GP200 exhaust advice.

[DamionHoward.]

Evening. Just after advice/opinions please. I’ve got an Indian GP200 apparently “stage4” tuned running a 28mm dellorto with a Scootopia 42mm clubman and it is pretty rapid but seems to run out of legs at 69 mph (speed tested on GPs) I’ve been looking at the Avanti Exbox ST but I’ve seen the SIP clubsport silent but I can’t find any online reviews for this exhaust other than cut and paste jobs from the SIP website has anyone got one or had one that can give any help or advice good or bad around either of these pipes please?

[shamrockexpress]

i would have thought theres not alot to gain by going from one box pipe to another other than relieving yourself of 300 quid.......i would have said to try a JL3 expansion or likes of a pm25 or stirling style exhaust be a good bang for buck....

[DamionHoward.]

i would have thought theres not alot to gain by going from one box pipe to another other than relieving yourself of 300 quid.......i would have said to try a JL3 expansion or likes of a pm25 or stirling style exhaust be a good bang for buck....

I like the look and sound of a box pipe but I’ve been looking on the Cambridge Lambretta website and their figures quote 12bhp on the scootopia and 16bhp on the Avanti. I’ve not much experience of expansions other than a Fresco and a PM back in the 90s I’m willing to listen to any and all advice.

[Rich Oswald]

If you are getting 69mph from that set up you are doing well and no change of box pipe will give you anything more than maybe 1mph. Is it worth 3300 plus just for that?

[Nudger]

I've recently replaced a failed Scootopia exhuast with a SIP Clubsport on my Li Special. The build quality and fit is superb & the tone is lovely. Now my other Scootopia on my Stage 4 dl200 has also failed with a massive split & I've decided to replace it with another SIP Clubsport... We have so much choice today.

[LambrettaMarky]

If you are getting 69mph from that set up you are doing well and no change of box pipe will give you anything more than maybe 1mph. Is it worth 3300 plus just for that?

↑↑↑ Agreed from my limited experience

I've just fitted a 30mm PHBH Del Orto and JL3 exhaust to my SIL GP200 & will be happy if I can get to 69 mph! Not ridden it since the mods so my fingers are firmly crossed.

If I still want/need more speed then I'll either get the SIL barrel tuned by Mark @ MB Scooters or fit a GT240 kit and prepare for lift off & a hydraulic disc brake!

VAPE ignition system will be going on too.

[bookertmgs1]

Evening. Just after advice/opinions please. I’ve got an Indian GP200 apparently “stage4” tuned running a 28mm dellorto with a Scootopia 42mm clubman and it is pretty rapid but seems to run out of legs at 69 mph (speed tested on GPs) I’ve been looking at the Avanti Exbox ST but I’ve seen the SIP clubsport silent but I can’t find any online reviews for this exhaust other than cut and paste jobs from the SIP website has anyone got one or had one that can give any help or advice good or bad around either of these pipes please?

If you are getting a verified 69mph - quit while you are ahead. You'd be spending money for very little benefit.

[shamrockexpress]

Evening. Just after advice/opinions please. I’ve got an Indian GP200 apparently “stage4” tuned running a 28mm dellorto with a Scootopia 42mm clubman and it is pretty rapid but seems to run out of legs at 69 mph (speed tested on GPs) I’ve been looking at the Avanti Exbox ST but I’ve seen the SIP clubsport silent but I can’t find any online reviews for this exhaust other than cut and paste jobs from the SIP website has anyone got one or had one that can give any help or advice good or bad around either of these pipes please?

If you are getting a verified 69mph - quit while you are ahead. You'd be spending money for very little benefit.

my very thoughts,,,,,,ive not seen 69mph for a while ,,,whats it like..........lol

[shamrockexpress]

As already said i think youre at your limit,,,,,,,,,,maybe a nice bit of lift in the power band if you get the right expansion, but remember with changing any exhaust you need to ensure your jetting is suitable or just by changing exhausts could lead to other issues which might be for the worse.
I had a stage 4 with 28mm delly and afr box pipe years ago and i often seen 70mph on slight uphill a roads which left friends on tuned scooters struggling, i will be going back that way soon.
regards

[DamionHoward.]

Thank you fort he responses and advice. I think I’ll just leave it as it is whilst it’s running fine and see what can be done whenever it gets to the stage where it needs a rebuild.

[Warkton Tornado No.1]

Having read this Post & responses, out of curiosity I looked @ Scootopia’s website & the images of their 42 mm Clubman would seem to indicate a reasonably well thought out product. The two part manifold & long cone are preferable & I’m guessing that the tailpipe may be marginally larger than some competitors, which - IMO - is a good thing as it so often contributes to preventing an engine from overheating. The fact that this engine runs a 28 mm carburettor means that there is more to ‘exhaust’ so this particular Clubman would appear to be non restrictive.

As other contributors have said, a ‘Real World’ 69 MPH is pretty good with current fuels & you’d probably only gain more with an expansion chamber.

Over the decades, I have gained some experience of exhausts from OEM to gutted - ‘straight through’ - OEM, Clubman’s up to 50 mm Ancillotti’s & various expansion chambers. What I believe to be critical are the bleedpipe dimensions. Not only does the tailpipe contribute to the cylinder temperature, it can so easily be overlooked by ‘backing up’ @ WOT or on the over-run as I recall on Cadwell’s ‘Club’ circuit where my bike would absolutely fly out of the hairpin, only to be passed in the dip of the next long straight. This dilemma was purely due to the tailpipe size - plus my ignorance

To sum up, I’d be interested to know the tailpipe bore of the exhaust & - although it may benefit even more from being enlarged - I would suggest that it’s longevity & performance may be improved further by re-engineering the mounting to the engine.

Vibration is what causes an exhaust to split & fail. The last DIY Clubman type exhaust I constructed incorporated bobbin type AV mounts in conjunction with sprung connection of the cone to the ‘U’ pipe. This was achieved by the main, top (to crankcase side) bracket & bending the cut edges in opposite directions & mounting two bobbins between. The bottom (to crankcase bottom) bracket was simply bent down to a right angle & a bobbin fitted between that & another DIY right angle bracket to fit in place utilising the single M8 fixing point. As the ‘box had been gutted & sliced to allow greater ground clearance, a silencer was essential & this too was mounted with AV mounts.

To this day, my view is that Innocenti got an awful lot of things ‘right’ by comparison with the competition & shed load of components spawned by many hoping to capitalise on the gullibility of many of us. For very good reason, they used simple crankcase breathers fitted with wire mesh filters, crankcase mounted gear change components made of steel, rather than colourful soft alloy etc etc. Yet, despite having the knowledge in allowing for vibration as demonstrated by the laminated horn mounts, that same philosophy was not extended to the exhaust