Carb help please

[alke46]

I found the article by Kool aid kid to be very useful in helping me understand and finally get my bike to a sweet spot. I had read dozens of posts on several forums but the by ear method wasnt working for me. I just dont have enough experience. When I realized how rich or lean was affecting the idle and knowing I buttoned everything else up .. Took a couple of tries but my bike runs great.

http://www.thegsresources.com/_forum/showthread.php?199096-Adjusting-the-Idle-Mixture-on-CV-Carbs

I have not read this thread but the OP is working with vm carbs. At least that's what I suspect since his bike is a 78 750. This thread is about the cv carbs. I don't know if it matters or not, just throwing it out there.

 

[BurtyMcSquirt]

stock exhaust 4 to 1

 

[Boriqua]

I have not read this thread but the OP is working with vm carbs. At least that's what I suspect since his bike is a 78 750. This thread is about the cv carbs. I don't know if it matters or not, just throwing it out there.

It wasn't so much the physical manipulation of screws that helped me solve my issues but the part in the article where he describes symptoms and causes. I had a high idle and I kept being told it was an air leak when I had gone through the bike 100 times and it was sealed tight. I did at one point have my uno filter dry out which caused me to lean out but when I went to paper things got a bit easier.

After reading the article I started tuning based on what the bike was doing when warm. At first hanging idle so if all else was good I just had it set up to lean. So went up half a turn and it would slowly die at lights. Too rich. Turn down 1/4 and it would idle. So it was that diagnostic that helped me get there. so while the carbs may be different that little bit of information was immensely helpful to this newbe who had struggled and basked in profanity for weeks.

I've since checked the plugs and they look great but it was really that little bit of info that drove it home for me.

For months I was afraid to go to far from home but I have since put several hundred miles on her and she runs great.

 

[alke46]

Yeah once you get a little bit of confidence in them, they will take you almost anywhere without issue. This is particularly true after you've got the electricals taken care of.

 

[BurtyMcSquirt]

I found the article by Kool aid kid to be very useful in helping me understand and finally get my bike to a sweet spot. I had read dozens of posts on several forums but the by ear method wasnt working for me. I just dont have enough experience. When I realized how rich or lean was affecting the idle and knowing I buttoned everything else up .. Took a couple of tries but my bike runs great.

http://www.thegsresources.com/_forum/showthread.php?199096-Adjusting-the-Idle-Mixture-on-CV-Carbs

This was a really informative article. Great post.

 

[BurtyMcSquirt]

I thought I'd shoot you guys a pic of my plugs. Looks rich.

 

[Steve]

stock exhaust 4 to 1

So which do you have, stock or 4 to 1? :-k

No GS left the factory with a 4 into 1 exhaust system.

.

 

[BurtyMcSquirt]

So which do you have, stock or 4 to 1? :-k

No GS left the factory with a 4 into 1 exhaust system.

.

Oh. Well in that case I have no clue. It has no markings on it but I do know it will need to be replaced, its fairly well beat up and all rust.

 

[BurtyMcSquirt]

If your valves are tight (the usual situation), the intake valve closes while the piston is coming up, which lets some air out. The only place for it to go is back through the carb. It picks up a bit more fuel, because the carbs don't really care which way the air flows through, they are going to add fuel. On that cylinder's next intake cycle, the valve opens, the piston goes down and, you guessed it, you get a THIRD dose of fuel in the mixture.


.

So 6 out of 8 valves weren't measurable with my set of gauges (go down to .03mm) and at the .03mm feeler it wasn't even close to making it through. Currently recording shim settings to purchase the ones i need to adjust.

 

[Steve]

Have you looked into the GS Shim Club? A simple exchange and a token gratuity, you don't have to purchase shims.

Unless you want to start your own collection, that is.

.

 

[BurtyMcSquirt]

Have you looked into the GS Shim Club? A simple exchange and a token gratuity, you don't have to purchase shims.

Unless you want to start your own collection, that is.

.

No I haven't. Still quite new to everything on the site so any direction to community resources is greatly appreciated. I will certainly check it out, thank you.

 

[hannibal]

Also, my local dealer let's me swap shims for free. Walk in with the old shims and out with the correct ones.

I have K&N pods and stock exhaust. The PO increased mains from 100 to 110. Pilot jets are stock at 15.

 

[Hinermad]

So 6 out of 8 valves weren't measurable with my set of gauges (go down to .03mm) and at the .03mm feeler it wasn't even close to making it through. Currently recording shim settings to purchase the ones i need to adjust.

If you can't get a gap measurement, you can't really tell what size shim you'll need. For example, if the present shim is 2.65 you might need a 2.60 or a 2.55, you just can't tell. So be aware that you might need to get extra shims in smaller sizes just in case.

 

[hannibal]

A tip I've read is to try to spin the shim bucket. If you can spin it, you have some clearance so go down one size (2.65 to 2.60). If you can't spin the bucket, then you have no clearance so try a shim two sizes smaller (2.65 to 2.55).

 

[alke46]

Don't know if you are aware of this practice or not, but you can remove your shims 1 at a time and replace it with a quarter. While you have the 1st one out, record and even measure the shim. Once you have done this with all of the shims, you can maybe switch a shim here and there and possibly reduce the number of shims you need to replace.

Also, don't rotate the engine without something in the bucket. You can damage the chrome on the cam lobes.

 

[BurtyMcSquirt]

So was able to adjust the valves, seal any holes in the exhaust, installed 110 mains, I'm 2.5 turns out on the mix screw and 1.5 turns out on the air screw. I have not balanced the carbs yet because I'm still looking for a balancer that I can borrow. The bike starts up well and idles a little high. I took it around the block and the moment I try to go beyond throttle it dies. If I try to go into second gear it dies. I can make it around the block in 1st gear at 15mph and lots of pops from the bike. Suggestions at this point???????

As always thank you for your time.


Justin

 

[Big T]

What's a mix screw?
Fuel screw - 1 turn out
Air screw -2-3 turns out
Needle - up one notch
Pilot jet - ?
Mains @ 110- may still be lean

 

[BurtyMcSquirt]

I ordered a carb rebuild kit after I purchased the bike and swapped everything out. I just noticed that at some point a PO did the same thing and bumped the pilot jets from stock 15 to 17.5. I just put the 17.5's back in. So you feel the 110's make it too lean still but the 115's are too rich? Float bowl heights are set at 26mm (stock setting is 23mm +/-1). I have a carbtune pro coming in on Friday so I can get them balanced.

Any other suggestions. Thanks.

 

[allojohn]

Set the float height to 24mm.

 

[BurtyMcSquirt]

So I'm not certain I want to keep messing with these carbs anymore and thinking about replacing them entirely with a rack thats more pod friendly. Any suggestions for 1978 gs750e?