Gentlemen,
I have recently aquired a WM20 with frame and engine no WM20 110432. I have a couple of questions:
1) The registration document says it's a 1939 but judging from this website it's a 1945 ? It has the cutaway fuel tank that doesn't point at 1945? It came to Norway in '47 and I have been able to trace most of it's history back to then. Is there any way to trace history further back ?
2) There seems to be an issue with the gearbox. 1st and 3rd gear will not engage properly, but 2nd and 4th works just fine. Is this a common problem, and what could be the problem?
Any help is highly appreciated
Regards, Tom
email (option): rustadeng(@)gmail.com
Hi Tom..Welcome to the forum...Your M20 is a later model and definitely not 1939, though it is not uncommon for the registered date in the documents to be incorrect. Parts such as the tank type are not a reliable indicator of the year as they are all interchangeable...The frame number is the only important piece of information when dating a bike as this is used to record the year of manufacture.
If you have a postwar data plate (a rectangular brass workshop plate) this has the post war registration on it and that information can be used to access existing records. I think that can now be done with the frame number as well, as the records have been digitalised...but don't quote me on that! However, even if your bike is in there it will only provide minimal information. Records for motorcycles were not very detailed and are incomplete anyway.
Your gearbox problem is more complicated...there are various things that determine whether the box will function correctly.
The first thing to do is establish that the clutch is functioning correctly and is correctly adjusted, as this has some influence on gearbox operation. Note as well that these boxes will not select all the gears correctly when static...the inertia created by the gearbox running is necessary for the proper engagement of the selector dogs...so the only way to fully test them is to ride the bike....Ian
email (option): ian@wright52.plus.com
Hi Ian,
Thanks for your swift reply. There is no brass plate on my bike so I guess I will have to cross fingers and hope the frame no can be traced.
I have had the bike running and the clutch seems to be working OK. When trying to engage 2nd and 4th gear, all I get are some funny noises. Guess I will try to adjust the clutch to see if that helps before I split the gearbox.
Tom
email (option): rustadeng(@)gmail.com
Hi Tom..on clutch adjustment..the operating arm on the gearbox should be vertical with the handlebar lever pulled in after adjustment....Ian
email (option): ian@wright52.plus.com
Hi Tom..the adjustable tie rod inside the outer cover is used to set the gearbox in the correct position. Unfortunately it is not possible to determine whether it is set correctly purely by examining it. Setting is done at the assembly stage to position the selector dogs on the layshaft correctly between 1st and 2nd gears and this is checked through the inspection cover on the back of the box. Apart from the inspection plate being difficult to access when the gearbox is fitted to the bike if you do manage to remove it you will then not be able to see the required parts.
So, any adjustment to the tie rod made without seeing inside the box will be a 'stab in the dark' and purely speculative.
Also this may not be the problem and in that case by making random adjustments you will only succeed in introducing another.
Incorrect end float on the shafts, worn selectors forks, dogs and gears, incorrect setting and faults in the ratchet and pawl assembly are all possible factors affecting the selection of gears.
If you determine that the clutch operation and setting is within workable tolerances and you still have problems with the selection of gears I would consider removing the gearbox to check these aspects. That would also be a good opportunity to fit a sealed main bearing to improve oil retention...Ian
email (option): ian@wright52.plus.com