Mixture Screws 1 Turn Out - Still Running Rich

Started at 3 turns and progressively wound them in half a turn at a time. I'm now at 1 turn out and the plugs are still getting a fine black powder coating on them and it's still spluttering a little which tells me it's still running too rich. I have seen some improvement since winding them in.

I set the float levels a little lower than they should be the otherday, so I'm thinking it's not that.

Ran it with no air filter as well and it made no difference.

I'm ready to pull the carbs and change the mains back down to the 102.5's I replaced with 105's recently to see if that's causing it.

Any other suggestions?

 

This leaves a few questions I assume this is on one of your 650's? Is it sputtering and sooting the plugs at idle or also at open throttle? The main jets won't affect things at idle. I would check your choke plungers to see if they are fully seated. If the bike idles well at one turn out then fuel is getting in from somewhere. Only logical place for that at idle is the choke or enrichment circuit. Since you have set the float heights low that eliminates the other source.

 

I don't mean to insult anyones intelligence here, but this is a problem I had a while back. It turned out that my "choke" cable was was pulled too tight before being fastened into the bracket off the carbs. This always led to fuel being introduced via the choke even with the lever fully off. Disconnect the cable from the bracket and see if that is the culprit - simple, easy fix if it is.

Good luck.

 

You are not insulting anyone here
We do not know how much the person (who asked the question) knows about "how things work" or may have overlooked when re checking.

Always check the obvious first, I have heard of atleast one other who pulled his Hog down to component parts only to finally notice the had left the fuel tap to "OFF".

Oh and it does seem to point to the choke in this case.
Float level is checked and ok (how did you check? Clear tube to the float bowl drain method?), all 4 running the same, runs great cold not when hot.

Does the bike start and run well Cold with "NO" choke?

Choke not closing (for some reason)?

 

I'm fairly certain it's not choke... will double check though.

Yup clear tube... all very close.

Starts with no choke from cold (haven't used it yet, but it moves smooth as silk)... runs sweet when you're giving it a handful or revs are dropping but sputters on constant revs.

Hot or cold is no different.

 

Oh and Fraps... Thats what I'm going to double check

 

The Pilot Screw setting of 3 Turns Out ... pertains to the 32mm Hitachi's.

The BS-35 Mik's on the 900 are a different animal. And you just got done cleaning them babies right on down to parade-rest.

Professor Bendere Dunndat who has researched Mikuni 35's, noted that the Enrichment Circuit might be responsible for the ... "Looking rich situation"

Look to see that the Enrichment Valves are Closed when the Handlebar Lever is slacked to have them be closed.
A broken wire ... or a stuck or improperly routed cable will keep them open.
They are NOT like Hitachi Enrichment Valves.
Lifted-off the seat the rubber-ended valve allows fuel in.

With the cable SLACKED ... Observe the ~~> "Synchronization of the Enrichment Valve Lifting *Fingers* ... They need to be CLEAR of the Valve Stem's TopHat. Space.

They need to be BENT -- as necessary -- to insure that they contact the Underside of the Valve Stem Hats, all in sync, when the Activation Rod is turned moving the "Lifting Fingers" against the Hat Bottoms.

Do the "Best Idle" Pilot Screw Tweak until we can get the optimum setting by getting a READ from a ColorTune Plug.

I'm guessing ... ONE Turn ain't it. But, I got a sweet-running 900 down in the stable ... and I'll go see what the screw's set at if comes down to that.

 

The enrichment valve cable was tight, but routed properly. I have adjusted it to give the cable a small amount of slack.

I'm getting a colortune plug soon so will be able to set the mixtures properly... probably after the 23rd of May as I'm going to Australia for 3 weeks on the 30th.

On another note... I ordered a set of progressive fork springs today to take care of the soft front forks that I have. Might even consider swapping forks with the spare set I have that are not air adjustable and don't have the anti-dive system (neither of which appear to be working).

I'm going to continue to adjust, ride, check and re adjust until I get them a little closer.

 

I added 2.5cm of hard plastic dowel as a pre-load to my 900's front end and it's behaving nicely.

The Anti-dive's needed a complete Overhaul. The valve was sticking. There's illustrations in the Factory Manual.

 

I've got the manual

What I'm thinking is strip down and sort out the spare set so the bike can stay on the road while I learn how to get the forks to bits

 

I think I finally got it at 1/2 a turn out

Still need to run her a little further than down the st and back, but looks like I have it as close as I can without a colortune.

Thanks for all the suggestions

 

Sorry Blue... missed your post... It's the 900.... 650's still a fair way off being run

 

Good news.... Got my headers repaired this morning and while they were being weilded up I removed the carbs and retutned the mains to 102.5's and wound the mixture screws to about a 3rd of a turn and its running sweet... No more black powder on the plugs

Colourtune will hopefully arrive sometime next week so I can get em bang on.

 

Just when I thought I had it licked....

Took the bike on a 100km ride tonight and used about half a tank of gas :evil:

Still running rich me thinks and I'm fast running out of ideas... Rechecked float levels today, all sweet, quite low actually, petcock set to on, air filter has only done 500km...

I'm starting to wonder if the new, almost straight through, mufflers have anything to do with it running so rich.

Going to wind the mixture screws in a little further tomorrow and remove the air filter and see if that makes any difference.

Anyone got any other ideas? :?:

 

Your exhaust mod would likely cause a lean condition, yes?

Maybe try plugs of a different heat range?

Just a thought...

 

I was thinking of changing to iridium plugs... I also noticed today that no4 is leaner than no 1 So I might try adjusting 1 2 & 3 because they are all looking similar and leave no 4 where it is...

 

Alive,

Did you ever get this figured out? I'm in the same boat, except with my screws all the way in and I still idle rich. Cannot colortune it out. Checked and rechecked everything.

Help.

 

Hi Alive, are your carbs the BS 35 or 36, I have the 36 and the pilot mixture screws are 2 turns out, by the book, I know the 35s are way different. Wiz.

 

I sorted it by getting a guy with a fuel analyser and a sync tool to give it a good tune..

I do also have my needles on the last setting

Wiz... I think they're 35's

 

Dude, I just figured out the prob looking at the manual. My air jets are reversed.

The PO had them the same way so I never questioned if they were in the right positions.

Jeez.

 

I read your other thread and that did spring to mind...

 

Dude, I'm so relieved. I thought I was getting more stupid by the day.

 

hahhahah so is it running better?

 

In my mind it is.

The carbs are on the bench in the garage with the domes off. When I saw the current placement of the air jets, I just said "HOLY SHIT!" and then went to pour myself a very tall tumbler of whiskey.

The problems is solved as far as I'm concerned, but the actual work is not getting done until tomorrow.

I've said this before, but the wealth of knowledge in this forum is outstanding. Without it, I'd still be crying about the bike not running next season.

I'll update my thread tomorrow with results. Thanks again dude!