Gs850g stage 3 re-jet settings please

[kdo58]

I live in puyallup same sea level as you, I have the same bike I bought a jet kit, it came with three different size main jets, i used the middle size, needle in the middle, stock pilots jets, mixture screws toward the front top 4.5 turns out.

 

[chrisbock]

Thanks, I'll try it out.

 

[Steve]

As I was holding down the starter button, I tried the choke at various levels.

I think I remember you saying that the carbs were clean, but if it's not starting with the "choke" applied, it's possible that the enrichment circuit (the proper name for the "choke") is not fully cleaned. There is a tube in the body that sticks down into the bowl to pick up the fuel. Depending on the exact carbs, there will either be a tiny hole in the well in the bowl or in the bottom of the tube that meters the fuel for the enrichment circuit. It does not take much to plug up that hole. I use a single strand of copper wire to poke through the hole, then spray some carb cleaner through it to make sure it's open.

I think it has already been mentioned, but when using the "choke", DO NOT open the throttle AT ALL. That will destroy the high vacuum that it takes to draw the fuel and air through the enrichment circuit.

My mixture screws are at 3 turns out. Should I turn out the mixture screws drastically?

Unlike some other carbs, the mixture screws are controlling the addition of a mixture. Note that this is different than a fuel screw or air screw that will adjust the mixture. The mixture screws in your carbs control a mixture that is set by the pilot fuel jet and the pilot air jet. The adjustment screws merely control how much of that mixture is admitted to the engine. Yes, opening the screws (turning them left) will richen the overall mixture, but three turns is plenty. When the engine finally fires up and runs, you will have to fine-tune the mixture by turning them in. They might end up in the 2 to 2 1/2 turn range, but the 3 turns out setting just acts a bit like a "choke" to richen the mixture a bit for easier cold starting so you can tune it.

Would a turn and a half really keep the engine from firing?

It might fire, but won't really be proper. When they were new (and still sealed to the EPA-mandated settings), they might have been in that turn and a half range, but they were also notoriously "cold-blooded" due to that lean setting. They run SO much better when set between 2 and 2 1/2 turns.

Conversely, would turning them in to 2.5 from 3 have that much of an effect?

As mentioned earlier, when the bike is warmed up, you will need to fine-tune the mixture, and the screws will probably end up in the 2 to 2 1/2 turn range. The only reason for starting at 3 turns is to have a richer mixture for easier cold starting.

Just wondering before I go meddling with the only other adjustment I can think of.

You are quite correct in the number of adjustments. There are, in fact, only three variable adjustments on those carbs: 1) float height, 2) mixture screws, 3) idle speed. The only other adjustment would be the synchronization of the throttle blades, known as "carb sync". If you have either poked something under the butterflies or simply eyeballed the gap, that should be close enough to get it started, but will need to be checked with a set of gauges before you fine-tune your mixtures.

.

 

[chrisbock]

Went to 4.5 turns on the mixture screws, same results. I'm at a total loss as to what the issue is. I've done a bench sync on the valves also, or carb sync. I have a balancing tool for adjusting the mixture screws, after its running. Is there some sort of common mistake when re-jetting (if everything is cleaned and reassembled correctly) that would cause a problem with starting the bike? Also, after dipping the carbs, I used a matchstick with a wire from a wire brush to clean out all the tiny hole and ports. Then used air to blow them out. Thanks for the idea though.

 

[chrisbock]

When I attach the carbs to the bike, and tighten the nut on the throttle cable stay, is there a chance that it is pulling open the valves and bypassing the idle circuit? It does seem to tighten the cable slightly when reattaching it. Going back in to check it out.

 

[chrisbock]

Well, loosened up the throttle cable till slack. Tried starting with mix screws at 4.5 and 3 turns out. Not the culprit.

 

[Guest]

Seems I read further up when you bench synched, that you said;

Quote;I've done another bench sync, with a paperclip this time and 1 1/2 turns in on the throttle adjuster, for slight opening of butterflies.
Try closing the throttle adjuster screw, the bike will not start if you are giving it any throttle at all which may be what is happening here.

 

[chrisbock]

So, I've been told (I'll figure out how to quote when I get to my comp), that you have to open up the valves a sliver after the bench sync. I understand what you mean by needing them closed for the idle circuit. I'll try it out, and see if that helps. Thanks

 

[koolaid_kid]

So, I've been told (I'll figure out how to quote when I get to my comp), that you have to open up the valves a sliver after the bench sync. I understand what you mean by needing them closed for the idle circuit. I'll try it out, and see if that helps. Thanks

Not exactly. You do it at the end of the bench synch, it is the last part of the synch. IOW, you use the paper clip and each adjusting screw to adjust each butterfly valve the same. Then, at the end, you check each one to make certain that every single butterfly valve is open exactly the same amount. Steve likes to shine a light, as he demonstrated earlier. Both methods work. Now, with each butterfly valve still open that slight amount, install on the bike, hook everything up, and give her a go.

 

[chrisbock]

Seems I read further up when you bench synched, that you said;

Quote;I've done another bench sync, with a paperclip this time and 1 1/2 turns in on the throttle adjuster, for slight opening of butterflies.
Try closing the throttle adjuster screw, the bike will not start if you are giving it any throttle at all which may be what is happening here.

So...which is it. When I did my sync. I used a paperclip to set each valve the same. The paperclip leaves a pretty large sliver, and I've read that after completely closing the valves, turn the throttle adjuster back in 1.5 turns. Ive done that, and it leaves them open a nice sliver.

Now, with each butterfly valve still open that slight amount, install on the bike, hook everything up, and give her a go.

I've tried with the valves open slightly, and completely closed, without effect. But I would still like to know which is the proper procedure. Thanks

 

[koolaid_kid]

They need to be slightly open. One paper clip's worth. Trust me, I found out the hard way the very first time I rebuilt a set of carbs. Closed = NO AIR.
And your mixture screws need to be 2 1/2 turns out. No more, no less. Period. And your pilot jets need to be stock and fully seated.
Any deviation from these 3 crucial settings = NO START.

 

[TheCafeKid]

Just for grins, and since they're easy to get to, try backing the mix screws in to like two turns out, or 1.5. If your plugs are wet with gas, then you know it's getting fuel, but it's possible that its simply too rich to fire.
I know it's frustrating, but without being there none of us can actually see wtf is going on so we are all just giving educated suggestions.

I've had some issues like this before, and you just need to keep plugging away and eliminating any possible culprits one at a time. This is certainly not the time to rush anything and just spin screws and knobs willy nilly hoping for a silver bullet miracle. I've had carbs, for instance on a 550ES I worked on for a buddy, that simply wouldn't fire with the screws turned out the normal baseline amount. But I made sure they were clean, all the settings were correct, etc etc and then by playing with the mix screws a half turn at a time it finally fired. The port that the pilot air/fuel mixture goes through to reach the carb throat is TINY. We are talking maybe a third of a milimeter or thereabouts so a half turn in or out is actually a large adjustment.

Which brings me to another thing. If you remove the carbs and look into the throat on the side that fits to the engine, at the top, just near the butterfly valve, you'll see a small hole. Look closely, it is as I said, very small. I can't recall without looking but you may actually have to open the butterfly to see it. Anyway, if you run the mix screw in, til it's lightly seated, you can usually run your fingernail over that hole and feel the tip of the screw sticking out. If so, back the screw out a few full turns, and feel again. If you can still feel the tip, it's broken off in the port, and the port is effectively closed no matter how many times you turn the screw. If so, this would be a large reason for your issues.

If one or more are broken off, remove the screw, and flip the carbs upside down. Usually with a dental pick, or a flat head screwdriver or the like, you can push just hard enough on the tip to pop the broken tip out. Be careful not to gouge the hell out of the throat, but some fine scratches won't really hurt anything.

If you get em out, you'll need to replace them with new, let me know and I can send you a couple.

 

[koolaid_kid]

If you read through the posts, Josh, he's been turning them out rather than in. I believe that is an issue, and I agree with you as far as going less rich rather than more.

 

[chrisbock]

I checked for the mixture screws being broken off, and everything looks good. No broken tips. I've tried starting with the mix screws at 1, 1.5, 2, and 2.5 turns out from lightly seated. It sounded like the engine fired for 1/2 a second at 1.5 turns, but nothing after that. I'll continue with slight adjustments over the next few days. I'll reset my valves for a paperclip size gap and try again. Thanks for the input.

 

[koolaid_kid]

You should also be checking your plugs periodically to see if they are wet or not.
Best of luck.

 

[tkent02]

I'll reset my valves for a paperclip size gap and try again.

 

[koolaid_kid]

I saw that too and it gave me pause. Then I realized he left out the word "butterfly".