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1980 GS750 Carb issue

  • Thread starter Thread starter daWrench
  • Start date Start date
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daWrench

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I have a 1980 GS750 that has been stripped down and is basically tires, seatpan, and engine. I've gone threw the carbs and cleaned them, put them back on and now she will start on either and idle. She will not rev up though, soon as you rack the throttle she dies. I've never messed with vacuum carbs before so I'm lost, Its like she's not gettin any fuel over idle. Can someone help? I have detailed pictures of the bike on myspace, my myspace url is...( www.myspace.com/daWrench1963@yahoo.com)
 
Did you change the O rings on the carbs & the O rings on the intake boots? Is the airbox on it as that will cause a problem if not. Make sure it's well sealed.

Are the diaphragms in good condition with no holes?

Did you remove all the jets & clean them etc as some will not unblock without removing them.
 
same thing happened with my bike. you need to tune it a bit. turn the mixture screws in and turn them out 2 turns. let the bike idle then back them out slowly until the rpms stop going up. then adjust the idle speed screw to proper idle.

one thing to try before you do that ^^^ let it idle and blip the throttle. (does blip and rack mean the same thing?) do the rpms go down or up first? if they go up, does it come back slowly or smoothly?if it comes back slowly, its lean. smoothly is OK. if it goes down first, its running rich.

P.P.S. make ABSOLUTELY sure your pilot circuits are clean. i "cleaned" my carbs like 6 times before i got that last piece of grime out.

P.P.P.S. airbox sealing is good too, just as salty monk said. silicon caulk is what i used. on top of the air filter and the two side caps.
 
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Dang! I went threw the carbs but not well enough. I looked at the carb clean thing that is posted on this site and printed it out. I'm gonna go back threw them again, the proper way! No air box, I want to run K&N pod filters, is that an issue???? At idle if you pull the throttle while at idle she dies, no up or down just dies!!! Spray either in it with throttle wide open she revs great but nothing after that. The bike is striped down and bobbed out, but no cutting to fram. Basically tank, seat pan, and tires! No rear shocks, no fenders, just struts and a side tag mount.:-sThanks, ya'll are helping!!!
 
PUT THE CAN OF ETHER BACK ON THE SHELF!!! :shock:

It is far too easy to get carried away sprayng ether and the results can be catastophic. :oops:
If the bike is that hard to start when it's cold, it likely needs the valves adjusted.

First of all, your problem when you "rack" (blip) the throttle is that your airbox is not installed. You need something on the intake side for a bit of restriction. A stock airbox is best, but individual pods will also work. Keep in mind that you will likely have to re-jet the carbs to compensate for the extra air that will be flowing through the less-restrictive carbs.

If you just want to prove that your carbs are working without the hassle of installing the airbox, fold a shop rag in half, spread it across the opening of the carbs. Use nylon zip-ties to hold it to the mouths of #1 and #4. This should stretch it nicely across #2 and #3, too. Now the engine will be responsive enough to even take it around the block for a test ride. Note that this setup is NOT a good enough restriction to gauge the effectiveness of jetting changes, it only smooths the airflow enough to let the bike run.


.
 
Alright, good I can run pod filter's. I knew that jets were in order for proper tuneing but I'm just tryin to get ol' girl running again. The bike sat for a couple year's out side before it was given to me. It doesn't even have 90% of the wire harness, I've got the ignition strait wired to see if it would fire off. It did first try once I found the right wires. Oh yea, no mufflers! I realize jets are a prioraty. I tried the rag thing already.
 
Jeeez. 90 percent of the harness is missing? Id be worried bout more than jets...
 
Why! Nothing is going back stock, and its not the wireing keeping it from running either! At idle the timing is working and the chargeing system is chargeing. I'll figure out lights and a horn later!
 
Get K&N pods and a Dynojet jetting kit. Without the Dynojet you'll be pulling your hair out trying to jet it right.
 
Thanks again guys. I'm gonna get these carbs striped down and back together, order some pod filters and get this beast running! Dynajet kit huh? I'll see if I can get one and jet it accordingly. Thanks!
 
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