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potto

2 questions for those wiser than me

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I have changed my decompressor so it barely opens,will my 349 Cota start if I setup that way? previously it opened to far and the bike won't start as I think not enough compression?,anyone working this way

As i'am going more trail than trials I would like to fit a headlight,I see a cut black/white wire off the coil wire and presume that's a 12v from the charging system which I again presume is a 12v DC dynamo ??? ,can I run a headlight off that?,if DC I won't need a rectifier correct? (thinks that's right) as most newer bikes are AC.

Have found a semi period correct headlight which should do for my needs.

 

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If you have the decompressor open at all then the bike won't start.  You need to let it go part way through the kick, once over compression.  I had a 348 in tne day and found no need for a decompressor, but there was a technique.  Unless you have an injury or problem that prevents you giving a full kick then you should be able to develop this so you don't need the decompressor.

I'd guess the electrics as 6 volt from memory.

Edited by 2stroke4stroke

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Agree also, no need for decompresser, find tdc, then one good swift drive through on the kick start should do the job. Build  🏋'S

 

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Only my opinion but, you don't use decompressor for starting on 2/S. Used to give a bit of engine braking on the downhills and avoid stalling due to using too much rear brake. Not the same as using one on a 4/S to aid easing over the top of comp stroke before kicking.

 

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1 hour ago, lsv said:

Only my opinion but, you don't use decompressor for starting on 2/S. Used to give a bit of engine braking on the downhills and avoid stalling due to using too much rear brake. Not the same as using one on a 4/S to aid easing over the top of comp stroke before kicking.

 

Thanks all,makes sense ,I know 4 strokes will start with a decomp,never had a 2S with one so reason for asking.

And yes charging system is 6volt as to it being AC or DC I still don't know,I guess when I next start the bike I can test,again I presume a DC system will only develop 6v constant,my Spanish manual says magneto flywheel so think that's the case anyway.

Thanks again :).

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2 hours ago, lsv said:

Only my opinion but, you don't use decompressor for starting on 2/S. Used to give a bit of engine braking on the downhills and avoid stalling due to using too much rear brake.

 

Also the most reliable way of stopping an over-revving engine.

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6 hours ago, cleanorbust said:

Also the most reliable way of stopping an over-revving engine.

That's SO true,if the bike falls over ,I'am keeping it as I have no kill switch also,think its handy to have besides,have stripped the valve cleaned it and relapped it,new cable bought today,levers a bit poo made of "muck metal" so may replace it later.

Headlamp is 35w 6V hope I can find one that works in a later 12v headlight :(.

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If you want an easy way to ride your Cota at night and don't need to get road registration, you can use a cheap LED light bar that will fit across the front of the fork tops, do a great job of lighting the way and not be sensitive to voltage.

Bikes like yours can be started with the de-compressor engaged, if you use the type that are fitted to some chain saws. This type are "cocked" by hand prior to starting the motor, and as soon as the motor fires, they snap shut automatically. A friend has fitted one on his 325cc Italjet in an effort to prolong the life of the notoriously weak kickstart shaft, and it works beautifully. No good as a kill switch though!

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11 hours ago, feetupfun said:

If you want an easy way to ride your Cota at night and don't need to get road registration, you can use a cheap LED light bar that will fit across the front of the fork tops, do a great job of lighting the way and not be sensitive to voltage.

Bikes like yours can be started with the de-compressor engaged, if you use the type that are fitted to some chain saws. This type are "cocked" by hand prior to starting the motor, and as soon as the motor fires, they snap shut automatically. A friend has fitted one on his 325cc Italjet in an effort to prolong the life of the notoriously weak kickstart shaft, and it works beautifully. No good as a kill switch though!

Thanks,just plan to have a headlight only,bike will never be made road legal,hot tip on the chainsaw decomp sounds like the ticket for me,I guess it would have to be modified to fit with the 14mm plug thread?? do you have any other details by any chance?,cheers.

Edit.... have googled chainsaw decomp valves and appears they are a fairly small thread,appears 9mm and 10mm are common,I will most likely use an old 14mm sparkplug and make an adaptor,will visit local small engine place tomorrow,will update .

Edited by potto
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3 hours ago, potto said:

Edit.... have googled chainsaw decomp valves and appears they are a fairly small thread,appears 9mm and 10mm are common,I will most likely use an old 14mm sparkplug and make an adaptor,will visit local small engine place tomorrow,will update .

Might want to check out Royal Enfield decompression valve on eBay, might save you some work and $$

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19 hours ago, oldaz said:

Might want to check out Royal Enfield decompression valve on eBay, might save you some work and $$

Thanks but that's the type I already have,I need the chainsaw one as it self closing when the engine fires,have been researching and the big bore 2S VMX guys are using them to good effect,appears many of these bikes have weak kickstarts,I did find one for Montesa,Bultaco Maico and others for 14mm plug thread but it was crazy money and only a modified chainsaw one.

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22 hours ago, potto said:

Thanks but that's the type I already have,I need the chainsaw one as it self closing when the engine fires,have been researching and the big bore 2S VMX guys are using them to good effect,appears many of these bikes have weak kickstarts,I did find one for Montesa,Bultaco Maico and others for 14mm plug thread but it was crazy money and only a modified chainsaw one.

Picked up a chainsaw decomp valve yesterday,10 x 1mm thread ,plan is to gut out old 14mm long reach plug drill and tap it for the valve should work.

My spares arrived from In Motion yesterday (thanks Pete) ,new Venhill clutch cable is a gem...well made item didn't know how knackered my old one was ,very close to breaking @ the clutch arm end.

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