Hi all My valves are the later ones, as sold by Draganfly, and are 1/8" too long. This messes up the valve gear geometry and has caused problems. I've managed to track down a new replacement exhaust valve, but still looking for an inlet. The club spares might have some, but the Singles section ...

quote="simon.holyfield"] Do you know that the needle and needle jet are not worn?[/quote] Nope, no idea and don't know how to check. It was improved by increasing the slide cutaway, so I'm getting there. If fitting the correct main jet doesn't help, I'll then replace all the jets and slide...

The needle has no markings on it other than a 'D' at the top above the top groove. Is this the correct needle I wonder? More research to do...

Next stage will be to reduce the main jet from 250 to 200 (not much effect low down though) and take a bit more off of the slide.

OK, plenty of fiddling today. New B6HS plug fitted. Starting & running OK, but too rich still. I "converted" the slide from a 3 to nearly a 3.5 by rubbing on wet & dry on a flat surface. (Stopped just short by a few thou though to do it in stages). Dropped the needle down - clip in...

Thanks Will. The carb choke size matches the inlet tract diameter perfectly though, which is surprising if a smaller carb is 'correct'. I do know from my racing past though that big carbs don't always make for faster lap times. Thanks for the feedback guys - I'll have a fiddle today. I think a bigge...

Hi all My W/NG framed 500 trials had a monoblock carb on when I bought it in a non-running state. It is a 389/30 carb with the following settings: Pilot jet: 30 Needle jet: 106 Main jet: 250 Slide Number: 3 Although the bike starts and runs well, it seems really rich low down. The plug has lovely sa...

Thank you Michael - really useful information.
Adrian

Burlen say the 2-stroke and 4-stroke bodies are different and not interchangeable. http://amalcarb.co.uk/rebuilding-mark-1-concentric-carburetter The spray tubes are different, but if you have the kit to sort that out, you might be able to work out something from their specs for a VH monobloc. SG T...

hi surrey cycles done the jets for my concentric carbs for my ariels he knows is carbs and i have no problems with my carbs he is very good i get my carb parts and carbs off him when i go to kempton park shows or jumbles give him a ring on 01342 716120 he will help you That is very useful - Thank y...