Saturday, September 4, 2010

Trying to Breath

It was 2 weeks ago when I decided to change my air filter,  for a K&N unit. This would allow the bike to breath a little more, and given it has straight through pipes, this was long overdue..

As much as I thought this would be a 2 minute job and we'd be on our way, I was once again proved wrong...

When the K&N filter went in and the extremely restrictive induction snorkel was removed, I fired her up and took off up the street...

As I twisted the throttle,  the bike initially took off as expected,  but soon fell into an enormous hole between 2000 and 4500rpm and then took off like I did when I thought I was being chased by a snake on my uncles property, when I was 12 years old...

Standard Induction Set-up



Restrictive Induction Snorkel



Snorkel Removed for Much Improved Air Flow





No doubt, there was enough encouragement to know there was a definite performance gain , but clearly the fueling was unable to keep up...

So it was time I hunted around for some 125 main jets (110 standard ) and mid range needle shims, but after much frustration I was unable to find anything but 1 set of 130 mains jets in Australia and no needle shims to speak of... Sure 130's may sound a little rich. but without the shims, they may be there or there abouts.....

So I set myself the task of pulling off the carbs and hoping for the best... Now, I could go on and on about how I am going to spend the next 2 weeks re growing the skin on my knuckles from having to work in such tight spaces,  but lets get on with the results.....

Carbs Removed, with Fuel Bowl Removed to Access Main Jet ( Cables remain attached )




Houston, we have a problem....

Yes that's right, I had it all back together,  but as I begged the engine to kick over,  there wasn't a chance this was going to happen...

As I fought the panic and went through the possible mistakes I could have made, I remembered that I was extremely low on petrol when I rolled into the garage yesterday ... Was it possible that I had run out of petrol at this exact time ?  In desperation, I turned the fuel tap to reserve, waited a few seconds and prompted the start button to answer my every wish... and yes ! there it was, the perfect idle I had been so used to.... ( crisis over ... phew )

So, with my fingers crossed, I rolled on the gas up the street and the flat spot was gone and the top end was stronger than ever.. To ensure it wasn't a one off,  I went for a longer ride and it seems I was in the zone, with response, torque and power all at the top of their game.. 

Knowing that the mid range was more than likely,  still a little lean, I have ordered some needle shims and some 125 main jets from o/seas. On arrival I will install these and with any luck it will only enhance the mid range, but I will be happy for the shims to just richen up the mid range and help keep the engine cooler...

Once again it was only an hours work, but a significant gain... I must say, the effort verse reward on the Thruxton has been second to none and some part of me feels, this story has only just begun....

Short Video : Not Great Sound Quality

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