Need jetting help please for GS1000 1979

[KEITH KRAUSE]

Just checking, have taken the slides apart and I only have 2 spacers, the DJ spacer and the thicker factory spacer, do I need to buy the thinner spacers please.

Dave

The thinner plastic spacer that goes under the e-clip, missing or not, has no effect on mixture. It's there to eliminate metal to metal contact between the jet needle spring and the e-clip. The factory felt the need to use this spacer or they wouldn't have designed it in. Friction between the two parts is one obvious reason. Also, the spring end could possibly "catch" on the e-clip if the spacer isn't used and cause unintended operation or wear?? Without the parts in my hand I'm not sure the spring CAN hang up over the e-clip but it's just a thought.
What happened to the spacers? I can't say how critical it is that they be installed, only that they should be installed. If you can't locate any I guess you can make some or choose to run without them. I'm sure many members here have some laying around. I know I have only one complete set for spares that I have to keep.

[nitrogs]

Hi Keith,

Have completed the 3.5 position mod. I am faced with another problem, I bench synched the carbs, then vacuum synched. The funny thing is I cannot lower the tickover below 2000rpm. The idle adjuster is turned fully out so it looses contact with the throttle cam. I have checked the throttle cables and they are loose any other ideas please.

[KEITH KRAUSE]

Hi Keith,

Have completed the 3.5 position mod. I am faced with another problem, I bench synched the carbs, then vacuum synched. The funny thing is I cannot lower the tickover below 2000rpm. The idle adjuster is turned fully out so it looses contact with the throttle cam. I have checked the throttle cables and they are loose any other ideas please.

I know exactly what you've done but it's not as easy to explain in type.
You've simply over-adjusted the slide adjuster screws at the top and/or the bench synch wasn't done right to begin things. I've done it myself years ago and was surprised it happened, given how many times I'd done it correctly. You can incorrectly synch or adjust the adjusting screws so the bike will have a high idle even though the idler tip is off the throttle pulley. I'm sure you've noticed that over-adjusting a single slide screw can actually raise the other 3 slides? I've seen this while bench synching. It starts a nasty chain of adjustment that ends up as you've seen.
I always simply started over. This means removing the carbs again. Trying to do it on the bike can give poor results and more frustration.
I'm not sure if I can explain this easily but you have to loosen up the slide adjuster screws and start over. Loosen all the holder nuts for the slide adjuster screws and back off the idle knob so there's plenty of gap between the tip and the throttle pulley. You should be able to loosen all the adjuster screws so they are REASONABLY uniform (how much thread is visible above each holder nut). I've found they don't need to be exact but should be reasonably close to each other. If all 4 are backed off correctly then they will be "relaxed" and none will be actually raising its slide.
Now with all tension removed from the throttle shaft you should be able to start your bench synch over. Be sure all throttle arm to throttle shaft bolts are correctly torqued to approx' 4 ft/lb to begin with too.
Slowly adjust each slide until it barely rests at it's lowest point. Using the slide cut-away "nick" is the best way to do this. When the slide stops lowering, stop turning. Otherwise, you will effect the other 3 slides. Adjust all 4 to a uniform, maximum closed position. Now raise the idle knob enough to allow the bike to start initially. Don't worry about setting it too high, you can adjust it correctly as soon as the bike is running.
Warm up fully and then hook up your vacuum tool. Note the initial vacuum levels. If you did the bench synch carefully, you may be lucky and see only one that's a bit off from the others. You should find them all with adequate vacuum to begin with. It's generally much quicker and easier to adjust the higher level(s) DOWN to match the lower levels. Adjusting "down" also helps you avoid the problem you created.
Don't over tighten the holder nuts for the screws.
By the way, to back up a little, you should also check for the fully OPEN slide position too. I cover this in my VM bench synch post you may be aware of ? I have to leave for a bit but will help you with that if you need it.

[nitrogs]

Hi Keith,

Thank you for those last comments as always you were spot on. I decided to take the carbs off and visually check the slide nicks engine side and was amazed at the difference. So have bench synched again as you have described, fastened the carbs back on the bike and connected up the gauges. Unfortunately it is now 22:00 here and I cannot start the bike (your children asleep next door). I just craftily started the bike on tickover for a few seconds and the idle adjuster now works fine (for peace of mind). Roll on tomorrow!

[hampshirehog]

The other thing you could have done is put the shaft that connects the slide arms in back to front (i.e. 180 degrees out). One side has a slight bevel that guides the bolts in, the other side is a just a flat ending thread. I've done this before and baffled myself - and looking at it you'd think it can't possibly make any difference but it can.

[KEITH KRAUSE]

Hi Keith,

Thank you for those last comments as always you were spot on. I decided to take the carbs off and visually check the slide nicks engine side and was amazed at the difference. So have bench synched again as you have described, fastened the carbs back on the bike and connected up the gauges. Unfortunately it is now 22:00 here and I cannot start the bike (your children asleep next door). I just craftily started the bike on tickover for a few seconds and the idle adjuster now works fine (for peace of mind). Roll on tomorrow!

OK. Hope it runs well and you're done.
If you do need help, I work all day tomorrow but I'll try to check in in the evening here.
Hope for good news from you.

[49er]

The other thing you could have done is put the shaft that connects the slide arms in back to front (i.e. 180 degrees out). One side has a slight bevel that guides the bolts in, the other side is a just a flat ending thread. I've done this before and baffled myself - and looking at it you'd think it can't possibly make any difference but it can.

Are you sure that this is possible?. There's a locking key that prevents the shaft from floating during throttle operation. This key would end up out of position as would the throttle cable fulcrum, if the shaft was installed incorrectly.

[hampshirehog]

Are you sure that this is possible?. There's a locking key that prevents the shaft from floating during throttle operation. This key would end up out of position as would the throttle cable fulcrum, if the shaft was installed incorrectly.

I don't think I explained it very well; I didn't mean getting the 2 ends round the wrong way (ie swapping left for right) - as you say that would be obvious and wouldn't fit at all. What I meant was spinning the rod on it's axis 180 degrees.

You'd think it wouldn't matter, and maybe it doesn't usually (I never used to notice which way round I put it and things worked - I couldn't have been that lucky) but I got it wrong once, worked it out and have always ever since checked it's right.

[nitrogs]

Hi Guys,

Struggling with the carbs. Struck her up to vac synch,showing a low vacuum, in fact very low vacuum on cylinder 3 on low rpm 1100/1500 compared to the other three cylinders which are fairly equal. The vac picks up on cylinder 2 but lags the others at 3000rpm. If I adjust other cylinders down to the low vac on cylinder 2 this is what loses me the ability to adjust idle , i.e ticksover at 1800 rpm, no matter how much you unscrew the idle adjuster. Any ideas guys please

[49er]

I don't think I explained it very well; I didn't mean getting the 2 ends round the wrong way (ie swapping left for right) - as you say that would be obvious and wouldn't fit at all. What I meant was spinning the rod on it's axis 180 degrees.

You'd think it wouldn't matter, and maybe it doesn't usually (I never used to notice which way round I put it and things worked - I couldn't have been that lucky) but I got it wrong once, worked it out and have always ever since checked it's right.

Ok, it appears that Suzuki stuffed up their drilling and tapping of your shaft if that happened. If drilled accurately, you should be able to assemble the slides 180 deg apart without affecting the slide syncro.

[49er]

Hi Guys,

Struggling with the carbs. Struck her up to vac synch,showing a low vacuum, in fact very low vacuum on cylinder 3 on low rpm 1100/1500 compared to the other three cylinders which are fairly equal. The vac picks up on cylinder 2 but lags the others at 3000rpm. If I adjust other cylinders down to the low vac on cylinder 2 this is what loses me the ability to adjust idle , i.e ticksover at 1800 rpm, no matter how much you unscrew the idle adjuster. Any ideas guys please

Dave, if you have followed Keith's suggestions for getting your slides synced with the adjuster screws centralised, you should have been good to go.

You need to consider the following things.

1. You have something drastically wrong with the carbs, or you have a serious air leak in the inlet system. When you have one bank seriously lower than the others, it's better to adjust the vacuum upwards instead of bringing the other 3 down.

2. I don't recall reading that you have successfully completed a compression check? Low compression on that pot will affect your synching attempts.

3. Have you recently done a valve clearance check?

These are the most likely areas to re-check.

Just an after thought, you're not running VM carbs on a later model CV head are you?

If so, the port and carb boot diameters will be badly mismatched and likely to cause the slow running conditions that you're describing here.

[KEITH KRAUSE]

Hi Guys,

Struggling with the carbs. Struck her up to vac synch,showing a low vacuum, in fact very low vacuum on cylinder 3 on low rpm 1100/1500 compared to the other three cylinders which are fairly equal. The vac picks up on cylinder 2 but lags the others at 3000rpm. If I adjust other cylinders down to the low vac on cylinder 2 this is what loses me the ability to adjust idle , i.e ticksover at 1800 rpm, no matter how much you unscrew the idle adjuster. Any ideas guys please

Dave, I know what you're dealing with and it's not easy to describe the fix in type. I doubt anything else is causing the vacuum problem because you've synched before without issue. Obviously you've just adjusted too much and the carbs will react as they've done.
You DO mention # 3 being low from the start and it makes me think you could have induced a vacuum leak by not connecting the vacuum tool correctly?? If you're SURE the tool is connected right and your bench synch has been done carefully...
I've always found that after a good bench synch, the vacuum levels are all high enough so no drastic changes are necessary. Maybe just my luck? Then I simply lower the high ones to match the lower ones. Not much adjustment is needed. However, if yours are off quite a bit more to begin with and using my method seems to lead you into trouble, then by all means reverse your adjustment procedure. To get them reasonably even, adjust them any way that looks like it's easiest. I'm sure you've seen on your vacuum tool that making a change to one cylinder can effect another? After all, thet ARE connected. Sometimes you have to "split" your adjustment and SLIGHTLY adjust two cylinders to get them to match, instead of focusing on one cylinder. Hope I'm not just adding stress. Like I said, it's much easier to be there than type what's happening.
Years ago I had this problem a couple times and each time if I adjusted the vacuums higher and higher, trying to even them, I soon reached the point where I kept turning down the idle knob until it no longer could lower the idle. I stopped doing it that way and also paid MUCH more attention to my bench synch to begin with.
I think I'm not helping you much right now and I wish I could be there to help. Starting over is the only way I know of to fix this problem. If you keep ending up with the same problem I'm not sure what to say.
Using a base idle of 1,000/1,100 rpm's is very important though. Be sure the holder nuts for the slide adjuster screws are backed off enough so you can make smooth turning adjustments as needed. The nuts can turn with the screw and complicate simple/minor adjustments.
Just be sure you don't over-heat. Use two big fans. The more wind the better.

[KEITH KRAUSE]

Dave, if you still need help, try this...
Re-bench synch as I said earlier. Loosen all 4 adjusters and set them reasonably uniform. Adjust the slides as carefully as you can.
Now, UNIFORMLY turn all 4 adjusters in the appropriate direction that will ADD some vacuum straight accross. If done carefully, the slides should still be uniform but this method should help stop any initial too-low vacuum levels. "Temporarily" snug things down in preparation for start up, just so things aren't loose.
Maybe this method will counter something you may be doing that's resulting in such low vacuums at start up.

[nitrogs]

Hi Guys,

Thank you for the comments. Just wondering, I am using a auxillary minimoto petrol tank for my fuel supply to do the synching. Does the vacuum pipe that usually connects to the fuel tap need to be plugged or something or is it okay left disconnected. Havent been able to play today unfortunately. But can say yesterday, played very close attention to the bench synch and all looked good, started well. On the synch gauge and 1, 2 and 4 cylinders looked fairly consistent but number 2 cylinder down on vacuum. Thank you for your words of wisdom Keith I will keep trying.

[hampshirehog]

You need to plug the vacuum pipe otherwise it'll suck air straight in and you'll get way off figures.