Lost idle

I have riden my '83 750 Maxim a lot this year with no problems. Yesterday three hours into a ride, it started dying during idle. At first I thought maybe it was heat related because it was a hot day, but later after a cold start it did the same thing. It starts fine if I use the choke, but when I turn the choke off the RPMs go down to about 500 and it dies.

After reading some of the posts in this forum, I tried setting the petcock to prime (didn't help), and inspected the plugs. They look clean.

Any other suggestions for a novice mechanic?

I don't know if it's relevant, but the problem started after a resturant stop. There was an opportunity for someone to tamper with it, though I have no reason to think that they did.

 

Try the idle ajustment screw in the middle of the carb banks airbox side.

 

Idle adjustment as listed and maybe bad fuel too , clean da carbys out might help if not the other stuff...

 

I agree with HooNz sounds like bad gas, if you dont have an inline filter you may need to pull the carbs and check the screens under the needle and seat valves, if they are cruded up you might want to pull your petcock and see if your pimary filter in your tank has come loose.
I alway recomend an inline filter, cheap insurance.... only a couple of bucks.

 

I wish more bikers understood the importance of an inline fuel filter. It's a lot easier to pull it than pull the carbs. Since the bike still runs I would add a half a can of seafoam to a full tank of gas and then ride the bike a good long way. This can have wonderful effects without oulling the carbs. I always try the easy things first since I am from the "lazy days of summer" south. Too hot to do much around here.

 

Thanks for the suggestions.

I tinkered with the idle adjustment this morning. I had to turn it quite a bit to get it to 1000 RPM. Now it runs rough, and once I throttle it, it is very slow to come back to idle. Something has changed dramatically.

It seems to me if it was a fuel flow issue, that the problem would be more evident at high speed than at idle. I don't really have the confidence to tear into my carb yet. I'm thinking that I may have to take it to a pro.

One other observation. I have noticed for some time now that when cold I get significant valve lifter chatter. What are the chances that valve lifter wear that could have suddenly reached a critical stage?

Hope you all have a good holiday.

 

I found the wonderful Seafoam stuff two blocks away from home at Advance Discount Auto parts, They also stock oil filters (Fram) for my 86 Maxim. If you have one near you check them out.(not an endorsement just a nice find)

 

After reading the symptoms more closely(ADD) it almost sounds like a clog somewhere in your fuel system or a really bad case of bad gas. Drain the tank check the petcock and do the seafoam thing. As far a the valve clatter goes you may need an adjustment and carb sync. Oil level is also critical, old oil = lost viscosity.

 

Quite a few symptoms there now , the clatter could be anything , camchain ect valves do not normally "just start" clattering , maybe your just listening more intently , oil a issue too , so i would suggest if you know someone get them to have a listen look about to see what they think...

good lick...

 

Are you sure you changed the idle adjustment????? Sounds to me you might have changed the middle carb sync screw. Idle screw is at the back of the carbs and the sync screw is at the front.

Original problem may have been bad but now may be a good tune required.

 

Oil is not an issue. I changed the oil and filter about a week before. It is clean and full.

I did adjust the lone screw behind the carbs. I think in the book they called it the throttle stop adjust.

I bought some Seafoam yesterday as suggested, but haven't used it yet.

 

The very 1st thing to look at is the vacuum line to your petcock, is it still hooked up? (good prank?? by a bad person maybe at the restaurant) Check both ends of the vacuum line are hooked up and check it for cracks or vacuum leaks.


Ok, so how do you feel about pulling your tank? :? (it's easy, just 1 bolt)

The 1st thing I would do is, pull the fuel line off of the petcock and stick a piece of fuel line on the petcock and drop the fuel line in a jar or some kind of container to catch the gas. (Put the petcock in run before you unhook any lines though, and do this in a well ventilated place)

Turn the petcock to prime and see if you get good flow out of the tank... that should tell you if the problem is in the tank if you get really slow flow.

This will help you to decide if the trouble is indeed in your carbs or in your tank/petcock.

If you have bad flow: I'd pull the seat and then the tank, drain the tank and pull the petcock. Look for debris in your tank or the primary screen to be plugged or off. (if it had come off, there is a good chance the screens on your seats are plugged too.)
If everything looks ok, the next thing to suspect is the petcock.
The petcock can be rebuilt but you better get the o-rings and diaphram and stuff 1st.
If you have good flow: then the problem is most likley in your carbs.... :evil:
from the way this came on I'd suspect the needle & seat screens might be plugged (if they are then the primary screen is most likley broken)

You might not have to go all the way thru those carbs..... you might be able to clean the screens on the seats. (do all 4)
Those float bowl covers are supposed to be able to be removed while still on the bike!!?? but for my $$ I'd just as soon pull the carbs. ( this is a fairly hard job if your new to this stuff)
If you can work on the carbs without changing the sync settings or pulling them off the rails you might be able to get by without syncing them, but you should start to look for someone who can do that for you soon.
Be careful not to change the float settings by bending the metal attached to the floats. :roll:

If the fuel flows good from the tank :?: and you don't feel comfortable woking on the carbs.... just dust of the old billfold, and, well, you know the rest.
GOOD LUCK

 

Good News fellow bikers,

I drained the tank, removed it, tested the petcock, found no problems.
I belatedly installed an inline fuel filter, reassembled everything, and put in a gallon of gas with a couple of ounces of 'Sea Foam' as recommended above. After starting it up and after warming it up a bit I soon had to crank back on the idle adjustment.

This evening I added some more gas and sea foam and went for a one hour ride. I had to stop twice and turn down the idle some more. It appears like the 'sea foam' cleaned out the problem and saved the week end (not to mention time and $).

Thank you all for your advice.

I am a happy biker tonight ;-)

 

Glad to hear things are looking up for you, sometimes it's that simple sometimes not. luck was on your side.