[ridenski]

97 zrt 600. It ran great all last year. Then a lost it side hilling in the spring corn snow and the machine slid directly into a large fir tree. Hood damaged and left header bent in half (completely blocked.) I had to make it up a steep hill to get out (nobody could tow it) So, I took off the header and tried starting it. To my surprise, it ran and had power. I only ran it for 5 minutes and it was running well but loud. Then it sat all summer and fall. After cleaning the carbs and emptying the gas tank. It will now start on the first pull just like it used to but it has no power. It will only go up to about 7100 rpm. I replace the fuel filter and check all the slides of the carbs to see if they are opening all the way. They are. I used an inline spark test on each cylinder and the light remains on. (no flashing.) I used a compression test made by yamaha and I think I did it right but I am not sure? here is what I did: I wired the throttle open and took out all the plugs. Then I put the tester in each cylinder and pulled about 5 times. This is what I got. PTO cylinder is 100psi. The middle and right one are about 85 psi. What's going on here and what do I need to do next?

 

[badcat33]

put some oil in the cylinders and try again if it comes up a lot its the rings

 

[rjhoop1]

97 zrt 600. It ran great all last year. Then a lost it side hilling in the spring corn snow and the machine slid directly into a large fir tree. Hood damaged and left header bent in half (completely blocked.) I had to make it up a steep hill to get out (nobody could tow it) So, I took off the header and tried starting it. To my surprise, it ran and had power. I only ran it for 5 minutes and it was running well but loud. Then it sat all summer and fall. After cleaning the carbs and emptying the gas tank. It will now start on the first pull just like it used to but it has no power. It will only go up to about 7100 rpm. I replace the fuel filter and check all the slides of the carbs to see if they are opening all the way. They are. I used an inline spark test on each cylinder and the light remains on. (no flashing.) I used a compression test made by yamaha and I think I did it right but I am not sure? here is what I did: I wired the throttle open and took out all the plugs. Then I put the tester in each cylinder and pulled about 5 times. This is what I got. PTO cylinder is 100psi. The middle and right one are about 85 psi. What's going on here and what do I need to do next?

Shifted your motor and binding the clutch now?I dunno

 

[pyro1955]

Running a two stroke without your exhaust is not a good idea, sounds like you may have smoked your rings at a minimum. No backpressure equals very lean burn... Hope I'm wrong for your sake.

 

[ridenski]

Running a two stroke without your exhaust is not a good idea, sounds like you may have smoked your rings at a minimum. No backpressure equals very lean burn... Hope I'm wrong for your sake.

I have thought of that. I have determined the problem is that that cylinder (the one I ran without exhaust for a few minutes) is the one that is not firing. I can see spark when I ground a plug or use a inline spark tester. I have cleaned the carbs 3 times and even switched carbs and yet the cylinder is much cooler than the other two and the spark plug still looks new. You can touch the pipe.
But when I do a compression test, I get like a 100 lbs and it leaks down very slowly over a few hours. This cylinder actually has MORE compression than the other two. I just don't get it. Any one: Please tell me what is wrong here?

 

[ridenski]

Shifted your motor and binding the clutch now?I dunno

No, that is not it. One cylinder is not firing even though it has spark and is getting fuel.

 

[jrinhof79]

Check the choke plungers, on my zr500, it says that if one cylinder is dead at idle, the choke is possibly stuck. Thats what mine was doing, and if I gave it throttle it would bog and than come to life, let it back to idle and you could here when the cylinder had "shut down". Ended up taking some 0000 steel wool to the brass plungers and all is good now.

 

[ridenski]

Check the choke plungers, on my zr500, it says that if one cylinder is dead at idle, the choke is possibly stuck. Thats what mine was doing, and if I gave it throttle it would bog and than come to life, let it back to idle and you could here when the cylinder had "shut down". Ended up taking some 0000 steel wool to the brass plungers and all is good now.

I don't know... I have tried two different carburetors. Even when it is running, it only goes about to 7000 rpm and it should be at least 1000 more. I'm thinking I damaged the rings/ piston/ cylinder some how.

 

[clintonior13]

sounds like you need a new pipe , hood and set of SPI pistons my guess is with new pistons you'll be looking at 135psi on all cylinders.

 

[Bubanator]

i would strongly recomend doing the top end. it sounds to me like you may have a jumper wire on the ignition coils burnt or a loose ground wire. had the same problem with my 600. make sure you have all 6 pipes on and they are all very well sealed. its not carbs. ignition, possibly a stator. i have also seen sleds with timing keys that are sheered off, bent, or misaligned do the same thing, one cyl hot, the other(s) cold.