Advice on starting after valve shim adjust. She's proving tough

[Steve]

Just because you have fuel in the bowls does not mean it's getting into the cylinders.'

Have you tried cranking it to see if the plugs get wet?

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[cp___32]

No fuel to the plugs, they're dry. My comment was in regards to someone saying petcock/vacuum tube issue. Drained the bowls and then cranked and it pulled fuel into the bowls again so I know that part of things is working. Also it's a brand new Suzuki OEM part. No leaks in the vacuum line from the petcock to the carbs, good seal (nice tight fit). No kinks in the fuel supply line. Tried starting it on prime and on run.

As I had said before, the bike was running. I was riding it, I just could not get rid of a bad hesitation/bogging from 2-3K rpm regardless of throttle. Since all the guides suggested that valve clearances be checked (in addition to a bunch of other things I had already done) I figured I would check the clearances. The only thing that has changed on the bike since it was last running are the valve shims and that I had to bench sync the carbs back to normal because I had monkeyed around with the adjustment a little too much trying to get the bogging to go away (thought vacuum overall was just set too low). OEM everything, very well sealed airbox, carb boots, exhaust system, when I cleaned the carbs I had put in a K&L kit in case some of my jets were bad. Didn't make a difference. Since everyone says the OEM Mikuni parts are better and there was no difference in performance I took the carbs apart again, cleaned everything again, and put all the old OEM guts back in.

Floats are set from the groove where the gasket sits (not the ridge or lip) to the flat on the carb float as per the manual (Checked both the Clymer and Haynes manuals).

Mix screws are 3 turns up from lightly seated because 2.5 didn't work so I gave them each another .5 turn to see if I could get fuel flowing.

[Steve]

If the plugs are not wet, fuel is not getting through the carbs. Because there is fuel in the bowls, you know that fuel is getting TO the carbs, just not THROUGH them.

I really hate to beat on what is apparently a dying horse, but the only way fuel is going to get through the carbs is via the enrichener ("choke") passages or the pilot jet passages. It doesn't really matter how many times you might have cleaned them (and cleaned them and cleaned them), there is still something that is stopping the fuel.

Then there is always 'starting technique'. Hopefully you know that when using the "choke" to start the engine, you do NOT touch the throttle?

3 turns out on the mixture screws is good, as long as it's three FULL turns. I consulted one member over the phone several years ago, he swore the screws were out three turns. I went to visit him, found they were 1 1/2 turns out. He counted each 'flip' of the screwdriver as one turn. After the bike starts and warms up a bit, you can tune the mixture. Might end up at about 2 1/2 turns or so, but 3 just gives a slightly richer mixture to get it started easier.

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[londonboards]

You've double checked the float bowl passages - haven't you?

If the starter circuit is block you are a dead duck.

Check this thread:

http://www.thegsresources.com/_forum...n-Mikuni-bowls

[cp___32]

Yup. Carbs have been pulled and cleaned twice this summer in an attempt to get rid of my stumbling issue. I could see one passage, possibly getting clogged somehow maybe, but not all 4. Tank is perfectly clean, all new fuel lines and a new petcock complete with pristine filter screen.

I'll do some more fiddling around with the mix screws to see if I can get it started. Definitely 3 full turns (I do the turns in 1/2 turn increments, so each 180 turn of the screw head is a 0.5).

If you're interested in what the bike was doing before I pulled the carbs I posted a video to youtube. I used my scope and checked the carb goings on with the airbox off. The stumbling coincides with the brass cylinders fluttering and a backflow of fuel. That's why I thought it could be a valve issue. I'm getting fuel into the combustion chamber and then at one point the pressure changes and I'm getting fuel blowing back through the carbs into the airbox. Not sure if that's normal because I've only got my bike to go on but thought it was worth a look since I had the tools. If nothing else, cool to see what happens in there.

https://www.youtube.com/watch?v=a5OqSU8gYz0

[londonboards]

Fiddling with the mix screws won't stop it starting. You are not getting any fuel into the combustion chambers.

Take out the air filter and start the motor with some carb cleaner. Then you'll know for sure:

[hjfisk]

Did you get the plug wires back on correctly?

[cp___32]

Yeah, plug wires are on correctly.

I got it running once I backed the mix screws out about 8 full turns (close to the top). Tried lowering them down and the bike would stall out and not start again. The rightmost cylinder won't run until I've got the mix screw right at the top. Back to this problem again. It'll start and idle ok with the mix screws way up. Ok fine, doesn't seem right but whatever. Try to do a sync and get that dialed in. Shut the bike off and then back on and it struggles to start. Give it a little choke and then the revs climb like crazy. Let off the choke and the revs come down a bit and stabilize but are too high for idle. I back the idle screw down, nothing, nothing, nothing then the bike idle drops way low and almost dies. Turn the screw back to a normal idle and it sits for a second, then races again.

So now what? Main jets? But why would a stock bike need larger than stock mains? I can't figure out why this bike is so friggin hard to dial in. Been through the carbs twice this year. probed every orifice I could find. Sprayed carb cleaner everywhere. Ultrasonically cleaned them. (We don't have carb dip here in Canada so that's the best I can do). They look squeaky clean inside and out. Swapped out all OEM parts for a K&L kit just in case something in the carbs was screwy. No difference. Checked the markings on the kit vs OEM and they're all the same sizes. Put OEM stuff back in after cleaning again, still no luck.

[MechMessiah]

I'm having a very similar problem to you. Just did a top end rebuild, got it to start and took it for a test ride and now nothing. No fuel seems to be getting to the chamber. Best of luck man! Hope you figure it out and if you're interested here's my post on the issue.

[gearhead13]

I was looking at your video and seemed strange to see the slides moving that much if its not under load. How high are you revving it? Hard to tell with no audio. Are the springs in place on top of the slides?

[Steve]

Poor running at low throttle openings is a sign of clogged pilot passages.

Buy new pilot jets.
Check the starter jet.

If it is not firing at all, and the plugs are not wet after a decent attempt to start, then you are not getting any fuel into those chambers.

Just because you have fuel in the bowls does not mean it's getting into the cylinders.'

No fuel to the plugs, they're dry.

If the plugs are not wet, fuel is not getting through the carbs.

So now what? Main jets?

You can lead a horse to water, ... but most people would rather ride it there.

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[cp___32]

I get it Steve, but considering with my no spark issue a few years ago I was told replace this, then that, then something else, now it's the same deal with the fuel flow. Everyone says if I change the air intake or exhaust I need to rejet. That totally makes sense. What does not is why an absolutely stock bike with 18K miles on it would need larger jets. I have yet to hear someone say that it's common to need new jets for stock bikes just because.

If it's a matter of needing the same size, but the old ones are worn somehow, I've covered that with a K&L kit which made zero difference. I can't imagine the K&L stuff being THAT bad that it's as bad as screwed up OEM stuff.

So if I get new jets, what am I looking for? One size up (whatever that means), a drastic change? Just keep ordering parts till it works?

As for the video it was about 1/4 to 1/2 throttle steady and as the revs climb to about 1800 rpm the sputtering starts. That's when you see the fluttering and the backflow of fuel into the airbox (toward the camera lens).

[londonboards]

OK so you checked the float bowl starter circuit passageways?

Now this was my other mistake once when I first rebuilt the carbs: I put the spring for the needle in the throttle slide on the wrong side of the red washer:



This has the effect of keeping the main jet closed so it would stall as soon as you opened the throttle more than a smidgen, like this:

Is this what's happening to yours?

Don't get too phased about jets right now. We just need to get fuel in the combustion chambers (assuming your jets have some kind of hole in them!).

Post up some photos of your carbs if you can and the whole bike.

[bwringer]

A couple of observations gleaned from the above:

1) When discussing the valve clearances, you appear to be mixing units between hundredths of a mm and thousandths of an inch. You imply that you had to make drastic moves in the valve clearances, which is one sign of unit confusion. That said, it may or may not keep the bike from starting, but it certainly won't run very well. This is worth at least a few moments of honest introspection.

2) Yes, the K&L carb rebuild kits are in fact complete crap. I don't know why otherwise reputable places sell these, and I don't know why anyone in the age of Google buys them. The float bowl gaskets are usually OK (but compare them to the originals carefully to make sure all the holes got punched out correctly), but for the sake of all that's good and holy, don't use any of the other bits in these little sacks of random junk.

3) You've most likely made some sort of minor error in assembling and/or cleaning the carbs. A few common errors are detailed just above. There are many other potential errors. Without the bike in front of us, all we have is guesswork.

4) Yes, it is entirely possible for the idle circuits to clog over just a few weeks of inactivity, especially in warm weather. These passages are TINY.

5) Main jets are irrelevant to the immediate problem, and you shouldn't need to change them unless there have been drastic exhaust/intake changes. Mains only come into play at throttle openings at and near WOT. OEM main jets don't wear out.

6) Canada's a big place. You might mention approximately where you are -- perhaps there's a GSR member with relevant experience nearby. Sometimes another set of eyes on the problem can be very helpful.

7) Apologies in advance if this gives offense, but... check your attitude. You're obviously frustrated and angry, and this inevitably leads to narrowness of thought and vision. We've all been there. Much of this discussion is already starting to go in circles as you angrily cut off certain lines of discussion. Do whatever is necessary to get back into the right frame of mind. Walk away for a while, accomplish some other task, go for a ride if you've got another bike around, or do whatever you need to do to get back into the correct frame of mind. Motorcycles are fun, dammit!

[JTGS850GL]

OK so you checked the float bowl starter circuit passageways?

Now this was my other mistake once when I first rebuilt the carbs: I put the spring for the needle in the throttle slide on the wrong side of the red washer:



This has the effect of keeping the main jet closed so it would stall as soon as you opened the throttle more than a smidgen, like this:

Is this what's happening to yours?

Don't get too phased about jets right now. We just need to get fuel in the combustion chambers (assuming your jets have some kind of hole in them!).

Post up some photos of your carbs if you can and the whole bike.

The assembly on the left side is correct.