tweaking jet kit - move clip or smaller main jet?

[Anonymous]

78 GS1000 - K&N pods - Kerker 4-1 - Dynojet Stage 3 kit

I'm just about there with getting my carbs right since putting in the jet kit but the problem is after about 2 weeks the plugs inevitably foul out. Currently I have the 138 jets and initially set the clip according to the instructions, moving it up one notch at a time till the stuttering went away, which ended up being 2 or 3 notches up. (I installed it back during summer and haven't ridden much so I forget exactly. ) Carbs were synced and float height was checked. FWIW the weather than day was rainy and a little cool.

Anyway the bike pulls hard with no flat spots or anything that I've noticed, getting pretty close to redline. I checked the plugs several times over the first week or so and they were on the dark side of tan so I thought I had it dialed in. With the sporadic riding I've done since then, when my plugs first fouled I thought maybe I'd flooded the bike while trying to start it and that somehow caused it. I've been riding pretty much daily for the last 6 weeks now and after 2-3 weeks, sure enough I have to change my plugs. My riding is 99.5% city riding, generally between 4k-6k so my first thought was maybe with the Oregon weather getting a little cooler I needed a hotter plug but that wasn't it either.

Does stepping down one jet size and starting over with the needle height sound like a reasonable solution? Considering the rev range I spend most of my time at I'm not sure and I'd like to avoid buying jets I might not need if I can help it.

[Anonymous]

Reply: 78 GS1000 - K&N pods - Kerker - Dynojet Stage 3 k

Never had plugs foul that quickly being 1 jet size too rich and needles a little off. Never. Might be something else. Otherwise - if you don't have platinum tipped plugs in - usually that buys you a jet size (runs leaner) and makes spark more reliable.

[Anonymous]

I hadn't even thought about Platinum plugs, probably cuz I heard so many horrible things back when I had an EX250. Frankly I'm a little surprised at how fast my plugs are fouling too, especially since aside from being a *bit* smelly the bike doesn't act like it's that rich.

I wonder, could one's starting procedure cause plugs to foul? I usually start with no choke and gradually increase it till it starts. That's the way I've always done it and never had a problem on other bikes anyway...

[KEITH KRAUSE]

Hi. I've got a '79 GS1000 with V&H megaphone, 1085 pistons, K&N ovals, DJ stage 3 jet kit, Dyna "S", etc. We do have some differences, but try this set-up.
Keep the 138 mains,
Needle e-clip in 4th notch from the top,
Stock pilot jet is fine,
Pilot fuel screws (underneath) 1 1/2 to 1 3/4 turns out, (you'll most likely have to fine tune, but this will get you close)
Adjust the side air screws for highest rpm's and then re-set the idle to 1,100 rpm's with the idle adjuster knob,
Remove the two floatbowl vent lines,
After checking the ignition timing and valve clearances, vacuum synch the carbs so the most difference between highest and lowest levels is 1/2" or less at 3,000 rpm's,
Be sure the filters are oiled correctly.
By the way, cam timing of 106 degrees both intake and exhaust works very well on these bikes.

[Anonymous]

carbs

Sounds like low speed fouling to me if your checking them after doing a lot of around town driving, I fought my low speed mixture, for about 2 weeks then I pulled my exhaust and used the exhaust analyser, and I quite fouling the plugs, each setting weather its mid range (needle) or 3/4 to full throttle ( main jet )has to be set and corrected according to that throttle postion witch involves a throttle chop method and a plug reading

[mike J]

While we you guys are on the subject of jet kits. I bought an 1150 that had a pipe, filters and a stg 3 jet kit in it already. The bike doesn't seem to pull as hard as it should. Anyway, I pulled the slides out tonight and it looks like whom ever installed the kit may have put the needle assy back in wrong. They had it spring in first (in the slide) followed by the needle then the metal washer and finally the plastic washer on top. This may be correct but this way the spring can slip past the cilp on the needle. can someone one confim what should be the assy order? TIA Mike J

[Anonymous]

carbs

mike go to bikebandit.com and click on oem parts the info you need is there

[mike J]

I went to bikebandit.com. The part diagrams are to fuzzy to tell exactly how the needle assy goes together, can anyone help with this? Mike

[Anonymous]

My carb settings are nearly spot on to what yours are Keith. I'm starting to think maybe it's a weak spark problem instead, especially since I just noticed that the battery looks like it's nearly as old as I am and the plug wires have seen better days. I'm gonna buy a new battery today and check the coils...and speaking of coils, I was thinking this mod might not be a bad thing if necessary http://www.kzrider.com/ignition_upgrade.shtm but does it matter than I have a Dyna ignition? It seems that it's usually suggested when ignition is stock?

[KEITH KRAUSE]

My carb settings are nearly spot on to what yours are Keith. I'm starting to think maybe it's a weak spark problem instead, especially since I just noticed that the battery looks like it's nearly as old as I am and the plug wires have seen better days. I'm gonna buy a new battery today and check the coils...and speaking of coils, I was thinking this mod might not be a bad thing if necessary http://www.kzrider.com/ignition_upgrade.shtm but does it matter than I have a Dyna ignition? It seems that it's usually suggested when ignition is stock?

I can't answer the ignition mod' question. I have a Dyna S too and Dyna coils. I went through all my connections when I rebuilt my bike and I've never had a spark problem. Maybe if you replace the battery and clean every connection and check the plug caps, your spark will improve. If not, try the mod'? If you have the $ I recommend the Dyna coils. They're supposed to put out 35,000 volts instead of the stock 10,000. Is your spark a decent blue color, or only an orange color? Should be blue.
When you say your jetting is nearly like mine, what exactly are your settings? Your city riding is mostly on the needle circuit with an overlap with the pilot circuit. The overlap can be considerable. The pilot screws underneath are sensitive and just a 1/4-1/2 additional turn out will change the plugs a lot. Your needle may have to be adjusted a 1/2 position lower (with the jetting spacer). Your rainy weather will cause a richer condition too. Don't underestimate the effect the pilot screws have on city riding.
Tell me what exact jetting set up you have so I can try to help you better.
I assume the carbs are clean inside and you say they're synched VERY well? Did you replace the manifold o-rings? Any other symptoms beside fouling plugs? Any fuel coming out of the floatbowl overflow lines, even a little? Black exhaust when you rev' it?
Are all four plugs uniformly dark/fouling?
A few more thoughts: are the floats adjusted to .94" which would be perfect? Did you replace the two plastic spacers on the jet needle and in the correct order? Thicker one on top the e-clip, thinner one below? O-ring that fits the bleed pipe/needle jet in good condition?
Check out my '79 1000E at my website if you like. Just click the WWW symbol below.

[Anonymous]

heh heh well I guess my settings weren't as spot on as I thought. The pilot screws were closer to 1 3/4-2 turns out so I set them all to 1 1/4 and I'll go from there. I just installed the new battery and cleaned the contacts and I'll pick up new wires and caps just to be thorough. Dyna coils are next on my list but it'll have to wait a while or my wife will kill me. I was thinking about that igniton mod as a cheap and workable substitute for new coils.

As for other symptoms....there'll be a slight bit of black smoke from time to time when I rev it but nothing else I've seen. The plugs are evenly and uniformly black and crappy looking. No fuel overflow.

Carb sync...when I synced after installing the jet kit I thought I had all four very close but I'll do it again just to be thorough, less than 1/2"@3000 rpms. Is there a certain level all four should be at or is getting them as close to even as possible what's most important?

I set the floats to spec according to the Haynes book I have. It's not in front of me so I forget exactly what that is. Spacers on the needles were put back in the correct order and the o-ring looked fine. I do want to replace the manifold o-rings but I'll be damned if I can find them in the parts listing at Bike Bandit. The closest thing I found are the o-rings for the airbox-carb boots. If you've got a link or a part number handy I'd appreciate it.

Thanks very much for your help.

[KEITH KRAUSE]

OK. Your first post said you weren't sure where the needles were set. I said put the e-clip in the 4th position from the top, not knowing where they were to begin with. I assume they are in the 4th position now and you're getting black plug reads. Your plug results are from riding mostly around town. Now that I know what your current jetting is, here's what I would do.
Finish cleaning/checking your electrical connections and repair the leads. Get some NGK plug caps. You need (2) YBO5F and (2) XBO5F. You'll have to splice the new leads on because the stock coils have the leads built in. Clean and re-check the gap on the plugs. A new set would be better. B8ES. Do that wiring mod' if you can. Your spark needs to be blue.
Check your ignition timing.
Put the needles e-clip in the 3rd position from the top.
BE SURE the floats are set to .94/.95". Double check what your manual said. They can be set between .90 and .98" but why not set them in the middle?
Do a good manual synch (by eye) to make the vacuum tool synch easier.
Install the new manifold o-rings, Suzuki p/n: 09280-32006. Apply some hi-temp' bearing grease to them to help them last and torque to 6 ft/lb. So get rid of the Phillips and buy Allens.
Leave the pilot screws just the way you have them for now.
Warm up the bike and on the centerstand, adjust the side air screws (filters on) for the highest idle and then re-set to 1,100 rpm's with the idle adjuster knob. They generally end up about 1 3/4 turns out. Do you know how?
Now do the vacuum synch (filters oiled and on). If you have no mechanical problems, you should not have to worry about how high the levels are. If you did the manual synch correctly and turned up the idle adjuster enough so the bike will start initially, the levels will be in the correct range. Just get them close as possible without over-heating the bike. If the difference from the highest to lowest level is only a 1/2" or so, you won't have any mixture problems. I adjust mine at 2,500-3,000 rpm's. Don't over-tighten the holder nuts on the throttle valve adjuster screws. Torque to 3.5 ft/lb. Now adjust the side air screws again as before.
Go test. Get plug reads after cruising around and IF YOU CAN DO SAFELY, get some reads after a few miles at 1/3 throttle. That's moving fast, so be careful. If performance and plug color is good at 1/3 throttle, then it's just a matter of tinkering with the pilot screws a bit to get the pilot circuit good. Let me know how it goes.