VTR250 - Popping, crackling and fart arsing at high rev throttle off - Normal?

[darkwolf]

I've tried searching but have been unable to find the answer so I thought I'd cast my question into the all knowing KB ocean and see what I caught.

I've done about 6,000KM on the bike now but ever since I did a training day at Ruapuna, I got caught coming into the carousel in second (definitely my fault) and decided to just hold the gear out until I got out of the corner. Hit about 85KPH (previously I hadn't gone over 70KPH in second in 4 months of ownership) on the speedo and then changed gear. When I let off the throttle the engine backfired :confused: just a pop or two. I continued to go round the track though and then found I could also do it in third coming into Kelford. :laugh:

Since then it's been much more willing to backfire. It's gotta stay in the higher end of the rev range (about maxed out actually) before you let off the throttle and then sure enough... POP! :eek:

I haven't been too worried because I'm a bit of a child and it makes me giggle - manly giggles mind- and I have just been putting it down to the high revs and sudden closure of the throttle. But I'd just like to be sure. Otherwise, there are no signs to concern me.

So is backfiring at high revs on a carb v-twin normal or should I take her apart and have a good poke around?

[bogan]

Its probably only leaning out under those conditions, if it runs fine everywhere else I wouldn't worry about it. However it could be a symptom of either fuel screws or float heights needing adjustment (or other things but those are the easy ones).

[actungbaby]

Usually just un burnt fuel my vfr 750 does it when forget kill switch is on
And try strat it then flick it off and pops after it fires.

this guy chch used to do on purpose on his xr 200 flick the switch on then off
with trottle open bang backfire.

if does when back the trottle of sounds just normal

though bogan knows more about these bikes i never had working one

I've tried searching but have been unable to find the answer so I thought I'd cast my question into the all knowing KB ocean and see what I caught.

I've done about 6,000KM on the bike now but ever since I did a training day at Ruapuna, I got caught coming into the carousel in second (definitely my fault) and decided to just hold the gear out until I got out of the corner. Hit about 85KPH (previously I hadn't gone over 70KPH in second in 4 months of ownership) on the speedo and then changed gear. When I let off the throttle the engine backfired :confused: just a pop or two. I continued to go round the track though and then found I could also do it in third coming into Kelford. :laugh:

Since then it's been much more willing to backfire. It's gotta stay in the higher end of the rev range (about maxed out actually) before you let off the throttle and then sure enough... POP! :eek:

I haven't been too worried because I'm a bit of a child and it makes me giggle - manly giggles mind- and I have just been putting it down to the high revs and sudden closure of the throttle. But I'd just like to be sure. Otherwise, there are no signs to concern me.

So is backfiring at high revs on a carb v-twin normal or should I take her apart and have a good poke around?

[darkwolf]

Ok well that's reassuring. I was going to try a higher octane but had worries it could cause fouling of plugs so decided against it.

[Tony.OK]

Ok well that's reassuring. I was going to try a higher octane but had worries it could cause fouling of plugs so decided against it.

Higher octane won't foul plugs, most jap stuff runs better on higher oct pump gas.
The popping could just be a small leak in exhaust system somewhere, that can draw air in and mix with unburnt fuel.......pop crackle!

[Sable]

Higher octane won't foul plugs, most jap stuff runs better on higher oct pump gas.
The popping could just be a small leak in exhaust system somewhere, that can draw air in and mix with unburnt fuel.......pop crackle!

^That. Octane ratings are more to do with compression ratios/detonation than anything else.