VTR1000.ORG

Sounds more like a standar d Honda or aftermarket copy. Does it have a blade standing up from it at right angles towards the front?

i agree in that im suspicious of the stubby cans but the thing is the bike ran fine for a week or so so i dont doubt theyve caused the problem but im wondering what theyve slowly broke ? ive been searching this and the superhawk forum for similar issues and it always comes back to petcock diaphram. i seem to be able to get a good vacuum by sucking on the pipe , ive not got any fuel leaking and im not running rich (i think) but im gonna go out now and look again at the whole system as best i can. ill report back on the filter too. if todays tinkering doesnt fix it (and i doubt ill be that lucky) ill put the old cans back on.
keep the advice coming cos im grabbing at straws.
thanks everyone.

Well put it this way, the exhaust system is a tuned length so when you go changing the length you upset the operation of it and the tuning. Specifically the way it scavenges the fuel as the pressure wave pulse up and down the system, the positive pressure waves pulse to the end of the pipe where they collapse and convert into a negative pressure wave and back up the system towards the cylinder.

As for the diaphragm, sucking on it is not exactly accurate and is just a quick check that will show any obvious signs of wear/damage. If you only have a pinhole or small tear then you may not notice this by sucking, but it can have an effect on things at higher pressures/speeds with fuel flow. To test is properly you either have to strip it down and physically check it, put a new one on or use a vacuum gauge which will give you a more accurate reading. But a word or warning if you decide to strip it down. You will either have to use some sealant or silicone when putting the petcock casings back together and you wont be able to test it until it has fully dried. And watch out for the little spring inside, so carefully pull the casings apart.

(:-})

Its fixed ! It turned out to be a small blob of algae on top of one of the main jets . So a big thank you to everyone and just a quick note for anyone who's stumbled across this thread because theyre having a similar problem. Dont be afraid to get into those carbs , despite looking like a daunting job its easy , no special tools or skills required and it only takes about an hour from start to finish. Also you never know what else you might learn/discover. I found the from carb rubber wasnt done up so now my bike runs smoother and stronger than before. Bonus. I also discovered non-standard jets . Double bonus.

I found the from carb rubber wasnt done up

The from carb rubber. Is that French.

Which rubber.

(:-})

cybercarl wrote:

I found the from carb rubber wasnt done up

The from carb rubber. Is that French.

Which rubber.

(:-})

i assume he means the front rubber boot at the base of the carbs, they're easy to forget to tighten when refitting the carbs....
well done for sorting out your problem dude....
my only issue is a voyage of mechanical discovery, normally ends with me either breaking something or having to ring carl to bail me out of trouble....

Good point for some reason I was visualising a carb breather hose or something.

Bigpants...Carbs are fun to play and tinker with.

(:-})

Good find, well done

Chris.