I have on a free flow can with stock CAT and it made a noticeable difference. How ever, the CAT box and stock filters are the biggest flow restriction in my mind. I also know with singles and twins, the correct back pressure and jetting is very important.

• Who has done these changes with success and what are the pitfalls?
• Are the power gains considerable or hardly noticeable?
• Is there an after market ignition pack and does it work?
• Is it better to simply make peace with the power delivery and keep it stock?

Hi Louis,
Firstly, the CAT box isn't a CAT, but a pre-silencer/heat-tube and doesn't seem to be restrictive.

There isn't big power gains to be had from the TA engine without major engine work, but, improving the fuelling makes a difference in the feeling of the delivery and the throttle response.

There isn't an aftermaket ignition pack available, but I've had some success playing about with the Throttle Position Sensor, which suggests the TA would benefit from a couple of degrees advance of the timing depending on the quality of the fuel/octane available in SA.

There also seems to be a massive difference between bikes, some owners easily achieve 58mpg and some can only manage 43mpg.

I'm on my second one now, the first seemed very torquey in the midrange with a custom set of header pipes and a modified airbox.
My current bike was very flat, unecomonical (43mpg). I have been very disappointed with it's performance and have been 'playing' around with various fuelling options over the last year. Sitting at 90mph, the bike now feels to be pulling harder when opening the throttle (before it was a case of watching the speedo increase 1mph at a time) and am achieving 240 miles to the tank.

I'll be looking into the timing next and also the spring length in the carbs over the next few months.

 

I considered timing, as I’ve had big success on small bore motors with this before. How ever, that was way back when we had 97 octane leaded fuel and timing advance could be done with no risk at excessive knock or damage to the rings. There are some additives available for lifting knock resistance, but I don’t trust it and don’t want to go that far. To much hassle anyway.

You mentioned your first Alp was very torque with custom pipe and air box. What else was done to it and what pipes and air box do you run now?

Is it not perhaps the pipe and box that did it for your previous Alp?

 

The custom headers gave a heathly increase in midrange power and torque, it suffered at the top-end though. It also benefitted from the needles being machined (to lower them) and the airbox opening up (drilling holes in).

The newer bike didn't respond as well to similar mods, it's still a 'work in progress', but it's feeling a lot better.