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Cota 247 Motoplat Ignition Set-Up... Clueless!


riffraffretro
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I started with the kill switch, because I only put it on a couple of weeks ago, and moved it when putting on a new clutch lever ... but it's working normally.  With the black lead off the coil it reads as grounded for a full rotation, but I could be missing something or not reading it right.

I'll be pulling the flywheel later and having a nose around, I only need it to run for one day then the engines coming out for new mains!

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I can't imagine getting my 247 running (not even for one day), despite working through pretty much, every conceivable reason for it not starting (notwithstanding spending a serious amount of cash in the process).

I've resigned myself to the fact that it makes for a pretty decent storage shelf in the garage, but not a great deal else.

Edited by riffraffretro
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I forgot to update this - having pulled the flywheel, I found a little sliver of wire floating around ... no idea where it came from, as all the stator wires are nice and tidy, and nothings been catching.

I cleaned everything I could find and put it all back, and it worked just fine for my other half to do a trial on Sunday - the engine is now out.

@riffraffretro - sorry to hear that, maybe it's time to start spending money, though :huh:

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7 hours ago, riffraffretro said:

I can't imagine getting my 247 running (not even for one day), despite working through pretty much, every conceivable reason for it not starting (notwithstanding spending a serious amount of cash in the process).

I've resigned myself to the fact that it makes for a pretty decent storage shelf in the garage, but not a great deal else.

 

Don't give up on it just yet, brother.  Contact point ignition systems are pretty simple critters, and I'm willing to bet that the problem will be simple and silly and you are close to nailing it even if it means spending a little $$. 

Oh, and you have been misinformed.  These things make terrible storage shelves. I currently only have two non-runner Trials bikes in the scuderia (a 1972 Montesa 25 and a 1977 247 in boxes), and they don't shelve stuff worth a damn.  :lol:

Edited by brewtus
Forgot about the box turtle 247
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15 hours ago, riffraffretro said:

I can't imagine getting my 247 running (not even for one day), despite working through pretty much, every conceivable reason for it not starting (notwithstanding spending a serious amount of cash in the process).

I've resigned myself to the fact that it makes for a pretty decent storage shelf in the garage, but not a great deal else.

Does it run at all or completely dead?  They are very basic machines   - so start with the basics - is it fuel or is it spark.  

If it is spark - is there any spark at all?  If there is spark is it strong enough - make sure yo have gap correct ie: standard plug setting is too wide

If it's fuel and it won't kick at all - then what have you done already ... the Amal is notorious but once set up correctly it will run for years

Other things to check are compression and leak down - engine seals are a common problem.

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Thanks Keychange

I've replaced and relocated the condensor (adjacent to the coil, correctly earthed), replaced the points and adjusted within spec using a TDC tool, correctly fitted and torqued the flywheel and replaced the plug - again, correctly adjusted. There appears to be a decent spark (none prior to replacement of the condensor and points).

Additionally, I've replaced the spark plug cap, cleaned the Amal carb and replaced the fuel line.

After a few kicks, the plug base becomes saturated with fuel (pre-mix of Unleaded and Castrol Power 1 at 50:1), and the kicking action offers sufficient resistance to indicate adequate compression.

I've even attempted bump starting (too many times to mention), but it's still dead and refuses to start!

Wondering what else to do next, or whether she'll remain as a handy garage shelf/storage platform, until I get adequately miffed to set fire to the lot/break the bas*ard for parts and by a 300RR!

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Ok so you have spark and even if the timing wasn't perfect it should fire unless it is too advanced so err on retarded if you check again. 

The 247 doesn't have much if any gear reduction on the kick starter and is notoriously hard to kick and easy to bugger the starter gear ( which you cannot find replacements for ).  I use a decompression valve on the spare plug.  I  have an old Yamie XT250 with no decompression  valve and Cota  takes twice as much kick as the Yammie ..  So your assumption that compression is good just based on kick strength may not be correct.  

I assume you have tried a fresh plug - even if it looks perfect  and I repeat the gap is critical 0.4mm as the old ignition system can't throw a spark any further when under compression - so just because you have spark with plug removed does not mean it will spark when installed.  

My 247 can be hard to start when cold - so after a couple of  tickles I turn fuel off so as not to soak the plug.  It can take 20 kicks to fire when cold ( decompression valve invaluable ) but once warm will generally start first kick.  Why not try some starter spray just to see if it fires - then you will know if fuel/carbie is the issue.

 

 

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Personally I think 50:1 is not a good idea on an old engine - the old bearing aren't remotely comparable to modern engines.   You may have to lean off the mixture as you are delivering 2% more fuel ..not sure if that is significant or not.  That oil  "is for use in modern, high speed, high performance 2-stroke engines."   I would seek advice as to how suitable for an old, low performance, piston port engine.

Edited by keychange
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Thanks for the pointers again guys... genuinely appreciated.

I'm confident that the timing is adjusted correctly (checked, double-checked and checked again), so will try a few variations on starting technique (fuel on, tickle carb, fuel off), starter spray and perhaps fitment of a decompression valve, in the hope that something bears fruit.

Thereafter, it'll be off with the head to check the top end, followed by engine removal and strip, should nothing improve. And, all from a bike advertised as needing "Oils and a fettle to make perfect"!

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On ‎08‎/‎12‎/‎2017 at 2:04 AM, keychange said:

Personally I think 50:1 is not a good idea on an old engine - the old bearing aren't remotely comparable to modern engines.   You may have to lean off the mixture as you are delivering 2% more fuel ..not sure if that is significant or not.  That oil  "is for use in modern, high speed, high performance 2-stroke engines."   I would seek advice as to how suitable for an old, low performance, piston port engine.

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50:1 with a modern oil is fine, it offers a greater film strength that the oils from the 70s don't, that why you can run at 50:1 instead of the mainly 20:1 the old oils needed. 

back on topic, how good is the spark, some look fine, but once in the engine and getting the fuel/air mix, it's just not good enough to fire the engine up.

Id fit an electronic ignition if it was mine 

Edited by shakennstirred
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I'm beginning to wonder if the problem is down to a weak/insufficient spark.

I'm toying with the idea of fitting an Electrex CDI ignition system, but am getting miffed at constantly sinking cash and time into a bike that hasn't turned a wheel since purchase! If something doesn't give I'll likely torch the thing/set to it with a sledge  hammer!

The alternative is to spend out on something new(er) and go enjoy the winter!

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