KDX200 hard to start/not running

[CarsonMcI]

Hey guys, so I'm new to two strokes but I just got a kdx200 and the only way I'm able to start it is to kick it with the throttle open just a smidge and even then it takes 10-15 kicks. Once it's running it revs nice and is responsive but when you put it in gear and let out the clutch it just doesn't want to take any gas and bogs and dies. I've cleaned the entire carb and the jets and made sure the floats were set to spec with a caliper and I've also tried a brand new carb as well as a new spark plug and none of this has helped. I have followed carb tuning tutorials as far as adjusting the needle jet as well as the air screw and throttle screw and none of it seems to make a difference in starting it or it running. I'm kinda stumped here and any help would be appreciated! thank you

[kdxsully]

Low compression can make it hard to start.

[bufftester]

Being a 2 stroke, you have to open the throttle to start it, just the way 2Ts are. As for the carb adjustment, lots of folks skip right over the first part...make sure everything is mechanically sound with your motor. That means inspecting all the rubber boots between the airbox/carb/motor for leaks and cracks. Ensuring you have good compression, leakdown to check crank seals, fresh gas/oil/plugs/clean filter/muffler packing (if required). Once you've done that then you're ready to clean the carb and run through the tuning.

[KDXGarage]

If you just got it, did you have a test start and ride before buying? How was it then?

Check compression, air filter, reeds, etc.

I am guessing fuel or air issue.

bufftester, my KX250 and YZ250 will start with the choke on and no throttle. When I have had to touch the throttle, it meant old fuel, dirty carb or something small. Cracking it does help, though.

[doakley]

FWIW, I've developed a cold cranking method that appears to work well for my 220. Open fuel valve for 2-3 sec, close. Open choke, open throttle about half then release back to closed position. Then and ONLY then, kick it quickly in succession. Usually fires on kicks 2-4. Turn the gas back on and after 10 sec or so +/- depending on outside temp, push the choke back down. Thirdgenxli beats me with a stick if I rev the bike while it is cold so I just let it sit and happily idle away while I get ready. ;) After this, the bike cranks on 1 or maybe even 1/2 kick. I've had a lot of cold cranking problems and this system seems to work for my bike. YMMV

[kdxsully]

FWIW, I've developed a cold cranking method that appears to work well for my 220. Open fuel valve for 2-3 sec, close. Open choke, open throttle about half then release back to closed position. Then and ONLY then, kick it quickly in succession. Usually fires on kicks 2-4. Turn the gas back on and after 10 sec or so +/- depending on outside temp, push the choke back down. Thirdgenxli beats me with a stick if I rev the bike while it is cold so I just let it sit and happily idle away while I get ready. ;) After this, the bike cranks on 1 or maybe even 1/2 kick. I've had a lot of cold cranking problems and this system seems to work for my bike. YMMV

Haha that’s complicated

[doakley]

Maybe, but it beats the hell out of ether.

[bufftester]

On mine I turn on the gas, pull the choke up, crack the throttle, and its always running by the third kick. Once warm a half hearted stab will start it, or barely rolling and a bump start. My big point was that he needs to make sure the bike is sound mecahnically or he's going to chase his tail, get frustrated, and move to an orange bike, and none of us wants that lol

[CarsonMcI]

so it supposedly had a new top end when I bought it and you can tell from the new gaskets poking out from the sides. and the guy I bought it from said it just needed carb work so I got a good deal bc it didn't run. I don't have a compression tester but I did check the reeds and looked for cracks in the rubber spots as well as checked the air filter. All seemed really good and brand new looking. Reeds had no gaps or tears. I'll have to rent a compression gauge to check the compression. would low compression mean it would rev fine but kill itself if it's trying to run in gear? Thank you guys for replying!

[KDXGarage]

Biggest lie on used dirt bikes is "fresh top end".

Did he hand you the receipts?

Take the pipe off and look inside the cylinder. Go move the kickstarter a little and look, then repeat until you can see the cylinder wall / top of the piston, etc.

Which brand new card did you try??

Which spark plug model?

Be sure all the electrical connections are dry and secure.

[kdxsully]

so it supposedly had a new top end when I bought it and you can tell from the new gaskets poking out from the sides. and the guy I bought it from said it just needed carb work so I got a good deal bc it didn't run. I don't have a compression tester but I did check the reeds and looked for cracks in the rubber spots as well as checked the air filter. All seemed really good and brand new looking. Reeds had no gaps or tears. I'll have to rent a compression gauge to check the compression. would low compression mean it would rev fine but kill itself if it's trying to run in gear? Thank you guys for replying!

That kinda sounds like a jetting issue if you ask me

[bufftester]

I agree, but you want to take care of the big stuff first. And when you clean the carb you need to note the jet sizes for the pilot and main, those numbers are important to this discussion. What level did you set the floats too? 16mm is OEM, but most find that 18mm works a bit better in general.
If it was running before the PO did the top end, then it should be running after, no carb work needed. When you adjusted the air screw did it make a difference in the idle speed? That's the first step. The jetting guide in my signature is easy, as long as you only change one thing at a time and don't skip around.

[CarsonMcI]

I agree, but you want to take care of the big stuff first. And when you clean the carb you need to note the jet sizes for the pilot and main, those numbers are important to this discussion. What level did you set the floats too? 16mm is OEM, but most find that 18mm works a bit better in general.
If it was running before the PO did the top end, then it should be running after, no carb work needed. When you adjusted the air screw did it make a difference in the idle speed? That's the first step. The jetting guide in my signature is easy, as long as you only change one thing at a time and don't skip around.

The air screw didn't change anything on how it idled, I have to keep throttle slightly open to keep it running if I let go of the gas it dies. I did set the floats to 17mm and I'll have to look at the numbers on the jets when I take the carb apart again.

[CarsonMcI]

Biggest lie on used dirt bikes is "fresh top end".

Did he hand you the receipts?

Take the pipe off and look inside the cylinder. Go move the kickstarter a little and look, then repeat until you can see the cylinder wall / top of the piston, etc.

Which brand new card did you try??

Which spark plug model?

Be sure all the electrical connections are dry and secure.

nope no receipts, just took his word by looking at fresh looking gaskets on the engine. I put on a Keihin carb. I did get a look at the piston when i took out the reeds to check them

[kdxsully]

Well, that piston doesn’t look new. You have the spark plug in? I struggled to cycle my engine with one hand like that with the plug in. You might need a top end if that’s the case

[rungrandpa]

Compression test is needed.

[rungrandpa]

I think compression test is needed. Mine measured 145 psi which wasn't bad. I put a new piston in and it runs and starts better.

[CarsonMcI]

So I did a compression test and I got between 95 and 100, this was cold because I couldn't start the bike to warm it up lol. 100 is obviously less than 145 so could that be my problem?

[CarsonMcI]

Well, that piston doesn’t look new. You have the spark plug in? I struggled to cycle my engine with one hand like that with the plug in. You might need a top end if that’s the case

yeah plug was in haha

[kdxsully]

Well, that piston doesn’t look new. You have the spark plug in? I struggled to cycle my engine with one hand like that with the plug in. You might need a top end if that’s the case

yeah plug was in haha

I think it's a lot easier to push start a bike with low compression. Try that and see if it's easier to start. If it still doesn't start pull the head and see what the cylinder looks like. That piston looked scuffed up. You might need rings at the very least. 100 psi is technically in spec I think, but barely.