GS1000 valve clearance problem

[NitroGS]

Hi Keith,

Thank you for the reply my friend, that's what I am going to do. I shall remove the carbs and fit the 138 mains as suggested. I will let you know how I get on.

[KEITH KRAUSE]

OK. One other thing, be sure to oil the filters correctly.
I only mention it because it's very easy to over-oil them following the K&N instructions. "Oiling each pleat" can lead to too much oil unless you're very quick with the pass. When re-jetting, it's even more critical to get the filters oiled right. The engine doesn't just suck out all the extra oil in a few minutes as many think. They'll still cause a rich condition.
With the spray can, I just make a quick pass from about 4" and I hit between 2 and 3 pleats per pass. Kind of hard to explain perfectly. I just want to stress the point to be careful. Talk to you later.

[saaz]

It is interesting following this thread, wish it was 25 years ago! I have a 78 GS1000, MTC 1080 kit, flowed head, stage 3 cams (9.8mm lift, modified ramps), race type exhaust and 28mm Kawasaki Z9 carbs (they were the go back then). 120# mikuni size jets are all it can take, as it flows too much to put in bigger ones. I also use K&N oval filters (one per two carbs). Also have Newtronics electornic ignition, bandit coils and stuff. Fournales shocks, Akront 18" rims, nothing much else.

Get that bike going, we need more on the road. I still have to get a gasket kit fitted to mine (I have it), has been sitting for the last year or so. I am afraid I am too busy with work then riding (also have a Honda ST1100, so riding distance is nor much of an issue). Hopefully I will get active with the GS again in the next year or so.

[NitroGS]

Hi Guys,

What a long day. Removed the carbs from the bike, removed the float bowls and fitted the 138 mains. Retightend all the parts and fitted the carbs back, the choke lever fixing bracket needed a little tweaking downwards to ensure the choke sliders seat fully closed, not a problem. Put some gas in the petrol tank whilst removed from the bike to test the petcock, all sealed no leaks. Turned with a screwdriver to prime, no petrol, tested the vacuum side and all works okay. So attached a brand new section of petrol pipe to the carbs and a new vacuum pipe. Used a small funnel directly into the carb feed pipe and filled the bowls that way all seemed to seal okay. Tried starting the machine, see fired up initially on 2 cylinders (1 and 4) and sounded rough after a minute or so she fired on all four, and was crisper on the throttle. Checked the float bowls and drat!. Petrol was seeping from the gaskets on carbs 3 and 4. Carbs off again extra tweaks on the carb screws sorted the issue. Everything connected back up and starter pressed again only seemed to be firing on 2 cylinders and this time it didn't try to fire on cylinders 2 and 3 (pipes noticeably colder). Whipped out the plugs to confirm, laid them on the head and cranked the engine, good fat sparks at cylinders 1 and 4 and no spark at cylinders 2 and 3. Do I need to check all the connections and what else should I look for please.

[KEITH KRAUSE]

First of all, it sounds like you have the infamous '80 model petcock on there. Because they're designed to be a pain in the ars, the '80 model petcock requires constant cranking to initiate fuel flow. Fuel will not flow just by turning the slot. These petcocks seem to have two "on's" and no true prime but that's the way it is.
As for the no spark problem at 2/3...
Since your Dyna S is new, it's not likely that you have a bad module/sensor. But if you swap the black and white wires and the spark transfers to the opposite plugs, it suggests a bad module/sensor. If the sparks stay with the same plugs, that suggests a bad coil or wiring problem.
The Dyna S uses only one hot wire so all four would be effected if it was a bad connection at the supplied Dyna split connector.
Double check the white and black connections.
Another thing to check is the gap between the rotor and the module/sensor for 2/3 (the right side module). It should be between .025" and .040". Any larger than .040" and the module may not switch due to low or no voltage.
Check the above first. It's not impossible to fuel foul the 2/3 plugs only but loss of spark at 2/3 would suggest an electrical problem. If it passes all checks and sparks well during testing, then it could be this isn't a poor connection or bad part problem, but a mixture/vacuum related problem. When you first checked for spark, did you swap the plugs around? If a plug is still wet, the spark will track down the wet plug to ground and you won't see a spark jumping the gap. I can only assume the 2/3 plugs are gapped correctly. The factory calls for approx' .027" though Dyna says a little larger gap, about .031", is better with their ignition and coils.
A mixture/vacuum related problem could result from a poor bench synch. That's the most common cause. You said the carbs are rebuilt and it would figure they are adjusted equally in all other areas. Used carbs are always a gamble and we'll hope it's not an internal problem with them. Let's check the electrical and re-bench synch if any doubt and go from there.
Even though the petcock apparently contributed to a poor start up, the petcock could only cause a poor start up from lack of fuel supplied, and a lack of fuel wouldn't have anything to do with the plugs not sparking when you took them out to check them. Only a wet fouled plug or weak/no spark condition would cause your problem.
Talk to you soon. Don't get discouraged. Things happen.

[KEITH KRAUSE]

One other thought and after checking the previous...any chance you set the timing wrong at module 2/3? If not advanced correctly (usually too retarded), this would in effect "richen" the mixture and the plugs could lose spark quickly from wet fouling. I assume you know how to check the timing and advancing action either with a timing gun or during a static check? If any doubt, tell me and I can help you time it.
Gotta get to bed. 12 hour day tomorrow. Talk to you later in the evening.

[NitroGS]

Thanks Keith for your kind words of advice, there is no way it is going to discourage me, I love this bike. I will try what you have mentioned and I will let you know. When I looked at the 2 and 3 plugs after running the engine for 3 minutes, with them not firing I expected to see them wet but funny enough they weren't. Just going to have my breakfast then I am back out in the yard with the beast. Have a good day Keith.

[KEITH KRAUSE]

OK. Double check the electrical system as I said and if needed, we can focus on the carbs.
I'm off to work and can reply later tonight.
Hope to read good news when I come back.

[NitroGS]

Hi Keith,

Heres how I have got on today. It all started with tracing the fault for no spark at cylinders 2 and 3, swapped the black and white wires around and still sparks at the same plugs. Checked all connections particularly at the coil and found the black wire ring terminal on the coil supplying 2 and 3 cylinders had rotated round on tightening and was just touching the coil mounting post. Ah! got ya!. Re tightened connection and voila big spark, great!. Struck up the motor and set idle to 1100 rpm (quite rumbly). Started at number 4 carb air screw tweaking for max revs (or pickup in revs) I know from previous threads it can be hard to tell but I can honestly say there was no pickup in revs only when screwing in the screw the engine becomes lumpy and wants to die. So back out to 1.75 turns. Tried the other 3 carb air screws and basically the same there no pickup in revs. So decided to connect up the Morgan Carbtune to view the vacuum readings, results shown here Keith http://www.minimotos4u.com/gs1000.htm . The readings shown are for idle and 3000 rpm. So removed the petrol tank and connected up two long hoses one petrol line and one vacuum line and attached each, removed the carb tops. With the engine chiming at 3000 rpm I set the vacuum levels the results can be seen here http://www.minimotos4u.com/gs1000.htm . Carb covers back on. Noticed Keith that those damn float bowls are weeping any ideas how I can sort that one.

[KEITH KRAUSE]

Glad you found the spark problem. Easy to over-look something, isn't it?
When adjusting for highest rpm, there are too many variables to list here that can effect the rpm's and give unexpected results.
Sometimes a bike will idle pretty well at initial screw settings and with further adjustments the idle will pick up a couple hundred rpm and you've found the sweet spot. Other times the bike will idle well but any significant screw adjustment just causes a lumpy idle or near stall, but no rise. In that case, you've still found the highest rpm, or what is sometimes called "the best idle". In many cases, this "best idle" will work for you. If you end up having other pilot circuit related "problems" as you re-jet, then there's a chance your pilot jet is the wrong size, which is the most common cause of trouble when adjusting for highest rpm. But your stock pilot jet, as long as it's the correct length (there are 2 lengths of PJ for these carbs), should be fine as per the DJ kit instuctions.
When adjusting the screws, unexpected results can be so many other things or a combo of many. Just to name one... ignition timing. You know how you typically just line up the timing marks and say it's good? But how can you truly trust the marks are spot on? The marks/stamping may be a tad off. The sensor plate isn't the most precision part either. The sensor magnet may not be truly centered in the rotor, etc, etc. It can add up to where the true timing is several degrees different than what you think you're setting. Without a dial indicator to help you find true top dead center, you have to trust the timing to all these parts.
My point is, there are other things that directly effect something like adjusting the air and pilot screws. Some of these things take more knowledge and more tools and time than many of us care to deal with.
Sorry for the ramble.
As for your highest rpm method attempt, remember that the bench synch can greatly effect the screws operation too. You can't expect the screws to give perfect results if the vacuum levels (and thus the varied mixture ratios per cylinder) are too unbalanced. I may not mention it enough but in your case, I'd try the highest rpm method once more, now that the carbs have been vacuum tool synched. I'm not saying you WILL hear a real difference now but you should try it again. You may even find later that if you make enough additional pilot fuel screws adjustments, the air screws may benefit from a final fine tuning.
As with the basic jets involved with a re-jet, the screws adjustments and the results, vary some from bike to bike.
Your vacuum synch looks good to me. Fine job!
As for those leaking float bowls, I can only assume they are installed flush with the carb bodies. I think I mentioned earlier that the bowls can be installed so that they don't quite set in. I first noticed this when I was a lot younger and while installing the bowls with the carbs on the bike. In that condition, if the bowl was just a tad too forward (towards the engine) it would somehow cause a tilt. I had to kind of slowly wiggle the bowl flush into place and be careful of centering it right. Many times you can hear it "snap" into place. I have no problems now but it can be something that happens and you have to aquire a feel for it.
If that's not your problem, I assume the bowl gaskets are new and the gasket surfaces are clean? If so...
I always replace those Phillips bowl screws with stainless steel hex heads (or regular zinc plated if that's what you can find). You can snug them up much better. Don't apply too much torque to the hex heads but they do a better job.
The next thing that will work and I've had to do myself from time to time, is to use a gasket sealer to help it seal. You don't need to apply much. Just rub some on each side of the gasket as a thin film. That way, no significant amount will squeeze into the bowl chamber as the screws are tightened. I've used Permatex 2, or 2B, form-a-gasket sealant with no problems. It's a non-hardening, pliable, fuel proof sealant. Works for me.
If you have problems and can't find a good sealant, then you may want to try a thin coat of typical bearing grease to help "soften" the gaskets. Bearing grease works well on valve cover gaskets. It helps them seal and the gaskets come off much cleaner the next time. I have not tried it on bowl gaskets but the gasket material is the same and I see no reason it wouldn't work.
One last thought though, if you bought aftermarket gaskets, they may be made of a material that simply doesn't crush just enough and a sealer may be mandatory. Some gasket materials out there are simply too hard to crush down under such little screws.
Hope this helps and I'm looking forward to the testing. Just be careful when high speed testing. I always feel a little funny about describing how to road test the jetting and chop off to get plug reads, but without a Dyno, what else can we do?

[KEITH KRAUSE]

It is interesting following this thread, wish it was 25 years ago! I have a 78 GS1000, MTC 1080 kit, flowed head, stage 3 cams (9.8mm lift, modified ramps), race type exhaust and 28mm Kawasaki Z9 carbs (they were the go back then). 120# mikuni size jets are all it can take, as it flows too much to put in bigger ones. I also use K&N oval filters (one per two carbs). Also have Newtronics electornic ignition, bandit coils and stuff.

saaz, good to hear from you. I don't see you here much.
I'm not sure about your statement...120 mains because it flows too much.
A seemingly small main, from my experience, is all you can use to feed those mods?
Maybe the 1 into 2 pod filters contribute here? Why that set up?
I also have no knowledge of that ignition system. The Bandit coils put out about 10K volts? Any chance you may have a weaker spark and don't realize it? What ignition timing do you run?
Maybe it's the carbs or a mis-match of mods. I just can't understand the 120 main. Ahhhh!!!

[NitroGS]

Many thanks again Keith for your replies. I will definately try the air screw adjustment again my friend. The bowl gaskets I used are part of a K and L repair kit. I did order the allen screw carb replacement kit for the 1979 Suzuki GS1000E but for some reason they sent me short screws which were only grabbing 4 or so threads, this was when I first assembled the carbs and we got those leaks. So i replaced the allen screws which because of them being short I thought wouldn't give much torqing on the bowls with the original phillips screws. But we still have some seeps. So I take onboard exactly what you say, I shall get some correct length allen screws, check the bowls aren't too far forward and use a small amount of sealant. I have had my fairing and front fender sprayed and it should be ready for collection on Friday. So road testing all being well should be then. Don't tire yourself too much with those 12 hour shifts Keith, speak to you soon.

[NitroGS]

Hi Keith,

Just to let you know i tried the air screw adjustment again today, no pick up in revs on adjusting at either carb. Only the lumpy effect on turning one carb at a time inwards. Hope the new carb float bowl allen screws arrive tomorrow nd the bodywork. Just out of interest I know it won't probably mean anything but having warmed the bike up stationary to full operating temperature, I looked at the plugs and they are well brown. Will be in touch my friend.

[KEITH KRAUSE]

OK. Like I said before, no need to be too concerned about how the air screws effected the idle. Certainly not unless road testing brings up something else. As long as the bike is idling well and at the factory recommendation of approx' 1,000 rpm's, you're off to a good start. There's bound to be some fine tuning to do to the pilot circuit but it should be idling pretty steady.
As for the plugs being "well brown", I've never heard it put quite that way. If you're saying they look on the rich side, then don't be too concerned about that either. The bike must be tested under LOAD conditions and under FULL ignition advance. Idling compromises any plug read. To be as accurate as possible when road testing and reading the plugs, the throttle/ignition must be "chopped off" from whatever throttle position/jetting circuit was being tested. The engine must be under load at that moment. The bike can't be allowed to idle at all, such as just coasting to a stop before turning it off. At anything under 1,800 rpm's on your bike, without the ignition timing advanced, combustion isn't optimum. The plug color will darken. Yes, a truly rich pilot circuit would give rich reads under any conditions but there's no reason to think you are rich at this time.
If testing says you are rich, then it would certainly figure that simple leaner adjustments at the pilot fuel screws would make things right. I mean, your mods can only lean the mixture and you have a completely stock pilot circuit. You now have the pilot fuel screws set initially to 1 1/2 turns out. Because your bike comes straight from the factory with the pilot fuel screws as little as 1/2 turn out, your initial adjustment of possibly 1 full turn richer could be more than what's needed. That's what you want...to be able to set the pilot circuit right without going to a 17.5 pilot jet. The DJ kit REQUIRES your model to run a completely stock pilot circuit. The new DJ jet needle factors into this because it comes into effect so much sooner/earlier throttle position, than the stock jet needle. So you shouldn't need to do anything more than tinker with the screws. The pilot circuit is sensitive to adjustments and it can take some time. DJ, or any jet kit maker, will tell you that you may have some minor "driveability" issues after re-jetting. There are just too many variables and some are beyond what the kit can overcome. Once correctly jetted, any issues should be minor, such as what some may consider excessive deceleration pop...things like that. Trying to completely eliminate a minor issue can result in something worse. For that extra power you WILL see, you may have to allow something "less than perfect". But as I said before, with the bike tuned right and ready for the re-jet, you should be very happy with the performance when finished.
In my opinion, it's better to get the jet needle right before focusing on the pilot circuit. There's just too much "early" jet needle effect with the DJ needles as they overlap the pilot circuit sooner than the stock needles.
The overlap between any two jetting circuits can be the hardest to fix. You can find yourself adjusting two circuits to fix what you think is one jetting circuit problem. The jet needle setting will have a much broader effect than the pilot fuel screws. So the needles should be set first, then you add any necessary pilot fuel screw adjustments to make the minimal throttle position performance right. Don't know if I'm explaining it well but it's easier for me at least.
Test the jet needles at a solid 1/3 throttle on level or preferably gradual uphill ground. Judge performance and chop off to read the plugs. If the performance and plugs are acceptable, then you can immediately test the pilot circuit. You want minimal throttle position and the same level/uphill road conditions for the pilot circuit. I test at a steady 35/40 mph in 4th/5th gear. 4th may be better most of the time. This minimal throttle opening assures you that the jet needle will have no significant effect on the performance or plug reads. In your case, nothing more than pilot fuel screw adjustments, and maybe some fine tuning of the air screws in the end, should be needed. If your current testing weather is a bit cold or hot, then you may find yourself fine tuning for a happy medium later on as conditions get colder/warmer. The pilot circuit is very sensitive to screw adjustments and outside conditions.
Last thing to do is full throttle for the mains. The other two circuits will have no significant effect on main testing. Hopefully, top end will be good and roll ons/passing power will be strong.

[KEITH KRAUSE]

Just one other thought as I'm off to bed..
I know nothing about these split fire plugs you say you have. I don't know how they effect the spark of the higher voltage Dyna system. I always recommend the NGK B8ES plugs. Just wanted to mention that.
Also, though it shouldn't matter now, my past experience says you were very lean by running the 120 mains. That's a good 2 full sizes smaller than the 138 DJ main which equals approx' a 130 Mikuni main. Your jet needle seemed lean too. I've had no luck with the stock needles unless the needles had the clip at the bottom (5th) position. Sometimes, not even that was working.
I don't know if you tested well, but if you did, the Harris exhaust must have flowed poorly or other tuning issues and/or the climate there must have richened things quite a bit. And when you add that you ran stacks, I just have to believe you were very lean.