More HP

[RickBlaine]

I have heard that the Skorpion's Yamaha 660 engine can be re-tuned to get 150% more power. Does anyone know how this is done, or who can reliably do it?

I have a 1995 Skorpion.

[steveweck]

I have seen motors that put out over 80hp at the rear wheel. These motors have been bored and stroked to a diplacement around 780. Extensive head work and big cams are also part of it. Jack at Axljak had two of these motors for sale on his website earlier this year. I think they are gone now but he was asking $4,500 each. I think that may have been a bargain. I just started rebuilding my motor and all the modifications add up quickly. To do it right you should do it all at once instead of going back and forth biulding and tearing down. I've settled on a mild state of tune. I'm boring the cylinder 2mm over and using a hi compression wiseco piston. I have cleaned up the heads a little and will be installing new Kibblewhite valves. I'll be installing a Hot Cams Stage 2 camshaft and spring kit to finish off the head. For now I have to work with the stock carbs but I'm investigating other options.

steve

[DAVID THOMPSON]

site member Wonky works at Slipstream Tuning and can tell you what
you need to get in the range you want with out doing a bunch of stuff that is not productive

ar dave

my feeling is that unless your raceing any thing beyond 60hp at the rear wheel is a gas hog for no good reason other than you want to loose your drivers license

[Wonky]

Hello buddy, glad to hear there's another Skorp on it's way to maturity!!!!

The best way forward, we have found, is exactly as David has stated, for the full "unleash the fury" tune you would find the bike an absolute terror to use on the road. 80+BHP on a single cylinder will piss the locals off with its bellowing exhaust note/rumble and the power/reliability would be a tad over the top for leisure use, although if your a power muncher and you have deep pockets then fair play.

Personally as Dave has also suggested, a 102mm bore on the barrel(standard is 100mm) and a Wiseco 102mm piston or a JE 102mm piston is then complemented with a Carrillo rod, this is vital, the bigger bore pushes the standard rod to it's limit and as Dave also stated, not having the whole job carried out all in one go will cost you for sure.BAD!
Next you will require a cam, as stated again by our budding enthusiast DT, and finally you will require the head Port & Polish work (Gas Flowed). This is a much more reliable way of unleashing enough power to really open up your engines potential without jeapordising it's durability and life. We carry out this work on a regular basis and find that this suits the "Street Tune" category. Having a twin pipe system made works really well on the XT660 engine and helps your bikes heart breathe more successfuly, like adding a bigger lung capacity! You can also add a set of CR Carbs, around £700 over here, that will also unleash the power. This mod can be added at a later date with a set of K&N filters and a little mod with your air-box housing. That reminds me we also add a Slipstream modified Dynojet kit.
We tune Eric Mersers racing Skorp, he races in the states and is about 60 years old, kick-ass. We have also carried out work for many other US Skorps that attend many meetings throughout the year.

Hope this helps...

[Wonky]

Eric Mersers MZ Skorpion - (Full Race Tuned)XT660 Engine modified by Slipstream Tuning!

[Wonky]

And some more...

[basser23]

Rick,
Wonky is spot on as to his recommendations! Depending on how far
you want to take it..$ wise.
There are many differrent combinations that seem to work quite well.
Again it's a matter of how far you want to go...you could just do head
work and hotter cam/carbs,add dual exhaust, or new 2 into 1 to use
your side stand, bump the compression up to about 11 to1 so you could
use 93 octane pump gas...etc.,etc...
I personally feel about 60 rwhp is more than sufficient on the street...with
15-43 gearing...
Chip,

ps: Been to Slipstream before...terrific folks

[tuny]

[basser23]

Tuny, he probably uses a roller starter..it is a set of rollers that are attached to a car or truck wheel..sort of like a dyno roller. The bike is
placed on the rollers which spin the rear wheel...not practical for the
street obviously...

Chip

[basser23]

Wonky,
Would you have an e mail address for Eric Mercer? or where in the states he is located?
Thanks
Chip

[Wonky]

The bike is for RACE ONLY and not suitable for street as stated above, you would need to use a roller starter for the bike!

[Wonky]

I'm afraid i'm not at liberty to pass on any information without asking Eric first. Anything i can help you with?

[basser23]

Wonky,
Just wanted to know where he races basically...East or West coast etc..
and what race organization(WERA , CCS) he competes in.. I appreciate your position.
Thanks
Chip

[Wonky]

I will find out for you and ask him if i can pass on his e-mail to you if he says it's ok to do so! No probs buddy and thanks for not taking it the wrong way!

[RickBlaine]

What do these sorts of mods cost?