I have recently been given a 43S (L80102) and have ticking over problems, I also have to have the choke on or it cuts out, it has to have a lot of revs to keep going which in turn brings in the cutting blade. It is quite old, I guess about early 80's, and still cuts quite well, and I don't mind having a tinker, so would love to bring it back to it's best, I plan on a full strip down and paint this coming winter, so if anyone has any info you have on adjustments for the carb they would be much appriciated.
I have found the same model on ebay which I have as clarification, http://www.ebay.co.uk/itm/QUALCAST-SUFF ... 2a12a476c3

Cheers

Mike
PS What would be the best meathod of sharpening bottom blade and cylinder, I have access to a lathe and workshop facilities, for when i strip down mower in the winter.
Use forum pm facility.

Hello Mike,
With regard cylinder sharpening, we had a discussion on this previously so given my current lack of enough hours in the day I hope you don't mind me posting a link to this; viewtopic.php?f=10&t=6790&p=63222&hilit=atterton+and+ellis#p63222

The bottom blade was with ref to an Atco, I believe, so will not be very applicable to a 1980s Punch 43S. However this link is to a sketch that will be more relevant to your mower...The actual blade will have a slight cramping upwards to the front 1/2" which I ommitted to sketch. http://i32.photobucket.com/albums/d12/S ... tion-1.jpg The bottom blades are often only suitable for grinding if they are very lightly worn because if a worn blade was to be fully ground back it would remove all the potential adjustment for cylinder set. Genuine bottom blades were better made than pattern replica ones...at least they were 20 years ago..
43DL, mower that came before 43S, suffered from wear to the cylinder shaft caused by over loading of the very narrow bearing races. This wear could be addressed by metal spraying. I'm not sure if the bearings were improved for 43S.??

Early models of this mower had a Dellorto carburettor and this was quite problematical to set up. As standard it only had adjustment for mixture at slow speed running and a throttle stop tickover screw with a fixed jet for main mowing speed. Often the slow run mixture had to be set quarter of a turn rich from optimum slow running setting, a poor compromise, but it was to allow a pick up from tickover to mowing speed and to avoid cutting out or hunting whilst mowing. The central carb main jet tube used to regularly block with bits of grass. They were also slow to warm up needing a short period of half choke. Some Dellorto carbs were later retro fitted with an adjustable main jet screw within the carb bowl nut and a matching new central jet tube to try to improve the set up.

If you do attempt any tuning...always do it outside..never indoors...due to exhaust fume risk. Best results may be on a grass surface as any hard surface will see vibrations that will give erroneous results. Make sure the engine is properly warm by mowing use rather than free reving. And do be aware that a pick up in revs will see the blades start to turn via the centrifugal clutch.
If in any doubt seek assistance of a local agent.

Clive.

Thanks very much Clive

I have a lot of tinkering to do over the winter!