Running rich, I need some advice, please

[gs450sjip]

Gents,

I'm new to this forum, but have been studying it for a year now. I have a 1980 GS450S with 6,000 miles. It was stored for 30 years, I am trying to get it recommissioned to ride. Here's what I've done so far:
Cleaned carbs by dipping in Berrymans (twice), replaced o-rings, needle and seats (genuine Mikuni), floats, adjusted the float height to the lowest fuel level within spec. Adjusted idle screw to 1 1/2 turn out. Replaced all jets with genuine Mikuni of the correct sizes. The airbox is original with a new filter. The exhaust is original, the bike is unmolested.
The entire ignition system is new from battery to spark plugs (Dynatek), the timing is correctly set. The cylinders have 150 psi compression on both sides. The bike starts up very fast, especially when cold. No enrichener is required. The left cylinder spark plug runs very black and sooty. I have swapped the needle and seats and floats from one carb to the other with no change. When running, the engine sounds strong and healthy, after warming up some, it starts to "burble" from 1-cylinder. One original float was sunk, I replaced that. The airbox was incomplete when I got the bike. I suspect PO was trying to "lean it out" by removing the lid, filter etc. which it does do. So.....where do I go from here? I appreciate all responses and guidance. Thanks GS450SJIP

[tom203]

You're sure about correct jet sizes ? see link below
How about petcock problem- fuel dribbling down petcock vacuum hose to left cylinder?

http://members.dslextreme.com/users/bikecliff/images/carbspec_float_height.html#A01

[koolaid_kid]

Welcome to the forum.
When you rebuilt the carbs, how many turns out did you set the pilot air/fuel screws (the ones on the outside that used to be under the caps)?
Have you tried adjusting them yet?

[gs450sjip]

running rich

Welcome to the forum.
When you rebuilt the carbs, how many turns out did you set the pilot air/fuel screws (the ones on the outside that used to be under the caps)?
Have you tried adjusting them yet?

I set them at 1 1/2 turns out. I thought that would be close. I did try to adjust them, but that means setting them at 1/2 to 1 turn out. Not much change, so far... gs450sjip

[gs450sjip]

You're sure about correct jet sizes ? see link below
How about petcock problem- fuel dribbling down petcock vacuum hose to left cylinder?



http://members.dslextreme.com/users/...eight.html#A01

I used the sizes listed in the manual, and stamped on the jets where applicable. The only difference was I believe on the pilot jets, the originals had holes on the side, where the new replacements did not. I read where that did not matter. The petcock was really grungy, I dipped it, polished the seat, and reassembled it, then tested it. I opens fine under vacuum, and does not leak or drip when I remove the tank. On another note, I also did the relay mod to the coils. The battery is fully charged, when running it puts out adequate voltage from the alternator. gs450sjip

[koolaid_kid]

Bingo. There is your problem. You need the ones with the holes. They function differently, I forget the technical details but you must use the same type as stock.

[gs450sjip]

Bingo. There is your problem. You need the ones with the holes. They function differently, I forget the technical details but you must use the same type as stock.

Really!!?? that simple? Whoa, I read that it was merely a design change and did not affect the operation. I will put the original ones back in and see if it changes anything. Thanks for the tip, I'll let you know.. gs450sjip

[Mr. Sinister]

Sounds EXACTLY like my problem. Installed new NGK plugs, left side black and sooty, right side looks brand new.

[Steve]

One other point. You said you "adjusted the float height to the lowest fuel level within spec". You just used two different terms as if they are interchangeable, but they are not.

The float height is the distance from the carb body to a specified point on the floats, when the carb is inverted and the float needle is just barely closed.

Fuel level is the actual level of the fuel, measured against a specified point on the carb body, when the carb is installed on the bike and has fuel in it.

If you adjusted the float height to the minimum number, the float will actually ride a bit high (remember, you are setting this with the carb upside down) and the bike will run richer.

If you set the fuel level to the minimum number, that takes some more explainatin. The measurement is something like "4-6mm below this point". If you set it to the 4 (the minimum number), it will run richer. If you set it to the 6 (the minimum height), it will run leaner.

.

[gs450sjip]

One other point. You said you "adjusted the float height to the lowest fuel level within spec". You just used two different terms as if they are interchangeable, but they are not.

The float height is the distance from the carb body to a specified point on the floats, when the carb is inverted and the float needle is just barely closed.

Fuel level is the actual level of the fuel, measured against a specified point on the carb body, when the carb is installed on the bike and has fuel in it.

If you adjusted the float height to the minimum number, the float will actually ride a bit high (remember, you are setting this with the carb upside down) and the bike will run richer.

If you set the fuel level to the minimum number, that takes some more explainatin. The measurement is something like "4-6mm below this point". If you set it to the 4 (the minimum number), it will run richer. If you set it to the 6 (the minimum height), it will run leaner.

.

Maybe I omitted a word or two...I should have said, "I adjusted the float height TO PROVIDE the lowest fuel level..
I understand your meaning completely, thanks. I just didn't put it into words correctly.. gs450sjip

[Steve]

Well, either way, you might want to adjust the float level/fuel height to be as close to the MIDDLE of the range as possible.

Adjusting your jetting by adjusting your fuel level can be frustrating because differences in fuel level will affect ALL the circuits, but not necessarily the same way or by the same amount.

.

[gs450sjip]

Well, either way, you might want to adjust the float level/fuel height to be as close to the MIDDLE of the range as possible.

Adjusting your jetting by adjusting your fuel level can be frustrating because differences in fuel level will affect ALL the circuits, but not necessarily the same way or by the same amount.

.

I agree completely. But for now, I will install the original pilot jets and nothing else, just to see if it leans out some. If successful, the fine tuning can begin. There were so many issues with this bike (ignition and fuel) that had many of the same symptoms, which can drive you crazy, I'll just change one thing at a time now that I'm getting closer to getting this on the road. Hopefully tomorrow, I'll have some positive news.
Thank you for the suggestion. gs450sjip

[pete]

Welcome!

George is spot on with the pilots.

When attempting to jet mine originally I could only get the ones with the holes in the sides, always too rich no matter what I did. Went back to stock and they're ok, my richness is due to my mains and needles but that's a different story.

With your float height, did you set it as per the Clymer manual? If so, it's actually incorrect for the 80 - 82 models and should be 26.6mm +/- 1mm.

Also, you say you have a Dyna ignition, is that the DS3-3C kit? If so, how does it go? I'm loving mine...

[gs450sjip]

Gents,

Ok, I tried a few things last night individually. Changed to the original pilot jets...sorry to say, no change
Set the idle screws to 1/2 turn out...no change
unhooked the vacuum hose from the petcock at the carb, capped it off and ran on "prime"....no change
Put fresh plugs 1 heat range hotter in..ran at 3500-4000 rpm for 3-4 minutes, hit the kill switch...left cylinder plug black, right cylinder, ok but on the dark side. Exhaust fumes burn your eyes when running. I am not inexperianced at this sort of thing, but I have to say, I feel like I'm chasing my tail on this one. I am open to all suggestions. I set the floats at 0.925 inches or 23.51mm. I don't recall what manual I got that from. 26.6mm +1mm equals 1.085 inches. That is a lot different that what I have them at, are they off that much?

Pete, yes the Dyna GS400 kit is what I used per your thread, it when right in, did not need to notch the plate, only had to set the timing on the right cylinder, no actual marks on the left side..

[pete]

I'm certainly far from a guru when it comes to carbs... best I can do for myself is give them a good clean and make sure they're set per the manual. As for tuning, I just richened mine up to cater for the pods and pipe and left them that way for the time being although I really should try to tune them better.

Good stuff on the Dyna, and yeah the notching I did was not necessary after all that, could've left it alone quite easily.

The float height is definitely that much different. If you set them to 23 or so mm's you'll have too much fuel in the float bowls. I believe that's the right measurement for the older 400 and 425's and that Clymer just didn't update with the correct measurement for the 450's.

I know 26.6 is right as I got a factory reproduction manual and it's very clear in there that it really is that much different.

This may be a silly question but in your first post you said you swapped the needles and seats and floats, but did you try swapping the pilots and mixture screws as well? Are the pilots definitely the same size? If memory serves correct they should be 17.5's.