Author Topic: Carbs will not stay synced (Read 1621 times)

friedfish80 · « **on:** April 30, 2010, 07:02:58 AM »

It all kinda started about 3 weeks ago. Bike was running awesome. Then my girlfriends brother ran into a dumpster with it and it all started to go down from there. Im amaised that the only issue with it was a busted up headlight. That was a quick duct tape fix. (fans of the red green show know how this goes) A week later I get a total bog down of power. I limp it home and parked it. Due to life and bad weather I haven't been able to get to it for 2 weeks. Hooking up my morgan carb tune I find the carbs are out of sync. Spending my time getting them all in order I button it all back up and go for a ride. Bike runs awesome! For 7 miles. Then I got that total bog in power. I Get it back home again and hook up the carb tune again and sure enough there out of sync again. I set them again and go back out. I think i only made it a mile this time and it all goes bad again. Ride back home and park it. Time to go to work. I get home and sync them again and all is well. I run it for about 10 min as im chatting with my neighbor and then go out. I don't even get out of the apartment complex and it gets out of whack again.

I have never had this much of a issue keeping them synced with my bike or any other of my friends bikes I worked on. I understand that im doing this from memory and im gonna look it up really quick in the book now. But its 1.5 turns out from bottom with the air screws and then the adjuster nut on top of the carb with the carb tune hooked up. Im sure the floats are fine being that its just the air flow threw the carbs thats out of whack. Im not leaking any gas or have any rideability issues when things are working right.

O sorry. 76 750F with a 78K motor in it. 4-1 exhaust running open and pod filters. I know this is the wrong setup according to the board but the bike has ran like a top with this setup for the 3 years I have owned it. Never a issue before keeping it in tune.

flybox1 · « **Reply #1 on:** April 30, 2010, 07:17:18 AM »

(yoda voice) A delicate balance inside the carbs there is....hhMMMMMMMmmmm

first thing i would do is think something dislodged inside the tank and made its way into carbs.
you are assuming the carbs are still perfect inside....pull them and make sure.
clean and inspect everything. bench sync them again. you just might find something...

friedfish80 · « **Reply #2 on:** April 30, 2010, 07:19:55 AM »

I dont think anything got into the carbs. I run a inline filter before the carbs

Ayrity · « **Reply #3 on:** April 30, 2010, 07:23:04 AM »

sounds to me like it is probably something either gas flow related, or something dislodged as another poster said, maybe in the carbs. I would take the carbs apart and check the float height, they could have been bent way out of line by a hit, and I have seen a jet get half knocked out of its seat by a small accident, so check those too. other than that, you checked for spark? checked to make sure youre getting fuel flow out of the petcock and your fuel lines are not kinked? Could be youre just starving the engine of fuel, and if one of the lines is kinked or blocked it would throw your carb reading way out of whack.

friedfish80 · « **Reply #4 on:** April 30, 2010, 07:43:59 AM »

Ok guy. I ripping the bowls off now. I'll report back in a bit.

Bob Wessner · « **Reply #5 on:** April 30, 2010, 08:03:00 AM »

You might want to check for vacuum leaks between the carbs and head also.

friedfish80 · « **Reply #6 on:** April 30, 2010, 08:16:12 AM »

Quote from: Bob Wessner on April 30, 2010, 08:03:00 AM

You might want to check for vacuum leaks between the carbs and head also.

sorry I forgot to mention I hosed it all down with carb spray looking for leaks.

kslrr · « **Reply #7 on:** April 30, 2010, 08:31:51 AM »

Also check for loose valve tappits. Carb balance has to do with air flow, and the valves control air flow.

Ayrity · « **Reply #8 on:** April 30, 2010, 08:43:22 AM »

oh also, remember to balance the carbs after doing the tappets AND after the bike is warmed up

Duke McDukiedook · « **Reply #9 on:** April 30, 2010, 09:13:52 AM »

And tappets are checked with the engine cold.

Ayrity · « **Reply #10 on:** April 30, 2010, 09:16:04 AM »

good clarification dukiedook, I knew there was a better way to say what I meant haha, need to be more direct with my advise...

friedfish80 · « **Reply #11 on:** April 30, 2010, 09:25:32 AM »

Tappets were check after the crash. But i have had issues with them looseing up lately. ill check them out once it cools off later.

Got the bowls back on and now im pissing gas and can only get .1 mile from my garage before it all goes bad.
I never have a problum with it on the stand. just once i get on the bike.

friedfish80 · « **Reply #12 on:** April 30, 2010, 04:58:17 PM »

Well ripped off my carbs and gave them a good cleaning. Adjusted the valves and thats all good there. It started to rain so i ran it into the garage. Threw the tank on and im now fuel is now dumping out out of the sides of the bowls now. Im gonna try pulling them off again and put new gaskets on, sync the carbs and see what happens now. but it started good and reved well, for a min and then went to crap. Have in mind i dident sync the carbs yet. No need to since im gonna take the carbs back off.

About 24 hours of work now in the bike and im slowly starting to work backwards now.

BeSeeingYou · « **Reply #13 on:** April 30, 2010, 08:19:30 PM »

If you have fuel leaking out of the carbs it sounds like a problem with the needle valves and or floats. Either a leaking float or a bad seal or junk on the needle seat is not shutting off the flow of gas when it reaches the proper level in the bowl. The proper level should also be below the gasket.

friedfish80 · « **Reply #14 on:** April 30, 2010, 08:33:12 PM »

Honestly float height is something I have never checked. Nor do I know how to check. I'll look that up and get back at it again. Thanks all for the insite. It's getting very fustrating to be doing all this work and get nowhere. Sometimes it feels like I'm working backwords and my fustration blinds me from other things that may also be a cause.

seaweb11 · « **Reply #15 on:** April 30, 2010, 08:36:34 PM »

Man, you are a keener

I would have had a nap by now

Good luck, interesting reading.

BeSeeingYou · « **Reply #16 on:** April 30, 2010, 08:59:05 PM »

try and get the fuel leaking dealt with first. I am guessing you have the 78 carbs along with that engine. They do have a different setting than the 75F carbs and they are a bit different overall. It seems unlikely but check your floats to make sure they are floaters by holding them up to your ear and shake them. If they leak you may hear a little sloshing. Eliminate one thing at a time. Get the needle valve out and put a little carb cleaner on a q-tip and clean the seat and needle tip. Then set your float level. Make sure they are in right side up as on some of these carbs they can fit in either way.

friedfish80 · « **Reply #17 on:** April 30, 2010, 11:42:20 PM »

Quote from: seaweb11 on April 30, 2010, 08:36:34 PM

Man, you are a keener I would have had a nap by now
Good luck, interesting reading.

have had many naps and gone to work all in this prosses. I haven't worked the 24 hours threw. More like 6-8 hours at a time.

But I have gotten so good at setting up my carb sync. I can do it in it feels
like under 5 min and I don't have to really remove the tank compleatly from the bike

friedfish80 · « **Reply #18 on:** May 04, 2010, 05:40:33 PM »

Got it working!

stumped all of you along with me too. I went and set all the valves. Checked the floats, resealed the cabs bowls and started to notice that it was only running poorly when i put the tank on. Then i felt a shock from the tank. The tank was shorting out on the frame. Ended up being a butt connector on the coil was undone and touching the tank. plugged that back in and it runs great now. I just need to replace the broken pull cable and im all set.

I have a jump in the throttle from time to time now. I cant seem to narrow it down to anything in particular thats going on. totally a random thing. But as you ride all you got to do is pull in the clutch and rev it and its fine. Im guessing its the broken pull cable. The cable is fine itself. Its just end part that mounts to the carb itself with the adjuster nuts on it snapped.

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Author Topic: Carbs will not stay synced (Read 1621 times)