Idle Adjustment

[kalbo]

Ok, I am new to the Vmax scene. I have recently bought my first and loving it. I have noticed that the bike seems to idle a little slow. So slow, it will sometimes stall, when stationary in traffic if you don't keep the rev's up. I have tried increasing the idle speed using the adjuster and it works, but after a very short time it goes back to slow again? Any ideas why?

 

[tothemax93]

Whats the idle set at when your just sitting in neutral. Does it hold steady just sitting . The Idle should be set around 1000 RPM

 

[davesax36]

Also what happens when you blip the throttle in neutral? Does it drop back to the same speed, drop below and return, or drop really slowly after hanging a bit?

 

[kalbo]

I have run the bike and when its warm, I set the idle to 1000rpm. If I blip the throttle a few times it seems to drop back down to slow idle...It's as though it's not holding at 1000. ?

 

[kalbo]

A couple of times at slow speed, whilst maneuvering in 1st gear, it's cut out completely. I almost fell off it yesterday as the rear wheel locked up when it stalled. I have to keep the revs up with the throttle to stop it stalling.

 

[kalbo]

If I set the idle to 1000rpm it will stay at 1000 until I open and close the throttle, which seems to drop it back down again.

 

[davesax36]

Sounds super rich and bad sync to me. Does it smell a lot?

 

[kalbo]

It probably does smell a little rich. i'll take it to a mechanic and see if he can make it a little leaner. Maybe that will help, Thanks.

 

[MaxMidnight]

Surely 'does it smell a bit rich' would be subjective and, if I may be so bold as to suggest, perhaps not the best way to diagnose an issue?

Before doing anything else has the bike been given a full service? Assume nothing and change all filters and spark plugs, balance the carbs plus everything else on the list here.

If that doesn't address the issue then check if the carburettor tamper proof plugs are still in place and if not make a note of what the idle mixture screws are set at.
NOTE: Use a well fitting screwdriver (not the one used as a chisel/ tommy bar/ paint stirrer) and if the screws are tight then don't force them as they are brass and the ends can strip off easily.

Assuming a) the tamper proof plugs are out and b) the screws move feely you should notice the motor responding to having the mixture screws turned in or out. If that is not he case then it is possible that an idle jet circuit is partially or fully blocked. A can of fuel system cleaner would be a good idea regardless of any issues and if the idle circuit is only partially blocked may sort the problem.
If that fails then you will need to consider doing the 'Shotgun'. The method is described here.

You could also pull the plugs and see what colour they are which will give an indication as to the mixture.

 

[Barry barker]

What he said!

 

[kalbo]

Thanks Steve L. I will try the can of fuel additive 1st and see if that helps. I took it to my local motorcycle mechanic who said it didn't appear to be running rich. Mechanics over here in the Philippines are pretty basic. I tried a couple and neither had a set of vacuum gauges to check the sync of the carbs. I've noticed now that after the idle speed drops from 1000 down to 500, if left to idle for a minute or so, it slowly rises back to 1000. Perhaps, it is just a partially blocked idle jet. There's certainly no problem with the main jets, as she runs perfectly out on the road. Thanks.

 

[KDIMD]

Kalbo, your in Angeles City? I live in Manila and ride a 1994 vmax that has a supercharger. I am with Mad Dogs so go up quite a bit. I use Rod for my harley when it breaks down in AC. If you make it to Manila, I have a good mechanic that will come over to service my bike. Has nearly rebuilt the thing. Name of Teng Avila. Good work.

 

[KDIMD]

Also, you really need a carb sync. I have one, but since I switched to a holly carb, I put it in storage and cant seem to find it. Will be moving so will likely dig it up then.

 

[kalbo]

Thanks KDIMD. I used to use Rod Fulley, but i haven't used him for a few years now. I don't think he does much work himself these days, but has his young lads doing most of it. I have spoken with an American guy who I'm told is a 1st class motorcycle mechanic. He is in the States at the moment, but will be coming back to the PI in February. he said he will set it up for me. He has a fully equipped garage at his house here in Angeles. I have it idling better now after i adjusted the air/fuel mix screws on the carbs. If i can't wait until Feb, i may give Rod another go. Thanks

 

[mundmc]

Surely 'does it smell a bit rich' would be subjective and, if I may be so bold as to suggest, perhaps not the best way to diagnose an issue?

I never cease to be pleasantly amused by MaxMidnight's frustration with less technical approaches. That said, I had the same problem as you (progressively dropping rpm's once they were lower than 2000, eventually stalling), and I agree with everything he said.

If the problem persists at all after adjusting the AF screws, cleaning the pilot air jets using the shotgun method (followed by a carb sync) worked well for me. My mechanic told me it was voodoo. It was not, and I don't use a mechanic anymore thanks to this forum.

 

[kalbo]

All the idling problems disappeared when I replaced the exhaust system. (see my other post 'A stroke of luck') The previous owner had modified and removed the baffling in the original exhaust and this caused several problems, including loss of power at high RPM's and very poor idling. Trying to balance the massive lack of back pressure by adjusting the carbs was a losing battle. Fitting a newer original exhaust system restored the bike to perfect running condition.

 

[leecifer]

Just a thought but when i first pick up my max it would stall out when hot sometimes. It ended up being a corroded electrical connection that came from the rectifier causing poor battery charging. I guess it would be good to check anyways.