81 xj 650 maxim need help plz....

Well i got the bike going and everything was fine until the carbs started to make sucking sounds and if i pop the vaccume line off of the petcock it makes a slurping noise, spits out gas and is hot and can see steam coming out of the hose also....also when the carbs are making a slurping noise i think the gas is getting into the cylinders and into the oil so i have to keep changing the oil....and gas goes into the air cleaner area and leaks gas out a drain hose from the air box to the floor. I dont know whats wrong with it this is what i have done to the bike so far:

1. rebuild carbs including all new jets needle and seat for float. (havent replaced floats.
2. new plugs
3. new gas and vaccum lines
4. changed oil and filter a few times now that this is happening

The bike runs great but once you shut it off this happens. Is it the carbs? I have new needles and seats for the floats. But its odd and i dont know what to do. Any advice would be very helpful thanks!

gjewison

 

Did you check/set the float bowl level?

But you say it's spitting gas out of the vaccume line fitting...all of a sudden...

Just doing the logic: positive pressure where there should be negative. First thing that comes to mind is valves. Perhaps the intake valve is stuck open. Check compression.

Pull the caps off the other intakes. What's going on there?

Just making a few stabs. Hope it helps.

 

i have checked the compression its right where its suppose to be. I would like to check the float and bowl level but the drain screws are stuck in the dang bowl and im having a hard time getting them out...so i can attach a hose and check the level while they are on the bike.. Is there any other way to check or what the floats should be at? i just left them what they were from before, but i got the bike from a not so smart person..or could it be a bad float?

The bike runs great otherwise just when i shut it off it starts doing this. I just purchased the bike. I think its odd that its doing that also Any more help would be great!!

Do you think its the floats not stopping the gas? It makes a sucking sound almost when i shut the bike off like its sucking gas into the carbs...

TIA

 

From other posts, I've read that if you leave the petcock in the prime position, it'll flood and you'll get gas in your crankcase. So if you fuel level is too high, I would imagine the same thing would happen.

This may not fix your problem, but I'd pull the carbs and get those drain screws out. Heat, pen lube, and imact will get them loose. (Be patient. remember with heat to start away from the screw and work towards it. This will let the metal expand better...i.e., the outside metal will expand first allowing room for the metal around the screw. Plus, you don't want to heat the screw too much, cuz that will defeat the purpose of laying the heat to it. If you've applied a lot of heat--to the point where the screw is hot--stop, and let everything cool down.)

Might want to submerge your floats in water and check for bubbles and buoyancy.

I've never encountered your problem either on my bike or on this site, so I'm merely suggesting checking problem areas.

 

Are you ABSOLUTELY sure that what leaks out is GAS???

You might be running OVERLY RICH on Fuel that it 10% or more Ethanol.

The Ethanol ... failing to do a Clean Burn ... will produce WATER that will be expelled in some way.
If it in the exhaust system and NOT being expelled out the tail pipe ... it's going to BOIL ...

You will hear it boiling.
The STEAM is equally as powerful as Clean Burning Fuel.
The Steam will blow-by the rings and fill the crankcase with moisture.
The moisture will vent through the crankcase venting system and end-up in the AirBox.

And, on the floor.

Soak-up the stuff dripping on the floor with some paper towels.
Bring it outside and try lighting the wet paper towel with a match.

If it's gas it will ignite ... and you need to do something about your Petcock and Float Valves.

If you can't light it ... you're running way too rich.

 

its gas you can smell it pretty good. i took the petcock apart and cleaned it a while back but havent recently....could be the diaphram that is bad in the petcock also. The petcock has a on, reserve and, prime position. I do currenty have it in prime position should i switch that position might make a difference? Prime just allows the gas to flow freely the floats should still stop the gas from overflow correct?

I will check the floats tonight to make sure they are fine..how will i notice if they are leaking will the bubble enough to notice? I have the repair manual they haynes one but that dosent help for troubleshooting....
Thanks for the advice keep it coming.

 

Don't leave it in Prime.

That's part of the problem.
A big part.

If gas is seeping by the floats ... it has to go someplace.

 

ok im going to take it out of prime...if thats not the problem what else would be?

 

Maybe a stickey thread with stuff like the ever popular PRIME position on the petcock syndrome?

rich

 

well not sure it seems to run fine its not idling very good...also it seems to pop or misfire on cylinder 1 or 2 not very bad but you can hear it i think that the carbs need to be syncronized.


I also had to replace one of the pilot air jets and dont think its adjusted properly but i have to sync the carbs first anyone know of a quick way to sync the carbs without having to pay 90 dollars to get it done?

thanks in advance!

 

also i just pulled the plugs out and the tips are pretty white on all four cylinders engine is running hot it seems also.....is the engine running lean? Does anyone know a good way to sync the carbs to do it myself?

TIA

 

You gotta deal with it being LEAN, first.

Lean is NOT a good situation.
Do you know how to "Tweak-by-ear?"

 

no i dont know how to do that....whats the process that i can do to "tweak" the carbs?

I know i have to adjust the pilot air jet but do i adjust it in or out? I have looked in the repair manual and dont seem to find anything for troubleshooting much in there. I have fixed the gas problem by switching the petcock to on instead of prime.

HOW do i clean out the oil sump and clutch area to make sure i get the gas all cleaned out of there?

It seems to pop a little bit also and wont idle now that i have the petcock in the on position. Im think the carbs need to be synced and are causing the misfire? its not very loud but noticable.

 

f you can "Stuff" the YICS Passage ... then, you can do an "Old School Tweak" ... it's pretty simple, actually.

One at a time ... "Tweak" the Pilot Mixture Screw ~~> OUT.
I'm talking micro-tweak, here.

The Idle will IMPROVE as the Mixture Screw is Tweaked OUT.
Then, there will be a plateau where NO further improvement occurs.
Followed by where the Mixture becomes too RICH and the Cylinder begins to react to being adjusted too RICH.
(Misfiring, backfiring, coughing and popping)
When you arrive at the spot where the Cylinder begins to act-up from being too RICH ...
Tweak the Pilot Mixture Screw back IN ... Until you have a smooth-running situation.

Do this for All four Cylinders.

Now, at this point we KNOW that the Mixture is adjusted to be "Good on the RICH Side."
This is OK. You KNOW your adjusted RICH and NOT doing any HARM running this way.

Un-Stuff the YICS Passage and Road Test.

Cruise and put Power on.
If the bike stumbles a little bit at the BOTTOM of the Power Curve before letting-loose and putting some good power on ...
The Pilot Mixture is STILL TOO RICH.

You'll need to -- Microscopically Tweak the Pilot Screws IN ... like 1-Degree at a time and re-test putting the power on.

When she gets dialed-in ... as you Tweak-away the TOO RICH Condition ... suddenly you find ~~> The SWEET SPOT ... where there is just the right amount of Air-Fuel happening as you come-off Idle (Pilot) and transition into the Lower-end of the Power Band (Mains) ... without a burp or a hiccup.

This SWEET SPOT of fine-tuning is sometimes guaranteed "In Writing"

Accompanied by an array of flashing red and blue lights and a signed invitation to go and tell a Judge or Magistrate how well you have your bike running.

 

thanks rick.....what you mean stuff the yics passage you mean use one of them yic tools? I dont have one i would have to get one or make one i guess....am i able to adjust the mixture screws without one?

What do you think is a reasonable amount to pay to have a motorcycle shop do the job and get it running good? Not that i want to pay someoen but im not sure if the yamaha shop would let me "borrow" the yics..

thanks again!


YOU ROCK!!

 

Search:

Free YICS Tools for everyone.

I was rockin' long before your momma even knew yo' daddy!