Irratic idle...

[BassCliff]

Hi,

Send an email to Robert Barr. He's the (http://cycleorings.com) guy. I'm not sure of which screws you're talking about but he will be able to answer your questions.

Have you also replaced the intake boots and/or the intake boot O-rings? They are a common source for air leaks which cause an unstable idle. The thing is, to ensure proper operation you pretty much have to do it all - clean carbs properly, air tight intake and exhaust systems with no leaks, float height, proper jetting, bench sync, valve adjustment, vacuum sync, etc. If you don't know the complete history of the bike it's always a good idea to take care of all of the neglected maintenance from the last 20 years so that you have a good starting point for further troubleshooting.

And so you know, Dynojet and Mikuni use different measuring standards for their jets so you can't do a side-by-side comparison. There is a conversion spreadsheet calculator on my website (Thanks salty_monk!) and conversion charts all over the internet (http://www.jetsrus.com/FAQs/FAQ_miku...ihin_sizes.htm). Basically, the Mikuni jets are measured by the volume of gas passed (), i.e. a 130 Mikuni jet will deliver 130cc of fuel per minute. The Dynojet jets are the actual diameter, i.e. a 130 DJ has a 1.30mm orifice. A 130 DJ is smaller than a 130 Mikuni.


Thank you for your indulgence,

BassCliff

[Spyder]

Yes it is time to break down and do it. Where is the best place to get everything in one shot? i.e. intake boots, needles, and jets... I will get the o-ring kit from Cycleorings. The cap screws I'm refering to are the 20mm stainless allen heads he adverises on his site. it mentions a set of 8, I need 16, no?

[koolaid_kid]

Yes it is time to break down and do it. Where is the best place to get everything in one shot? i.e. intake boots, needles, and jets... I will get the o-ring kit from Cycleorings. The cap screws I'm refering to are the 20mm stainless allen heads he adverises on his site. it mentions a set of 8, I need 16, no?

Those are to screw the intake rubber boots to the head. 2 per cylinder, 8 total.

[Spyder]

ok, put it back together with the o-ring fixed and also connected the vacuum ports together. (1-4 and 2-3) Wow, night and day difference. runs so smooth now. I would say she went from iratic idle to nevous idle. but so smooth and powerful on the low end throttle. I'll hunt down all of the parts I need for the rebuild and take care of it after Brown County run...

[Spyder]

Those are to screw the intake rubber boots to the head. 2 per cylinder, 8 total.

OH! I thought they were for the tops. I need to find new ones. Mine are very beat up...

[andtheacademics]

ok, put it back together with the o-ring fixed and also connected the vacuum ports together. (1-4 and 2-3) Wow, night and day difference. runs so smooth now. I would say she went from iratic idle to nevous idle. but so smooth and powerful on the low end throttle. I'll hunt down all of the parts I need for the rebuild and take care of it after Brown County run...

Can you tell if the vacuum trick had a killer effect? I want any low end torque I can get my hands on... I'm having similar idle issues and am undoubtedly headed down the same road! Been following this post thanks for keeping it updated.

[Spyder]

Sorry, haven't Checked this thread in quite a while... Yes there was a substantial improvement in low end torque with the vacuum line mod. I also found the MAIN culprate for my idle issues.

And after I cleaned them all with my dremel with a wire wheel on it...


Major improvement, still not perfect, but not bad...

[fgh]

Wow! Very Interesting. As I read what you've done it looks like you installed hose barbs were the ports for attaching the carb sticks are. You then but lines between cylinders 1 and 4 and then 2 and 3. Is this correct? My 83 GS750Es also has a vacuum port on the number 3 carb that goes to the vacuum actuated petcock. Does yours have this and did you do anything with it?

Right now after installing K&N pods and a jet kit it is slow to return to idle at stop. The RPMs slowly drop and keep on going below 1000. It seems ready to stall but never does.

[tom203]

To fgh:

Note that Spyder has a 83 750T, while you have a 83 750E -looking at parts fiches (which are sometimes wrong), these models have different method of attaching carbs to cylinder head. Apparently, you have carb boots with an o-ring at cylinder head/boot interface,while Spyder's uses hose and hose clamp on a head projection. take a look at Spyder's pic and compare to your 750E. What have you got?

By the way, when you are sitting on bike, #2 carb is second from left and should have the vacuum connection to petcock on it.

[fgh]

You are correct. Mine has intake tubes that attach to the head with an o-ring to seal the joint. You are correct the vacuum line to the petcock comes from the carb throat on the one that is center left.

I have installed the pods and the jet kit. After going back to non-ethanol free gas to get the higher octane (the local Gate station only sells ethanol free in 89 octane) it seems to have developed this idle anomaly. After warm up when the choke is off the bike is slow to go to idle and it drops far below the rpm standard. The warmer it gets the worse it gets. After 10+ miles it will eventually drop below 1000 but does not stall. I am going to adjust the valves soon, waiting for the headcover gasket to arrive. Just hoping someone could perhaps point me in the direction of the problem. THANKS!!!

[49er]

If the bike has been tuned to ethanol fuels, it will run rich when running non-ethanol type fuels. Ethanol fuels produce more oxygen so the carb settings need to be enriched. Your slow drop below normal idle speed and nearly stalling confirms a rich condition.

You may be able to lean the pilot circuit enough by adjusting your mixture screws. Not sure if the needle height will need adjusting too for a clean stronger mid range.