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Carb Rebuild, now what?

  • Thread starter Thread starter gbrown
  • Start date Start date
G

gbrown

Guest
OK, I cleaned and rebuilt the carbs on my 78 GS750 and just got everything back together. It starts and runs on full choke, but dies if I start to close the choke or twist the throttle. Full disclaimer:

1. I dipped the parts and fuel bowl and carb top, but did not disassemble the bodies from each other. I used an entire can of carb spray and my air compressor to clean the bodies. I reassembled with new o-rings and gaskets. I also replaced the intake boot o-rings.

2. I installed new properly gapped plugs.

3. I installed a new air filter and painstakingly sealed the air box with weatherstrip.

4. I emptied the fuel tank, removed the petcock and cleaned both with carb spray and compressed air.

As I said, the bike starts right up (repeatedly), but dies if I shut the choke or twist the throttle. Additionally, for whatever reason, I checked the header and 1 and 4 are much cooler than 2 and 3. I'm not really sure where to start adjusting. Any help is much appreciated. Thank you.
 
If your bike runs on full choke (extra fuel) it stands to reason something is effecting your flow when off choke. If I had to guess the jets were not cleaned correctly. You need to go through each and every jet carefully. I just did rebuilt a set of carbs and after two weeks in carb dip the some of the jets were still plugged. It important after dipping to verify they are actually open.
 
Know it's a bummer but they're right, sometimes it takes poking jets with proper sized wire after removing and soaking to get them really clean. terrylee
 
You need to start by ensuring that all the jets are open.

When you KNOW that ll the jets are open, assemble the carbs and bench sync them.

When the bike is running (warmed up, off-"choke"), do a vacuum sync.

When carbs are synchronized, fine-tune the mixtures.

.
 
Steve and Terry..Note he DID NOT dip the bodies. He only used carb spary and his air compressor. So for all intended purposes he didnt do squat to them but waste air and carb spray.

They need fully torn down and the tutorial followed to the letter.
 
chuck hahn said:
Steve and Terry..Note he DID NOT dip the bodies. He only used carb spary and his air compressor. So for all intended purposes he didnt do squat to them but waste air and carb spray.

They need fully torn down and the tutorial followed to the letter.
Click to expand...
Thanks, Chuck, I missed that. :oops:

I saw the "I cleaned and rebuilt the carbs ...", then "I dipped the parts ..." and sort of filled in the blanks.
icon_shrug.gif


I should have read what was written, not what I wanted to see. :-\\\

Note to gbrown: Start over, do it RIGHT. (click the link) :cool:

.
 
When I worked at a Honda/Suzuki Dealership as a service tech we got hundreds of bikes come in that wouldn't run. The repair order just said "get to run". These customers didn't want to pay for a $400 carb rebuild. Most racks were never broken down and soaked. All the jets and air/fuel screws were removed and soaked. The needles and seats were cleaned/inspected. O-rings were only replace if they were shot. The floats were checked and seldom had to be reset. All the passages in the carb bodies were douched out with Honda carb cleaner making sure that the cleaner passed through the passage and came out were it should. Used carb cleaning wires to clean pilot jets along with spray. Reassembled, synced, and test driven. I never had a comeback. Was this the right way to do it? Probably not, but if you knew what you were doing the outcome was the same and the customer was happy and still had some bucks left to buy some overpriced Honda/Suzuki oil so they could go home and change their own oil and not feel like a total moron cause they couldn't get their bike to run. Dar
 
Heres the link to cycleorings.com The owner is a member here named Robert Barr. Get the VM carb kit and go to page 3 and select the 32 MM carb intake mainfold orings. While the carbs are off, remove the manifolds and replace the orings there also. Soak the dog snot out of the bolts with some PB Blaster or other penetrating oil a few times.

And we suggest using an impact driver with the right fitting bit to loosen them. press in on the impact to assure a good firm hold and give them a good smack ( Being sure the impact is set in the off positioin of course ).

Replace the phillips head with some allen heads and youll never be worried about stripped screw heads again.

http://www.cycleorings.com/VMkit.html
 
TeamDar said:
When I worked at a Honda/Suzuki Dealership as a service tech we got hundreds of bikes come in that wouldn't run. O-rings were only replace if they were shot.
Click to expand...

Now, that's the most vulgar thing I've ever heard.:-\\\

TeamDar said:
Was this the right way to do it? Probably not, but if you knew what you were doing the outcome was the same and the customer was happy...
Click to expand...

Actually, who's to argue with results that work? As long as it's safe & isn't likely to leave some rider stranded in traffic for some reason.

I think the situation on this site is that we have umpteen people who take shortcuts -- understandably, usually -- and then return for advice. The standard advice, of course, is 'Do it properly from top to bottom', which is the only way that person is going to have a baseline.

At least at the dealership there's a mechanic / tech who's going to test the bike to see if it needs a more thorough approach.
 
Last edited:
I hear you!! Just got the first cup of coffee down, but sadly I need to do laundry so I have work clothes for the morning.
 
Come on guys... Just got back from a 1 hour ride on the 850 and now need to go to work. Going to take the other bike out for that. Such a pretty day here it would be a shame for me not to get out and ride.:dancing:

Ride while the cloths are washing/drying. Come on... Don't make excuses.:-\\\
 
Duffel bags and bungee cords.
I use a laundry mat.
I do not always use the same one or even in the same town.
Different laundry mats = different roads to ride while waiting.
Have been caught in some downpours on way back home though.
Usually just the top layer wet again.
 
TeamDar said:
When I worked at a Honda/Suzuki Dealership as a service tech we got hundreds of bikes come in that wouldn't run. The repair order just said "get to run". These customers didn't want to pay for a $400 carb rebuild. Most racks were never broken down and soaked. All the jets and air/fuel screws were removed and soaked. The needles and seats were cleaned/inspected. O-rings were only replace if they were shot. The floats were checked and seldom had to be reset. All the passages in the carb bodies were douched out with Honda carb cleaner making sure that the cleaner passed through the passage and came out were it should. Used carb cleaning wires to clean pilot jets along with spray. Reassembled, synced, and test driven. I never had a comeback. Was this the right way to do it? Probably not, but if you knew what you were doing the outcome was the same and the customer was happy and still had some bucks left to buy some overpriced Honda/Suzuki oil so they could go home and change their own oil and not feel like a total moron cause they couldn't get their bike to run. Dar
Click to expand...

I was a tech myself, almost exclusively working on H-D bikes. What your saying is 100 % accurate and my experience as well although we DID charge for a full rebuild + parts whether or not we actually used them or not. If we touched your carburetor you paid for a rebuild & kit, period. NEVER dipped a body, not ever, until I worked on a GS1000 about a year ago for a friend which is how I ended up on the site. Full dip is the way to go but if you go in for service just know, whatever you ride, your going to get the minimum service needed to correct the issue
 
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