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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.

Standard piston ring end gap is 0.20 to 0.35 mm (0.0078 to 0.0137 in).

I suspect the shift eccentric may not be adjusted correctly. This is easiest to do with the clutch removed. Spin both shafts so that all 5 gears can be selected with a minimum of further turning of the shafts. The shift detent plunger and spring must be in place. Set the eccentric in the middle of its range. Now shift down into 1st and release the shift lever. If you see that the shift drum moves (ever so slightly) as you release the lever, then you need to adjust the eccentric. The plan is to have each downward movement of the lever put the shift drum in exactly the correct position. The shift detent plunger should not "assist" in rotating the drum even slightly, after you let go of the shift lever. Now pull the lever up into second gear. Release the shift lever. Once again, you should not see any further movement of the shift drum after you release the lever. If you do, then you are moving the drum too little, or too much, and that is what the eccentric adjusts for.

World Manufacturer Identifier (WMI) The first 3 characters of a VIN represent the WMI code that uniquely identifies the manufacturer of a motorcycle: The 1st character shows the country in which the motorcycle was built. Characters in this spot range from numbers to letters, and each country has a unique character representing it. The 2nd character shows the brand’s name. For example, "Y" stands for "Yamaha," "S" for "Suzuki," "K" or "S" for "Kawasaki." The 3rd is the manufacturer’s division or motorcycle’s type (ATV, scooter, superbike, dirt bike, etc.). The WMI section may have a different structure if the motorcycle isn’t mass-produced. Vehicle Description Section (VDS) The next 5 characters create the Vehicle Description Section, revealing most details about the motorcycle. The VDS reveals the brand, engine size, type, and frame style. The meaning and placement of characters in this section depend on the manufacturer. Check digit The security check digit is necessary to ensure the VIN is legitimate. This digit results from a special mathematical operation that puts all other VIN characters into a formula. The VIN number is incorrect or fake if the result doesn’t match the check digit. VIN decoders perform this operation during a VIN check. Vehicle Identifier Section (VIS) The Vehicle Identifier Section consists of the last 8 characters and tells us the model year, assembly plant, and unique serial number of a motorcycle. When buying a used motorcycle, you can always check the 10th character, which reveals the model year: "1", "2", and other upcoming numbers represent years "2001", "2002", etc. The letter "A" stands for "2010" while "B" is "2011", etc.

Contact Steve Odell through the Facebook "Montesa Cota 348" forum. He is located in BC. Also, on Ebay view seller Cyclesavant located in Oregon.

I believe you are looking for Steven Odell. You can find him through the Vintage Montesa forum on Facebook.

Forget the Chinese copies. They are not made with much precision and often prove difficult to tune. Take a look at an OKO carb. Full details at www.mid-atlantictrials.com.

Buchanan's Spoke & Rim, Inc. 805 W. Eighth Street Azusa, California 91702 Tel: (626) 969-4655 http://www.buchananspokes.com/

2.75 x 21 is a WM1 rim, 4.00 x 18 is a WM2 rim. Rim locks are identified as for WM1, WM2, WM3,etc. rims.

VM26 is probably a better size for the 348. However, take a look at an OKO carb, as shown on www.mid-atlantictrials.com. They are easier to adjust and are sold all set up for the 348.

Definitely bent.

https://www.inmotiontrials.com/

550 ml (18.6 fl oz)

Barnesy is correct. The parts diagram is for a later 348 and the 349. To make the adjustment first remove the clutch. Spin both shafts so that all 5 gears can be selected with a minimum of further turning of the shafts. The shift detent plunger and spring must be in place. Set the eccentric in the middle of its range. Now shift down into 1st and release the shift lever. If you see that the shift drum moves (ever so slightly) as you release the lever, then you need to adjust the eccentric. The plan is to have each downward movement of the lever put the shift drum in exactly the correct position. The shift detent plunger should not "assist" in rotating the drum even slightly, after you let go of the shift lever. Now pull the lever up into second gear. Release the shift lever. Once again, you should not see any further movement of the shift drum after you release the lever. If you do, then you are moving the drum too little, or too much, and that is what the eccentric adjusts for. There are other variables in this issue by the way. If the shift pawls are worn or damaged from impact on the shift lever, then you will not get the expected movement of the shift drum. If internal shimming of the 3 transmission shafts allows too much end movement, then you will not be placing the shift fork where it needs to be to select gears properly. If internal shimming of the 3 shafts puts one or more shaft out of line with the others, then you will not get the positive gear selection you need.

Their placement is correct. Size 40 jet at 9 o'clock and 20 at 6 o'clock.