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KTM 300 EXC 2000 (Carb setup?)

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Hey folks. We're currently having a hard time getting a friends KTM 300EXC to run. Unfortunately its on of the older ones (2000) where we couldn't find a manual (yet)... I've got one fomr KTM (in CD-form) that SHOULD include this bike, but only the forks were covered my friend told me.

 

Facts:

The bike wasn't ridden much at all, maybe 30 hours or so, but spend quite a lot time standing in a garage without beeing used for 8 years maybe...

High quality fuel was used, with a mix of 1:40 initially, then switching to a 1:50mix.

Initial tests looked okay (starting after kicking just a few times) but the first time out on the track was quite frustrating.

It seemed to start ok, but after 5minutes (slow pace) riding the carb started to drain fuel. My friend also described it's characteristics to be kinda lame (response, power). Bogged out a few times...After resatrting it again and giving it some revvs and some riding it at least stopped draining fuel. I then checked Mixture srew (wasn't much difference to tell, but would die with mixture screw all the way in, left it a 2 turns out) and raised idle just a bit.

Second ride was quite enjoyable then. Maybe 45minutes of slow pace enduro riding.

The third ride wasn't gonna happen since we weren't able to start the bike again at all. Nothing worked.

We checked the spark plug (kinda black, not not too oily) and checked for a spark. At first there was none. We cleaned the plug and rechecked. Spark was there. We tried to restart it again but it wouldn't. Once there were maybe 5-7 cycles that sounded like it acually fired and would pick up revvs but it died out.

 

Carb was cleaned today and it still won't start.

Main:175

Pilot: 45

 

testing at about 1000feet above sea, at abou 77F (~300m/25°C)

 

 

Have you any Cab setup recommendations for this particular bike, or any other things we missed to check?

Fuel lines seem to be ok, as noticed by the amount of fuel the carb drained when riding for the first time.

Spark is there, but maybe somethings not right with the cables or killswitch?

 

what else could be wrong? Intake diaphragms? piston, ring?

 

 

Unfortunately I heaven't ridden...or wasn't able... to ride the bike myself. I pretty much only helped kicking. The rider (my friend) also never really rode 2 strokes before... I'm not sure how much riding style would play a role but I suspect him to shift ealy and not revving really hard.... but on the other hand... its a 300, you know ^^

 

 

thanks in advance

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You're a good friend to help your buddy work on his bike, even kick it over, when he won't let you ride it.  

 

Not clear if you changed the spark plug.  That would be my first step.  Plug could be fouled even if it sparks when it's out of the bike.

 

Another common problem with a bike that's been sitting for a long time is the pilot get could be plugged.  You should take off the carb, remove the float bowl and carfully clean everything.  If the pilot jet is clogged (can't see light through the opening). Replace it.

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funny thing is the spark plug was new... fresh out of the box.. today he ultrasonic-cleaned the carb and tried again endless times... even funnier was that he switched to the old plug, let me kick the bike and it came alive after the second attempt... not sure if its me who is used to "kick 2strokes" or the plug... after riding to warm it up we tried the new plug again and it ran fine too. So lets hope it was the combination of a dirty carb and somone who isn't used to kick 2strokes... however I kinda doubt this was the end of the story... He just did some high rpm up'n'down the street riding...

 

But everything else aside, jet sizes seem ok to you?

...and 1:50 oil/fuel mix should be fine? or even a tad leaner?

 

 

And I will ride this lady fo sure somewhen in the future, but you know... its all new to my buddy and I don't want to be the one having more fun with his new toys than he does ;-P

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Im at about 1k feet above sea level and in my 2001 300 I was running a 168 main 38 pilot and the clip in the top position on the stock needle. my bike was still rich. I have put in a 165 main 35 pilot and a necj needle on the middle clip. It seems to rev better but I have not been able to ride it. I would think with a 40 pilot your bike is very rich on the bottom. Hope this helps. Im no 300 expert this is just what Ive done to mine.

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Just take a drive to Mattighofen and ask "Was ist loß?

 

haha, we could do that. we also could contact the local KTM dealer. But we like to solve these kinda problems on our own. Of course we will if we don't make any progress in the near future, but since that bike wasn't ridden for so long it might take a bit of breaking in again...

 

 

Im at about 1k feet above sea level and in my 2001 300 I was running a 168 main 38 pilot and the clip in the top position on the stock needle. my bike was still rich. I have put in a 165 main 35 pilot and a necj needle on the middle clip. It seems to rev better but I have not been able to ride it. I would think with a 40 pilot your bike is very rich on the bottom. Hope this helps. Im no 300 expert this is just what Ive done to mine.

 

thanks for that info. I kinda suspect the pilot circuit to be on the rich side but I didn't wanted to be too fast with that judgement.

On the other hand I had a 125SC that was probably set up too rich too. With me riding it I had no problems since I rode it in the meat of the RPM range, however a friend of mine who was totally new to MX constantly bogged it out with his passive riding style. We were only able to start the bike after cleaning the spark plug several times. Riding the same bike myself a week after was no problem at all.

 

 

ALSO, he (the 300 owner) talked about having found a fair amount of oil (2stroke mixture oil) inside the airbox (between filter and cab) after we were rinding. Can this be caused by excessive starting attempts, is something with the carb not right, or ist this maybe even an indicator for worn diaphragms? However this occoured before he supersonic cleaned the carb, so not sure if that plays a role anymore...

 

 

EDIT: another qeustion that came to my mind regarding to carb setup: is the bike supposed to die out when turning the mixture screw fully in, or should only a (slight) change in idle RPM occour? (warmed up)

Edited by impact125

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youtube slavens racing he has a video of a ktm 300 pilot circuit that will help explain the pilot and some about the air screw. I rode my ride today just around the yard not sure if the I'm going to be a bit lean on the pilot or not. Ill have to get it out and actually ride it to be sure. Not sure about the oil in the carb boot. It maybe from trying to start it. 

If your friend is lugging the bike run a synthetic oil (i use amsoil) at 50:1. The guy I got my bike from kept fouling plugs and was running that ktm motoex oil. I read somewhere that its a great oil if your running the bike hard but will gum up the power valve and exhaust if your not on the pipe a lot.  hope some of this helps.

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Oil pooling in the airboot is normal.  Just wipe it out once in a while when you clean the filter.  Yes, it should die when the airscrew is turned all the way in, assuming the idle isn't set too high.  Sounds like it starts and runs so you can work your way towards getting it jetted properly.  

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Thanks to you both! Your post are containing some helpful stuff!

I finally found the manual (3seconds of googleing :rolleyes: ...nevermind ) and the jet sizes seem to about right, but from what I heard/read so far KTM jetting tend to be on the rich side most of the time... but at least we can't be that far off...

We'll see... further test riding will be done today.... hopefully

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