Vmax Carb Problems

[atVMAX99]

Hi all! This is my first post to the forum and I'm starting with an SOS to all Vmax carburetor experts!

Due to my stupidity I left fuel in the bike over the course of the Winter and of course it gummed up my pilots on the carbs. The bike didn't want to hold an idle unless the choke was on. I came across a cleaning procedure on Vmaxoutlaw.com on the PAJ1 and PAJ2 circuits, which I did. I followed it precisely and insured I had carb cleaner coming out of all the pilot circuit orifaces. Got everything put back together and set the pilot screws 2 1/2 turns out and fired it up. The bike was able to idle without the choke which improved my original problem however the issue now is an unsteady/surging idle. I'll skip over the fine tuning details of the pilot mixture screws and sum it up with, at 75 degrees 2 1/2 turns out seemed too rich and at 40 degrees 2 turns out seemed too lean so I settled with 2 1/4 turns out. This was seeming promising however the idle was still surging and what I mean by this is, if you "goose" the throttle the rpms are VERY lethargic in settling back to 1000rpms. Sometimes it'll hang about 3000 for a few seconds then come back to 1000. Of course taking it for a ride sucked because when you give it gas and go to shift gears, rather then the rpms dropping in between gear changes it's like I never let go of the throttle. I made sure the throttle wasn't sticking by observing the throttle movement at the carbs while I twisted and everything moved in synch no hanging up linkage and when the throttle was let go it always rested on the idle adjust screw. I really scrutinized this because the symptons are like there's slop in the linkage but there's none that I can see. After I cleaned the carbs I made sure all the clamps were tight and even re-synched the carbs, the #3 cylinder was a smidge high.

Note: the carbs were never seperated from each other or removed from the bike during cleaning.

So to the carb experts, what did I do wrong, what did I overlook, what still ails this thing?!?

Any help would be most appreciated!!!

 

[naughtyG]

When was the last time you sync'd the carbs?

http://www.vmaxforum.net/showthread.php?t=3959

I'll bet that's your problem, I had a Max that did exactly what you described until I re-sync'd its carbs.

Also, you said you took your A/F screws out and set them back at 2 1/4 afterward. That's where they all are on mine too, but did you record were they were before taking them out, or is that where they were before already?

 

[Heretic]

Put a couple of cap fulls of Seafoam in the tank and run the hell out of it. This always makes my bike run better/smoother if its been put up for awhile. I think that if the RPMS stay high after 'goosing' it means that its rich.

 

[richwrench]

I say pull 'em & clean 'em. It's 10 years old - time for a good clean & check the floats. I think you'll find that VMAX carbs are some of the easiest carbs to remove compared to a lot of streetbikes. Not really a difficult job - it sounds like you are pretty mechanical. I would also throw a new fuel filter at it while it's apart - only a couple of bucks. Only other shortcut would be a generous dose of carb/fuel injector cleaner & ride the hell out of it for a day or so & see what happens...

 

[dannymax]

Welcome to the forum 99.....all of the above, clean 'em, sync 'em, Seafoam or BG 44K 'em and drive 'em!!

That should do it!! Good luck and let us know how it turns out.

 

[Jeffb]

To what Heretic said, I think a hanging idle is a lean running condition, a rich mixture will drop below idle then come back up to idle rpm. That is what I have always thought anyway.

 

[atVMAX99]

When was the last time you sync'd the carbs?

http://www.vmaxforum.net/showthread.php?t=3959

I'll bet that's your problem, I had a Max that did exactly what you described until I re-sync'd its carbs.

Also, you said you took your A/F screws out and set them back at 2 1/4 afterward. That's where they all are on mine too, but did you record were they were before taking them out, or is that where they were before already?

The screws were 1 3/4 out, I set them to 2 1/2 because the procedure recommended this setting after cleaning and re-adjust as needed. I re-synched the carbs right after I cleaned them along with tightening up all the clamps.

 

[atVMAX99]

To what Heretic said, I think a hanging idle is a lean running condition, a rich mixture will drop below idle then come back up to idle rpm. That is what I have always thought anyway.

This is an issue for me because I don't know if it's a rich or lean condition. I just got done messing around with it some more and set the screws to the original 1 3/4 out along with dumping 5 oz. of this Sea Foam that's been recommended. I started it and ran it for 1/2 hour in the driveway, it got to where the fan was coming on and the bike would hold an idle for a little bit then die and the idle was still hanging when "gooseing". I do own Color Tune but I couldn't seem to get it to display a rich condition so this idea was a wash in determining if the bike was too rich or too lean. I don't know if anybody else has had luck in using this product.

 

[atVMAX99]

I say pull 'em & clean 'em. It's 10 years old - time for a good clean & check the floats. I think you'll find that VMAX carbs are some of the easiest carbs to remove compared to a lot of streetbikes. Not really a difficult job - it sounds like you are pretty mechanical. I would also throw a new fuel filter at it while it's apart - only a couple of bucks. Only other shortcut would be a generous dose of carb/fuel injector cleaner & ride the hell out of it for a day or so & see what happens...

Yea I'm kinda leaning this way, I was trying to avoid the "Full Monty" cleaning and short cut this if possible but it's looking like I have no choice. I did pick up the Gunk Carb Cleaner that comes in the gallon paint can with the parts bin for this job. I was concerned about breaking the carbs apart to do this but I guess it's not a big deal? I do have the Yamaha shop manual which should cover this. I guess I'll need to replace the intake boots when I do this?

 

[Jeffb]

no need to replace intake boots, unless they have cracking or dry rot, inspect them.
Pay particular attention to the pilot jet circiuts, not just the jets. The pilot circuits that run through the carb need to be blown through with cleaner & air. Cleaning carbs is not very hard at all, the throttle cable can be a bit of a bugger though. good luck.

 

[dannymax]

This is an issue for me because I don't know if it's a rich or lean condition. I just got done messing around with it some more and set the screws to the original 1 3/4 out along with dumping 5 oz. of this Sea Foam that's been recommended. I started it and ran it for 1/2 hour in the driveway, it got to where the fan was coming on and the bike would hold an idle for a little bit then die and the idle was still hanging when "gooseing". I do own Color Tune but I couldn't seem to get it to display a rich condition so this idea was a wash in determining if the bike was too rich or too lean. I don't know if anybody else has had luck in using this product.

I had a Color Tune but it was jut too akward to use on the v max. I've heard of guys using it successfully, but I don't know how they did it. :confused2:
It should be a great product on something with more working room, like a lawnmower. :biglaugh:

 

[naughtyG]

breaking up and cleaning the carbs isn't hard, but you must have the right tools (correct size quality philips screwdrivers especially).
I put it all in pictures in 6 threads - here's the first one:
http://www.vmaxforum.net/showthread.php?t=5830

Also, I would make sure that your slides diaphragms are in good shape, but I guess you did that already if you did the shotgun?

 

[atVMAX99]

breaking up and cleaning the carbs isn't hard, but you must have the right tools (correct size quality philips screwdrivers especially).
I put it all in pictures in 6 threads - here's the first one:
http://www.vmaxforum.net/showthread.php?t=5830

Also, I would make sure that your slides diaphragms are in good shape, but I guess you did that already if you did the shotgun?

The diaphrams were in good shape and I thoroughly cleaned and lubricated the slides with WD-40. Nice documentation/pictures of your carb project. What problems were you having to make you do this? I was actually going to let the carb bodies soak in Gunk Carb Cleaner, I guess it's like Safety Kleen, and afterwards use carb spray and compressed air on all the orifaces. Also did you bench synch them with feelers first then vacuum synch or was you able to go right to vacuum synching?

Thanks for your info!

 

[naughtyG]

I decided to give'em a good clean after performing both peashooter and shotgun twice as I was having idling problems. Each time it helped, but only temporarily.

I'd be wary about soaking them - all those carb cleaners are great for gunk and metal, but they do eat rubber for breakfast. As I found in mine, a few o-rings and gaskets were perished, and replacing them helped. But the thorough cleaning only a full disassembly can provide was what did it I reckon.

As far as sync is concerned, I 'eye-sync'd them on the bench, and then went straight to vacuum sync on the bike. They were close enough to run and warm up that way.

 

[atVMAX99]

I decided to give'em a good clean after performing both peashooter and shotgun twice as I was having idling problems. Each time it helped, but only temporarily.

I'd be wary about soaking them - all those carb cleaners are great for gunk and metal, but they do eat rubber for breakfast. As I found in mine, a few o-rings and gaskets were perished, and replacing them helped. But the thorough cleaning only a full disassembly can provide was what did it I reckon.

As far as sync is concerned, I 'eye-sync'd them on the bench, and then went straight to vacuum sync on the bike. They were close enough to run and warm up that way.

Okay, I just finished ripping these things totally apart and cleaned the H*** out of them. I went with your advice against soaking them in carb dip and manually cleaned them. I even took the Pilot Jets out of the JET BLOCKS and cleaned them along with thoroughly cleaning the JB's and every oriface in them. Thoroughly cleaned the Coasting Enricheners and sprayed Gum Out in every hole there was in the carb body itself and ensured I saw Gum Out streaming out nicely from ports other than where I was spraying. I'm very confident there's nothing in these carbs now, 2 of the carb's Coasting Enricheners were "gummy". I eye synched them as you did re-installed everything and got the bike fired up this afternoon, managed to vacuum synch them and I went with 2 1/4 turns on the Pilot Mixture screws. It idled fine and revved fine, however it was still doing this hanging idle. I'm starting to think now it's coming down to not having the Idle Speed screw not set properly in conjunction with setting the Pilot Mixture screws because these carbs are sqeaky clean!
What was your procedure for setting the Pilot Mixture screws and the Idle Speed screw?

 

[maleko89]

Unhook the throttle cables that run from the junction box to the carbs. Pull the open cable manually and see if the idel still hangs.

 

[atVMAX99]

Unhook the throttle cables that run from the junction box to the carbs. Pull the open cable manually and see if the idel still hangs.

I'll try that, thanks!

 

[95spfldmax]

If your still having that "hanging-up" problem you might want to try spraying WD40 around the outside of carbs and intakes and make sure you don't have a vacuum leak. Listen for an idle change as you do it. That would cause this symptom as well.

 

[Jeffb]

does this thing have a jet kit of any kink, or is it all stock. How about air box, is it modified or anything. A hanging idle is caused by a LEAN condition. That is why it helps when you clean the pilot circuits, because these are AIR circuits, not FUEL circuits.
It shouldn't be throttle cable as this is a double pull setup, when you back off the throttle it pulls the linkage closed. Does it pop or backfire when coasting down the road.

 

[robsplatf4]

. A hanging idle is caused by a LEAN condition. That is why it helps when you clean the pilot circuits, because these are AIR circuits, not FUEL circuits.

+1 hanging idle is lean
Did you check those intake boots while you had them off. Might have a vacuum leak causing a lean condition.