Carb adjustment help needed!

[thill]

1989 Force 85HP.

Despite the typical rep, this has always been a flawless-running engine until last year, when it started stalling on some startups.

Posted for help, got the advice to open the idle mix jets just a touch, and it worked like magic! Back to running flawlessly!

But now my idle speed is a bit high. My idle screw is all the way back, so how else can I slow the idle down? It's up around 1100, instead of 800...

Thanks in advance for the help.

-TH

[Ludicrous]

Pull your carb and clean it. The reason you had to turn the idle adjustment up is dirty passage ways/jets in the carb.

[thill]

Pull your carb and clean it. The reason you had to turn the idle adjustment up is dirty passage ways/jets in the carb.

This is an older engine that truly runs flawlessly... I really HATE to mess with a good thing!

Not to mention the cost/labor of removing 3 carbs, stripping them down, cleaning them up, reinstalling them, adjusting them, synchronizing them, and then TRYING to get them to run as well as they do now...

I didn't touch the idle speed screws and I only backed off the mix screws about 1/16th of a turn. Is there really no other way to adjust the idle speed?

-TH

[billinstuart]

Usually the idle speed is a combination of ignition advance AND carb linkage adjustment. With the introduction of crappy ethanol laced fuel, carb base settings often have to be corrected.

Advancing base timing increases idle speed, retarding base timing slows the engine. DO NOT change the maximum timing!

[thill]

Bill,

Thanks for that info. I'll have to check my shop manual. So far, all it's told me is to back off the idle speed screw, which is already pretty much backed all the way down. I don't think it's even making contact at all.

I'm going to look in the section about base timing advance, and see what it says.

Thanks for the help!

-TH

[knotreel]

Nornally the two cycle engine (yours) will idle faster if its on the lean side of it's mixture window, window being the various mixures it will run at. Rich mixture the idle is slower and sorta rough and popping or heavy hitting, might see more smoke. Lean mixture it has a "weak" sound and is running faster, unsually smooth until it won't stay running and starts killing.

So, Ludicrous sugestion might be spot on as something in your carbs has changed (got dirty?) and caused it to have a low speed lean condition.

But you don't want to spend the money.

So you can try richening the idle mixture. the mix screw or nut you backed off, just unback (tighten) it about ther same or a little more amount. Then reset your idle speed screw which controls the buttery closed position.

Or there is an entirely different reason your engine has leaned out and is running too fast, these could be air leak or leaks such as at the carb mounting base, leaking crankshaft seals ( shop time) or maybe some loose inpection plates on the sides of the cylinder ( located about mid way up and may have two or more screws holding them) If you are unfamiliar with this then just look for any loose screws on the side on the engine.

However it's most likely just the carb issues again.

Good luck and may the force STAY with you. Could not resist that, sorry.

[thill]

Knotreel,

Thanks for the reply. Very interesting. I'll have to go inspect the engine carefully.

What you write is why I thought it was strange that the engine sped up a bit when I made the mixture more RICH. (to keep it from "sneezing" and then stalling at startup)

The original problem wasn't bad, only once in every five starts, and if I tapped the choke, it would go back to normal. I opened the jets just a little more, and it went back to great operation.

All this is making me wonder if I don't need to just take this engine in to get the carbs serviced.... The problem is finding someone honest, who won't try to pull a fast one. I've had poor success finding a good mechanic since moving to this area.

Hopefully, I can find the issue myself tomorrow afternoon. Thanks for the helpful information!

-TH

[thill]

Knotreel,

Thanks for the reply. Very interesting. I'll have to go inspect the engine carefully.

What you write is why I thought it was strange that the engine sped up a bit when I made the mixture more RICH. (to keep it from "sneezing" and then stalling at startup)

The original problem wasn't bad, only once in every five starts, and if I tapped the choke, it would go back to normal. I opened the jets just a little more, and it went back to great operation.

All this is making me wonder if I don't need to just take this engine in to get the carbs serviced.... The problem is finding someone honest, who won't try to pull a fast one. I've had poor success finding a good mechanic since moving to this area.

Hopefully, I can find the issue myself tomorrow afternoon. Thanks for the helpful information!

-TH

[Sea Hawk]

thill I agree with Ludicrous, if the initial problem happened out of the blue and you went and adjusted the fuel mix ,what in my opinion you should have done was to rebuild the carbs ,I too have a carburator motor and runs perfectly fine, but every once in a long while ,I do rebuild the carbs ,to be exact three times in ten years ,also a friend of mine with a Yamaha 150 hp carb did lose some speed at top end, but other wise was running fine, he rebuild the carbs and there was the lost rpm ,I know this has nothing to do with your problem, but if you din't touch the motor and the rpm was lower ,I think you should have rebuild instead of adjusting the idle ,I won't get a mechanic if you have the manual, is not that hard and you probably do a better job, I saw a mechanic rebuilding a set of carbs and the only thing he used from the kit was the gaskets ,he said that all he had to do is clean the parts ,witch is true ,but if the customer paid for the hole kid replace everything ,thats why I do it my self.

[catch 22]

maybe you should try pulling the spark plugs and see if they tell you which cylinder is running lean. If a cylinder is lean on fuel it is also lean on OIL (it's a Force so you probably pre-mix). Like the old saying goes "you can pay me now or you can pay me latter", half assing or not properly repairing a 2 stroke fuel system is usually the beginning of the end, it's not just fuel but also the oil your engine needs.