Carb Rebuild, now what?

[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.

[tkent02]

Do it again.

Do it right this time.

[nejeff]

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.

[terrylee]

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

[Steve]

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.

.

[chuck hahn]

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.

[Steve]

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.

Thanks, Chuck, I missed that.

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

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

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

.

[chuck hahn]

Steve...link up the VM one too. Its a 78 750 so it should have VM26s.

EDIT....Click here for the VM tutorial.

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf

[TeamDar]

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

[chuck hahn]

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

[robertbarr]

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.

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

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...

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.

[Steve]

Steve...link up the VM one too. Its a 78 750 so it should have VM26s.

EDIT....Click here for the VM tutorial.

http://members.dslextreme.com/users/...rb_rebuild.pdf

Right again, Chuck.

Maybe I just need to turn off the computer and go for a ride.

.

[chuck hahn]

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.

[greg78gs750]

Do it again.

Do it right this time.

summed it up pretty well there.

[JTGS850GL]

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.

Ride while the cloths are washing/drying. Come on... Don't make excuses.