I've moved away from Cat because of stuff like that. Finding 20yo parts is hard enough, but paying premium prices for them is worse. Had a headgasket go on my 01 ZR800.... 2 o-rings.... over $50. For 2 o-rings. Then parts like fuel pumps aren't available in OEM or aftermarket new, used ones selling for more than new did with no guarantee of condition... yeah....Textron/Cat killed Cats for me. Sent from my SM-G991U using Tapatalk

I had an 02 that wouldn't open all the way. I was shocked (and p!ssed) at how much that tiny thermostat was.....3x more than the OEM was in my Ford Diesel..... but it fixed the problem for me. If you don't know how old the coolant is probably a good time to change it out if you don't have a test kit. Sent from my SM-G991U using Tapatalk

The best way to check for bad valves is to find TDC at compression stroke and then wiggle the rocker arm. If there is play, the valve is good. If not, a new seat must be cut and new valve installed. I've tried dozens of times to install a new valve in an old seat, but 100% of the time I've had to continually replace that valve. It seems there is no way around cutting a new seat.

Good points! Concerning carbs, I keep some guitar wire around for cleaning jets and small holes. Chemicals don't do much. Regulators are common problems on these machines and if it runs better with the lights on, that's the problem. I bought the biggest baddest regulator Rick's Electronics sells because I fried 2 OEM ones. Rev limiters can sometimes be improved by using an older CDI, but the problem with rpms is the weak valve springs. One of the first models of these machines (250 model) had ovate springs which are super-stiff. Zuki only used them one year and I forgot which year since that was 5 years ago for me. If there are changes in the spark due to heat, then it means a coil somewhere has lost enamel due to age. That is common on the 80's models 230 quadsports that start fine when cold but are impossible when hot. Alternatively, cold starting problems could mean worn intake valve.

heres a little trick I figured out for hard starting atvs that seem to run but shut down and sputter out. If your having Backfiring through the carb, spitting gas out through the carb it maybe a bad intake valve not seating properly. To test this Pull spark plug out, move piston to TDC on compression stroke, Take some compressed air with a air nozzle in spark plug hole, make sure you can seal it to the hole so no air can escape. apply the air and listen for air escaping through the carb or the exhaust valves. that will determine if you have a bad valve. Best way to check for bad valves.

I put a 26mm roundslide from a 230 quadsport on and gravity feed tank and it runs like a champ. I spent the day seeing what all this machine will pull lol. I guess I need to find a 28mm carb somewhere. That's probably about right for this engine. This is just another reason why I hate CV carbs. Too many things to go wrong with them.