Good afternoon just wondering if anyone can help me find out the year of a Montesa cota I have just purchased frame and engine numbers are 51M5994 cheers Jeff

Hi Jeff,

Welcome to the forum.

This site should help :

https://cybermotorcycle.com/marques/montesa/montesa-numbers.htm

 

Cheers for that I will take a look 

Unfortunately prefix 51 covers the 348 and entire 349 model range so without knowing which number range was used for which model you can't tell what it is from the number

Ok thanks for that I will have to keep on investigating 

Put a picture of the bike on here or one of the facebook groups as it's a lot easier to identify the actual bike itself than from a frame number

51M5994 is a 348 Cota, probably a late 1977 or early 1978 model. Here is a chart of 348 Cota improvements from the start of production in 1976 through 1978.

51M000	First mass produced 348 Cota
51M3132	Change in filter housing is added deflator antiwater screen.
51M3699	Step is added chain guard on engine crankcase forwarding. Change speedometer.
51M3790	Change elements of the carburetor.
51M4722	New front fender.
51M5059	The 3rd speed gear on the secondary axis from 15 to 16 teeth to shorten development.
51M5599	Amending the bottom flange of the triple tree to open a passage for the cables.
51M5707	Improved gearshift by ensuring the pinion is free and moveable.
51M6828	Chain guide fixing hole diameter reduced. Spacers fixed to prevent wear.
51M7200	New Telasco “Hydrobag” rear shocks. Improved front suspension with gas. Improved spring tube protectors. New brake and clutch levers. Eccentric chain tensioning step further reduced.
51M10107	New rubber grips on handlebars.
51M11307	New black and gold tank decals. New fixing system and roller rocker gear which ensures the positioning of the new shifter and rear brake rigid optic headlight. New flywheel. New front suspension with air pressure suspension arm protector
51M12305	Rear shock suspension modified.

Thanks for that I don’t suppose you could tell me where I  can get  a new set up piston rings from could you it is a (STD +0) piston on the bike