The carb came this weekend, I opted for a 30mm Mikuni carb, over another Chinese carb as the price difference wasn’t much, the Mikuni was £25. The 30mm over 26mm means around a 33% area increase. Here are the two carbs side by side with the Mikuni on the left.
All I did was swapped over main jets so the Mikuni has a 110 jet over the stock 100 on it. I have yet to see if any further jetting is required, but I will be servicing the bike by the book again next week and will inspect the plug. It was a simple swap and the stock choke mechanism easily fit on as the Mikuni has a lever with a way switch fro full, half and choke, which is handy on a naked bike or go kart. The stock 42mm performance air filters will still fit on to the carb so no need to go out and buy any more air filters. After the work here is the new Mikuni on the bike.
While on the subject of the choke mechanism, here is how it fits, nothing complicated or special.
What I did was swapped the 13T sprocket up to a 16T as the 13T was brilliant in fifth gear but the rest of the time it was too close together, so I’ve opted for a 16T, possibly will try a 17T if I can get anymore performance parts down the line. I’ve taken the bike out for a ride and I’m impressed by the Mikuni carb, throttle response is a lot better and the entire power band seems to have improved.
My XTR-S Project 