Tim Tindall

So about 20 to 25 Thou' will be about the thickness of a business card then. Going down now to try to turn the needle screw again. Will let you two know the outcome later. Really appreciate you both trying to help me. Cheers.

Hi. Managed to get the little plastic bung out very easily, how you suggested with a small screw. Used a small watch makers screwdriver to try and turn the screw inside, but it seems solid ? and will not turn..Checked needle and hole in pipe where needle goes with magnifying glass and there is no coating and hole is clear and clean. Took muffler off again and cleaned the outlet port and muffler but there was no real amount of carbon just a bit of black oil, normal I would think. Checked spark, okay.Fuel pipe clear and not kinked. Put new fuel in mixed at 50/1. Started first pull, when primed, but still will not rev, just dies. I have sworn many times at the damned thing but it still will not rev !! Question. When I changed the coil I noticed there is a slight amount of adjustment from the pick up plate on side of coil to the flywheel. Should that gap be a certain distance apart ? Regards, Tim.

Great to have you back. The picture you sent of the brass insert is exactly the same as mine. I just assumed this is knurled then pressed in. Mine is totally flush with it's surrounding plastic so doesn't seem to have risen up. When you first told me about a plastic cap I thought it would be a plastic cap on top of the throttle shaft and not inside. Your picture has now shown perfectly what to do, thanks. Would you suggest taking the needle completely out for inspection or just give it a quarter turn to the left, to see if that works ? I have some carb cleaner that I could spray down the needle tube, to help ? Regards, Tim.

Don't know where you two have gone but would really appreciate some more direction on my last post. Regards, Tim.

Hi. The little plastic plug at the top of the throttle shaft is not plastic, it's a brass one that looks like it is knurled then pressed in. Like you I cannot see the needle would come out of adjustment. When I took the muffler off, as I said there was no arrestor gauze and the outlet port looked pretty clean, nothing obvious. My mechanical skills are quite good as I've had british motorbikes from been a small boy and have rebuilt Bultaco's and a 1957 Sunbeam S8. Also a full restoration job on a 1980 BMW R100RS. So have had good experience on Amal and Bing carbs + some Japanese bike carbs. That's why I am totally stumped with this little devil of a carb. It does sound like fuel starvation, ticks over fine and starts to rev and blades move but then won't rev anymore and stops if I pull the switch for more revs.

Only just got those pictures, many thanks. Did check the non return valve last night, all okay. Main jet hole also checked, clear and clean. Will still try the needle adjustment and let you both know the outcome. Regards, Tim.

Hi to you two helpful people. On closer inspection of that little rubber thing I realized it was a non return diaphram, so left it alone. All holes / jets are clear. I will give the needle adjustment a try. I would expect that anti-clockwise will pull the needle up ? I don't understand why it would have gone out of calibration though. The needle goes into a small tube that looks like it is made from plastic ? That would be likely to wear so would be letting too much fuel in ? But the plug doesn't seem wet... Regards, Tim.

Hi. Just got back from work. I checked and gently blew out all the air-ways. Did notice on the brass insert ( shaped like a pozi drive screw head ) there seemed to be a rubber diaphram in the middle of it. I thought it was strange, at the time. Going down to garage now to gently prise the brass jet out and see what the hell it is. Will let you know. Many thanks Tim.

Starts perfect and ticks over fine. Soon as you try to rev it up, it stops. Taken carb off, cleaned and put new diaphrams and gaskets in. Checked fuel lines for kinks / blockage, all ok. Put a coil on from another working machine and still won't rev up. Same with plug. Taken muffler off expecting to find spark arrester, as suggested in this forum. Nothing there !! Been on Walbro web site, watched video. Nothing they suggest I haven't done. Also, blades have free movement. Any suggestions please ? Tim.