Outside left cylinder wont fire!!!

[73Satellite]

RX warrior engine, harness, carbs, etc in attack chassis. Everything is connected and either cleaned or new. I cleaned the carbs, replaced the coil, replaced the plugs and the outside left cylinder wont fire causing rough poping idle at about 3 grand.

I checked the plugs and three cylinders are firing and the outside left cylinder wont fire. Its getting fuel and air but no spark. Besides having a break in the wire harness is there anything else I can do, check, or change to get the cylinder to fire?

Desperate...the snows flying and forecasts are for rain and melting over the next few days....I WANT TO RIDE!!!

Much appreciated.....thanks....John

 

[kinger]

Sounds like a TORS problem, is it hooked up or disconnected?

 

[73Satellite]

so I mixed the tors and stopped the popping and three t mrpm and am idleing normal at 1 thousand rpm but am still running on 3 cyliners. SO NOW WHAT??

 

[73Satellite]

thx all evey thought counts!!!!!

 

[rxwarrior]

Have you swapped the coils between the cylinders to check for a bad coil?

 

[maxdlx]

Is the plug wet. Maybe you have no vacum to that carb thus no fuel. the slide won't move without vacume. Maxdlx

 

[73Satellite]

plug is wet coil changed brain box changed still no firing of cylinder.. wtf? Compression?? Bad plug?? Other than that.....it runs ok on three cylinders.

ANY IDEAS???

 

[kinger]

You could swap plugs from a good running cylinder adn figure that one out. I would also swap a coil, if that doesn't move the bad cylinder then you know its not getting a signal and its time to start tracing the wiring.

BTW why would you convert a attack to a carbed engine? What display are you using now, you have to ditch the fancy attack one for the RX one right?

 

[73Satellite]

EVERYTHING is an RX in apex chassis to include the guage pod. I have changed coils, plugs, have fuel to the cylinder, but still not firing the outside left cylinder. I can only suspect wiring. ?????????????????????????????????????????????????????

 

[73Satellite]

I put the RX motor in the attack chassis because I threw a rod through the attack block due to overheating multiple times after leaking coolant after a crash. Then I shot it with my 45 miraculously caused only the oil tank and chaincase cover to have holes. All else was ok.

Used RX parts in an updated chassis.

Fun project....hate to go back to first gen technology but its still a Yamaha and it works. I saved in buying an 04 twisted chassis broken bulkhead bent rails etc......using all the parts and doing something different.

It runs 2.just not perfect. What to do?

 

[Rockmeister]

As kinger and rxwarrior suggested, have you tried swapping coils and plugs?
Have you done a compression check?
Have you checked the slide to see if it opens when you blip the throttle when running?

Try simply laying a spark plug on the head plugged into the coil and see if it sparks.
If it doesn't, you know it is electrical. If it DOES spark, check mechanical/compression, etc.

Need to do troubleshooting tests that give you definite yes and no answers.
For example, YES you have spark on that cylinder, or NO you do NOT have spark on that cylinder, anything else is just guessing.

Try the things suggested, and come back with yes and no answers and we can help you out alot more!

PS I strongly suspect it is the coil or wiring to the coil, so I would check that first for sure.

 

[73Satellite]

cylinder sparks, I have compression, I have fuel, what else?

 

[maim]

let that cylinder sit overnight with the plug out. this will allow the gas in the cylinder/exh to evaporate. i have seen with cars and trucks (snow blowers too) that if it floods badly enough the oil needs to be replaced as well. just some food for thought.

 

[73Satellite]

thanks for the ideas.

I took it for a ride yestserday and it seems that when I open the throttle enough expecially wide open the cylinder kicks in and I have all sorts of power and can lift the skis. However when I return the throttle to less than 3/4-1/2 it bogs again and sounds like it runs on three.

Is the a fuel problem? and how do I fix it? Carb clean or ???

 

[kinger]

That is definitly a carb problem, the pilot jet is plugged on that cylinder. Why did you say it was not firing if it had spark? Could have narrowed it down right away for you. Anyway godo luck!