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MKIII 850 commando starting problem

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MKIII 850 commando starting problem

Posted by michael_wallace at February 15. 2017

New fuel,Choke on (single Amal MkII con), started first time and ran great. New battery fitted ign. on then the phone rang. I left the ign. on for at least 15 mins when I returned there was a hot plastic smell. Tried to start to no avail, occasionally firing and now wont start. I have decent sparks (maybe not good enough). So I'm now thinking new plugs and coils. They've not done much mileage but are years old. The plugs quickly get wet so fuel there.

Any suggestions welcome.....not get the Honda out.

Mike

Re: MKIII 850 commando starting problem

Posted by christopher_winsby at February 15. 2017

Previously michael_wallace wrote:

New fuel,Choke on (single Amal MkII con), started first time and ran great. New battery fitted ign. on then the phone rang. I left the ign. on for at least 15 mins when I returned there was a hot plastic smell. Tried to start to no avail, occasionally firing and now wont start. I have decent sparks (maybe not good enough). So I'm now thinking new plugs and coils. They've not done much mileage but are years old. The plugs quickly get wet so fuel there.

Any suggestions welcome.....not get the Honda out.

Mike

Check all electrics. Where did the smell come from? Have you still got the 2MC capacitor? if  original probably due for removal or replacement. Coils can short to case and to frame if not insulated.

I would remove tank and check under for melting and shorts. All depends when last checked out?

Re: MKIII 850 commando starting problem

Posted by john_holmes at February 15. 2017

If you have fuel and sparks then try new plugs, modern fuel fouls plugs really quickly.

 

Whats your ignition,  all the electronic ignitions turn themselves off after a few secs to protect themselves and the coils, with points one coil would have got very hot and maybe damaged, but as you have sparks they should be ok.

Re: MKIII 850 commando starting problem

Posted by Martyn Watson at February 15. 2017

Previously john_holmes wrote:

If you have fuel and sparks then try new plugs, modern fuel fouls plugs really quickly.

 

Whats your ignition,  all the electronic ignitions turn themselves off after a few secs to protect themselves and the coils, with points one coil would have got very hot and maybe damaged, but as you have sparks they should be ok.

Like john says, with a contact breaker system when the ignition is left on and one set of points is closed the coil is continuously energised and will over heat. Also the condensor will be connected across the battery and could fail internally and cause a short.

Spark quality is more important than just a spark.

Re: MKIII 850 commando starting problem

Posted by alan_sessions at February 16. 2017

I kept burning out my mk3 warning light control unit - it gives the smell you describe. If it is shorted inside, you will have a problem - disconnect & isolate all wires to it & you may be able to start. My original fault was done to a couple of duff cells in the battery - I had zeners, rectifier,coils etc checked & they were all OK.

Re: MKIII 850 commando starting problem

Posted by donald_tovey at February 17. 2017

Previously michael_wallace wrote:

New fuel,Choke on (single Amal MkII con), started first time and ran great. New battery fitted ign. on then the phone rang. I left the ign. on for at least 15 mins when I returned there was a hot plastic smell. Tried to start to no avail, occasionally firing and now wont start. I have decent sparks (maybe not good enough). So I'm now thinking new plugs and coils. They've not done much mileage but are years old. The plugs quickly get wet so fuel there.

Any suggestions welcome.....not get the Honda out.

Mike

I did the same thing. It burnt the coils out. I left mine on overnight. A new set of coils sorted my bike out. I run a Boyer system on mine without a power box. It's a question of replacing one item at a time if you don't have the correct tools and the knowledge to use them.

Best of luck, but in sure you will get it going eventually.

Re: MKIII 850 commando starting problem

Posted by christopher_winsby at Saturday 09:43

Previously christopher_winsby wrote:

Previously michael_wallace wrote:

New fuel,Choke on (single Amal MkII con), started first time and ran great. New battery fitted ign. on then the phone rang. I left the ign. on for at least 15 mins when I returned there was a hot plastic smell. Tried to start to no avail, occasionally firing and now wont start. I have decent sparks (maybe not good enough). So I'm now thinking new plugs and coils. They've not done much mileage but are years old. The plugs quickly get wet so fuel there.

Any suggestions welcome.....not get the Honda out.

Mike

Check all electrics. Where did the smell come from? Have you still got the 2MC capacitor? if  original probably due for removal or replacement. Coils can short to case and to frame if not insulated.

I would remove tank and check under for melting and shorts. All depends when last checked out?

If you have not gt one, get your self a cheap multimeter. You can then carry out a lot of basic tests.

Re: MKIII 850 commando starting problem

Posted by michael_wallace at Friday 08:01

Thanks Gents,

I forgot to say I have a new assimilator and fitted with Boyer. So I`ll take the tank off again, check wiring and replace the coils and plugs. Decent multimeter I have already. Spark quality is a valid point.

see you on the road.

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