Sputtering issues
 

Hello,

I started the bike after about 2 weeks of not starting it. I started just fine. I rode for about 40-50km in the city, taking 2 short brakes in between. Then parked the bike in the sun (~35C) for a few hours.

Then I started it to get back home- temp gauge showed around 58C. Pulled the choke half way (as it has always needed on a half warm engine), rode for 1-2 minutes at very low speed (residential area), got to ~75C, closed the choke.

Accelerated to get through junction- the engine sputtered and almost died. Crawled through that junction at low rpm, then opened the throttle- the engine stopped. After a few more tries of revving- stopping, I pulled the choke again, and with it fully pulled it ran fine. Got to the nearest petrol station (3-4 minutes), filled the tank (had about 3,5L left), and then the bike ran fine until home.

The only time this has ever happened was the time I almost ran out of fuel (had 200ml left). Otherwise the bike has been running great.

From what I know it could be:
Electrical:
1- spark plugs - but they were replaced last month
2- ignition coils / CDI

Fueling:
3- bad fuel- it's possible, but why did the bike run fine earlier that day?
4- fuel petcock
5- dirty carb needles

Anyone got any opinions on this? I'd lean towards #4 or #5, but is there any quick way of at least partly checking #4 without removing it from the tank?

My guess would be clogged petcock filter from gunk in the bottom of the tank. I've had this happen on several bikes. Runs fine until the fuel level reaches the clogged part, then acts like a dirty carb. Put more gas in the tank, and the problem goes away. Repeat.

If it happens again, open the gas cap. Maybe the gas tank vent is clogged.

Thank you both!

I've ordered a petcock rebuild kit that should arrive in the next days. Just in case it might be needed.

@Xbolt22 : my bike doesn't have the petcock on the tank as it's from 2001, will there be a filter inside the tank regardless?

@xeris : is there any other vent other than one of the 2 loose hoses coming from the backside of the tank?

I'm also thinking of replacing ALL rubber hoses involved with fuel and vacuum.

There is two hoses. The smaller is the vent, the larger is overflow.

There is a filter on the "straw" that goes into the tank.

Here's what I did today:

-removed all gas from the tank

-managed to find a good angle and see the filter from inside the tank. It seemed identical to a new one like this https://www.cmsnl.com/honda-vtr1000f.../#.XTcSLkdS8uU , no apparent varnishing or dirt

-blew through the ends of both hoses. The thick one blows through the overflow port from under the gas cap, so the thinner one is indeed the vent. It was very very hard to blow through- and at about 1" in it seemed to have the liner collapsed. On closer examination it wasn't a collapsed liner (not that it'd have one...) - it was actually a cocoon (likely of a moth)! So I took a thin screwdriver and cleared all that crap and now it blows through at a much higher rate (though still less than the other hose, but that's probably normal due to the smaller ID).

So problem solved maybe? Didn't have the time to test it, and it wasn't that sunny and hot as to reproduce the conditions that triggered the issue either.

Rode the VTR for about 600 kms this weekend, including the bike staying under the blazing sun for a few hours in between rides.

It ran fine, so the issue is solved...

Later last year it started randomly sputtering and quickly stalling while idling at stop lights. Only when it was hot and the tank was almost empty.

I'll replace the petcock diaphragm and all fuel lines as soon as the weather gets warmer and see how it goes from there.