fuel screw help

[Jason the terminator]

I found on Bikecliff's site how to adjust the fuel screw properly. Now I can't find it and want to tune my carbs in the a.m. so I can finally ride for the first time this year. Please help me !

 

[BassCliff]

Hi,

What carbs? What bike?

Hint: Put your bike year/model in your signature file.


Thank you for your indulgence,

BassCliff

 

[Jason the terminator]

34mm CV carbs.

 

[Nessism]

34mm CV carbs.

Set the screws at 2.5 turns open from lightly seated to start. Warm up the bike and then tweak the screws slightly and take note of changes in the idle speed. You want to achieve the highest idle speed possible. Many times you can not really tell much idle speed change when messing with the screws in which case just stop. All screws should be pretty much the same number of turns open - typically 2 - 3 turns open. Needless to say you will have to do a vacuum carb sync if you want the best tune. Please don't skip this step.

 

[BassCliff]

Hi,

Did you follow the Carb Cleanup Series? There is a link on the GSR homepage and your "mega-welcome". The "idle mixture screws" are under protective caps which must be removed in order to gain access to the adjustment screws. If these screws have not been removed and the O-rings replaced, then your carbs have not been properly cleaned. See the READ ME page on my website for more information and all of the maintenance tasks you should perform in order to have a safe, reliable GS.

Thank you for your indulgence,

BassCliff

 

[Jason the terminator]

Yes I followed the cleanup series although they really didn't need it. It only has 6,000 miles on it and never sat with fuel in them. Dip them, new o rings, new bowl gaskets, Dyna jet kit installed so I think I have all the bases covered. The PO never jetted it for the V&H exhaust he put on. I am all set to sync I just need to know how to adjust the idle mixture screws properly. First time adjusting carbs on a bike and want to make sure I do everything the way it should be done. Thank you guys for all your help.

 

[BassCliff]

Hi,

OK! It sounds like you're ready. This is the physical location of the "idle mixture screws" and vacuum adjustment screws (looking down from above the carb rack).

Here are links to the adjustment procedures.

Plug Chops-Highest RPM Methods
(by Mr. tkent02 and Mr. psyguy)

Synchronize Carburetors
(With the Morgan Carbtune)

Synchronize Carburetors
(on bwringer's site)


Thank you for your indulgence,

BassCliff
​

 

[Kurtgun11]

I just did my 81 GS550L. It would not run at less than 3 turns out on the mixture screw. UNtil you get the mixture right, you really can't really proceed. I then used a friends Morgan setup and finally got a reliable 1200 idle.

 

[Jason the terminator]

I'm having some issues now. I can get it to idle great but as soon as I touch the throttle it stalls. Nothing is clogged and I don't think the boots are leaking.

 

[niclpnut]

you have stock pilot jets in there?

Sure the float height is correct?

Does the rpm drop as soon as you blip the trottle? Choke off?

My choke cable was hanging up and causing it to get extra fuel and bog if touched the throtle.

Nic

 

[Jason the terminator]

you have stock pilot jets in there?

Sure the float height is correct?

Does the rpm drop as soon as you blip the trottle? Choke off?

My choke cable was hanging up and causing it to get extra fuel and bog if touched the throtle.

Nic

I adjust to what the manual said could not get it do anything but idle. Went back to the float hieght that I found it at and wont even start now. Yes stock pilot jets and no the choke is not hanging up. It just dies as soon as the throttle is touched.

 

[BassCliff]

Hi,

Is the stock airbox installed with a clean lightly oiled air filter?


Thank you for your indulgence,

BassCliff

 

[Jason the terminator]

Hi,

Is the stock airbox installed with a clean lightly oiled air filter?


Thank you for your indulgence,

BassCliff

Dynojet stage 3, K&N pods, Marving race 4-1 All 3 brand new

 

[BassCliff]

Hi,

I adjust to what the manual said could not get it do anything but idle. Went back to the float hieght that I found it at and wont even start now...

Hmmmm. The float height should be 22.4mm (+/- 1mm). But it's best to set it right in the middle of the range. In other words, 22.4mm float height.

Seems like you've been very thorough. I'm scratching my head on this one. :-k


Thank you for your indulgence,

BassCliff

 

[Jason the terminator]

I pulled the bowls off and triple checked everything. There was no blockage anywhere and float height correct. The bench sync was still spot on. I guess the next step is to check the diaphragms, needles, and mixture screws. Anything I should look for other than a tear in the diaphragms or some sort of blockage? Dealing with these carbs has been the worst experience I have ever had right from the moment I started tearing them down.

 

[Steve]

A tear in the diaphragm will not prevent application of throttle. A tear will only prevent the slides from opening as the engine speed increases, so you should have very crisp response to throttle "blips", but might have limited power at higher throttle openings because the slides are not open enough to allow proper air flow.

Everybody has their favorite setting for a starting point when adjusting the mixture screws. I used to start at two full turns out, Nessism apparently uses 2.5 turns. I had so many cases where I had to keet richening the mixture, I now use three full turns as my starting point. Yeah, they might end up at 2 or 2.5, but the richer mixture will help get them running in the first place, then you can fine-tune from there.

Where are your mixture screws set now? Try them at three, or even a bit more, turns out. If you have to go past four turns, change the pilot fuel jets to one size larger, as there is not any difference past four turns.

.

 

[Jason the terminator]

I started at 2.5 out.

When playing with the idle I could get it to idle as low as 750rpm but never above 1750rpms.

 

[Jason the terminator]

Got home today put the carbs on with all new clamps just to make sure there was no leaks.I pulled the choke, hit the key and did nothing but crank over. Pulled 1 plug and it had a little soot on it. Gave it a quick wipe and looked like the new plug it is. Turned the key and had spark, but just for fun put all the old plugs in. Hit the key and it came to life and ran for about a minute. I'm getting 9.5 volts to the coils and was wondering if this is too weak of a spark to burn all the fuel and the cause of my problem.

 

[Nessism]

9.5 volts is pretty low. If your battery is fully charged I'd tear in and find out what's wrong. If all else fails, I'd do the coil relay mod.

 

[Jason the terminator]

9.5 volts is pretty low. If your battery is fully charged I'd tear in and find out what's wrong. If all else fails, I'd do the coil relay mod.

I was going to do one after I got it running. I wanted to put green coils on also. Before anyone asks it was fully charge and has been on the charger all day. New stator and rectifier last year. what should the voltage be at or around?