VTZ250 cutting out

[IkeKrull]

Hi there,

had a bit of an issue today - I was riding down the motorway, and the bike started losing power and cutting out - like it was running out of gas - I pulled it over to the side of the road (was so windy today i didnt want to fumble around for the reserve switch while riding), tried to fire her up again again, but nothing, switched to reserve and she was back up and running.

However, whats strange is that when i went on the kiwibiker ride over the takas, i got 200kms out of the tank and never hit reserve - the bike also never missed a beat - I filled the tank on the monday after the ride, and 95kms later, its cutting out on me on the motorway.

Now, the 200kms were all highway kms, and the 95kms were all stop-go traffic kms, with a couple of ~20km motorway trips.

But it doesnt seem right to me at all - when i went to fill it after the incident today i expected there to be almost no petrol in the tank, but it only took 5 litres before it was full again - it has a 13 litre tank so i'd expect to put at least 8-9 litres in after hitting reserve.

Anyone experienced this before? I'm a bit of a noob, so not sure what to check - it pulls pretty hard, smoothly and while it does seem to have choke issues - it backfires when the choke is right out on the overrun and the idle tends to hunt unless the choke is set 'just right', i dont think that has anything to do with the problem.

Fuel filter? what else might it be? Thanks for any help you can offer

[jeremysprite]

killswitch? that's my favourite problem.
clogged fuel lines, if you've been running crap through them. Carbs? Could need a clean.

[What?]

I hope your "choke issues" only relate to when the bike is cold / warming up. If you are fiddling with the choke at operating temperatures, a trip to a shop is in order.

As for the fuel, your bike probably has a little gauze filter on the fuel intakes inside the tank. Drain the tank, remove the petcock and remove the gauze filters (NOT the tubes). Blow backwards (with gentle compressed air) though the petcock, on both main and reserve settings to make sure it's all clean. Now put it back together and install an in-line fuel filter between the petcock and the carbs.

Another possibility - your bike may have a vacuum operated fuel shut-off valve (I don't know if it does or not, but follow the fuel line from the petcock to the carbs. If it goes via an aluminium device with another hose attached, that is the vacuum tap). If it has one, the vacuum hose may be perished or split.

[IkeKrull]

OK, that sounds like a good place to start - the bike had been sitting for some time before it was sold to me, so sediment may have blocked things up.

As for the choke, well, i give it quite a bit to fire it up when cold, then, once it has warmed up a bit and will idle solidly at 1000-1500rpm, i can back it right off and the bike will idle happily and run fine, but unless i leave the choke on a bit at all times, it will 'chuff' and backfire from the exhaust pipe really loudly on overrun - this usually manifests itself when coasting downhill with a closed throttle, or when rolling from fully closed to a little bit of throttle.

I'm thinking this may be a timing problem, but i'm not much of an expert on bikes, so my 'give her a bit of choke and that richens the mixture up enough on overrun to eliminate the problem' solution has worked for me.

If its on a bit too much, the idle is high and surges a bit (reminiscent of the vacuum leaks that affect my car from time to time), and if its not on quite enough, i get the exhaust pops. So yeah i do have to mess about with it a bit while the bike is operating, but once it is set in its sweet spot, then i leave it alone. Half the problem is that most of my riding is a short trip from home to work, and back again, so most of that trip is done with the engine being fairly cold. So i do find myself adjusting the choke at each traffic light stop to bring the idle down if it is too high.

So i wonder if it is a split or popped of vac line that is the root cause of all this... hmmm....

[limbimtimwim]

So i wonder if it is a split or popped of vac line that is the root cause of all this... hmmm....

Those bloody vacuum operated taps are stupid. They are defeatable.

[Wasp]

WAIT A SECOND, VTZ OF DOOM?!

you have Insanity_rules/my old bike? if so i know exactly whats wrong with it

[Flyingpony]

Are you trying to tell us you ride your bike 1km from home to work?


Your bike has got some issues with its fuel, air and/or spark system.

The choke should only be used to help start a cold engine. I run my bike for at least one minute before setting off and 1km down the road it gets switched off and that's it until the next cold start. Your bike should behave the same. If it doesn't, then you've got a problem somewhere.

Check your spark plugs, they might be old and worn out. Best to just replace those anyway. High air mositure could cause engines to die when their sparkplugs are worn.

Clean your air filter!

Clean your fuel system as the others have already mentioned.

[IkeKrull]

Wasp: I'm the guy with the VTZ you chatted to at the top of the takas on the way back from the KB ride on sunday - you had to follow me riding like a nana, on the way down. I reckon if it was your old bike, you would have recognised it then.

My ride from home to work is not far, basically from kingston to upper willis st. for those familiar with wellington, or about 2-3kms i guess.

Flyingpony: I generally try and give the engine some time to warm up - (my car is an turbocharged RX-7 so i have a healthy appreciation for the proper oil, water and maintenance you should give a highly-strung engine) - but the idle behaviour doesn't settle down for some time after cold start, and the more i think about it, the more i think there probably is a vac problem.

However, it cut out on me today again on the motorway, and ran quite happily on reserve again, so i think theres definitely crud in the fuel filters, irrespective of a vac leak. If there was crud in the carbs, youd think it would exhibit the same behaviour on reserve as it would on the normal fuel pipe.

Thanks for your help everyone, and its good to see you havent killed yourself on your death machine yet limbimtimwim - have you grown your beard back yet?

[Wasp]

aye, ovbiously not mine then but IR nick named his the vtz of doom when he bought it from me.

mine had a problem with the reserve setting on the fuel tap so its probably a good place to start

[B-rad]

Drain the carbs and see what the petrol is looking like. Might have a rusty tank.

[limbimtimwim]

and its good to see you havent killed yourself on your death machine yet limbimtimwim - have you grown your beard back yet?

257km/h! No. Clean shaven.

[IkeKrull]

Sure enough, i pulled off the tank, and found that the vac hose that connects the petcock to the vac nipple on the carb was persished, split wide open, and basically rooted.

So i cut the crappy end off and clipped the hose back on the nipple. Fired it up, and it immediately idled about 10 times better, the bike runs much smoother, no longer backfires and the choke can now be left completely off after initial startup.

I also found the fuel tap was on upside down, so the 'on' setting was actually the 'reserve' setting.

All fixed up after about 5 minutes work - pretty happy with that. Cheers for the help.

[jord]

Yeah had the same problem,check the fuse under your seat,(yellow wire) unscrew the black thing and clean it out.Check it is conecting properly if need be put some tin foil in at either end or other metal as it may just be the fuse jumping around in its little casing.Problem solved. Enjoy riding the mighty vtz!

[What?]

Beauty. It's usually the simple things...