Optimum performance - where to Start?

[Steffan]

I am hoping that all will be well with the Skorpion next week.  If so then I plan to spice her up a bit over the forthcoming year. I plan to start with a barely road legal silencer to free up the breathing but where from there. I don't want to bugger the economy and I am not attempting to create a road racer. I just want to add a little performance and character - making her more driveable. So I am hoping that the tuners will give me the benefit of their experience in terms of what comes before what: Carb, Head(gas flow), cams, etc???

many thanks

Steffan

[guest27]

Handling before engine.

Sort the shocks and the steering - not saying it is not sorted or good, but was always the mantra we got as lads and funnily enough it seems to work.

R

[Steffan]

I am well on the way then Rog, handling is first rate (on the bike, still ridden by a big blouse mind). What I am after now is more ponies and more punch in the delivery

Steffan

[guest27]

Ahhh - well button up the blouse then. 

That is my 2p worth over and done with...

R

[beeman]

It's like a bit of string how much have you got.

I'd make sure the bike is in good condition first maybe stiffen forks a bit and good shocks on the back. change brake fluid and make sure all callipers are in top class condition and the pads are OK. If the engine is worn or on the way out this is the best way to knacker it.

Next k&n filters and dyno jetted to make sure mixture is OK.

Remember the idea is to get the gas in and out as efficiently as possible.
So Gas flowing, if done right, helps here and can help fuel economy.

Then a road/race cams the heads off anyway. A good thing now is to check the bore for wear etc.
Rebores there is no substitute for cubes as they say.

Raising the compression is also a route to consider.

Stiffer valve springs are a good idea if you accidental over rev it with the new found power.

Changing the carbs can free up the air flow but remember larger bore carbs often lead to a loss of bottom end power as the wider bores are slower to react to quick opening of the throttle. Venturi effect I think (although more learned club members may correct  me.

If it was me I'd put a better exhaust and k&n filters, gas flowed head and higher/ longer lift cam. either skimming the head or a high compression piston fitted but not too high compression and stiffer valve springs.

Finnally take it to be dyno'd and set it up right. Why pay all that money and not have it set to it's optimum performance. it is the best part of the tune up as you now have it in print exactly what the bike is kicking out. Yet loads of tuned bikes miss this bit out. All they get if they are lucky, is a plug chop to check the mixture on full throttle.

beeman

ps if it goes bang its nowt to do with me

[Steve H]

Not sure why but I was never tempted to fiddel with the SZR engine. It was quicker and felt stronger than the SRX so I was happy. That said theres something to be said for doing something just for the fun of doing it.
My approach would be less restrictive silencer, remove the inlet horns from the airbox and maybe drill a few holes in it. Not sure about the Muz but the SZR air filter was quite large so I'm not convinced a K+N would be of much benefit. A DynoJet kit or a few hours on a dyno with someone who knows what they are doing would (not easy in West Wales) should show some benefit.
After that I' d go for a Stage I or II cam. Stage II usually need different springs to allow for the hight lift so factor these into the cost. They wont be of much benefit on a Stage I.

[beeman]

"O" I forgot, the biggest upgrade is weight reduction, also the cheapest but hardest for me. All I have to is loose 3 stone!

[guest27]

"O" I forgot, the biggest upgrade is weight reduction, also the cheapest but hardest for me. All I have to is loose 3 stone!

Yup £1000s spent on titanium this and magnesium that and - ooh a double portion of chips to ruin it all...

R

[mini-thumper]

I suspect this was my downfall when racing. A small capacity solo bike carrying the weight of an outfit!  That said, I enjoyed myself, while it lasted, at the back with all the other lard arses. .

BB

[peterj]

All good advice so far, but a couple of thoughts. Flowing the head will only achieve anything if the head is the point of restriction. I have no experience with 660's, but I've been told SRX's flow well above their stock potential and I suspect that the 660 is even better.

I've had good results with a long duration, modest lift cam combined with a high compression piston on the SRX. Required compression was specified by the cam maker (CSL Cams of NZ for mine), so if you go that route talk to your cam maker first. It didn't stop pinging until I put a very free pipe on though, and that also definitely helped in the go department. The 660 pipe may be better flowing than the SRX one though.

My mods resulted in enough grunt midrange to make the clutch start slipping - (plates still well within spec - fixed with some preload washers), and a small but welcome improvement in mpg - very important in outback OZ, particularly if your bike wants higher octane than normal ULP. I think the stock carbs helped there. Not sure if the stock 660 carbs need to be changed to get more go at the top end though.

[bullet350]

i'd go for a silencer and a dynojet kit & air filter.
in my experience, for general use stick with the standard airbox as individual filters seem to only make things worse. after jetting it'd gain a little somewhere and loose a lot somewhere else.

so,
         keep the airbox with a k&n.
         dynojet and silencer.
         get it set up properly on a rolling road.

as for gas flowing, the skorpion has a 5 valve head. almost all who tried 5 valve have returned to 4 valve (yamaha and audi mostly) so i'd leave it alone or see about a 4 valve head if you want to go that far.

usually the three things i mentioned are enough to get a noticeable improvement in bhp without the bike becomming less 'rider friendly'. and they're not going to cost a fortune and involve taking the bike off the road.

as for handling and brakes the skorpion is on a par with the best superbikes out there. i pissed off many a crotch rocket on my skorpion sport.

350bullet

[guest7]

I can't believe you guys, you're misisng the most obvious improvements to a bike's performance:
Anodised footpegs
Tinted screen
illegal can with NO jetting changes
Tiny numberplate (helps the police to stop you and find your can is illegal)
stick-on tank protector
Leather suit with knee sliders

If it works for soooo many GSXR owners then why can't it work for you? :-)
GC

[guest27]

GC

You forgot the colour cordinated colostomy bag holder.

R

[Ian]

I would of thought that my posts over the last few months would of put anyone of this idea!

As I've already chucked my self down this road here my advice.............Don't do it....

But if you must ........

K&N's are a good place to start ,the cone type need 2 or 3mm trimmed of the sides to make them fit on the standard carbs,
They will fit in place of the rubber tubes going to the air box.

Full race can or as near as possible

Warning the sound of K&N's and a race can is very addictive !

The dynojet kit is a wast of money , All you get is a spring and 2 drills for about £70.
The same can be achieved with a small drill and a pair of wire cutters,
The carbs can be left almost standard as they run rich and you have the mixture screw to play with.

Mine ran K&N's and a Renegade race can without Jet changes and without any problems ,except for Mr & Mrs plod.

I recommend a hotcam this is one part that has made a very noticeable difference in performance to my skorp and it only cost £50 of ebay.......A stage 1 cam can be fitted without other mods , stage 2 needs beefed up valve springs and possible machining of the valve guides to give clearance.....

The next step is a piston and conrod ,Unless you go for a 100mm one and your con rod is in first class condition !

Best of luck !
 

[beeman]

Don't forget the stick on carbon fibre, must be worth 50 mph advantage, give or take a mph or two.