Running on one cylinder. Geting spark + gas ?????

[yamaha125cc]

I have a 1998 zr 500 and its running on one cylinder. The spark plugs work and have good spark. Spark will jump 2 inches. Pull the plug out and its wet but if i feel the exshaut it hot on the left but cold on the right cylinder. So the left side is not running.

If the sled is running and i pull the plug on the right it stays running but if i pull the left it shuts off. But the right is getting spark even tho it dosent fire.

I have no clue what the problem is?? The only thing i can think is its not getting enoff gas? Idk

Unless its the coil? or cdi? but why would one side work and not the other, but it cant be the coil cuz it has spark. idk

Any sugestions? Thanks
Has anyone had a similar problem and how could i fix it. thanks

 

[dirtball08]

I would do a compression test on that cylinder. You don't want more than 10 psi difference between cylinders. Could be bad piston rings, or a bad piston. Good luck.

 

[barleyfarmer]

If the plug is wet on the side that isn't firing it could be a stuck choke cable or you dropped a cylinder.Check your compression.If you don't have a tester just pull your plugs and put your thumb over the plug hole and have someone pull the rope and you'll be able to tell if your down on compression by the air blowing out!Not scientific but it get you pointed in the right direction!!Oh and a heads up some guys on here are real dicks when you ask for advice!They can get quite nasty so just ignore them!Good luck!

 

[kimrick]

Sounds exactly like mine. All the same symptons.

Put my thumb over cylinder and no compression.

Yup, either rings or piston gone.

 

[yamaha125cc]

Well i put my fringer over the whole and my dad pulled it and its blows my finger right off. Dont have a tester but il borrow my uncles and find out. I did it 2 weeks ago and it was 135 and 132. But i just went for a nice long ride on lake superior and its was running great. Then went out today and now this.
btw thanks guys!

 

[barleyfarmer]

Take your carbs apart and clean them.Might be a stuck float or some crap in them.Check your choke cable operation,you might have a broke cable or stuck plunger.

 

[retiredpop]

I'm not familiar with those sleds but can you swap the carbs just to prove or are they rack style?

 

[KORE]

Ok just went thru this! On the side that isn't firing grab a 12mm wrench and undo the carb choke. Just follow the choke cable back to the carb and take out the brass fitting at the end of the cable. You should be able to pick it right out. On the end of the cable is a brass fitting called the plunger it may be seized If not clean it up with emery put it back together. Let us know if this worked.

 

[yamaha125cc]

Ok just went thru this! On the side that isn't firing grab a 12mm wrench and undo the carb choke. Just follow the choke cable back to the carb and take out the brass fitting at the end of the cable. You should be able to pick it right out. On the end of the cable is a brass fitting called the plunger it may be seized If not clean it up with emery put it back together. Let us know if this worked.

Il check tomorrow and let you know thanks

 

[yamaha125cc]

KK well i pulled out the carb and ... clean no durt anywhere. so i finshed cleaaning it and reinstalled it and it is working fine now. Running on both cyilenders everthing is a okay.

Kore I seen the little copper piece you are talking about but it would come off with out me braking it. So i left it alone and its works fine now.

Must of beena small piece of dirt in one of the holes and it just blew out.

Thanks guy for all your help.

 

[KORE]

Sounds like it might be seized in. If you were able to turn the fitting out but not pull the cable and plunger out then I would say that it is the case. However if it runs then ride on!!