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question about syncing carbs

Old Mar 29, 2010 | 12:33 PM
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question about syncing carbs

Hi everyone.
Was thinking about syncing my new to me 01 firestorm and well I don't have the bike set up for the vaccuum lines (no Honda dealer close) and not sure if syncing would help but figure it couldn't hurt before its maiden voyage.
reason is it idles fine, cleaned carbs, new pilots, but if I throttle up reasonably it revs up fine. If I throttle more aggressively it seems to be lagging on one cylinder. thought maybe tonight with the tank lifted and airbox exposed I could visually watch the vaccuum bodies react to throttle application and make small adjustents as needed to have both carbs react the same. Am i way off base here and should not touch it or had anyone adjusted things in this manner with positive a outcome.
thanks for any feedback if you've been down this road.

Last edited by firedawg1998; Mar 29, 2010 at 12:34 PM. Reason: spelling
Old Mar 29, 2010 | 12:42 PM
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The airbox has to be closed and buttoned up in order to sync the carbs so there is no way to do it without some sort of vacuum gauge.
Old Mar 29, 2010 | 12:59 PM
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oh, thats depressing, I figured I could do this tonight, had the tank lifted and airbox lid removed, was waiting for the little one to wake up before I fire up the twin hindles.
I guess I will just have to take it out tomorrow (just insured it an hour ago) and see how it runs.
Thanks for the reply and probally saving me some grief.
Old Mar 29, 2010 | 02:34 PM
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I doubt you could get anything accomplished visually. Probably just make it worse.
Old Mar 29, 2010 | 03:11 PM
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I searched around the forum, and found reference to a Twinmax carb syncing tool. It seems to be the way to go. I ordered one, but I do not have it yet. I ordered it from the site below, but since they are made in France, you should be able to get one easily (UK?).

http://www.rlmotorcycles.com/cgi-bin....72021&pid=582
Old Mar 31, 2010 | 05:48 AM
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Shockingly I could not resist but to physically look at the carb in motion. Don't twist hard, cause a flame will spit out of the carb and lick your eyebrows. anyways, the rear carb looked a hair more open than the front and the rear plug was quite abit darker than the front. So remembering my setting, I backed off the rear carbs sync 1/2 a turn and the motor smoothed right out and the rpms went up two hundred, yet I backed the carb off. From there I adjusted the rpms down to 1300 and any throttle applications were smooth as butter, no earlier hesitation.
Had my first ride today, what a power house, it has a 43 rear but a slight twist rollin in first to 2/3 throttle and the front end comes a foot off the air until I back out of it. A little more power than my DRZ sm, I think I could really get used to this.
Wanna thanks the folks that helped me set up my first bigbore twin. Zero bog with a .030 needle shim and the 48 pilots make her idle and start real pretty.
Old Mar 31, 2010 | 08:01 AM
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by a fitting for your front carb and attach a equal length vacuum line(to the rear), make yourself a sync tool and sync your carbs for under $10 total. It's easy once you do it once. There are many who have done this.
Old Apr 1, 2010 | 08:19 AM
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I like the way you think! If the synch screw was out that far, that means someone tried to adjust it before and really did it incorrectly. You might be able to do better with some form of vacuum gauge, maybe not. If it is running very well now you could call the job complete.

There certainly is more than one way to synch carbs, the vacuum method being accepted as the most accurate way for everyone to do it (same method with repeatable results). I have read of a guy over on the GS forum who sticks a hose into his ear and points the other end into the air intake stream of each carb, comparing the difference in sound and making adjustments accordingly. This works for him on a 4 cylinder engine.

Originally Posted by firedawg1998
Shockingly I could not resist but to physically look at the carb in motion. Don't twist hard, cause a flame will spit out of the carb and lick your eyebrows. anyways, the rear carb looked a hair more open than the front and the rear plug was quite abit darker than the front. So remembering my setting, I backed off the rear carbs sync 1/2 a turn and the motor smoothed right out and the rpms went up two hundred, yet I backed the carb off. From there I adjusted the rpms down to 1300 and any throttle applications were smooth as butter, no earlier hesitation.
Had my first ride today, what a power house, it has a 43 rear but a slight twist rollin in first to 2/3 throttle and the front end comes a foot off the air until I back out of it. A little more power than my DRZ sm, I think I could really get used to this.
Wanna thanks the folks that helped me set up my first bigbore twin. Zero bog with a .030 needle shim and the 48 pilots make her idle and start real pretty.
Old Apr 1, 2010 | 05:47 PM
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thanks for the responses, just can,t wrench these thing without forum help nowadays. put it through 260 k yesterday, lots of first gear wheel lifts and still pulled 47.4 mpg. very happy its not 35 like others misfortunes, zero bog, but 1500 $ for insurance, traded up today for a 1280$ policy. crazy eh?
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