Pattern Carbs - A cautionary tale
Posted: Thu Aug 18, 2016 3:34 pmMy newly rebuilt TS250 has a pattern BVF carb. Initially I had problems with it refusing to to allow anything less than a 2k tickover. Not sure what the problem was but after a strip down and checkover all seemed well.
Today I took the bike for an 80 mile round trip. Nearly home. I was cruising at about 50mph but when i backed of for a corner the bike kept gaining speed! The slide had jammed in the carb. Luckily there was no one close behind so I was able to switch of the ignition and trundle to a halt. Took me a while to suss the problem which was the little brass pin on the RH side which locates the slide in the bore. This had moved outwards allowing the slide to rotate to the point where it jammed on the tickover adjustment screw.
I tapped the pin back in place but it went so easily that it is clearly a loose fit and back home I used some araldite to hold it in place pending a proper repair.
If you have one of these pattern carbs whether for 125/150 or the 250 variants it might just be worth checking if the pin is loose!
PeterF
Today I took the bike for an 80 mile round trip. Nearly home. I was cruising at about 50mph but when i backed of for a corner the bike kept gaining speed! The slide had jammed in the carb. Luckily there was no one close behind so I was able to switch of the ignition and trundle to a halt. Took me a while to suss the problem which was the little brass pin on the RH side which locates the slide in the bore. This had moved outwards allowing the slide to rotate to the point where it jammed on the tickover adjustment screw.
I tapped the pin back in place but it went so easily that it is clearly a loose fit and back home I used some araldite to hold it in place pending a proper repair.
If you have one of these pattern carbs whether for 125/150 or the 250 variants it might just be worth checking if the pin is loose!
PeterF