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349 Cota Rebuild Specifications.


kombivan
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Hello Folks

I have a 1979 349 Montesa Cota that I am going to get the engine rebuilt and as there are no workshop manuals for these can you guys tell me things like piston clearence, cylinder head tensions, casing bolt tensions, and anything else that you know about like Firing position, point gap, well i'll leave it to you guys keep the info coming as I am sure others will use it as well thank you.

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Kombivan, I have pulled out a very old montesa cota 247 service manual and full parts diagram / numbers manual. It is probably useless to you but the head nuts are 14.5 ft-lbs to 18 ft-lbs the cylinder nuts are 22 ft-lbs to 25.5 ft-lbs

The crankshaft pinion nut is 58 ft-lbs

The magneto flywheel nut is 65.25 ft-lbs

The clutchplate nut is 14.5 to 18 ft-lbs

The counter sprocket nut is 58 ft-lbs

John

Edited by jfc
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Thank You has anyone anymore info I am particulally interested in the tension for the casing bolts with the rubber seals. also what is the origional sproket ratio.

Also type of spark plug. Wiring Diagran for 1979 349 cota also are the statos for 247 and 349 the same

i know the cam on the flywheel is different.

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Kombivan, I have had the same problems finding information. If you PM me I can send you a PDF of a manual with all the torque settings, oils and quantities and factory specs for the bike. Or you could visit todotrial.com and download the manual. It is actually for the 349/4 but from what I can see most parts are common. Oh, its in Spanish, but the important stuff is in English too.

Andrew

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I don't think the translation would be that important. It is basically a full owner manual with a parts book etc. I've been able to get the info that I wanted and I can't speak Spanish at all! Rather than putting your email address up for all to see, if you send me a personal message (an option on the drop down menu by your user name) I will forward the file to you. Or as I said in my previous post you could visit todotrial.com and downlod the manual in PDF format.

Andrew

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Engine

Cycle / 2 stroke

Cylinder / one

Bore / 83.4mm

Capacity / 349.6cc

Compression ratio / 8. 5: 1

Ignition

Altinator / Motoplat

Points gap / 0.4mm / 0.0157inch

spark Advance before TDC 2.7mm /1.05inch

Spark Plug

NGK / NGK BP-5ES

Bosch Theormic grade / 160 + 175

Electrode Gap / 0.5mm / 0.0216inch

Thread 14M x 1.25 x 19

Carburettor

Make / Amal

Type / L-2627/215

Diffuser diameter / 27

Main Jet / 145

Low speed Jet / 20

Gas Valve / No4

Sprayer / 107

Position Needle / 2a (2B1)

Adjustments and Tightening Torque

Miniumn Diametral clearence between pistion and Cylinder 0.045mm / 0.0018inch

Maxiumn whipping crankshaft ends mounted on the crankcase / 0.030mm / 0.0012inch

Recomended Tightening Torque

Cylinder Fixing nuts / 2 - 2.5 m.kp / 14.5 - 18 ft lbs.

Cylinder head fixing Nuts / 3 - 3.5 m.kp. / 22 - 22.5 ft lbs.

Crankshaft pinion nut / 8 m.kp. / 58 ft. lbs.

Magneto Flywheel nut / 12 m.kp. / 87 ft. lbs.

Clutch plate Nut 2 - 2.5 m.kp / 14.5 - 18 ft.lbs.

Main Crankshaft Bearings 25x52x15 / bearing Number 6205 / C3 C3 having correct clearences

We still don't have the tension for the casing Bolts for the centre casing with the rubber o-rings anyone know this tension?

Edited by kombivan
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Sproket Ratio

Counter Sproker / 10 teeth

rear hub sproket / 40 teeth

Chain pitch / 15.875mm /5/8inch

Roller Diameter 10.16mm / 0.400"

Face between plates / 6.48mm / 0.255"

Primary Drive

Pinion Crankshaft / 20 teeth

Clutch Toothed gear / 64 teeth

Transmission Ratio / 3.20

Gearbox 6 speed.

Wheels

Front / wm1 / 1.6 ...Trial......2.25" X 21"

Rear / wm2 / 1.85....Trial.....4.00" x 18"

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  • 1 month later...

Hi everyone,

I have my Cota 349 engine on the workbench because the magneto side main bearing has some slight up and down play. I've never worked on a two stroke before and this is the first time I've seen main bearings installed from the outside of the crankcase. It appears as if a new bearing could be installed without splitting the cases IF the old bearing could be removed. I wonder if any of you has tried it.

regards,

Dalton

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  • 1 year later...

Hello I'm back, I dropped my 349 off for the engine rebuild a couple of weeks ago then when its finished I have another 349 to start on. My back had been giving me a hard time but looks like I will soon be back on a bike frame is getting powercoated have new tank new guards new everything been polishing up the wheels be off to the respoke girl this week. Won't know myself had both of these cots for 10 years collecting the bits and pieces to get them back to their glory.

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