Carbs Again

[TopCatGr58]

Hey Lorenc,

Aside from not seeing #2 and 3, sounds like you have the carbs mains dialed in pretty good IMHO!
T.C.

[skids]

LOL, good one Ken!

Originally posted by Ken Talbot


Tells me you don't have any gloves!

[lorenc]

Ken. Your right, I dont have any gloves. Dont need them unless I'm going to pull plugs out of a hot motor and I figured the outside 2 were close enough to the other 2 since all the pilots are the same. Maybe I should assume anything.

I agree the bike is running well right now but does anyone know why I cant use the enricher to start it. It still floods it out when I use it and wont idle by itself until it is warmed up.

Thanks for all the help. You guys are PRICELESS. Your going to make a phne guy into a bike mechanic yet..

[skids]

Make sure that the brass tube has that hole near the carb body clear. Also, the gasket must have a passage to vent that hole if I remember correctly. I think there is a channel in the bowl's gasket mating surface between the brass tube and the hole in the gasket(?)

Originally posted by lorenc
I agree the bike is running well right now but does anyone know why I cant use the enricher to start it. It still floods it out when I use it and wont idle by itself until it is warmed up.

[TopCatGr58]

Originally posted by skids
Make sure that the brass tube has that hole near the carb body clear. Also, the gasket must have a passage to vent that hole if I remember correctly. I think there is a channel in the bowl's gasket mating surface between the brass tube and the hole in the gasket(?)

Kinda like this:



T.C.

[lorenc]

It Works!!!!

Thanks guys. We got it!

The gasket was still covering that hole in the carb body close to the brass pole. I could blame it on the guy who helped me replace the float needles BUT I wont. I had those carbs apart at least 4 times by now. (I can take them off in 20 minutes. Putting them on takes about 30.) I should have noticed it.

Do you think I should start over with the pilot screws 1st, then sync the carbs again? Pilot screws are still @ 3 1/4 turns out.

[mro]

Not sure how others do it.
Like to sync first, allows smoother lower idle.
Adjust pilots and then sync agin.


mro

[scott0757]

This may also solve my problem. Runs great once I get it started but the enrichers are basically useless. I crank and it chugs and sputters but never can get the bike to run with them on. I have to turn the enrichers off. In fact, if the bike is running and I pull the enricher to either the first or full stop, the bike quickly dies.

Just so I understand, the photo shows the gasket covering the hole adjacent to the vent tube, but open on the other side. The fix is to open the hole near the tube, right?

I'll look at this when I replace the jets (due to new, bluing exhaust).

Thanks guys.

[xollob]

Looks like there's some carby-wisdom in this thread: maybe you can collectively answer this one -

Carb leaky problem this winter, so I stripped them and replaced all the little float-bowl-type seats and seals. While I was at it I "hey, I could replace those tired old jets........" (although the old beast was still running fine - oops)

eBay furnished me with a rebuild kit for the four carbs, jets and all, ostensibly for my 1980SG. Now the new pilot jets did look a little different from the originals, but not by much, so I carefully finished the job, and hey presto, no more drippy leaks. I replaced the old and holey diaphragms too.

However.......

Now the beast runs great with huge gobs of throttle, but the idle is horrid. Alternately she stalls, coughs, then spits back on the over-run. It sounds and looks like it's runing lean, but I can't check the plugs for colour as I can't reliably take it for a spin even round the block.

Could this be caused by incorrect jets?

[mro]

Hi xollob

SG,
stock air box and exhaust then supossed to have
115 mains in 1&4 and 120's in 2 & 3
pilot jet 42.5
starter jet 25
--------
If carbs are clean then
Fuel level in bowl (23mm height)
carbs sync and pilot screws adjusted
(can't adjust pilots till you get it to idle, so would start em out 1 1/2 turns)
_____
If above has been done then would re-install old jets.
Some other manufacturers do not lable jets same as Mikuni so can give you problems.
_____

Also on occassion have found the little pointy end of pilot screw broke off and stuck in carb body. Seems to make that cylinder run pretty bad too.


mro

[xollob]

mmmmmm.......

pilot screws, eh?

I suspect these carbs are not original. They've always worked fine, but maybe switched in a previous life, as there's no pilot screw on the bodies. The idle can crudely be cranked up with the central screw, but that's a bodge.

Oh, and we need to consider (a) MAC exhaust, and (b) K&n filters (although currently running bare so as to expose the sliders (1 and maybe also 4 are rising sluggishly, another mystery - I can't locate a vacuum leak)

Ah, the complexities of life

[mro]

no pilot screw on the bodies

Most likely pilot screws are still "capped off" (1980+ BS34 III carbs)
Think there is a tech tip explaning this.
Small metal plug center top front of carb (little round goodied on carb body hiding pilot screw)
Use an 1/8th drill bit and carefully drill hole in cap/plug, then can use a sheetmetal screw and plyers to pull plug out and expose pilot screw.

Can not properly clean this fuel/air circut w/o removing screw as well as adjust it.


mro

[xollob]

thanks mro,

I believe I now have a Fathers' Day project in the garage. I was up half the night starting a rebuild (1970 Triumph), and this was gnawing at me. I've relied on this bike for years, and we usually get along.

Good to know what carb it came with - and it has run so well with this set-up that I'm confident they are good for the year. I've sourced cruddy carbs from '79, and they were clearly the earlier model. Nothing salvagable.

I'll try to tack down that tech tip, watch this space.

Julian

hey, I'll enclose a picture with the next post, if I can just figure out my wife's digital camera