Need a little help!!!

Hey guys.

Well I have been trying to figure this out for a bit and am a little stumped. I have an 82 yamaha maxim that has had this problem since I have owned it. The Bike would run for about an hour then it would lurch a bit, rev down and eventually stall. I would have to wait a couple hours then it would start again and I could ride it for a bit till it did it again.

I new I was flooding it. So after the engine would get hot I would check the 4 exhaust and one would be cold. That made me think maybe the carbs needed a good cleaning so I striped them down and they were a mess. I got them all back together and the bike started and ran better then it ever had but on my first test ride it did it all over again.

So im trying to do my own wrenching best I can and am hopeing you guys can offer up a few suggestions as to where to start. My best guess is one of the cylinders is miss fireing and causeing the bike to slowley flood but I figured I would ask the pros on here first.

Any thoughts would be greatly appretiated.

Bugz

 

Does it stall while riding or while at a stop light? If at a stop light your mixtures may be off. Colortuning could solve that.
If its dying while your riding you may have the wrong jets installed in your carbs. Could be flooding while your riding as it warms up.. Just MO.
My jets were all messed up and it was making my bike revved waaay higher than it should have until i fixed it.
But this def sounds like a carb issue
-Chris

 

You've probably already done this but I would check the state of the spark plugs, coils and battery. My brother had a slightly similiar problem with a virago that was due to a faulty coil (though a v-twin is obviously a very different bike).

 

Sounds like a plugged gas cap vent to me. Or a crack or split in the vacuum line.

 

You need to determine if the problem is FUEL or IGNITION Related.

While you have the Bike Running:
Set the Petcock to PRI (Prime)
This will Bypass the Vacuum Operated Valve and keep the Carbs Fueled.

If you stop. Turn the Petcock back to ON or RUN ... so you don't Flood.

If you don't experience the "Stalling-Out" Issue ... you might have a Bad Vacuum Hose as the previous Poster mentioned.
A Faulty Petcock Vacuum Valve.
A Slipped Petcock Wafer.

In short ... IF it will run OK without Stalling-Out running it in PRIME ... you have a Petcock or Fuel Tank Related issue you need to troubleshoot.

Editors Note:
Petcocks. Petcocks have Rebuild Kits. They cost about a third of the Price of a NEW Petcock.
The Old Petcock lasted over 25-Years.
If you do the Math ... It's worth getting a New Petcock rather than installing a Kit.

 

I had an MG that did this and it ended up an ignition problem.

 

I've had a few MG's. too.
I used to keep a small hammer under the front seat to tap on the SMITHS Fuel Pump to bring it back room being dead.

 

Ok guys thanx for the tips. I will try a few things on it tomorrow.


Rickomatic- does one exhaust not being hot to the touch not make it more of an engine problem as opposed to fuel.

I don`t have much experiance so I appreatiate the advice. I will try what Rick suggested and let you guys know. I also have a filter between the tanks petcock and the carbs to try and cut out the rust from the tank. So you might have nailed it rick. I will take the filter out of the circut tomorrow and try that.

Thanx again guys I will let ya know.
Bugz

 

I used to keep a ROCK in my '68 MGB for the same purpose; to beat on the footwell behind the passenger's seat (where the fuel pump was mounted) to "wake it up." The car would start to act like it was running out of gas; grasp rock, POUND floor; you heard a soft "purrrr" as the fuel pump woke up and back in business.

I think those were Lucas pumps though Rick. Too funny.

 

They could easily be unrelated. The cool pipe inidcates that something isn't right in that cylinder. If it is completely cool, then that cylinder isn't firing, and the problem could be something like a bad plug. If it is warm, but not as hot as the others, it could be: a) the pilot screw needing adjustment b) the carb isn't providing enough air/fuel, and other things as well, I am sure.

You should pull the carbs again and go through Rick's complete instruction list to clean out carbs. You will need some fine wires to get this done. I recommend the cheapest set of Light gauge electric guitar strings you can find. The smallest two strings will be very helpful in cleaning out the enrichment circuit and various small ports in the manifold side of the butterfly.

 

I had the "cool pipe" problem with my XJ550 when I first got it. Although the plugs looked fine replacing them solved it. Cheap fix if it works.

 

Take a Spare Spark Plug and Plug it into the Spark Plug Wire Cap of the Cylinder that is not Firing.
If you have SPARK ... The Mixture is either Too RICH or Too LEAN to fire.

If you have Spark ...
See if the Cylinder will fire.
Use a Rubber Bubble Syringe and a short length of Vacuum Hose.
Plug the Hose on to the Manifold Vacuum (Sync) Port.
Plug the end with your finger.
Fire-up the Bike.
Let some Carb Cleaner dribble into the Vacuum Port from the Syringe.
If the Hole FIRES the Cleaner ... you Troubleshoot the Problem from the the Combustion Chamber ---> Back ... to the Fuel Tank.
Bad air leak.
Mechanical malfunction.
Missing fasteners.
Clamps not tight.
Intake Manifold leaking at the Cyl Head Joint -- Bad O-ring and Gasket.
Throttle Shaft Seals.
All issues related to a Carb not delivering fuel.
Beenie Screen, Clogged Float Seat, Stuck Float, Clogged Jets, Float Height, Passages.

Chech to see if the Manifold Vacuum is present and strong as the others
Bad Sync

 

Ok so I pulled the plugs and im getting spark. Im gonna try swapping to new plugs just to be sure. (thanx Johntc) The battery is brand new and I metered it to make sure it is charging at the right amount.

I will have to go get a syringe to try the carb cleaner method but that sounds like a good next step. I did clean the carbs out as well as I could. I followed ricks carb cleaning methods and the carbs were so rough that its possible they need another clean. I dont have the "yics tool" but maybe I will ripp it down to the shop and see if they can tune it right in for me.

I will let you guys know how it goes.

Thanx again
Bugz