SYNCing carbs is a GOOD 'thang'

[UncleSpot]

...'went over to Pat Kelly's house last night and he synced his carbs and showed me how it's done - the Clymer book is ok, but there's *nothing* like seeing how it's done right

Pat used a 'vacuum/mercury' device that you 'see' how well the 4 carbs are 'tuned' to each other - GREAT device and it's less than $40 from MOTOworld (there's a shop locally) so I'll be picking one up REAL soon...

we went for a 'test ride' afterwards, and got out on the highway... my bike's *never* been THIS smooth... we were cruising about 80mph when I thought about opening it up a little bit....
POW - my goodness, the bike hit ~6kRPM and went into 'overdrive'! I looked up to notice the speedo was well into the triple digits... Man was I fortunate a cop didn't snag me - when you're going over 100 in 'Can'tAffordYa' that's *automatic* jail time... not good...

...anyway - if you *thinkk* your FOUR carbs aren't 'exactly right' sync them - you'll be AMAZED! I sure am!

[Pat Kelly]

I think cutting off the rotted end of the vacuum hose to the advance and reattaching made a bit of a difference too.

[Dennyz]

I found color tuning has the same impact on the idle and low-end power.

[CRXSi90]

Good to hear, I can't wait to give mine a try! I rode the bike home with a rotted end on the ignition advance hose, wrong spark plugs (2 steps too cold, and recessed ceramic + electrode), and probably some non-firing cylinders. I haven't ridden it since, but it sure runs nice! I've fixed the above problems, but I'm betting it could use a synchronization. I think I'm going to go with the cheap method of putting a hose with a liquid in it on the intake manifold port, between the cylinders in question, and see which way the fluid moves. Adjust the screw until it is even, then do the other two, then the center ones. (1+2, 3+4, 1 or 2 + 3 or 4) It is supposed to be more accurate because the liquid that you have in the tube (water, oil, anything that won't hurt the engine) is sure to be lighter than mercury.

Thats my plan, at least. (although I can see why a mercury set would be convinent)

Kevin

[skids]

Ya, me too. The carb synch is really for idle and just off idle.

Originally posted by Pat Kelly
I think cutting off the rotted end of the vacuum hose to the advance and reattaching made a bit of a difference too.

[pgg]

Runs smoother at speed too.

[Pat Kelly]

At Big Island Deuce there were several bikes had their carbs sync'd.
There was some debate there and in posts as to if they should be sync'd at idle or at a higher speed. I sync mine at 1500 RPM for the following reason.
When sync'd at idle the tension between the carbs is against the stops. I take my RPM's to a little higher and lock my cruis control. This way the carbs are sync'd with the throllte cable pulling on them. I noticed that when set at idle, all even, then broght the RPM's up even slightly, that they were then uneven. The reason for syncing the carbs is for all 4 to share the load equally. I would rather have that equality when I'm riding, not sitting at a red light.
Right or wrong that's how I do it.

[justyn.smith]

Thatks Pat for the clue, I just synced my carbs and noticed that after reving the sync went out. It took 4-5 attempts to get them to stay in sync after a rev. Setting the carbs with the throttle part open (not the idle screw adjusted) makes sense, I'd just be worried about sucking all that mercury into the engine!

[dbyers]

I have never synced carbs and I need to buy a kit. Can anyone tell me a good brand to get that will not break the bank but is easy enough for a rookie to use.

Thanks,

[Pat Kelly]

Raising the RPMs won't suck the fluid into the engine. It's when you let off the throttle that the vacuum draws it in. Just twist slowly and smoothly and you'll be fine. No need to go over 1,500-2,000 RPM.
Some swear by vac gauges (dial type). I have the mercury sticks (environmentally unfriendly). The stick set-up cost me about $40.

[skids]

That is a good point. If you were to synch them at higher rpms, say 3500, then they would be way off in the lower rpms where the synch is really intended. Don't ask how I know! :-)

Originally posted by Pat Kelly
At Big Island Deuce there were several bikes had their carbs sync'd.
There was some debate there and in posts as to if they should be sync'd at idle or at a higher speed. I sync mine at 1500 RPM for the following reason.
When sync'd at idle the tension between the carbs is against the stops. (snip)

[pgg]

Same. With a vac gauge idling at 1000 - 1100, then setting the needles even, at 2000 - 3000 the needles are out - 1&2 verses 3&4. Tweaking the middle screw makes no difference. I last set mine even at 3000. Still idles perfect. Skids, sounds like your bike's not tuned properly.

[UncleSpot]

...if you want to get the same vacuum carb sync setup that Pat Kelly has, log onto http://www.unclespot.com/CarbTuner.html and check this GREAT tool out!

Pat and I synced our SX11s and *MAN* do they run better - and this 'tool' is REALLY affordable! <$50


...you can just order it from Motion Pro (http://www.motionpro.com/index.php) in San Carlos Can'tAffordYa (½ way b/w San Francisco and San Jose)
...there's a section that you can check if there is a dealer in your area...

I'm picking mine up on Sunday -

[Bill__Woods]

I got a sweet set of Carb Synch Vacuum gauges from JC whitney. I will recommend them to everyone, because I am verry happy with them.

[crunchbird]

I have a unit called Carbtune II that is like the mercury setup, but it uses polished stainless steel rods instead of of mercury. Works great. I ordered it online from the UK, and it showed up in just a few days.