1997 model (situated in a KTM Sting) DT125 engine, with powervalve, and a DellOrto carb (all is OEM/standard, only garages has been servicing until I got it): As long as Ive had this bike (couple of years), it has been hard to start from cold: Battery OK, startermotor runs fast and nice. Emergency shutoff-button is fine. Carburettor has been dismantled and cleaned. Dont have thorough workshop manual for the carburettor, but AFAIK it looks fine. Idle and mix screw is both adjusted as spec'd. As soon as it starts, it runs as it should. RPM is about 2.500-3000 when on full choke, and it needs the choke for a few minutes. The choke seems to work fine, at least the engine need choke to run OK when cold, and will cut out if I use it on hot engine. Spark plug should be correct spec, and is almost new. Looks dark brownish after a ride. Its restricted to 13 HP (exhaust, and possibly CDI), and is quick as 13 HP can be Very little is done with this engine since it was new, and now its 25.000KM / 15.500Miles. Could it be the reed valve/blades? The intake flange is rubber, will this leak? It looks pretty OK, but have not checked thorough. Any typical faults on these engines I should look for?
Thanks for quick reply. Yea, maybe the rings are worn. I just had the head off, and didnt check thorougly, but I made myself a promise to get a overhaul with a new piston, top bearing, rings, and get the sylinder "honed" (is that a correct word?) No test, I domnt have the equipment here. But I guess it should be easy to reveal when driving? Cause the bike is running nice. I have OEM sprockets (13/48), and gets 75 Mph quite easy, and 80Mph if I can wait some seconds, and it accelerates nice from 50 to 75Mph. Well, at least better than what I expected 13 HPs should do What seals do you mean when you say crankshaft? Do you mean cylinder and cylinder head gaskets? Just changed those, and are pretty sure they are perfect now. Anyway, it is no change in cold starting. Yes, it might be a bit rich. I mate has borrowedd my "colortune" tool, I give him a call to get it back so I can do a better adjustment of the carburettor
What about the reed valve/blades?
BTW it starts at once, if I use start-gas. And it starts pretty OK if its less than 1 day since last time I used it. The big trouble gets when it has been still for a week or more...
Tonight it is cold enough to make trouble: -5°C, and more than 24 hour since last run. Full choke, throttle full on-off 5-6 times, then no throttle, started after 2 seconds! So, maybe the trick is to turn the throttle on-off some times before I try to start. I also turned off the choke just after starting, holding the rpm manually at 2-3.000 for a minute, and then the idle where low but steady, and only limited amount of smoke. Hmm, I might have found the trick
