Urgent help!!! Drz400

[11jakey]

Thanks for replying.

So you'd say fuel?,
Cause I'm stuck whether it's fuel or coil or regulator etc.
I cleaned the jets with brake cleaner and blew them through. I checked the float valve and it moved free with the float.
I am not sure how to check the vent on my tank cap? It has a key lock?
I have only been on the road so far haven't had a chance for green lanes yet. So no water and it has been running great previously then all of a sudden it cut out and would occasionally start up and run great for 10min then splutter and cut out and wouldn't start. Now it won't go atall.

Yes the carb was a right pain in the a****!!! What's the best way to remove it? Cause my way was awful.
I shall check the vent tubes this week on carb, the one off the top? And one going into the airbox?

Whatver the problem is, it started at a splutter and ended as it cut out. Compression great. Timing great. Spark there is one? Perhaps coil isn't giving a good enough one? Air is fine.

Only advise on how to clear the vent on fuel cap would be great! As I'm not sure how to test.

[11jakey]

It won't even run with the fuel cap removed.

[Larry]

Do you mean it now won't start at all with the fuel cap removed, or it will run for a while and then die?

Agree with BYT, sounds like fuel starvation. Is there a kink in the hose btw the tank & the carb? Is the fuel tap FULLY open? (It sounds like fuel is reaching the carb, but too slowly, eventually the fuel level in the carb drops and the bike dies. When you leave it a bit, the fuel has time to flow into the carb & fill it again.)

(The hiss def does sound like the breather hose is blocked though so funny it won't work with the cap open.)

[kentWR]

You do have the vacum line hooked back to the petcock don't you?


Have you checked the oil level?
Stator coil resistance were within the range?
Valve clearence were all within those stated in the sevice manual?
Compression test which service manual states should be 135psi what was your reading if you have checked this?

re carb removal. I have found that if you take the upper and lower subframe bolts out and pry the subframe back then slide the upper bolt back in the frame it holds the subframe back enough to give a little more wiggle room

[Dave]

Compression tests and stators? are we at that stage now? Damn things must be grim!

I bet he hasn't flushed the fuel system yet :/

If you think it's electrical:
You can do a spark gap test which will be a pretty solid way of measuring how good the components are which contribute to the spark.

Spark gap test is NOT the test of using a feeler gauge to measure the gap on the plug, it's testing how far the spark can arc.

Do that.

But like the majority i think its a fuelling issue. Did you drain the tank yet and flush it out? Could be filled with debris or water in the bottom.

You said early on that you were getting pops or afterfires?

That's a big clue for bad fuel mix.

Afterfires can be from lean or rich mixtures. Normally I get them just before I need to switch to reserve.

If your spark plug isn't looking fouled I'd say there's a lack of fuel making it to the cylinder.

[11jakey]

Thanks for your replies,

Battery charging is perfect, valves fine, spark fine, air fine, vacuum fine, fuel seems fine? when it does run occassionaly when left for ages and ages, it runs spot on! thats the weird thing, then it will just cut out after 15min or so, i had a mechanic look at it last night but he couldn't be long so he didnt wait long enough for it to cut out and not start again, it is un rideable! it needs to be running to the point i know its reliable for the green lanes!

I have changed the fuel and put fresh in, although i only just filled it up, yeh i got pops and spluttering etc..

even with fuel cap removed it doesnt make any difference,

im lost! so the mechanic is getting it on Saturday and will have it for the week and leave it running at the workshop til it cuts out then he will go investigate the problem! hopefully fix it.

[Dave]

Great, let us know the result!

[Beerbelly]

I had this on one of my scooters... Crap in the fuel pet cock - drain fuel and check it. Drove me nuts for a week till I checked that last bit!!!

[Billy]

Easy fix, a gallon of fresh petrol,a box of matches then buy a KTM with the insurance payout....................

[Dave]

Yeah it's defo worth looking at the whole system. It's like when you think your PC is broken but you just forgot to flip the switch at the wall :/

[kentWR]

Yeah it's defo worth looking at the whole system. It's like when you think your PC is broken but you just forgot to flip the switch at the wall :/

That's different. That's called old age!