Two-stroke question

[marks]

my DT230 has developed a problem over the last 1000k or so.

Its blowing lots of smoke and running 'fluffy' on the overun like the plugs fouling partially on deceleration. For the first time ever it fouled its (new) plug on a hillclimb on Saturday (I was lugging the shit out of it) - the plug was dripping wet. When the throttle is open it runs as well as it always has although fuel economy is marginally worse

I have:
put a new plug in
cleaned the airfilter
checked the oil pump setting
I'm using the same 'injection specific' spectro 2 stroke oil I always have.

Its either running too rich or burning too much oil - I don't know enough to tell which. If I had muck in the carb wouldn't it run lean? How do you check the float level - could that be it?

any help appreciated as I'm out of my depth here

cheers


Mark

[babysteps]

Have you played around with the Jets?

[NordieBoy]

Worn main jet?
Worn needle jet?
Float level too high?
Split o-ring in carb?

[Bass]

I presume it has a variable displacement oil pump linked to the throttle in some way?
Is there any possiblity that the oil pump control linkage has jammed somehow so that the oil pump is on full output all the time?? The hangup could be inside the pump.

I think that the fuel level in the carby would have to change a great deal to produce the symptoms that you mention. Still...take the float and the float needle out. Check that there is no fuel in the float, i.e. that it has no leaks. Clean out (compressed air is good) the incoming fuel passage above the needle. Given the age of the machine, there should be no need for anything else.

[kevfromcoro]

Crankshaft seals???????????

[PeteJ]

Mark, I suggest you start with basics and move up from there. Yes, the seals could be on the way out, but do the carburetion -oil pump - mechanical progression first.

1. Can you tell if the wet on the plug is fuel or oil? If you can, that'll point you in one direction or the other.

2. Fuel: check the float level, as has been suggested. Also check that the carb is not leaking fuel into the crankcase when the machine is not running (ie fuel tap problem. Your symptoms are typical of that.)

3. Oil - the oil pump setting, as has also been suggested.

4. Unsure if fuel or oil: (a) replace the air cleaner element, whether or not it looks clean. They don't cost a lot. (b) disassemble the carb (they're not all that difficult if you put the bits, in order of disassembly, on a white sheet on your workbench). Check for noticeable wear and buy replacements as necessary.

4. It could be that you are running a spark plug that is too cold for the riding you're doing.

5. None of the above: take it to a bike mechanic. It will save you time and money. Don't ask how I know.

Cheers

Pete

[Eddieb]

Not that a know squat about 2-strokes in terms of what to look for but from your symptoms I'd go with Bass's reply.

You mention fuel economy is only affected marginally. I would expect economy to be affected significantly if it was overfuelling enough to blow smoke, yet only a small amount of excess oil will cause smoke.

I'd also expect performance to be affected if it was overfuelling but you comment it runs as well as ever while on the gas.

[XF650]

How many km's has your 230 done Mark?

[Bass]

You mention fuel economy is only affected marginally. I would expect economy to be affected significantly if it was overfuelling enough to blow smoke, yet only a small amount of excess oil will cause smoke.

I'd also expect performance to be affected if it was overfuelling but you comment it runs as well as ever while on the gas.

Got it in one!!! The tolerances on those injection pumps are so fine that the least little bit of crap can upset them.

It's radical but Mark can verify this for sure by draining the oil tank and running it on pre-mix.

[warewolf]

Tried the Off Road forum? Many more 2t experiences over there.

Oil injection systems can be problematic, such than many ppl disable them and use premix. Could you do this as a test, to see if it is a carb/fueling problem, or an oil injection system issue? Don't know how easy or plausible this would be on your DT.

[marks]

How many km's has your 230 done Mark?

about 12000k I think

Thanks everyone for the input

I'll work through the suggestions and let you all know what happens

[MXNUT]

Another thing that nobody has mentioned is the rear muffler packing getting so soaked in 2 stroke oil it is not letting the engine breath properly.
Remove the rear muffler ( and any plastic side covers necessary ) and go for a good run up the road and see if the smoke starts to decrease.

Also remove the expansion chamber and check that the exhaust port in the cylinder does not have a large carbon buld up which will decrease exhaust flow.

[junkmanjoe]

sell it, while its still going.....

[Motu]

Mine had done 25,000km before it developed any problems.It was the left crank seal that went....and I didn't pick up on the symptoms before the mains went.It effected carburation only on cruise,it ran like shit then,but perfect under acceleration.It could lead to a lean condition....but will go oil rich as it pumps in the same amount.Pull the left cover off - you won't be able to see the seal because of the flywheel and starter.I'd run it and spray in carb or brake cleaner and see if that effects the running.

It could be the muffler too,although mine was untouched....and they don't come apart for cleaning and repacking.

[marks]

sell it, while its still going.....

that's a serious possibility

in the current environment I don't know that I can justify keeping 3 bikes maintained and running and my younger son has only ridden it twice this year.

I'd fix it first though