Engine starts but won't idle

After the tank is de-rusted you must use an internal coating to prevent further rust starting again.

I use and recommend the fuel tank sealer from www.caswellplaing.com

 

After installing the carb back, I charged the battery to full, jumped the fuel pump to fill the system back with fuel, went to start it... ... still no idle, still the same symptoms...

I'm pulling hair out... what might it be?
We've checked:
- Battery (charged)
- Fuel pump (working)
- Carb jets (cleaned)

Now that I think about it, when I pulled the diaphragms from the carb, I did not check/clean that top end hole where the needle goes in...

But what else could the problem be?

Thanks

 

Could be one or more leaky float needles maybe. The top end hole you mention never really needs any cleaning, but it's very easy on older diaphrams not to get them seated properly in their grooves.......but that has nothing to do with your idle problem. Are you sure there are no air leaks past the mounting boots and that clamps are tight ?? Are the throttle butterflies closing almost fully at idle ?? Could be really bad carb synch if you lost a spring.

 

Mounting boots are properly seated and boot clamps are tight.

Throttle butterflies closing fully/almost fully at idle/closed position.

The diaphragms looked to be in good clean shape. I made sure the washer, needle, sprint, and holder are all accounted for when removing and installation of the diaphragms/vacuum cover area.

Isn't carb sync only a problem/necessary if I had actually disassembled the carbs all the way down, and removed their linkages (separating the carbs into 4 pieces)? I did not take it apart that far, so I did not do any carb syncing procedures.

 

OK, you're aware that the boots need proper placement ?? They are marked "carb" on one side, and must go on with the narrow slot at the top center position.......just exactly according to info from the Bible.

Did you use carb cleaner spray+ compressed air to blast through the idle mixture screw holes while the idle jet itself is removed ??

 

Hm. I wasn't aware of that, but the boots stayed either on engine or on carb when I pulled them off, so nothing should have changed... I'll check on that when I get back.

 

I've seen a few cases where a shop installed them wrong. What about the mix screw passages, you cleaned them ??

 

Did you use a small steel wire or #12 guitar string to verify that the pilot jets were actually cleaned and open to the full diameter? And the air bleeder cross-drilled ports? And the choke jet? And the mixture port? etc... Check out this porn to see all the places that need to be clean for that thang to work right.
http://vfrworld.com/forums/1st-2nd-...r-circuit-identification-porn.html?highlight=

 

@squirrelman I've just double checked, the boots are installed correctly.
Re: Mix screws: No, I have not, until now. I have now removed idle mix screw for #1 and used compressed air to blow through it... should I use carb cleaner instead? I WANT to say when I blew through the hole, I did not feel an immediate blow from the "Idle Mix Exit Port", until a moment later. COULD mean that it was not fully open. I still ahve yet to go through the other 3 screws.

@kenneybobby Lovely porn. Im assuming it is really only used for checking where the circuits go and if they blow through?
When I blew through the mix screw for #1, I can feel air coming out of the "Idle Mix Exit Port" (image 5 of 6). Was I supposed to feel it come out of another orifice? (ie. an air or fuel inlet?)

Also, anyone have extra/know where I can buy replacement idle mix screws (with caps, since I am missing two caps)? One of my mix screw is both cap-less, and the top got stripped down... There is no place for a flathead...

 

arty2: You're making progress !!

Huh ?? Otherwise un-employed minimum wage people are @ phones @ telecenters worldwide-- NOW !!-- just waiting for your call and credit card number with expiration date @ over 50 websites to sell shit like that online.

Or call your nearest Honda dealer and order through them, showing some respect for the hard-working owner still keeping it open. arty:

Carb spray through idle mixture hole is a must, best done with idle jet removed, followed by compressed air or lung power, as mentioned. Count the turns on the adjustment screw and be prepared to fine-tune it later if you have idle problems.

 

Hehe sounds good. Thanks. Now back to this carb... I am hopeful these mixture screw cleanse will help... Not sure where else can I check for clogs otherwise (again, after following toe cutter's guide).

 

You've exhausted about 95% of the possible technical issues we advised you to check, so the only other option is operator error, right ??

 

Where's the fun if we think that way?!? :eyebrows:

I'll try to get some mix screws soon, wrap up cleaning with some carb cleaner, reinstall and see what happens... That is, if my work schedule allows

Thanks! Letting me know those are most of the things to check, et al. made me feel good... Fingers crossed that [more thorough] operation will solve this little bugger...

 

If YOU can't fix it with OUR help, we all feel defeated, really !! The very last step of defeat is taking it to a repair shop or dealer, and we cannot allow that ! NEVER !!!

 

Hehe I agree.. I do NOT want to take it to the shop... It's expensive and... weak/fail. lol besides, if I can get through this barrier, then I can proudly say I know a thing or two about working on my bike's carbs! Shake this demon off me*.

*Where I came from, no one does mechanical work... not even fill their gas tank themselves... I am determined to go well beyond my status-quo

 

It's like my old bike shop boss used to say when I would say I couldn't fix something. "Is it broken now?" and I would say "yes." And he would say "Then you can't hurt it!."

He would also say "Fix it or throw it away." We never threw a bike away.

There is hope. Someone built it. It ran right once. It will run right again.

 

Make sure to keep track of the little spring, flat washer and oring that goes with the mixture screws.

Then yes you want to spray (berryman$) carb cleaner into the idle mixture screw hole and it should flow out the mixture exit port. If you cover the exit port with your finger then it will come out the transistion ports under the lip of the butterfly valve.

If those mixture screw ports were clogged then your bike would never be able to idle, but when they are cleaned out it will run perfectly.

If you have a dremel tool with cutoff disk or a hacksaw blade you can cut a slot in the head of the mixture screws to use a flat blade screwdriver. Don't really need the limiter caps for anything that i know of--it will run without them.

 

@Big_Jim59 I agree! I've heard variations of that saying... my head is kept up high because of it!

@kennybobby Good call on the hack saw.. I just happened to have one sitting around. I just wanted the cap so I can just go at the cap, rather than the screw itself... ah well, nothing major. Problem now is, I just cut the top of the screw, and am still unable to turn the screw... I think someone/time must have tightened it... I'm still trying to come up with other ideas to get a better hold of the screw so I can turn it before I have nothing left to work with...

I ended up buying a carb rebuild kit for a Goldwing [1500cc, 88-91] so I can have a brand new mixture screw there.

Meanwhile... I will go through cleaning the other 3 per your guidelines.

 

Note on the mixture screw. These seize up sometimes. Before you try drilling or resort to physical violence my advice to to leave it alone. 1) You can destroy the carb messing with it. 2) More than likely it seized in the proper position, it's just dirty. Pulling it out would make cleaning easier but a good vat dip could do the same and not endanger the carb body. 3) Even if you can't clear that jet, if all the other carbs are working correctly then it will idle, not great but it will work. Better a lumpy idle than a destroyed carb. I had this happen on my Bandit project and I had to let one of the jets stay because it was beyond retrieval.

By the way, I got the Bandit running great without removing the frozen jet.

 

Looks like it already had a good dose of the vise-grips.

Maybe you can pull the rack and dip them in pine oil or in an ultrasonic cleaner. But if the screws have been bottomed out and seized up then you will need to go to a machine shop where they can mount them in a vise and precision mill them out without damage to the carb body.