pogbird

Thanks for the advice. I'll upgrade the fuel first and hope. After that I'll strip it and see. Pog

I have a Gas Gas TXT 2001. It has recently developed a single sharp tap/knock after the throttle is blipped. I have owned the bike for three years and it has never done this until this year. I have never heard the knock at any other throttle position or time (load/no load) when riding. I run normal unleaded with motul synthetic at 75ml per 5 litres. I appreciate that at this age the engine is likely to need some TLC I just want some idea of the likely cause and the size/cost of the repair job.

Only semi naked?

Jesster For what it's worth, my guess is based on some of the sales pitch I recall for upside down forks. (By the way. My Dad claims that these are the right way up based on some ancient old bone shaker he recalls) One of the reasons given for conversion to upside down forks was the reduction in the ratio of unsprung weight to sprung weight which is crucial in world of high performance suspension. On a road bike it was not initially thought to make much difference as the bike was heavy and the already low unsprung weight ratio was also more affected by heavy tyres, wheels and brakes than the fork outer, its use on road bikes was initially thought to be very gimicky. On a light bike like a motocrosser with light wheels and tyres the extra unsprung weight added by the fork outer was deemed to be worth the trouble/investment to remove. While I appreciate that the average trials iron falls into the latter category of light weight etc. The suspension of a trials bike is not being asked to deliver wheel control with the same speed of suspension movement and conditions. Thus the unsprung weight ratio is not so crucial. Add to that the likelyhood of damage to important and expensive stanchions on a bike with upside downies which is ridden on and around rocks for most of it's life and the balance probably comes out in favour of conventional forks. Pog