Idle Problems...

My 650 Maxim will sometimes not go back to idle after being on the road awhile or if its just sitting in the driveway running it will suddenly jump up to 3000 rpm or more if I let it go that far without playing with the choke or using the cluch to slow it down If Im on the road.....

I just got the bike used last year.....Im a drag racing gearhead, but new to motorcylces..... it allways smells like it running really hot but am I wrong to think that it should smell like that since its air cooled?

thanks for some help to a newbie!

nitecruz.com

 

Welcome to XJBikes Nitecruz !

Try starting your bike, get it to idle (not at 3000) and spray water on your exhaust. All 4 should boil the water, if 1 doesn't, you just found the cyl. or carb that needs work.
The plug is firing, but there's not enough gas.
To test that, remove the air cleaner cover and give quick 1/4 second shots of starting fluid. If this raises the idle speed, then you've confirmed at least one is running lean.
If you're lucky, you can just adjust the idle mix screws (4)
Use the search feature here for carb cleaning, syncronizing, and idle mixture.

 

Another cause could be a vacuum leak. If all the above checks out, take an unlit propane torch and run it around the intake boots. With the gas swirling around the outside of the boots, if you have a vacuum leak, it'll suck it in and you'll hear an increase in engine Rpm's. You may have a cracked boot or bad gasket or loose clamp. You may need to jiggle the carbs while you're doing this test, too.

 

Nitecruz my bike has had the exact same problem since I got it last year. It used to be quite bad and would race up to 5000 rpm. Since then I have worked on the carbs (clean / float levels / sync) and adjusted the valve clearances. It is now improved and will only occasionally idle at 3000 rpm after it gets really warm. My next thing is to replace the intake boots. I can see cracks on them but not really sure if they are leaking. I tried the procedure that Gamuru suggests but it didn't work on my bike. (I couldn't even get the rpm to increase when supplying propane to an open vacuum inlet.) So instead I tried the soapy water trick. When I sprayed soapy water on the intake boots while the bike was running I get some bubbles forming. So I have ordered replacement intakes. Hopefully this will solve this long running issue.

 

Oh, and another thing I did was back the throttle stop screw way out to compensate for the high idle. It means you sometimes need to give the bike some throttle manually. But I find this more convenient that dragging the clutch while sitting at a stop light. Of course, this is just a stop-gap until I can get the real problem fixed. I am also planning to do a colortune adjustment to set the idle mix once I get the new intake boots.

 

I used to drag the clutch to keep it from racing at idle. I think that's not a very good solution. My clutch wore out pretty quick (well, quicker than I expected). I have to say, leaving the idle low and giving it some gas now and then is a better and cheaper solution that having to change out the clutch!

 

thanks guys!

I'll be checking those ideas out! From the prices Ive seen on cluch packs, I dont wanna tackle replacing cluches anytime soon ether!!

I'll be checking this forum often for more ideas......keep em coming...

....cruzin all nite.....

 

I don't have this problem with my bike... It start easy
and idles between 500 and 1500. Hate to fix something
that is not broke but, my boots are cracked and if the
bike is off for a few hours carb. 1 floods the cylinder.
So I have some carb. work to do.

Where can I buy a set of new boots for under $180???

 

get some silicone and repair it if possible. thats what i did, works like a charm!

 

I just used high temp black RTV on my boots

 

The high temp RTV sounds good.
I ordered the dynojet kit and pod filters.
Think I saw a blog on tunning here, somewhere.
Its going to be 'fun'

 

Kellyjoe- - until you fix your carbs right, go buy a $5.00 fuel cutoff valve for a lawn mower, put it inline next to your fuel filter.

One of our members had a bike / car / garage fire that looked like 10 Grand in damage! Your fuel petclock doesn't work right and needs a rebuild kit, #1 carb needle and seat can be dressed up with ultra fine sand paper, or just buy new, or just wait it out; the engine vibrations alone may eventually "polish" the needle and seat.

Someone here just bought boots on E-Bay for $40 used. They aren't cheap. Have "fun" with your carbs !

 

I had a Yamaha XZ550 Vision for many years, they also suffered from cracked intake boots. One of the fixes that worked well was to cut lengths of bicycle inner tube with a hole punched for the vacuum pipe and stretched over the boot. They stay tight and form to the shape of the boot and since they are black seem to blend in well. If you go the RTV route the inner tubes make a nice covering as well.

 

That kind of racing is due to the Bike running on the Main Jet Fuel Supply.

You might have something as simple as a Sync issue
a stuck linkage issue
a lazy return spring

Turn out the Idle Adjustment Rod and get the bike to Idle without Main Jet Supply.
Butterflys closed.
You have to adjust the Pilot Mixture Screws to accomplish that.

Once you have the Bike Odling on its own a complete fine tuning would be in order.
But, revving-up to beyond 2,000 rpm's means you have Main Jet Fuel ... fueling the fires.
Until you can close-off the butterflys and have the bike Idle onn the Pilot Mixture Supply, alone ... you'll be getting high-revving until you do a complete tune-up.

Don't forget to lube every pivot and moving part on the Carbs with some Marvel Mystery Oil.
Stuck Linkages is a likely culprit.

 

I have a problem with carb 4 the slide doesn't move down by itself (gravity pulls it down).
All 4 springs are the same length, don't know if that means anything.
Don't know how to chk vacuum above the slide.
Don't know the best way to clean varnish off slide or if thats the problem.
Whats the best way to clean or check slide????

I do have other problems I'm working on also.
Blown head gasket.
Floats need to be level (carb. 1 leaks fuel)
floats valve looks clean and stops fuel when held by finger.

 

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Title: Clunk Test

Author: RickCoMatic

 

Thanks about the Clunk Test... I have a much better throttle response now.
I was just thinking earlier that the rpms drop to slow but, now its better.

Well I need to find a blog on tunning a jet kit.