Help needed - Carb problems

[Hawkins]

Hey all,

Hope one of you gurus can help me out on this one. Our season is short here and I'm missing precious days.

Anyway, here is what I have:

1980 SG with a 79 F engine, 1980 SG carbs
New p/u coils
New XS650 coils from Mikes XS
New timing chain
Valves adjusted
Spark timing not adjusted yet (waiting on light)
New idle mixture screws from Mikes XS
Floats don't leak or bind
Floats adjusted so that fuel is at lower edge of carb bowl rim
Bench test carbs - no leakage
mains: 110
pilots: 45
air: 185

The problem (s):

When I put the carbs on the bike, it fires up nice, but then begins to run rough. "Sneezes" out of carbs 1 and 4. Switched coils but still sneezes on 1 and 4. Remove the carbs and the boots are full of gas (all four). These two problems may not be related. If I can get it so the flooding stops, I'll work on the sneezing separately. May be coincidence, but simultaneous trouble with 1 & 4 sound like spark trouble on that half of the system to me.

Last night I began to disassemble the carbs to check everything again.

One idea that came to me last night after I talked myself out of "accidentally" wasting gas on the header pipes: last year I dipped the carbs for cleaning. I removed all rubber components I could find, including the butterfly shaft seals. Could there be a hidden seal somewhere that I missed??

Any other ideas?

I'll go back to the original mixture screws now, just to rule that change out.

Thanks in advance guys. If I can get her running now and no other probs this summer, I'll be seriously looking at the EFI/DIS conversion that mainlylinuk and shutchis are working on. Too many friggin delicate mechanical components in the stock setup.

[Hawkins]

oh yeah

I also have new float needle seats and needles from Mikes XS.

I have new plastic floats from Mikes as well, but I went back to the stocks after the angle on the adjustment tab got too crazy - they are not the same as the stock floats.

[Artic_rider]

Gas pouring out is usually...

Leaky floats...are they brass or the plastic kind (shake em, if you hear a sound while you shake em there leaking, and won't work corectly)

Your float height might not be set correctly.

Your float needles, and or seals may be worn out.

Or what I think it is...and correct me if I am wrong, but... Your valve seat assembly is either not all the way seated (ya you might want to get a rubber hammer and give it a wack...OR the o-rings on the bottom of that seat are toast. Did you take the seat out when you soaked it? if you did, then I would say there just not pressed in all the way, and if you didn't then I would say the rubber o ring is gone.

Had the exact same problems as you last month, so this should give you a start.


BTW!!! since your gas was leaking out...I would strongly recomend draining your oil and changing it ASAP...before you start it up again...Gas+oil+bearing in the motor = Mother F&ckn headache. I am sure someone will post and correct me now



Just saw your second post...go with the solution of pressing the seats in more. As far as the float heights...do a search and you will find posts on how to set them corectly. Oh and one more thing. Howdy my fellow Canuk

[skids]

#45 pilot jets are a little big usually. If I run those in any of my bikes, I end up with very small pilot screw settings. Remember also that there are different float settings for later (vs. earlier) carbs. Read the plugs for a given rpm problem, they usually tell you something.

[Hawkins]

Skids, I'm pretty sure that those jets were 42.5's ;ast time I looked. Last year I broke down on the road and had a local shop work on the bike. IMO, that's when the trouble really started. They messed with the carbs for a timing problem, and put bigger jets in for some reason. Would that difference in jet size give visible amounts of gas in the carb boots? I tried her today with a quarter turn out on the mixture screws and still dumping gas through.

Arctic, I think the floats and needle valves/seats are ok because it holds on the bench for as long as I mind to leave it there. But, I'll have another look - I'll try anything at this point.

Thanks guys.

[skids]

Re: oh yeah

By that, I hope you meant that you went back to OEM plastic floats. If yours were metal, you need to identify to carbs for sure. It seems that the floats are too high if the fuel levels are at the mating surface. I don't know for sure as I have never done the manometer tube method: I always measure the distances upside down. Make sur that the pressed-in brass jet is clear. If no air is bleeding to the emusion tubes (under the mains), it will draw fuel at a much faster rate. Sorry I can't be of more help.

Originally posted by Hawkins
I have new plastic floats from Mikes as well, but I went back to the stocks after the angle on the adjustment tab got too crazy -

[Hawkins]

Thanks Skids. I guess you mean the air jet in the carb inlet horn? I'll check that.

The OEM floats were plastic. Also, the carbs don't vent to the airbox like the earlier models did.

Is it possible that the vacuum slide needles have reached their wear limit and are always letting some fuel leak past?

Has anyone ever used slides and needles from a 79F in 80SG carbs? I have a set that are much better than what's in my 80 carbs.

[skids]

[QUOTE]Originally posted by Hawkins
Thanks Skids. I guess you mean the air jet in the carb inlet horn? I'll check that.

Yes that is the jet.

The OEM floats were plastic. Also, the carbs don't vent to the airbox like the earlier models did.

One of the other holes in the inlet horn vents the carb. Make sure that venting is clear.

Is it possible that the vacuum slide needles have reached their wear limit and are always letting some fuel leak past?

Has anyone ever used slides and needles from a 79F in 80SG carbs? I have a set that are much better than what's in my 80 carbs.