I knew an S1 was an "involving" bike, so here goes with my first real problem. When I run on low revs i.e. reving up to 3 to 4 thousand going through the box all is well but any attempt to stay at, or above 4 starts a sputtering and a classic fuel starvation type of stop. It requires next to no time to fire up again and all is well. I've checked the carb, float bowl clean, main jet and emulsion tube secure and clear, no in line filter fitter, tap and tank filter clean. Do'nt think it's the tank not venting as there was no hint of hiss on opening the cap and anyway it restarts so quickly the vacuum should still be blocking flow. The only thing that looks odd to me is that the in tank filter even though it's not blocked seems to flow fuel really slowly, (I'm used to old Japanese taps that when the pipe was removed would give a good rate of flow). Any ideas please? My next move is to run with no tank filter to see if it is restricting flow, and maybe check the float height?

_________________
'40 Indian Chief, '19 Kawasaki Z900RS Cafe.

Run with the filler cap off and see if it does the same, that will tell you if it is a venting issue.

_________________
08 Specialized Langster

When ron had the bike the problem was the vent pipe on the filler getting pinched under the tank.

If you blow up the vent pipe,you will get a surge of air back
That should show the tank valve is working ?

_________________
Should Have Stuck To making Tubers

Unless it has a non return valve in - which it does - otherwise fuel would come out under braking.

_________________
Sept 2017. Email will find me.

Thanks for the advice, and as suggested it seems to have been the tank vent pipe. How I'm not sure as it was easy to blow through but when I checked it out it had a kink behind the engine/swinging arm casting which must have been fully pinched occasionally. Now re routed and all seems well.

_________________
'40 Indian Chief, '19 Kawasaki Z900RS Cafe.