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And let there be life....not

  • Thread starter Thread starter altermad
  • Start date Start date
A

altermad

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Ok so I have a 78 GS750B 70,000 just cleaned carbs, checked valve clearances and adjusted, replaced plugs, adjusted the Carb Air screw to 1.25 turns out as suggested, Replaced airbox boots, Adjusted point gap on f1-4 to .03mm f2-3 were at .03mm and went to start and not even a chug. What am I doing wrong? Any Idea's...... Thanks
 
Point gap seems a bit small. You sure you have the decimal in the right place? The point gap for a '79 850 is 0.3 mm, not the 0.03 mm that you specified.

You mention the carb air screw is set to 1.25, how about the fuel screw? Should be about .75. This is the screw on the bottom of the carb.

After you change the point gap, prime the float bowls in the carbs. (Tkent got that in while I was typing.) When they are full, use full choke and NO throttle.

.
 
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If your experience is anything like mine is, your battery might have dies while repairing and replacing everything else?


Steve,
do the carbs on an 81 gs550 have a fuel screw? Does it need to be .75 turns out as well?

Thanks,

Cory
 
Life for 3 mins She sounded good, then died

Life for 3 mins She sounded good, then died

Now she is driping really slow out of the #4 carb bowl. Maybe high float? When doing this my "fuel" screws were 1.25 out, should I try again with .75 ot just take carbs back off and adjust #4 float? Any other suggestions?

BTW I got it primed good then she fired like she wanted to I am so exicted I know she can run good!
 
You can adjust floats, fuel screws with the carbs on the bike. Pull the bowls.
runs for a few secs only? Choke on or off?
Throttle open or closed?
Is the throttle open too far at idle for the choke to work?
Give better details, please!
 
KRISTI'SGS550 said:
Steve,
do the carbs on an 81 gs550 have a fuel screw? Does it need to be .75 turns out as well?
Click to expand...
No. Your '81 bike had CV carbs that only have an idle mixture screw on the top of the outlet of the carb. If you are starting from scratch, start with the screws about 2 full turns out from lightly seated. Go for a bike to warm up the bike. When the bike is warmed up, adjust each screw slowly, listening for highest rpm. Re-adjust the master idle screw, if necessary, and continue with the rest of the carbs.

.
 
Steve said:
No. Your '81 bike had CV carbs that only have an idle mixture screw on the top of the outlet of the carb. If you are starting from scratch, start with the screws about 2 full turns out from lightly seated. Go for a bike to warm up the bike. When the bike is warmed up, adjust each screw slowly, listening for highest rpm. Re-adjust the master idle screw, if necessary, and continue with the rest of the carbs.

.
Click to expand...

Steve is right but for a '81 550, start at 3 turns.
 
tkent02 said:
You can adjust floats, fuel screws with the carbs on the bike. Pull the bowls.
runs for a few secs only? Choke on or off?
Throttle open or closed?
Is the throttle open too far at idle for the choke to work?
Give better details, please!
Click to expand...


When it ran it ran for a few mins ran steady for about 3mins, then RPMs started racing higher before she died. Thats when gas started to drip out of #4 bowl drain. I had tank set to reserve. I had choke up (I assume that means open) No throttle. I did hear a lot of air movement sounded Air was being sucked into the choke. I hope this is helpful as a description. And thanks for all of the help and support
 
There's no air movement with the choke, it's not a true choke, just an enrichment device which only works with the throttle closed.
If you hear air moving, you have a vacuum leak.
A vacuum leak makes it too lean at first, as it warms up and needs less fuel the mix gets better and the revs come up...

Or it could be running out of gas in the bowls.

I'd start with the petcock, just to eliminate it as a problem. Is it hooked up right and working correctly? Fuel flow sufficient? Only takes a few minutes to check it out.

And this leak, is it from the bowl gasket, the drain plug, or the overflow tube underneath?
You cleaned the carbs, did you put new orings in them too?
Where did you set your float levels? Did the float valves look good and did they seal?
Did you check the resulting fuel level in the bowl?
Have you downloaded the service manual yet?
 
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I am going to check the vacuum hoses.
The drip is from the overflow tube on underneath the VM carbs. Slow drip maybe one every five to ten secs.
Petcock has issues (I think) with hoses off she She runs flows gas out on prime and reserve like turning on a hose. On on she don't leak a drop.... I am guessing that the reserve should act like the on setting is this correct?
 
altermad said:
I am going to check the vacuum hoses.
The drip is from the overflow tube on underneath the VM carbs. Slow drip maybe one every five to ten secs.
Petcock has issues (I think) with hoses off she She runs flows gas out on prime and reserve like turning on a hose. On on she don't leak a drop.... I am guessing that the reserve should act like the on setting is this correct?
Click to expand...

PRI should flow always.
ON should flow only when a vacuum is pulled on the little hose, and only with more than about a gallon of gas in the tank...
RES should flow with the vacuum as ON but will run until the tank is dry.

You probably have a weak float valve causing the drip but it should run somewhat anyway, it may fix itself as it gets to running better. Or not.
 
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Progress :-) ok I went out this morning and adjusted the fuel screws (on top of bowls) to .75 she started then ran like a champ with the choke on. When running she doesn't drip or leak gas. After running for a while (5mins) she needed me to play with the choke then back to full open and vroooom high rpm so closed choke a little and she started to die so I opened it back up and ran good.

Air noise sounds like it is comming form valve cover and also a dime size hole in the pipe from the the center stand returning.

closed choke it died and gas driping rather fast out of #4 bowl drain. only when bike not running? It is about 32 degree's this morning. Any ideas? I added all detail I could think of if you need more It'll be my pleasure and I apoligize in advance for anything I might have left out. Thanks

Also Should I fix gas leak before syncing the carbs? Sorry for the million questions.
 
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Turn the crankshaft with a 19mm wrench until the points are at their widest opening. Then take a 16 thousandths feeler guage and reset the point gaps to 16 thou.

Earl


altermad said:
Ok so I have a 78 GS750B 70,000 just cleaned carbs, checked valve clearances and adjusted, replaced plugs, adjusted the Carb Air screw to 1.25 turns out as suggested, Replaced airbox boots, Adjusted point gap on f1-4 to .03mm f2-3 were at .03mm and went to start and not even a chug. What am I doing wrong? Any Idea's...... Thanks
Click to expand...
 
altermad said:
Progress :-) ok I went out this morning and adjusted the fuel screws (on top of bowls) to .75 she started then ran like a champ with the choke on. When running she doesn't drip or leak gas. After running for a while (5mins) she needed me to play with the choke then back to full open and vroooom high rpm so closed choke a little and she started to die so I opened it back up and ran good.

Air noise sounds like it is comming form valve cover and also a dime size hole in the pipe from the the center stand returning.

closed choke it died and gas driping rather fast out of #4 bowl drain. only when bike not running? It is about 32 degree's this morning. Any ideas? I added all detail I could think of if you need more It'll be my pleasure and I apoligize in advance for anything I might have left out. Thanks

Also Should I fix gas leak before syncing the carbs? Sorry for the million questions.
Click to expand...


Thanks Earl got the bike starting \\:D/ just these other questions now.
 
Oh god please let me ride!!!

Oh god please let me ride!!!

tkent02 said:
So it runs OK now when it's finally warmed up?
If not, what does it do???
Click to expand...

.....Noise might be timing chain I will grab a timming light today just to exclude.

I can't seem to get her to finally warm up to keep her going I have to play with choke meaning a couple mins after starting with the choke on the rpm's raise, then I lower choke a little and she sputters out. Once engine stops gas drips from #4 bowl. I can't get her to run with choke off. Should I try turning the idle adjustment screw in?
right now it is backed out just touching the part it pushes
 
Ok so I ran her again and found she was low on oil. sounds much better now. Rpms are running around 3000 with choke full open. This time after running 10 mins or so she started dripping really fast out of #4 bowl.
Is this the float?
Is this fuel adjustment issues?
Could it be Idle adjustment?
Would syncing the carbs now help at all?
She was warmed on the center stand and doesn't die unless choke is pushed down (closed) help please........
 
The problem is either the "o" ring on the float needle valve/seat is worn out or the float level is set too high and the float is raising against the top of the float bowl before it activates the float need valve to shut off fuel.

Earl



altermad said:
Ok so I ran her again and found she was low on oil. sounds much better now. Rpms are running around 3000 with choke full open. This time after running 10 mins or so she started dripping really fast out of #4 bowl.
Is this the float?
Is this fuel adjustment issues?
Could it be Idle adjustment?
Would syncing the carbs now help at all?
She was warmed on the center stand and doesn't die unless choke is pushed down (closed) help please........
Click to expand...
 
altermad said:
Ok so I ran her again and found she was low on oil. sounds much better now. Rpms are running around 3000 with choke full open. This time after running 10 mins or so she started dripping really fast out of #4 bowl.
Is this the float?
Is this fuel adjustment issues?
Could it be Idle adjustment?
Would syncing the carbs now help at all?
She was warmed on the center stand and doesn't die unless choke is pushed down (closed) help please........
Click to expand...


Horrible ain't it!

I had a similar carb overflow problem (when I set the petcock to prime) before I stripped, cleaned and replaced the o-rings in the carbs. I was advised it was likely a sticky float (which turned out to be correct) Try gently tapping the underside of the #4 bowl with the plastic handle of a screw driver (when the bowl is full) to see if it stops the overflowing.

Did you replace the the Large O-rings on the carb boots that are mounted on the engine? (accessed by removing the boots) Leaking O-rings might explain the sound of air sucking that you are hearing.

Did you replace all the O-rings in the carbs itself when you cleaned them? What did you clean them with?
 
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