1981 GS850GX Carb Problems

[Buster-boy]

Hi guys and gals.

Over this past week I replaced the cylinder head. One of the spark plug holes was stripped. I bought a new(er) head on eBay. The unsteady idle problem I had is now gone (r's would float from 1500-300 at idle, 3000 when pulling in clutch). The o-ring on #3 intake boot was not seated correctly (thanks to my mechanic ).

It starts just fine, idles at 1500 +/- rpm at open choke. Full choke it revs nice and smooth to about 4000-ish rpm.

Here's my problem - As soon as I twist the throttle, even the slightest bit, it bogs out and sometimes stalls (if I hold the throttle open).

While installing the new head -

- I checked the valve/shim clearances according to Clymers and all is good there.
- Valves/springs/tappetts seem to be ok as well.
- Found TDC, set timing as per Clymers (#1 at gasket level, 20 pins between #2 & #3 arrows)
- Replaced head gasket
- Head bolts torqued to 27 ft/lbs as per Clymers
-I did not check compression as I do not have a gauge but it seems to be good.
- Installed four new NGK plugs gapped to .028
- I transferred the intake boots from the old head, got the o-rings correct (each is new this season). I even used permatex when installing boots.
- I adjusted the throttle cable.
- Remonted carbs
- Air side intake boots are new this season as well
- Carbs were cleaned and rebuilt earlier this season

I have some questions -

1) Does this sound like I need to have the carbs sync'd? I know that's always a good thing to do, but does this sound like the most sure fire answer to my problems?

2) Is there a way to recheck the timing without removing the valve cover? Can I use a timing light instead, and if so, what marks do I look at? I made it a point to triple check my work on setting the timing. I even had my step-son check my work. It seems to be right, but you never know. Even off by one link can really louse things up.

I'm open to any and all suggestions or questions, and thanks in advance.

Jim C.

[Buster-boy]

Okayyyyyyyy, Jim hears the sound of crickets chirping on this one. 13 views but no one takes a crack at answering.

Anyway, I played with the throttle stop screw this morning and got it to idle around 950-1000 rpm. I can actually ride it now but it's still hesitant on take off.

Any guesses?

[rustybronco]

Were the carbs bench sync'd?
have you tried opening up the pilots 1/4 a turn. how does it then respond? if it's better then try 1/2 turn.
is the air filter in place and properly oiled?

[Buster-boy]

Um, I'll say no to all. I'm not much of a carb guy so i didn't know to do that. Tearing engines down and putting them back - not a problem, but tuning carbs - not so much. I'll give those whirl and let you know. Thanks Rusty!!

Jim

[rustybronco]

bench sync-ing carbs, is nothing more than setting the throttle plates so they are all the same distance between plate and the throttle bore. I do mine by sight. (holding up to a light source and looking for each gap to be the same as the others)

do that, put the air filter in place and set the pilot screws to the factory spec'd number of turns. that should get you close.

[Buster-boy]

I'll do that Rusty. Thanks and I'll keep you posted.

[rustybronco]

Roger Jim, I mean sure. (roger,roger... ) ok just Jim.

(it's been a long day)

[Bill C.]

Air Filter

If you have changed or modifed your air filter from stock you may need to open the air screws out from the stock settings. I have a KN airfilter in the stock air box and had to go to about 2 3/4 turns from lightly seated. Sounds like you are close just need a little tweaking. It can be frustrating when you are working with the carbs. Stick with it and you will get there.

[Buster-boy]

Bill, it's funny you mention that. I originally was going to go with single filters on each carb so we tuned it that way. That didn't work so well so we went back to the OEM airbox, BUT it has not been tuned back. In addition, I've removed the carbs 3-4 times and have not sync'd them.

I spoke to a couple of shops today on the phone and gave them a high level rundown of what's going on. They pretty much agreed syncing the carbs was the right plan of action (atleast for starters anyway). One of them gave me a good price and offered free pick up so I coudn't turn it down.

As I said carbs are uncharted waters for me and sometimes things are better left to the pros.

Thanks guys for you tips and pointers, but I think we're about done here. Take care and may God bless!!

Jim