Okay guys been having some running problems with my 250 as of late. First major problem I am noticiing is this winter in the cold she is having some trouble starting. It really began happening 2 weeks ago when I took her out of my shed and put her outside for 2 hours. When I went back to start her it refused to start. Put it back in my warm shed started but, lead to barly idling and I have turned the idle up. Kinda seems like choke isn't working but it is. I'm not sure whats up with that. Secondly, when I do have it running it tends to backfire compression. Is that some type of fuel problem? Possibly water in the gas causing it to run horrible all together? I am kind of at a loss for words as I do'nt really know where to go or how to explain any clearer. I would like to try to resolve this issue on my own without bringing her to the dealer for like the 50th time.
THX
Stealth

 

Hi Some thing to try before you go to the dealer
1st change spark plug
2. if gas is older then 3 monthes drain and refill with high octane
3. make sure air filter is clean
4. if the choke cable broke in closed or on position the unit will start but run bad when warm if it broke in open or off position it may not start, remove air filter and hold your hand with rag over the carb inlet to get it started
5. make sure your gas tank vent line is open just blow in it backwards
6. these small batterys dont last as long as a larger car like battery make sure it has a good charge only use a small 1 to 2 amp. charger, larger can warp the plates and you will have a junk battery.

I am from WI and I do hear about choke cables freezing up it works good while in heated storage area but when you get out in the cold the water in the cable will do 2 things you can ot get the choke on or eles the cable will not let the choke go off to get this issue behind you you just remove handle bar cable end and lubracate the cable. Good Luck

 

Backfiring while slowing using engine compression is a sign of too rich a fuel mixture. Caused by? 1.)Choke stuck on, cable broke or frozen. Does the lever move normally? 2.) Drop in idle speed can be caused by too rich a fuel mixture. Caused by? Usually a dirty air filter (clean it) or a change in float setting height or a float needle not seating properly (pull carb and check). 3.)Bad fuel is a possiblity for the poor running and hard starting. How long did the bike sit between last fill up and now? If it is a water problem, get some fuel dry but make sure it is "Isopropl Alcohol" type drier and add it to tank. Problem should clear out in 5 to 10 minutes of running. You can check for too rich a fuel mixture by pulling the spark plug and looking at it. If it is black and sooty looking, to rich a fuel mixture. You can alway take the air filter off and see if it starts and runs better. I suspect a combination of things. Like degraded gas quality, dirty air filter or maybe the choke is dirty and not closing all the way. Oh yeah, what year Cat are we talking about?

 

WEll fuel should be okay bout 2wks old, plug I have just gotta put it in. I am thinkin the carb is coming off so I can see if the jets are clogged or anything like that. Just check the choke cable that is workin fine so, its not stuck. I will try some of the other things you said. It just weird with the backfiring of compression, it bewilders me as to how it can suddenly start doing that.

Stealth

 

One other thing to check is valve clearance. 250"s and 300's seem to need the valves adjusted more than the other models. This can help your idle and starting problems, also the backfire problem.

 

ITs a 2000 Cat. I am very familiar with valve adjustments done about 10 of them alrdy its ridiculous. Dealer finally tore the top end down a year and half ago to find out that my 250 was one of the ones on that recall back in 2000 on cetain batches of the 250s, and 300s. Problem was the valves were made with the wrong material they were too soft and warped real quick. AC replaced valves, piston rings, gaskets everything under warranty about a year and half ago.

 

Valve adjustment will not cause this problem that he discribes as it came on to quick. It is most likely a fuel problem. It's strange but my 2001 AC250 have well over a year on the valve adjustment and it didn't need it then.

 

Well I will be messing with the 250 sometime today. Gona pull the carb clean it and then put some dry gas into her. Air filter looked fine yesterday when i pulled the filter. I'll see what happens after I do the other things. I will also throw a new spark plug in and see what happens. While I do have the carb apart I was thinking of rejetting what is a good jet kit for the 250's carb.