4500 RPM carb isssue

[LarryA_Texas]

At least I think it's a carb issue. 1981 GS850G. It has pods on it and a stage III jet kit. At any speed and in any gear it accelerates reasonably well up to about 4500 RPM, then it begins to sputter and bog down and simply will not get any higher RPM. Even sitting in the driveway in neutral it will take full throttle up to 4500 and then it's done. 1/4 throttle or wide open makes no difference. it accelerates to 4500 and sputters and holds 4500.

I have moved the needles both up and down with only very minor changes in the RPM at which it sputters out. No change in the needles has corrected the problem but raising them seems to make it worse.

The only thing that made a significant difference was taking the pod air filters off...with no filter it ran great. So, Too Rich, Right? Next I tried the float height and found them incorrectly high...so I lowered them all to the .88" spec. in the book. This made absolutely no difference in the way it ran.

So the needles are on the second ring, the fuel/air screws are currently at 3 turns. Tried from 2 to 3 1/2 and this seems to give me the best idle, but no change in the 4500 rpm issue. The jets are 160, from the kit.

A little more history here: I got this bike in non-running condition with the air filter lost. Added pods and rejetted and it was running like a champ. Start easy, idle good, run strong and fast....all that. Then I sold it to make room for a project bike I really want to keep...an '83 GS1100G.

I didn't realize at the time the 'friend' of my daughter's was actually one of the Beavis and Butthead duo, not sure which one. Anyway, he and his buddy decided to get doped up and go for a ride. After the accident he decided not to pay for the bike and I got to take it back home. I've repaired or replaced the forks, turn signals, handlebar and signal generator. Yup...the SG took an asphalt hit and was destroyed. I'm thrilled.

But the bottom line is I don't want to keep rebuilding this thing. I want to get it running reasonably well and sell it. Does anyone out there have a suggestion that doesn't involve spending a fortune on new parts?

4500 rpm isn't enough to say "Runs Great" even on Craig's List.

 

[Big T]

Well, not revving above 4500 is generally a non airbox thing

However, since it was running good before the accident, it's a different problem

And since it runs good without the pods, it's the pods. Either clogged up or over oiled.

Have you cleaned and reoiled them ??

 

[Nessism]

Normally I'd say ignition, but if it runs properly without the airfilters, it sounds like the carbs are rich as you stated. Maybe try installing a smaller main jet? You could try dropping the needle if you don't have any appropriate jets. Or just ditch the air filters and sell the bike as is. If the bike runs well, just play dumb and say the new owner needs to purchase his own filters.

 

[tkent02]

Normally I'd say ignition, but if it runs properly without the airfilters, it sounds like the carbs are rich as you stated. Maybe try installing a smaller main jet? You could try dropping the needle if you don't have any appropriate jets. Or just ditch the air filters and sell the bike as is. If the bike runs well, just play dumb and say the new owner needs to purchase his own filters.

On to something here, are these perhaps crappy pods, old plugged up pods or over oiled pods?
Maybe for some reason not flowing enough air?
Sell it without any if it runs correctly.
Let him talk you down a little if need be.
I'd buy it but you know how cheap I am.

 

[miket]

Lose the 160's

Lose the 160's

i assume the 160 jet is from the k&n kit your main jet should be around 132 leave all other jets stock / fine tune from there

 

[Steve]

Are you sure you are reading the right jet? :-k

I ask that because the pilot air jet could be a 160 from the factory, but that is in the intake throat, not the float bowl. If, in fact, it is your main jet (hangs down near the bottom of the float bowl) and it is a 160, you are WAY too rich. Stock jets are 115. I see no mention of a 4-into-1 pipe, so I would say that you might need something in the 120 to 125 range. If you had the pipe, I would agree with miket on the 132s.

.

 

[Guest]

throw in the ignitor and the coils from your other G and see if that makes any difference

however, if your main fuel jets are indeed 160s , first try smaller jets (as suggested)

 

[LarryA_Texas]

lose the 160s

lose the 160s

Thanks for the help. That's what I needed. I will look at the pods first for excess oil, then get some smaller main jets. Yes, the 160s are from the kit and like I said, they worked fine before B&B took it for a ride. I also can understand that 160, up from a 115 stock main jet seem ridiculous, but that's what was in the kit and what worked. And, yes, I'm sure it's the main jet.

It does not have a 4 into 1. It's stock. Well, slightly less than stock because they dented the crap out of the right muffler, so it's bound to have slightly less airflow...but it's not pinched off. It's probably slightly less than 1/2 the original diameter just aft of the footpeg.

When I got it the #3 pipe didn't connect well because of a rusted out crossover. It was destroyed and I had to replace it after I got it back. The pipes are all sealed up better than before. I did also think about the lower airflow from that. Maybe that's why the 160 worked. I'll keep at it and thanks to all for the advise. By the way...in the photos it's the one with a flame paint job if anyone wants an '81 850G. Starts good. Runs, uh...OK.

 

[Guest]

The 160 is a DJ number not a Mikuni number.
DJ# x .9375=mikuni#
Mikuni# divided by .9375= DJ#

 

[Steve]

The 160 is a DJ number not a Mikuni number.
DJ# x .9375=mikuni#
Mikuni# divided by .9375= DJ#

That would make it about equivalent to a Mikuni 150.

Still WAY too big.

.

 

[Guest]

That would make it about equivalent to a Mikuni 150.

Still WAY too big.

.

If he installed the DJ press in main air jet it allows it to take a bigger jet.
I put a DJ kit in Saltymonks carbs with a 170 DJ main and it runs great.
If he doesn't have the different main air jet I agree.

The symptoms to me say over oiled filters since it runs w/out them.

 

[LarryA_Texas]

filters

filters

Many thanks to those that answered. Tonight I was giving by bike the evil eye...more or less daring it to show me what's going on. Then it hit me...there's a puddle under the engine. Gasoline. And the top of the transmission case was wet with gas. Guess where it's coming from?

So, maybe 2 pods loaded with gasoline could be causing a rich mixture?

I put them, one at a time, in a mayonnaise jar half-filled with mineral spirits. After the first rinse, the spirits looked like gas. by the time I washed out the 4th filter it was the color of oil.

Once they dry out I'll let you know how it runs.

Thanks again.

 

[Guest]

Sounds like you have a bad petcock and float needle and seat.
I would check the crankcase for gasoline.