i have just bought a 948cc cali 3 of 1988 vintage, can any one tell me if it should have a H pipe fitted or not. the silencers have been replaced with a set of khines. but ther is no H ( balance) pipe fitted. my ex cali ev had one and i would have thought that the 948cc ( carbed) one would to. MICK,
There has been discussion on this BUT an H pipe does seem to help , you can retro fit one as long as the diameter of the pipe is the same.
I think the engine is basically the same as the older bikes they DO have a very long smaller dia part that goes way into the silencers, I cut it down on mine to fit the s/s silencers.
If you need to get one made Keihan list one and Roy at OSMC will make a stainless one up if he has not already got one laying around.
cheers GB i just wondered if thay had one as standard, i know i would help smooth out the tick over,
buzz2012-08-30 19:46:52
As far as I am aware all the big block Guzzis have some form of cross over pipe the older ones it is an “H” piece. The newer ones it is more a colostomy bag…
I thought so too. (Not the colostomy bag bit )
Not sure about the better idling thing, tho should equalise pressures between the pipes pre-silencers, but as far as I know the main purpose of a x-over pipe is it’s the simplest way to break the uniform cross section of the downpipe, this causes a negative pressure pulse to be reflected back to the exhaust port. This takes a finite time, ergo at one particular rpm speed (or short range thereof) the negative pressure pulse actively helps to suck more exhaust gas out of the port, allowing more air/fuel to go in to replace it. So is a power increase.
The shorter the path before the crosspipe occurs, the shorter the time period and hence the higher the rpm at which this happens. This explains why e.g. Le Manses have 2 cross pipes, the front one provides a power boost (theoretically) at some higher rpm than the rear one does (is in addition to).
Interestingly, BMW R80 has 2 cross pipes as well. From personal experience I’m guessing (and if I’m right) the front one gives it a bit more of a noticable extra ‘oomf’ at 90+ mph.