kombivan Posted December 11, 2012 Report Share Posted December 11, 2012 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. Quote Link to comment Share on other sites More sharing options...
jfc Posted December 11, 2012 Report Share Posted December 11, 2012 (edited) 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 December 11, 2012 by jfc Quote Link to comment Share on other sites More sharing options...
jfc Posted December 11, 2012 Report Share Posted December 11, 2012 Points gap 0.4 mm Spark advance at t.d.c 2.5 mm (21deg over flywheel Minimum diametral clearance between piston and cylinder 0.03 mm Maximum whipping crankshaft ends mounted on the crankcase 0.03 mm Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 12, 2012 Author Report Share Posted December 12, 2012 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. Quote Link to comment Share on other sites More sharing options...
andrewb Posted December 12, 2012 Report Share Posted December 12, 2012 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 Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 14, 2012 Author Report Share Posted December 14, 2012 would love a PDF File with the 349 info on it. I used to have a friend that could translate for me but they passed away. Quote Link to comment Share on other sites More sharing options...
andrewb Posted December 14, 2012 Report Share Posted December 14, 2012 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 Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 16, 2012 Author Report Share Posted December 16, 2012 thank you again does anyone know the correct size of the crankshaft main bearings as i have to get some before i drop my bike off. 349 montesa cota 1979. Quote Link to comment Share on other sites More sharing options...
nh014 Posted December 16, 2012 Report Share Posted December 16, 2012 Crankshaft bearings are 25 x 52 x 15, bearing number 6205/C3. Be sure to use C3 bearings for the correct clearances. Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 18, 2012 Author Report Share Posted December 18, 2012 (edited) 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 December 18, 2012 by kombivan Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 18, 2012 Author Report Share Posted December 18, 2012 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" Quote Link to comment Share on other sites More sharing options...
kombivan Posted December 18, 2012 Author Report Share Posted December 18, 2012 If you want any of this info suggest you copy and paste to word document to get a hard copy. Quote Link to comment Share on other sites More sharing options...
oldmonty Posted January 31, 2013 Report Share Posted January 31, 2013 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 Quote Link to comment Share on other sites More sharing options...
kombivan Posted March 8, 2014 Author Report Share Posted March 8, 2014 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. Quote Link to comment Share on other sites More sharing options...
kombivan Posted March 8, 2014 Author Report Share Posted March 8, 2014 yes you can fit main bearings without splitting the case very good idea. Quote Link to comment Share on other sites More sharing options...
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