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sherpat250

Cota 247: Spark, Compression, Fuel, but won't start!

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Hi all,

Just picked up on non-running Cota 247 (1975-ish), and would like to get it going. It has decent compression, good spark (at least outside the cylinder on the two plugs I tried), and it is getting fuel. I even tried a shot of ether starting fluid in the carby and cylinder, but it won't even pop...nothing at all. Any ideas on what to check?

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If you have a clean carb, fresh fuel and a new plug and timing is right I would suspect the crankcase oil seal behind the ignition, take the back plate off and look for tell tale signs of fuel leaking out if you have been kicking/bumping enough. Has the bike been stood for a long time, if so change the seals as they go hard inc the clutch side. Is the spark strong,if not could be suspect ignition. I don't get involved with Monts t b h but a 2 stroke is fairly straight forward.

Edited by bo drinker

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The 247 is a simple two stroke but from my experience can be tricky. Yes it could be the engine seals but do the simple things first.

1. make sure you are using a fresh plug and you have the gap set correctly - too wide and the spark fails under compression. The gap should be 0.40mm or .0157"

2. make certain that the timing is correct ie: 2.5 mm btc or 21 degrees - if you have it too far advanced (and it doesn't take much) it can be a bugger to get it to kick

3. make sure your carbie is clean - real clean. Mainly check the idle jet and make sure you tickle the carbie (there is no choke) - of course make double sure the air cleaner is clean

4. check for air leaks between the carbie and the barrel - these are common on Amal carbies as people tighten the nuts too much and cause the carbie flange to buckle (this can be easily fixed)

Finally the 247 can be a brute to kick over which places a lot of stress on the kick start gear especially when you are troubleshooting - replacements are not available so spend $30 and buy yourself a compression release - this will avoid damaging the kick start gear.

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I forgot the air leak at the carb manifold. The only Mont I ever owned suffered from this due to it being over tightened at some point before I owned it. :thumbup:

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I forgot the air leak at the carb manifold. The only Mont I ever owned suffered from this due to it being over tightened at some point before I owned it. :thumbup:

I agree with all the above but check the kill switch and all the earths, and she will go good luck

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One more thing that no one has mentioned. Make sure that the flywheel key has not sheared. They were prone to do that and makes the timing to go out of whack and virtually impossible to start.

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Thanks for these excellent ideas. I wondered myself about the timing of the engine. I never touched it, but it's possible the previous owner had it way, way off. This might explain no firing at all, even with starting fluid in the cylinder. I will be sure to check it out. One more quick question...how does the decompression kit install on the engine? Does it use the alternate spark plug hole that Cota's have?

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Yes the decompression valve screws into the spare plug and you have a small lever on the bars. As an added advantage you can use this as an engine compression brake going downhill - it reduces the back wheel locking up and produces a very popular loud farting noise :shutup:

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I bet you talked the previous owner into pulling it off Ebay...I had a pretty high bid ready to roll with Esnipe, and the auction evaporated.

I have a low opinion of people who pull auctions, especially when they lie and say they decided to keep the item.

Oh, well.

1-Just because a plug sparks outside of the cylinder, doesn't mean it'll spark inside.

Install a fresh plug.

Also...a plug will look like it's firing well out of the cylinder if the condenser is shot.

Change the condenser.

Hang it off the coil instead of burying it behind the flywheel.

Condensers have a shelf life and they're getting old...it pays to make them easier to change.

Check your clutch adjustment.

The slightest bit of slip can go unnoticed while kicking, but it'll keep the motor from turning enough to start.

So...how much did you pay?

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I'd like to thank everyone for the additional tips & comments. I plan to work on the bike over Christmas vacation, and will report back on what I find. One update--I did check the compression with a gauge and it is 90 PSI. That seems adequate, but I don't know if it's as high as it should be. Any further comments would be appreciated.

With respect to statement that I may have "talked the previous owner into pulling it off Ebay", that is not accurate, and I have sent an e-mail to the writer explaining the circumstances by which I came to own the machine. In short, I bought it after seeing it offered for sale at a trial event in NY, and my transaction never involved eBay. Best holiday wishes to all.

I bet you talked the previous owner into pulling it off Ebay...I had a pretty high bid ready to roll with Esnipe, and the auction evaporated.

I have a low opinion of people who pull auctions, especially when they lie and say they decided to keep the item.

Oh, well.

1-Just because a plug sparks outside of the cylinder, doesn't mean it'll spark inside.

Install a fresh plug.

Also...a plug will look like it's firing well out of the cylinder if the condenser is shot.

Change the condenser.

Hang it off the coil instead of burying it behind the flywheel.

Condensers have a shelf life and they're getting old...it pays to make them easier to change.

Check your clutch adjustment.

The slightest bit of slip can go unnoticed while kicking, but it'll keep the motor from turning enough to start.

So...how much did you pay?

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I'd like to thank everyone for the additional tips & comments. I plan to work on the bike over Christmas vacation, and will report back on what I find. One update--I did check the compression with a gauge and it is 90 PSI. That seems adequate, but I don't know if it's as high as it should be. Any further comments would be appreciated.

90 psi sounds low - mine was 135 last time I checked. When you check your rings don't be fooled by the wide ring gap which is around 2mm+ - that is normal. If you need new rings and have trouble finding them the standard size is 72.5mm x 0.75mm - 0.80mm thick (this thickness is very important as there are other Monty rings that are twice that thickness and they will not fit). I got mine from John Haberbosch of Rocky Mountain Montesa USA - john@rmmontesa.com standard rings number 2160.022 were $25.00 a set.

Have fun over Xmas - I can't think of a better way to spend a cold winters day ... we will be at the beach :)

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Flywheel woodruff keys shear on these bikes, pull the flywheel and check its a classic Mont problem. Always buy the proper key as they a chamfered, I recently obtained a Cota 200 cheep due to the same problem. Lap the flywheel onto the crank with valve paste before refitting for a tight fit on the taper.

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I'd like to thank everyone for the additional tips & comments. I plan to work on the bike over Christmas vacation, and will report back on what I find. One update--I did check the compression with a gauge and it is 90 PSI. That seems adequate, but I don't know if it's as high as it should be. Any further comments would be appreciated.

With respect to statement that I may have "talked the previous owner into pulling it off Ebay", that is not accurate, and I have sent an e-mail to the writer explaining the circumstances by which I came to own the machine. In short, I bought it after seeing it offered for sale at a trial event in NY, and my transaction never involved eBay. Best holiday wishes to all.

Sorry 'bout that, Kev...

Bad choice of words about 'talking the owner into ...."

Any bad feelings I have/had about the situation are definitely directed towards the guy who had it on Ebay and pulled the auction.

Enjoy the bike!

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One more thing that no one has mentioned. Make sure that the flywheel key has not sheared. They were prone to do that and makes the timing to go out of whack and virtually impossible to start.

I don't believe it - I have just shorn my flywheel key :(

Can someone tell me where to source a replacement engine # 21M23540 and;

how do I get the shorn off remnant out of the shaft - is dead smooth and tight as.... I tried a very powerful magnet ...other ideas?

Should I replace the spring washer - it appears tired to me and are left hand spring washers widely available?

Edited by keychange

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