1989 Rmx250 no start

[Shandogg0]

I have a 89 250 rmx will not kick start can push start, blue spark, took carb apart unclogged primary jet, main is 320 needle set at 4th slot. .010" air gap between flywheel & pickup coil, reed is good, woodruff key is intact, fouls plug excessively. Can anyone give me helpful advice :bang: .

 

[dirt bike dave]

Are you sure the reeds are OK?

Worn out reeds can make a two stroke nearly impossible to kick start cold. If the problem got gradually worse over time and you know the reeds are old, I would replace them even if they look OK.

Also, a worn out top end (little or no compression) will make it hard to cold start.

 

[txkawboy]

Yep and yep.
If it does not at LEAST have enough compression to make your thumb "fart", it will not even run (unless you pull it with a truck at 30mph...)LoL.
Fart Test
1. Remove spark plug
2. Hold throttle wide open with gas turned on
3. firmly place your thumb/other finger over the plug hole, completely and tightly sealing it off
4. kick the bikc over vigorously
5. the resulting compression will make your thumb "fart". Or not.

 

[Shandogg0]

comp is 140psi. a little low but should start. reeds look new. removed tank and carb. turned bike upside down, slowly cranked with plug removed, fuel came out of plug hole. reassembled, still won't start. backfires after a few kicks. I did notice that the pulser does not line up with raised portion of mag when@ TDC. is this normal? does anyone know how to time one of these things.

 

[BraapBraap214]

you said that you were getting spark so your flywheel gap is okay. The only timing on a two stroke is your flywheel position at TDC. maybe your flywheel isn't seated right? but gas seems to be more of your problem so let's explore that.
It's fouling plugs and putting excessive gas into the cylinder without starting. So your compression is fine becuase it can pull that much gas through your reeds, so go back even farther.
Your reeds could be worn but reeds don't provide gas-the carburetor does.
You cleaned your jets but is it jetted properly? (i don't think thats the issue though)
Take out your carb and take off the bowl. You need to reset your float bowl. Your float is stuck open letting all the gas from your tank run into your carb, (while modern carbs have an overflow i don't know if an 80's bike did or not.) so when you kick your bike your taking way more into your cylinder than you normally would. you're simply flooding your bike.


To reset your float bowl:
1. take off bowl,
2. put your carb upside down on your bench, table etc so that it's standing on the opening for your slide.
3. the seems on your float bowl should be PARALLEL to your work bench at this point. (or where the floot bowl seals/seats against the rest of the carb.
4. where the floats connect to the carb there is a metal flap that holds a cone shaped needle in place, you need to adjust this flap (up or down) so that it holds your float bowl parallel to the bottom of carburetor.
5. Reassemble and go riding.

I had an 86 Rm80 that had the same problem i ended up putting a lot more work into than i needed to (piston + rings, coils, new reeds) and the only problem was the float bowl was messed so check that before buying anything else.

 

[Shandogg0]

Went through carb again, changed sparkplug to manufacture spec. there was a b8es in there. i assumed it was correct one. it's running now, maybe it was a combination of both? it is running but sputters on acceleration, think i'm going to try changing needle position (give it more fuel?) before changing main jet. Any suggestions? Thank you.

 

[OriginalRider]

Went through carb again, changed sparkplug to manufacture spec. there was a b8es in there. i assumed it was correct one. it's running now, maybe it was a combination of both? it is running but sputters on acceleration, think i'm going to try changing needle position (give it more fuel?) before changing main jet. Any suggestions? Thank you.

maybe to hot of a plug to.br9 is usually what i run in my 250's but the days that im racing hard i throw the b8 in it.hotter is basically for racing if your not always in your powerband get a b9

 

[_JOE_]

maybe to hot of a plug to.br9 is usually what i run in my 250's but the days that im racing hard i throw the b8 in it.hotter is basically for racing if your not always in your powerband get a b9

This is exactly the opposite of the truth. You need a hotter plug for lower rpm riding because the engine isn't running hot enough to burn off the deposits on the plug. The hotter plug runs cleaner at lower temps. When riding wide open for extended periods a hotter plug can melt the ground strap and/or piston if the jetting is at all close to the limit.

Have you tried adjusting the air screw?

 

[BraapBraap214]

It's running now and wasn't before so i would stick to the carburetor issue. though it's not GOOD for your bike to run the wrong plug, it WILL run with the wrong plug.

is it spuddering or bogging?
If it's spuddering you need to give your bike MORE fuel, it's hesitating because it can too easily burn the gas brought into the cylinder- delaying your power. if it's bogging out and not hitting powerband you need less fuel. You can adjust these without having to rejet your carb, just adjust your needle position, if you can't fine tune-fix this problem then you need to change your main jet, then dial it in with air screw and needle.

or check your plug after you ride, it should look like charcoal and DRY. you need to
check while engine is still hot so wear gloves, but that will definitely tell you a lot about where your power is going. good luck