assume this answer is yes, but I just want to be sure).

2. Should I be connecting the vacuum gauges at the intake take-off points and just plugging the vacuum hose that I pull off the *carb* take off points to do the test? If this is the case, then what happens to the vacuum I'm testing for, once the vacuum hose is off the carb (when I pull the hose off the carb, doesn't that screw up the vacuum)?

And no, I haven't been drinking...yet.

Thanks for the help!
Jim
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post #2 of 29 (permalink) Old 06-27-2006, 04:13 AM
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Just put the plugs on the carb "take off" points and do the vacuum reading on the intake manifolds.The balance will be out cause the A.I. runs off the vacum from the left manifold.After setting up corectly reverse the hoses on the cylinders(left to right, visa versa) to allow for any inacuracy in your gauge.
I would be tempted to take the Californian evap ststem off and just put plugs back in afterwards,I sure no one else will know.

2018 Bonnie T120, X Pipe and Togas, 39 tooth rear, progressive fork springs, Bitubo WME +10mm shocks, Floating Brembo Discs, Dart screen, Barend Mirrors, Outex tubeless conversion, etc. etc.
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post #3 of 29 (permalink) Old 06-27-2006, 10:52 AM
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1. Yes
2. I can't tell any difference on mine between the intake and carb take-off points for balancing the carbs. I believe I would do the balance with the vacuum hoses disconnected; therefore, it would be easier to use the vacuum takeoff ports where the hoses were connected ( I believe that's what amanger said). Once you pull the hoses off the carbs, you have disabled the AI and CA emissions systems--don't worry about it for the carb balancing. What you are doing is setting the carbs so the slides are working exactly the same amount for a given throttle setting. Since you have the CA equipped bike, your vacuum between the two carbs is probably closer to equal when the system is connected than ours is with only the AI system connected to only one carb. Good luck with the adjustment screw--not the easiest to adjust and could be much easier if Triumph had used a hex or Torx screw with more threads/inch (still having a hard time thinking in terms of mm and pitch on metric screws).

Pipe blueing: I have never read where anyone has said their pipes blued the same on each side--with or without the AI system (doesn't mean it hasn't happened). I have read where many have said the left side (if my memory is correct) blued more than the right side. If I were going to worry about pipe blueing in any way, I would have the headers black ceramic coated and forget about worrying.

Larry

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2003 T-100 (790cc), NARK, NH Togas, 8100 rpm rev limiter, 158 main jets, 42 pilot jets (less than 1 turn out on pilot screws), stock needles--no shims. 13 A/F ratio from 1100 rpm to 4000 rpm; 12 A/F ratio from 4000 rpm to 6000 rpm; 13 A/F from 6000 rpm to 8100 rpm.:D
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post #4 of 29 (permalink) Old 06-27-2006, 04:04 PM
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Just out of curiosity, what readings did you get? I got an average of 27-28 psi at idle with a el cheapo gauge taken at the intake manifold, with the other plugged while the test one was hooked up.

My bike has been missing at 4-5 in high gear at light throttle settings, plugged the plugs and they were black!

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05' Y Thruxton...sold
05' B Thruxton...sold

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post #5 of 29 (permalink) Old 06-27-2006, 04:44 PM
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I don't think you need to be too concerned with the specific vacuum reading (how hi/how lo). What you're concerned with is that they both read (or can be balanced to read) the same at idle.

Now if there was a vacuum leak in one of the manifold rubbers, or one of the vacuum plugs was split, you'd probably see excessively low vacuum on that carb.

But if everything is buttoned up and there's no leaks, balancing simply assures that both carb butterflys are essentially open the same amount relative to each other, and that both carbs are 'seeing' the same amount of draw or vacuum from the engine.
Bob

GBNF: 03 T100 Luc Org and Silv: 122/42 jets, TORs, 18T, UNI filter, no AI, Polaris bellmouth, Metz 880 tires, Prog. 440 shocks (105/150 springs), 11-1124 frk springs, Thrux frk caps, gaiters, MotoTwin bars, 6024 lamp, htd grips, 12v outlet.
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post #6 of 29 (permalink) Old 06-27-2006, 10:52 PM Thread Starter
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My take too on this is that the pressure level isn't important, just that they're balanced. But since ya asked, I'll post tomorrow, when I actually do the work. (Got home too late tonight to get it done).

BTW, thanks for all the helpful responses. Makes it a lot easier to dive in and get it done...

Jim
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post #7 of 29 (permalink) Old 06-28-2006, 01:12 AM
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Whats the current favourite device for balancing the carbs,
Here in the UK, Carbtune is recommended a lot.

Anyone still do it by ear?
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post #8 of 29 (permalink) Old 06-28-2006, 03:41 AM
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15 ft clear fishtank hose same diameter as the vacum plugs(or slightly smaller) Find the exact centre,lenghtways,tape to a 4 ft bit of timber about 2" wide.Hang above bike height with loop at botom with enough liquid,preferably something that is nt going to harm your engine,ie. fuel injecter cleaner.Plug each end to manifold plugs.Start bike on fast idle.Adjust using very short screwdriver and much cursing till liquid is level on both sides of loop.Take off hoses and swap left to right.Takes about 15 min. Cost about $2-$5.

2018 Bonnie T120, X Pipe and Togas, 39 tooth rear, progressive fork springs, Bitubo WME +10mm shocks, Floating Brembo Discs, Dart screen, Barend Mirrors, Outex tubeless conversion, etc. etc.
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post #9 of 29 (permalink) Old 06-28-2006, 06:50 AM
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I use the 'fluid tube' you described, and it works very well.

If anyone here wants the plans, I'll post the link to a BMW Airhead site that provides it. I made mine a couple of months ago, and used it to balance the T100, W650, and will use it on the old Beemer shortly.

Bob

GBNF: 03 T100 Luc Org and Silv: 122/42 jets, TORs, 18T, UNI filter, no AI, Polaris bellmouth, Metz 880 tires, Prog. 440 shocks (105/150 springs), 11-1124 frk springs, Thrux frk caps, gaiters, MotoTwin bars, 6024 lamp, htd grips, 12v outlet.
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post #10 of 29 (permalink) Old 06-28-2006, 09:03 AM
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Quote:
On 2006-06-28 05:50, ohiorider wrote:
I use the 'fluid tube' you described, and it works very well.

If anyone here wants the plans, I'll post the link to a BMW Airhead site that provides it. I made mine a couple of months ago, and used it to balance the T100, W650, and will use it on the old Beemer shortly.

Bob
Yes I'd like link to the plans please - perhaps we should make it a WIKI :wink: :wink:
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