40 miles from a full tank!

I ride a 2001 KTM 200 exc on the trails. It's an epic bikes to ride but I've a couple of issues I can't get to the bottom of. First is the pants mpg. Now I knew a smoker wouldn't go far on a full tank but 40 miles to empty from a 10ltr tank! I've done a fair bit to this bike including a new piston, main bearings, crank seals (whilst doing a knackered out put shaft), reeds and a new pilot jet (42).I just can't seem to get any better than 40 miles tops. It pulls well and revs it's heart out. It's always been a bit lumpy on tick over and it has a tendency to foul plugs going down hill unless I pull the clutch and hold about 2000rpm.(that's the second issue).

Any ideas on where to start poking or is this a drawback of being a smoker.

I ride a 2001 KTM 200 exc on the trails. It's an epic bikes to ride but I've a couple of issues I can't get to the bottom of. First is the pants mpg. Now I knew a smoker wouldn't go far on a full tank but 40 miles to empty from a 10ltr tank! I've done a fair bit to this bike including a new piston, main bearings, crank seals (whilst doing a knackered out put shaft), reeds and a new pilot jet (42).I just can't seem to get any better than 40 miles tops. It pulls well and revs it's heart out. It's always been a bit lumpy on tick over and it has a tendency to foul plugs going down hill unless I pull the clutch and hold about 2000rpm.(that's the second issue).

Any ideas on where to start poking or is this a drawback of being a smoker.

Check the float level and fuel seat.  Sounds like fuel is leaking out the vent hoses as you ride.  Having to to hold throttle open to keep it running on downhills is another symptom of bad float level or leaking seat.

Cheers I'll have a tinker with the float levels again. The float needle seems OK as I can blow down the fuel inlet and the float needle will stop me blowing when I lift the floats. I had dropped the float level slightly as it would leak when on the stand.

Proper floats are essential. So is jetting. Spend some time adjusting each aspect of your jetting. Dont be afraid to try another adjustment when you think that your good.

Gearing can really help you too. I change CS sprockets depending on where I go. 13,14 or 15. They are $10 from Rocky Mtn and take 5 min to swap.

As well as just getting a bigger tank. I have a 4.2 IMS that allows my 300 to go over 100 miles depending on the conditions.

 

Keep workin it.

Definitely not right... I get about double those miles to my 2000 200EXC.. About 65 before I hit reserve, then another 20 or so after that...

Not sure how to help but something is up!  Good luck sorrting it out.

Had the carb apart and every thing seems clear. Float level is set quite low but not low enough to make it Rev up. Air filter is clear, air screw is out 1 1/2 turns. Took the plug out and it's black. May admit defeat and take it to a 2 smoke specialist by me. Hate it when I can't sort it myself

Had the carb apart and every thing seems clear. Float level is set quite low but not low enough to make it Rev up. Air filter is clear, air screw is out 1 1/2 turns. Took the plug out and it's black. May admit defeat and take it to a 2 smoke specialist by me. Hate it when I can't sort it myself

If you are not fouling plugs then the jetting cannot be that far off to cause the bad fuel mileage.  If you leave the tank petcock attached to the carb with the float bowl off try hold the floats up and turn the petcock on to see if fuel leaks by.  I usually put a rag under the carb on the cases while I do this.  I had a leaking seat on my 250 recently and had to take it out and clean it to get it to stop.  I have also seen a set of floats leak and fill up with fuel causing them to sink and let to much fuel in.  The carb is 12 years old possibly the plastic has worn a hole somewhere in the floats. 

Have held the floats under water for a min or two and no bubbles from them. It will foul a plug if I don't hold the clutch in and hold the throttle open going downhill. It seems to tick over on its stand OK but it would only do that for a minute while I open a gate on a trail. I get a little bit of oil in the rubber bellow after the air box after every ride but have been told this is common. The throttle repose in 1st/2nd gear is poor going onto the pipe if I open the throttle gradually. Seems like it's being choked. If I snap the throttle open it takes off like a scalded cat with the front about 3ft in the air (good fun but not what you want on a tricky hill climb). Can't think of anything else. Leaking main jet / dodgy float needle seal?

. It will foul a plug if I don't hold the clutch in and hold the throttle open going downhill.

 

You jetting is too rich or the motor has low compression.

 

 

It seems to tick over on its stand OK but it would only do that for a minute while I open a gate on a trail.

 

Your float level is too high. You need to adjust the float to close the needle lower.

Edited by v8rman

205 psi compression. No problems there (New piston). I've set the float at a lower level than KTM recommend and it doesn't start to overflow till the bike is over 45deg. May be a bad seat/needle on the float as mentioned. I'll try connection the carb with the bowl of to the tank to see how/where the fuel gets shut off as I lift the floats.

Make sure the pin that holds the float against the fuel valve and bottom of the carb is attached properly. The pin can fall out when installing the float bowl and you'll loose gas very fast

There are 2 stanchions that hold the float in place with ~1 inch pin.  Each stanchion has a hole that the pin goes in.  Sometimes the holes can get oblongated and sloppy.  When you set the float level it will look OK but the slop in the holes that the pin goes into make the float level vary when the bike is running.  If that's the problem, you can get some carb repair stuff at Napa and re-drill the hole.  I also attach a hose to the gas inlet when adjusting the float level.  I blow into the hose while tipping the carb to a 60 degree angle.  If the float level and needle/seat is correct I shouldn't be able to blow air through the hose when it gets to 60 degrees. 

When is the last time you checked the reeds?  Usually worn reeds effect bottom end throttle response and poor vacuum to keep the bike running off the bottom.  That may be why you have excessive oil in the air boot also.  Check the reeds to make sure they are sealing to the block and are not fraid.  Carbon fiber reeds do tend to fray at the edges.

 

 

I blow into the hose while tipping the carb to a 60 degree angle.

yep.

 

 

 

The throttle repose in 1st/2nd gear is poor going onto the pipe if I open the throttle gradually. Seems like it's being choked. If I snap the throttle open it takes off like a scalded cat

Sounds like your needle isnt the right one for your bike. You havent said what needle your running, or slide. This definately seems to be a basic jetting issue. These are time consuming as you should only adjust 1 thing at a time. 

So far youve told us that you have a 42 pilot with air screw at 1 1/2 turns. What needle/position and slide & main? What fuel rating? Are you sure that your air filter isnt over oiled?

Kx290. New reeds fitted last week as the old ones were frayed.

Right. Have checked the float needle and it works fine. It shuts the fuel off nicely. Have a new question about the main jet and needle. While the carb was off I put the slide and needle in place and blew lightly up the jet from the bowl. I had the idle screw turned right down and put light pressure on the slide and as I blew, air was passing. Is this a sign off a worn jet/needle or is this perfectly normal. Both look OK with no obvious marks. If it was leaking this could explain the boggy throttle response, fouling plugs. Also when I start the bike it revs it's nuts off unless I turn the idle screw right down (common issue I believe) and will have to turn the idle screw right in to get it ticking over one is warm. To my mind the leading jet could be acting like a choke as I don't need the choke on to start her up. Any thought before I invest in some new jets and needles?

Sorry tergog. Needle is noz H on top clip, main is a 180. Not sure about the slide. The fuel/oil I run is 50/1 putoline.

Kx290. New reeds fitted last week as the old ones were frayed.

Right. Have checked the float needle and it works fine. It shuts the fuel off nicely. Have a new question about the main jet and needle. While the carb was off I put the slide and needle in place and blew lightly up the jet from the bowl. I had the idle screw turned right down and put light pressure on the slide and as I blew, air was passing. Is this a sign off a worn jet/needle or is this perfectly normal. Both look OK with no obvious marks. If it was leaking this could explain the boggy throttle response, fouling plugs. Also when I start the bike it revs it's nuts off unless I turn the idle screw right down (common issue I believe) and will have to turn the idle screw right in to get it ticking over one is warm. To my mind the leading jet could be acting like a choke as I don't need the choke on to start her up. Any thought before I invest in some new jets and needles?

Missed the new reeds in your OP.  If floats and seat are good you are back to jetting.  When things go sideways on jetting for me I usually put everything back to stock for a base point and tinker with one part of the carb at a time.  In this case the new pilot,  what was in there before?  Needle did someone change it out or is it stock?    Main jet is it stock or did someone change it out?  

 

Your fuel mileage and fouling plugs is definitely a to much fuel to air ratio problem.  I have a 2012 250XC and rode 43 miles yesterday on the throttle pretty hard in quit a few sections and only burned through half of a 2.7 gallon tank.     

New jets on order. Going to use stock jetting and do a test ride next week some time. Will post when I see some results.

Interesting conversation when ordering my jets/needle. Apparently the brass receiver for the needle gets worn and will bugger up the fuel flow. This part is not a replaceable part normally but can be done by a few firms. He advised me to go for a leaner needle to compensate this, so I've ordered the I instead of the H that's fitted. If the new needle and jet doesn't cure my fuel issue, looks like I'll be sending the carb off. Fingers crossed.

We've had 3 02 200's. With the stock needle would get 40 miles, then go to reserve. Put in Sudco's DDK and hit 65 before reserve, and they run MUCH better. 45 pilot, 180 main for us.

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