82 GS750E wont rev

[charlie27]

hi,

I recently picked up an '82 GS750E with 1800 miles on it that was sitting for a long time. Major carb varnish so instead of rebuilding the set I picked up a rebuilt set off ebay - 32mm CV for that year.

To date - new oil, filter, air filter, spark plugs, fork oil, lube swing arm pivot, brake lines, tires, battery, etc, etc.

The bike starts up but as soon as I give it throttle it stalls - it wont rev. Same with choke on, off or in between. Just wont rev.

The intake boots are very pliable. I checked compression and all 4 cylinders are very good at 145-150 psi cold.

I am suspicious of the carbs given I didn't rebuild them. What is left to check before sending the carbs back?

TIA

 

[Tom R]

Don’t be intimidated by rebuilding the original carbs... probably your easiest option. That said.... Airbox on or off? Vacuum line from the tank to the #2 carb on? You don’t really have a choke on cv carbs, it’s an enrichment valve that gets its air from under the diaphragm - so I’m not sure if the needle lifts properly when it’s open. Even so, sounds like a lean condition and something is clogged up.... or the airbox is off.

 

[Guest]

Valve adjustment?

 

[Nessism]

Buying some used carbs off ebay and throwing them on your bike with the hope that they will work is extraordinary optimistic. You might want to check the Newbie Mistakes thread and carb rebuild tutorial linked in my signature.

 

[Guest]

Buying some used carbs off ebay and throwing them on your bike with the hope that they will work is extraordinary optimistic. You might want to check the Newbie Mistakes thread and carb rebuild tutorial linked in my signature.

Well one thing, he has two sets of crabs to rebuild for it lol.

 

[charlie27]

Yes airbox on with new filter
Vacuum line connected from cylinder 2
Supposedly reputable rebuild
I have good compression but did not check valve clearance based on compression and low miles
I was going to do that after u real it a bit

 

[jdvorchak]

Personally I'd contact the vendor and discuss it with him before doing anything with those carbs. Reputable or not we all make mistakes. Besides we, and he, have no idea of the condition of the bike. You could have easily overlooked something. Dirt etc in the fuel tank that plugged up something in the brand new rebuild is a real possibility. Since it's new to you and you've never actually had it running and riding there are a lot of variables. Are you letting it warm up for a full 2 minutes or so before trying to get it to "rev". Before I condemned the carbs I'd do a little more checking.

I'd let it warm up with full choke for a couple of minutes or until it starts to stumble. Then slowly reduce choke. These old bikes are somewhat cold natured and first few starts, after getting one running, can be a little touchy until you have a few miles and starts under it's belt.

I owned a 750E for a while and it was horrible when cold. If I let it sit for a week or two I'd have to use starting fluid to get it started. Also that bike had the mechanical advance rusted and frozen. Easy fix just take the pickup plate off and squirt some PB Blaster on the moving parts. They should free up easily. Do yourself a favor and mark the position of the pickup plate so you can put it back on correctly oriented. It's under the front right side engine cover and there is no oil in there so pulling it is a cinch. Seems like most of the old Suzuki's I revive have that problem.

 

[jdvorchak]

My previous comments about the mechanical advance would not cause it to not rev, off idle, as you describe. You would notice a frozen advancer above about 4k RPM and it would not rev to red line.

When you get your 750E sorted out I think you'll find it one of the most fun bikes made from that time period. It handled like a sport bike and acceleration? Like a little rocket.

 

[Guest]

Slides sound stuck
Check part numbers on jet needle and needle jet

 

[charlie27]

sent the first carbs back that were rebuilt by and "expert". Bought another set and cleaned and the bike runs fine. I think the slides were not lifting on the other CV carbs.

 

[steve murdoch]

Congrats on getting it running.
How about showing it off.

 

[charlie27]

here it is 1800 miles. It was a good find. New tires, chain, brake pads and braided lines and brake service, engine service, air filter and lots of disassembly and cleaning along with new carbs as the original carbs were unbelievably gummed up.

 

[steve murdoch]

Nice looking bike.
Great seeing a stock exhaust.

Gotta laugh at the background.....wet suit and surfboards.
For a lot of it is snow shovels and winter tires.