HELP! 1980 GS850G Starts, but stumbles-Pops-won't rev??

[BassCliff]

I will be double checking the float heights while I'm installing the DK Stage 3 Jet kit...

I thought I saw a conversion chart somewhere on this site that showed the Mikuni to Dennis Kirk Jet size comparisons? I can't seem to find it again. Anyone here have the link, or do you happen to know what the DK160 and DK165 jets compare to in Mikuni part numbers/sizes??

Hi,

I think Mr. Ranger was pulling your leg. I hope you mean "DJ160" and "DJ165". I believe you are talking about DynoJet parts, not Dennis Kirk parts. Dennis Kirk is a motorcycle parts retailer. DynoJet is a maker of jetting kits and other carb and performance related products.

You'll find a conversion calculator spreadsheet on my little website, probably in the Carb Notes section. Or just let me Google that for you and you can pick your conversion chart.

Why the difference in jet numbering? It's because the DJ parts are actual diameter measurements while the Mikuni parts are measured in cc's of fuel per minute, a volume measurement.


Thank you for your indulgence,

BassCliff

 

[Steve]

I used a broom handle. Simply tap(softly) the end of it into the fastener inside the forks.
Worked for me.

I tried that, too, on the first set of forks I did. Worked OK on the first one, but the second one rounded out the end. I cut a fresh end, but it splintered when I hammered it into place. Then I read about the all-thread with the doubled-up nuts at each end. I now have one setup for GS and another for the larger Kaw and Yamahas that have lived in my stable at one time or another.

Any suggestions on fork oil weight? I've read 15wt for "average sized riders"... Not sure what that means. I'm 6'3" and weigh 215-220, depending on what I'm wearing. Likely to get "aggressive" from time to time.

15w is a good place to start, but pay attention to what your suspension is doing. The only adjustments we can make all involve at least partial disassembly, so they are not easy to change on a moment's notice. We can change springs to change the rate, we can change spacer length to change the preload and we can change amount and viscosity of the oil. Assuming your spring rate and preload are correct, stay with the stock amount of oil for now. If 15w oil is not responsive enough, you will know it when your wrists start hurting if you ride on rougher roads. Even expansion joints on the freeway can do that after a few hours. If you notice that with your bike, a switch to 10w might be all it takes.

Remember, it's not the oil's job to support the bike, that is for the springs. The oil only keeps the springs from bouncing uncontrollably. Most racing tuners will say to use the lightest oil that does the job.


.

 

[Darin Jordan]

Hi,

I think Mr. Ranger was pulling your leg. I hope you mean "DJ160" and "DJ165". I believe you are talking about DynoJet parts, not Dennis Kirk parts. Dennis Kirk is a motorcycle parts retailer. DynoJet is a maker of jetting kits and other carb and performance related products.

Thanks for the clarification... What would we do without you guys??! :-k

 

[Steve]

What would we do without you guys??! :-k

You would still be walking.

.

 

[Darin Jordan]

You would still be walking.

.

Hahaha... or at the minimum... PUSHING!

 

[Darin Jordan]

Robert Barr O-Rings... Dennis Kirk DJ Stage 3 Jet kit, and Bike Bandit SGP Intakes... all arrive this week. Cover me... I'm going in!!:dancing:

 

[Ranger]

Robert Barr O-Rings... Dennis Kirk DJ Stage 3 Jet kit, and Bike Bandit SGP Intakes... all arrive this week. Cover me... I'm going in!!:dancing:

Have fun, shouldnt take more than 2 hours.

 

[Darin Jordan]

Have the o-rings installed on the carbs... working on the Jet kit now.

First thing I noticed once getting the float bowls off... the #4 carb float level was REALLY high (low on the measurement...) Something like 19mm or so. We DO measure these while they are just RESTING on the needles, right? And down on the step of the float? I have the tip sheet here from BassCliff's site. I'll go read it again to see if I missed it. I know that, typically, this is how you do it. Carb #3 was set correctly. Haven't gotten to 2 and 1...

 

[Ranger]

Have the o-rings installed on the carbs... working on the Jet kit now.

First thing I noticed once getting the float bowls off... the #4 carb float level was REALLY high (low on the measurement...) Something like 19mm or so. We DO measure these while they are just RESTING on the needles, right? And down on the step of the float? I have the tip sheet here from BassCliff's site. I'll go read it again to see if I missed it. I know that, typically, this is how you do it. Carb #3 was set correctly. Haven't gotten to 2 and 1...

While they're resting, correct. Make sure you're base you're measuring from is the little ledge inside where the float bowl rests on almost.

 

[Darin Jordan]

While they're resting, correct. Make sure you're base you're measuring from is the little ledge inside where the float bowl rests on almost.

Yup... that's where I'm measuring it. Just inside the gasket sealing ridge that runs around the mounting base. Really glad I'm going through this a second time. I should have paid more attention the first time around.

Just to double check... Stock motor, K&N Aircleaner Pods, and Kerker exhaust... 165-mains like the instructions suggest?? Kit came with 155, 160, and 165 Mains. :-k

 

[Ranger]

Yup... that's where I'm measuring it. Just inside the gasket sealing ridge that runs around the mounting base. Really glad I'm going through this a second time. I should have paid more attention the first time around.

Just to double check... Stock motor, K&N Aircleaner Pods, and Kerker exhaust... 165-mains like the instructions suggest?? Kit came with 155, 160, and 165 Mains. :-k

Told you so, about the first part of your post.

& Yeah, I'm guessing thats the stage 3 jet size.

 

[Darin Jordan]

2 and the float-bowl area of another done... 1 top and one carb to go... So far, so good...

Quick question just to make sure... When putting the needles in, the spring seems to push them off to one side a tad... I very carefully assembled, and also compared the slides both modified and stock, and they all seem to do that. Normal, right?? Not HARD pressed to one side, just lightly sprung there... Makes sense, since the springs can't exert perfectly even pressure, but just thought I'd double check.

Oh, and just like #4, #2 float level was WAY too high. About 19mm or so. I checked at both sides, just to make sure something wasn't bent, and same story there... Dead on at 22.4mm (.882"... without the gasket) now...

Attention to detail... attention to detail... attention to detail...

 

[almarconi]

Isn't it interesting that there was no jet kit installed,the float height was incorrect and according to the PO the bike STILL ran great :-k

 

[Guest]

Isn't it interesting that there was no jet kit installed,the float height was incorrect and according to the PO the bike STILL ran great :-k

"ran" being the key word.
They all ran great at some point.

 

[tkent02]

"ran" being the key word.
They all ran great at some point.

Most all of them ran great when they left the factory.

 

[Darin Jordan]

Well guys... THANKS to the help I received here, she's no longer a garage queen!

Got everything back together today, and took her for a ride. Felt GREAT!

Still need to officially balance the carbs, and get a few details buttoned up on the fuel system, like adding some quality breathers for the vents and crankcase breather line.

Seems to run pretty good, though it seems to get really lean from around 6500+. Kind of stutters, flutters, pops a bit up there. Pulls nicely to that point, however. Will need to work to figure out what's causing that. Any thoughts or advice on that would be appreciated. Current jetting is per the DJ Stage 3 Jetting kit, 3rd groove on needle with 165 mains. Floats are set right at the recommended 22.4mms. Should I have adjusted that for the larger jets?

Also, I noticed that, when I first set the fuel petcock to prime, I left it on a little too long. Fuel was coming out of the #2 carb's main air jet (2nd carb in on the right side??) If the float needle was working properly, would't the fuel stop filling the float bowl once it's full?

I rode the bike around for about an hour, went up and put fresh fuel in, and didn't notice any more fuel doing this with the petcock on "on", and other than the bike seemingly leaning out above 6500 (just shy of 7000, actually), it seemed to run fine, started right up, idled nicely, etc.

OH, and the front brakes are SOFT! Definitely need to work on that. Feels like the pads are dragging a little, and they may be glazed. They almost feel non-existant at this point.

Here are some pics from today:

 

[Steve]

Seems to run pretty good, though it seems to get really lean from around 6500+. Kind of stutters, flutters, pops a bit up there. Pulls nicely to that point, however. Will need to work to figure out what's causing that. Any thoughts or advice on that would be appreciated. Current jetting is per the DJ Stage 3 Jetting kit, 3rd groove on needle with 165 mains. Floats are set right at the recommended 22.4mms. Should I have adjusted that for the larger jets?

The float level remains the same, regardless of what else you have done.

Stuttering at 6500 rpm does not mean much unless you also say what the throttle opening was.
- If it was barely open while running in neutral, you were still sort of on the pilot circuit because the throttle wasn't open very much.
- If it was while holding it there in second or third gear, you might have been at half throttle, meaning the needles were in play.
- If it was while acellerating wide open, it would have been the mains that need attention.

Also, I noticed that, when I first set the fuel petcock to prime, I left it on a little too long. Fuel was coming out of the #2 carb's main air jet (2nd carb in on the right side??) If the float needle was working properly, would't the fuel stop filling the float bowl once it's full?

Carbs are numbered from left to right, as you sit on the bike. #1 is under your clutch hand, #4 is under your throttle hand.
ALL references to "left" and "right" are made that way.

And, no, the float does not always stop the flow of fuel. There could have been a little speck of dirt keeping the needle off its seat. It could have been just a little off-center. (The vibrations of a running engine will usually center it.)

OH, and the front brakes are SOFT! Definitely need to work on that. Feels like the pads are dragging a little, and they may be glazed. They almost feel non-existant at this point.

Have you done anything to them yet?

At the very least, you should have cleaned out the master cylinder and the calipers, as well as changed the fluid. Considering that the Suzuki manual suggests changing the rubber brake lines every 2 years, I would guess that they are about 29 years overdue.

Here are some pics from today:

Very interesting color scheme. I like it. :clap: :clap:

.

 

[Ranger]

Looks good,

It might have been a stuck float allowing fuel to leak but I don't know. Being lean at those rpms baffle me, it would be lean somewhere else on the power band but I don't remember the jets that are used during different throttle ranges.

Glad the weather held up, not looking good for my drive.

Bleed your front brakes, it'll help. Mine stop with one finger, trick is to feather the brake lever while you're bleeding because air bubbles will stay behind the master cyl.

 

[Darin Jordan]

Have you done anything to them yet?

At the very least, you should have cleaned out the master cylinder and the calipers, as well as changed the fluid. Considering that the Suzuki manual suggests changing the rubber brake lines every 2 years, I would guess that they are about 29 years overdue.

Nope... not yet, but it's next on my list. I'm planning on new Stainless braided brake lines, and some good brake pads as well. Looking to get a new master cylinder resevoir. Current one isn't leaking or anything, but it looks weathered.

Now that I know it runs, the rest is tinkering and weekend projects I think...

As for the running, the stumbling would occur when cruising along at say 3000, and opening up the throttle to get up and go. Would pull fine through 6500, then start stumbling. Reading through the Dynojet tip sheet now...

 

[Steve]

Looking to get a new master cylinder resevoir. Current one isn't leaking or anything, but it looks weathered.
...

I just replaced the one on my 850. Best price I found for the reservoir kit was Parts-n-More. I also got the rebuild kit and o-rings for the calipers.

.