Skorpion top speed only 90mph from newbie

[sulby]

Hi all.

Have recently got my Skorpion on the road after a rebuild that's taken me a couple of years.
Love it to bits and its such a giggle but the top speed is only 90mph.
The front sprocket is 15 with the rear being 39 teeth.
Is the gearing the problem or is it something more serious as it only revs to 5500rpm in top gear.
Any thoughts appreciated.

cheers.

[harold]

My Baghira is geared stock, 15/45, which gives a redline top speed of I think around 110. I had it to 95 mph last weekend on the Interstate, and it hadn't stopped accelerating. I just chickened out and felt lucky that I hadn't gotten a ticket yet. Universal tires get a little loud at that speed.
Even with this gearing, it will cruise at 70, and take off to 80 real quick with a little throttle. There are other posts about gearing here that would help you with what to choose based on the power your bike is making. Could be a tuning problem.

[angustoyou]

The mastiff is on 17" wheels, and the stock gearing is 15 / 43 for that. I'd say 39 is too much for the motor. You're aiming to hit the rev limiter (eventualy) in top, so I'd say as you're getting no where near it, it's the gearing that's out. A lot of people like to over gear their bikes, so that they are unstressed. Bugger that!

I'd just check the air filter's clean, and perhaps pop a new plug in while you're there.

[RiverDrive]

39 is stock on the sport. Don't forget the stock rear tire is 150/60

[Bill Jurgenson]

as mentioned above, the stock gearing too long. 15/39 is too long. Best for general road use is 15/43.
There must several pages on the gearing subject in the archives and why the 15/39 is too long and waht to do and what not to do.
Shorter gearing will help but it is not the cause.
Leaving apart the very real possibility that the timing chain is one tooth off (if the engine was apart), the most probable cause is the membrane of the secondary (CV) stage of the Teikei carb.
The slide does not open as it should. The membrane needs the spacer ring. This is a simple engineering fact and there is no sense in looking further as long as that ring is not installed.
Again, there's pages and pages on this topic, too.

[sulby]

Hi guys.

Thanks for your thoughts, much appreciated.
I'll try the easy things first like the gearing then the carb, but must admit it could be that the timing chain is one tooth out as the engine was apart to replace a knackered exhaust valve.
If the timing chain was one tooth out would I notice anything else, like lumpy tickover or not pulling cleanly through the rev range etc.

I'll let you know how I get on, and if anyone's ever over to the Isle of Man give me a shout......
cheers.

[basser23]

I have a question on chain length,using 15/43 on a skorp how many links? I've seen 108 and 110 using 520 chain...
any opinions?
Thanks
Chip

[Skorpion]

Chip,

108 for 39 tooth rear sprocket.
110 for 43 tooth rear sprocket.

[edfmaniac]

I was running 14/43 for a little while and had to cut my chain to 108 to make it work. Now I'm back to a 15/43 sprocket set up but it's tight with the shorter chain. My next one will be a 110 and I'm sticking with the 15/43 ratio. My Skorpion loves it.

[basser23]

Thanks guys..now I know,
Will be changing sprockets and chain soon...going to use the chain Bill j recommends. DID EV520

[willrideanything]

I was running 14/43 for a little while and had to cut my chain to 108 to make it work. Now I'm back to a 15/43 sprocket set up but it's tight with the shorter chain. My next one will be a 110 and I'm sticking with the 15/43 ratio. My Skorpion loves it.

Whats you rtop speed with this gearing? Whats it tach at at 80 ish? Where is the best place to get the rear sprocket? I run a Tour and was quite bummed to discover a 90 top speed. I can hit 85-90 in forth at red line, Fifth is just a save gas, WTH?

[Skorpion]

The top speed on my Skorpion Traveller with panniers fitted and 39 tooth rear sprocket 90-95mph,

The same with 43 tooth 112mph at the rev limiter, 100mph is no problem.