'lil Tomos help

[BikerMatt]

Hey everyone, new to the biking world. I've acquired a very nice and quite nippy Tomos AT50 and recently the gears have been a bit stiff and was wondering what it could be? Not sure if it has a separate little reservoir for gearbox oil as you mix the oil in with the petrol. I'm training in mechanics so don't worry about the big mechanical words...maybe a little Thanks

[hazza]

That is such a nice little bike! Would love one of those to mess around on.

As for the problems:

Does the clutch need adjustment?

Is the chain clean/lube'd and at the correct tension?

When was the last time the engine oil was changed?

When you say 'stiff' is that all the time or just when you initially put it into first in the morning?

Does it change smoothly without the clutch once under way?


Harry.
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3 Honda NC50's(Sold)-->'72 Puch Maxi S (Sold, want it back!)--> '90 Yamaha RXS 100 (Stolen)--> '87 Honda Cub 90(Sold) --> '95 Kawasaki Eliminator (Sold) --> '98 Bandit 600 (Sold) -->'07 SV650S (Current)

[Teflon-Mike]

Yes, the ENGINE is lubricated by putting oil in the petrol.
That's becouse its a two-stroke and they suck the fuel and air in via the crank-case so they cant fill it with oil to lube the bearings.

The GEARBOX although 'in unit' with the engine, has its own oil, and YES probably could do with changing.... you are probably not teh first owner to not realise this.

Four-stroke motorbikes, with 'unit' construction gearboxes, that is to say the gearbox is built into the same casings as the engine, often 'share' the oil, but not garanteed.

In days of yore, engines and gearboxes were two seperate assemblies each in thier own cases.... as most cars still are. This is known as 'pre-unit' construction, and many even had a third chamber between the engine and gear-box for the 'primary drive' usually a chain between the engines crank-shaft and the gearbox input shaft that had its own oil.

I have an old Montesa trial bike, a two stroke, and it has a 'unit-construction' engine, but that has pre-mix lubrication for the engine, then the primary drive, with the clutch in it, in one chamber in the cases, and the gearbox running in a seperate chamber in teh same unit casings, each with thier own oil bath, and of different grades.

I'm not familiar with the Thomos, I think its the minerelli engine? I doubt that it has a tripple case unit construction, BUT, could have. Worth trying to find a manual for it, if you can get one.

BUT, short answer is yes, gearbox has its own oil and it will need changing occasionally, while clutch will definitely need adjustement, and that doesn't just mean tightening up the slack on the cable, there is likely to be an adjuster on or inside the engine as well. Hence advice to find a work-shop manual.
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[BikerMatt]

Wow, thanks for the replies guys! I appreciate the help and all the useful info, I will keep it noted! A few days ago it was so stiff the gear lever bent went putting it into 1st gear and I have to use my hand to get it into neutral when I'm not moving I will have a nice ponder with my gearbox tomorrow, disassemble and what not and get the oil sorted and she also does about 45 quite easily

[bikenut]

hi dude,

find g/box oil drain and filler plugs, maybe level plug on clutch casing or amount and grade.

carefull if theres 2 drain plugs under the g/box ( unlikely a crank case drain for "engine" ( the 2t part )) one may be sprung loaded and may be a detent for the gearbox, if so then screw this back in without taking it out completely.

undo the other one, no spring load, then this will ( should ) be drain plug.

drain and examine, any bits?? or magnetic bit on end of drsain plug??

refill with correct grade and amount.

ifv over filled, oil may be dumped into airbox or overboard ( over the back tyre probably !!! ). the g/box will not be completely full! but up to level hole, dip stick or specified amount on clutch casing...

some pics under eng, clutch casin etc.

gear lever stiff and bends, perhaps the gear selector shaft goes thro the flywheel casdingf andf is in need of de corrosuion and/or lub.

presumie clutch cable if free and in adjustment.

some more pics and donty take it apart yet!!

[BikerMatt]

I'll get some pics when I get back from work or maybe sooner, thanks again!

[BikerMatt]

As I work at a garage, got it all sorted and most of the problem was the spark plug, would you believe it! So dirty!! V smooth gears now and a faster, smoother and more efficient ride now