[Hank is Here]

How can you tell if your carbs are out of sync from running a bike on the street? Currently when I hit the throttle if I have been sitting at a constant rpm in the powerband for a few seconds it feels like it give a little power and then the rest of the power comes a half second later. What could cuase this?

 

[GraVitY]

Carbs are out of sync. Mine did the same thing as well as a different vibration feeling in the pegs. Sync and you're all set.

Grav.

 

[tyger508]

how many miles you guys have on your bikes when they started doin this?

 

[Hank is Here]

how many miles you guys have on your bikes when they started doin this?

I have just over 11,000 miles. The bike was rejetted to 152.5 mains with no shims before I bought it (also desnorkled filter and full exhaust). I have put on at least 7000 miles without touching the carbs. Ionly get about 39.7 mpg now so maybe syncing them will do some good.


BTW nice jeep. Is it a FC150 with the F134?

 

[RandyO]

carb sync is recommended every 7500 miles in the owners manual... my experence... it needs to be done every 7500 miles

 

[tyger508]

how many miles you guys have on your bikes when they started doin this?

I have just over 11,000 miles. The bike was rejetted to 152.5 mains with no shims before I bought it (also desnorkled filter and full exhaust). I have put on at least 7000 miles without touching the carbs. Ionly get about 39.7 mpg now so maybe syncing them will do some good.


BTW nice jeep. Is it a FC150 with the F134?

it sure is, four on the floor, 4WD, 75 ponies, and 115 lbs of tourque. We just got it completly reconditioned so no more driving on the dunes of cape cod and flipping her over! Its a great classic though, i love driving it.

I bought my bike with 9K miles on it, and now it has about 14.5K, its still running great but i guess a carb synch is in order soon if thats what the owners manual says.

 

[japgen]

carb sync is recommended every 7500 miles in the owners manual... my experence... it needs to be done every 7500 miles

My 2001 has only 2600 miles....could the carbs be out of sync? I notice a little herky/jerky hesitation at mid rpm range. Not sure if it's a carb problem, or maybe clogged fuel filter. I have just changed plugs using NGK CR8E, and it made no difference. Bike starts fine and generally runs ok, just this jerkiness. What else could it be?

 

[andyauger]

Give it a shot

Your mileage sounds about right for the modifications. Hesitation sounds more like a mixture transition problem than synchronization problems, but synching is free, and easy. Also, the basic rule of thumb when troubleshooting is to start with the basics. So check your synch, your plug appearance and condition, your ignition wire condtition, rubber boot condition and installation (don't want any vacuum leaks), etc., before digging into the carburetors.

 

[avc8130]

Out of synch is usually characterised by a slow return to idle when you blip the gas. Jerky performance in the midrange could be out of synch, bad plugs, lean on the needle...host of others.
ac

 

[durx]

What RPM do you sync at?

 

[Northwind]

Where is the hesitation most obvious? A hesitation between 4500 and 6500rpm usually means you're slightly lean... Worth synching anyway, I do it every time the tank's up just as a matter of course, and while it never needs much of an adjustment it always wants a little.

 

[andyauger]

Always do the easiest things first. If you set up as recommended in the Tips 'n Tricks section synching is very easy indeed. I use a pair of vacuum gauges with in-line orifices to dampen out the bouncing in the gauges. The orifices are available at auto parts stores where they sell their tubing. They look like in-line connectors but have a brass insert.

I synch at anything off idle. 2,500 to 3,000 RPM is a good place to do it.

Vibration is the best indicator, but when in doubt just check the synch. Again, if you have tubing set up as in Tips 'n Tricks you can verify synch in about 2 minutes. If they're out of synch you'll have to raise the tank, no big deal.

 

[robdleejr]

got my 01 back in december. bike had 4300 miles on it last weekend, I think, when I did the carb synch. using a fluid gauge, the carbs were out of synch by several inches. my buddy said they were quite a bit off. no surprise since when i drilled out the brass plugs covering the idle mixture screw, i found the rear was turned out .5 turns while the front was out 2.5 turns. bolts overtorqued, etc...i don't trust the factory anymore. :-\ 

r