No power in 3rd/4th cylinders

[Thenewguy]

Hello everyone, I recently bought an 83 gs 750t with 30000 miles. The problem im having is that the 3rd/4th cylinders are firing. I had the carbs cleaned at a shop. new spark plugs, new air fliter, new battery, new petcock , inline fuel filter and new stator. With the carbs I myself have tried to sync them but im not a professional. If I switch the coil wires from clyinder 1 with 4. 1 will still fire no problem, 4 will not. Same if I switch 2 and 3. 2 will still fire but 3 will not. I repeated that process with the spark plugs and got the same result. Im at a lose of what it could be. Ant suggestions?

[mike_of_bbg]

I think the shop didn't do a good job on your carbs!

Is the bike stock? Do the cylinders come alive if you open up the throttle? Are the plugs wet with gas?

[tlepac]

It wasn't until I broke down and took the carbs apart and soaked the jets---all of them in Gunk for 24 hrs that I got my bike running right. Of course there was also the valve adjustment and the synching the carbs and a lot of general cleaning of electrical connections but the bike is now firing great! Read and follow the Bass cliff site carb rebuild steps and take a bunch of pictures as you tear down ---wish I had--and pay strict attention to detail and you can't go wrong!

Good luck

[chef1366]

Compression on these cylinders?
Fuel on the spark plugs?

[BassCliff]

Greetings and Salutations!!

Hi Mr. Thenewguy,

Yours is a common story. I encourage you to do the work yourself instead of paying some hack to ruin your classic motorcycle. Lots of information here in my "welcome thang". Feed your mind.

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[tdub]

i would say that it is almost certain its still some stuff jammed up in your jets... if you can buy some carb cleaner with a spray tube on it you can take your carbs apart an blast out the jets in the two carbs your having probs with. if you blow on them and you can see some light thru them, they are worth putting back in. when i got my latest gs (79 gs750) i took me taking them apart 3 times and bowing out the jets on non firing cyl. and two inline filters before i got rid of all the gum chunks,rusty deposits and whatever else out for good.
now im not sayin you will have to do it that much but i did and it has run very strong since. gasline antifreeze and fuel added cleaner also can help. if you run the spray in kind and spray it in the carbs that are good and then in the ones that are not good and stall the bike out by over spraying, leave it after stalling for a few hrs and repeat. that can somtimes help aswell with out taking your carbs off... that said i still recomend you tear down your carbs and get to know them as it is a good thing to know for a yearly tune up. its really not that complex