Carb syncing question

well, i was going to sync the carbs on my hurricane.. and i was just wondering what rpm this should be done at I've heard that it should be done at idle, and I've also heard it should be done a 1/4 to 1/3rd of beak tq RPM.. anyone have any info?

thanks in advance :)

I had questions for a long time when i had my 89 Hurricane..i gave up all reasoning and took it to the Pros at Honda...it was a lil pricey but better than i ever would of done on my best day.They Sync'd and cleaned and replaced and tightned. I had 25k on the bike the day i sold it and it ran strong enuff that the buyer asked me if i really wanted to sell it..Sometimes taking it to the Stealer for service isnt a bad thing.....Just my 2 cents.

I think the problem here isn't htat i'm not capable of doing it,, it's just that i need a little more info, and the haynes manual says diddly squat about it

Synching the carbs is basically just to make sure the bike starts up and idles well so you always synch at idle. Make sure you mainain the same idle rpms as you adjust each carb for best results. Synching has no affect on midrange or high rpms.

thank you :)

now i'll post my setup for cheap carb syncing

what I used to sync my carbs was a good 4 foot length of silicon tubing, a Tee fitting to fit, a glass bottle (600 ml- 1000 ml), and an ordinary engine vacuum guage.. I also had a small restrictor that fit inside the Tee to reduce pulsation

connect one end of hose to carb #2 (the one that's directly connected to the throttle cable) cut the hose to give yourself a comfortable length to work with, connect to one side of the Tee, port #2 of the tee should be drilled and sealed onto the cork/cap of the bottle, while the 3rd port connects to your vacuum guage. I had the restrictor on the side of the Tee facing the carb

this should provide you with a nice stable vacuum reading, I found it took about 5 seconds for it to build up the vacuum.. as they say, it's not important what the exact number is, just that all cylinders are the same.. just note what the reading is on carb #2 to start

then switch the vacuum line to carb #1, and adjust it to match, or near match.. the engine speed will fluctuate, and that will change the reading of cylinder #2, so you will have to go back and forth probably about 3 times until they are both identical.. you may also have to adjust the idle stop to keep it running. Then do cylinder #3 in reference to #2... then do #4 also in reference to #2.. when you're all done, just go through them all and make sure they are all the same.. you should be pretty close...

you can use a CHEAP vacuum guage to do this, as long as it is sensitive.. remember it doens't matter how accurate the scale itself it.. just that all cylinders read the same

this setup would cost me about 15$ if I had to buy everything new.. I had everything laying around already. it takes a little longer, but I can't justify 100$ on a tool that I'll hardly ever use

Synching has no affect on midrange or high rpms.

Are you sure about that? Synching the carbs on my bike cured not only rough idle, but cleared up rattling noises and rough running at mid-range and higher, gave cleaner throttle response and in general made it a much better running bike.

well.. I think there's some fuzzy language here.. it makes no differance at mid to full THROTTLE, now if oyu're cruising at 5000 RPM, but only 10% throttle, I think it DOES make a differance

Ed Zachary It generally won't have any affect on throttle positions over 5%. It will help with crisper throttle response off idle -- and when you let off the throttle to change gears you're feeling some positive effects from the carbs being in synch also.

Just out of curiosity, you mind if I ask how much the dealer charged for doing your carbs?

i took mine to a shop $300 for the carbs to be cleaned with includes a resync. but unfortunately they are still not working properly, so back to the shop she will go!

SYNC'N carbs, WHEEEE!!!!!!!!!!!!! I've met some good tuneup people..." I just do'm by ear", Walk away and giggle. NObody can get'm as close as a gauge, by ear, feel ,smell or "the force" !!!!!!!!!!!!! may I speek freely, of just another episode of, "i'd like to learn how to do that"!!!!!!?????

WARNING********* If you have or get mercury gauges(carb stik type)... any mercury, is to be treated w/ respect and safety guidlines!!!!!!!!
Dont leave merc "open" to the atmosphere, plug the ends of the tubes,when finished. this stuff boils off like steam, off a kettle. At room temp.

Don't suck on the lines for fun !!!!!!!!!

Dont heat it up... NO mr. science projects !!!!!!!!

don't pour it into your hand. Or try to pick it up. Unless you have to dispose of a spill... I believe it is illegal to just thow away.

NASTY stuff, exspensive (at a compound pharmacy)

Ok, I about(did) geek'd, when I sucked the merc resivoir dry, on my first atempt at sync'n, afew calls revealed... A. Nobody knew where to get more/any. B. Nobody knew if I just wasted my engine... Answers...
A. compound pharmacys. (they make drugs out of bulk ingreadiants) after he realized I was serrious, he said "180$, and 2-3 wks"!!!!!!! thankyou, bye. I called auto/racing, bike shops, people just confusidly giggled. One place, I called said," my brother, the gold prospector, has a bunch" EURIKA !!!!!!!!! also people who decomision thermostats(electritions and contractors) have to account for the Mec switches, and usualy have a bottle of it around. My new gold miner friend, thought it was a novel use and filled up my tictac size resivoir, for free. Thanks Clint !!!!!!

OH, YA...B. Hey, it went in my engine,****!!!!!!! No worrys!!!!! It dosen't hurt a thing, maybe a lb., would tho...
Keep that resivior phisicaly as low as possible,and the lines verticaly,as tall as possible, (my 1st mistake) and don't "gun the engine"(2nd mistake!!!!) no need, gently bring up the R's a couple 100, if needed, to resettle merc levels... Or bye bye !!!!!!!

One piticular local tunning legend, did a vw (only two carbs)for me...w/o gauges. he was off 3inches,(merc levels) when I took it home to validate/check!!!!
the sync, is a real improvment for throttle crispness, and should only be done at a idle, as chainstreatcher says. I do believe, if your sync is somewhat/really uneven, it helps to put them in eveness, all through the rpm range, but off idle, crispnes is mostly, what this is about.
Usualy one carb is static(unadjustable) and you would sync, the others to it.

Warm up the bike, set a large voulume fan,at the radiator.I set rpm, w/ a remote digital tac only. then sync, then readjust idle, then adjust the air bleeds, then finnish sync, then set idle again, checking the remote tac, and sync levels, all the time Gently blipp'n the R's, a couple hundred , every once in a while. It takes a few trys, work'n through the adjustments, to cordinate them into the sync, but you can do it, w/ patiance, and logic.
I use petrol. jelly on the o-ringed tubes, that you screw into the manifolds, to preclude air leaks... make sure you intakes are tight and your air box connections, as these"anchor" your carbs, befor you start.
I did a friends 92 vt 1100, in less than 10 min, yesterday, it perked right up!!!!!!!!!! (off, about 3"!!!!) and just two cyl.!!!!!!!!!

I've got a few bikes... and as everbody i know, could benifit, from a sync... I bought the 100+$ mac tool carb screw adjusting tool. Thumb wheel on one end, 1 1/2"bent, 55 degree 1/4" male socket end, the other. W/ 14'', between !!!!!! a great assortment of ends to fit all kinds of adjusters, including allen heads. WHOLE HEARTEDLY RECOMENDED, if you can swing it. They are truley horrible to reach w/o it, on most bikes, no ratchet slop, slipp'n off... sceamming !!!!!!!

I was amazed at the smooth take off response, after my first finished sync job. Have fun!!! Clean an