Petcocks and individual touches

[Monstyr]

I think I may have found one of the reasons my strada didn't seem to run well.
The electric fuel tap had been replaced by a manual one, and only now when the bike is in bits and I needed to drain the tank do I find out that the 'open position' on the one side is the 'off' position on the other.

Probably not the main reason, hopefully a good clean of the carbs will be whats actually needed.

I've also found the header pipe coming from the rear cylinder seems to have an extra length welded to it. The extra bit goes past the balance pipe about two thirds of the way inside the left side silencer, I've compared this with the parts catalogue diagram where the header ends just after the attachment point for the endcan. I was puzzled at first when the can didn't come off easily but undoing the mount gave me more wriggle room.
Can anyone explain this?

Who knows what other little individual touches this bike is hiding.

[MarkB]

Hi

There should be a link pipe between the two carbs so that both are fed, whichever fuel tap you use. Even if you've only been running from the reserve tap that shouldn't affect things.

The extra length of exhaust is, I believe, to make the rear exhaust pipe the same length as the front one, and optimise performance. My Strada has stainless pipes and silencers which don't have this feature, and it seems to behave very well anyway.

Good luck with your investigations.

Mark.

[72degrees]

I used to run the hill climb bike from just one tap on the Puch moped tank it used. It never suffered from fuel starvation. Most 2:1 systems also go to a lot of trouble to equalise header pipe lengths. It is a good idea for ultimate power, but unless the motor is tuned you may well not notice the difference. I once lashed up a 2: 1, to get my first hill climb special on the road for running in, by simply taking off the front cylinder silencer and clamping a U2 dry cell battery (what are those these days 'A'?) in the end of the pipe. It ran surprisingly well.

[Monstyr]

I have the two standard cans fitted, not a two into one.
What I found odd was that all of this extra pipe is inside the silencer, I'm tempted to cut it off as it also looks fractionally narrower than the header before it but will hold off doing rash things until I start to reassemble it.

[SteveMRC]

The original exhaust on my 500 Sei also had the extra length pipe on the rear cylinder.
I seem to remember it was a smaller diameter to the main downpipe. I always thought it was to tune the two downpipe lengths, they were not equal but something like a 3:4 ratio.

It rotted through where it was joined to the downpipe and came off with the silencer when I removed it one day.
I ran the bike without this extra length for several years with no apparent difference in performance.

It's fitted with a stainless 2-2 system now without the extra length pipe.

[3potjohn]

My K1 has black exhaust pipes ,the left one extends something like 10 inches and of a smaller radius into the silencer.
I thought it was something like making it the same length as the right hand one.As far as I can tell my bike runs well.
As this left hand pipe will need replacing (and I cannot get the correct type it seems)I was worried about this extra length issue, especially with the SS pipes.So interesting to hear that it seems not to make any odds.
And to think I used to live near a bloke who made exhaust pipes for James Hunt.Or was that a trumpet?