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Model 50 running

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Model 50 running

Posted by conan_fryer at October 08. 2017

I am new to the club, and am after some basic advice please, from anyone with the knowledge. My M50 '58' is a joy to ride, but I regularly need to change a sooty plug. I am running super unleaded, on full advance when riding with 25% air as she likes best. I am using the valve lift to stop the engine running. Does that all sound correct? Thank you

Re: Model 50 running

Posted by robert_tuck at October 08. 2017

Air (choke) slide should only be used for starting, if its needed to stop spitting back then the main slide or carb body is probably a bit worn, if the choke is used when warmed up or at medium to large throttle openings you will soot up plugs ,once sooted modern plugs can be reluctant to burn themselves clean notwithstanding how fancy or exspensive they are due to the lack of glaze on the insulator (deemed not needed with clean running computer controlled systems that everything now has), WHAT! your not still running a carb are you!!?.Imagine that how old hat.

Re: Model 50 running

Posted by Neil Wyatt at October 08. 2017

Previously conan_fryer wrote:

I am new to the club, and am after some basic advice please, from anyone with the knowledge. My M50 '58' is a joy to ride, but I regularly need to change a sooty plug. I am running super unleaded, on full advance when riding with 25% air as she likes best. I am using the valve lift to stop the engine running. Does that all sound correct? Thank you

 

Welcome to the club, Conan,

Another 57/58 single owner / member. How about a decent spares back up, EC? Silence is deafening!

OK, 25% air will be one reason why your plug might be sooting up.  The bike should be set up so that you need no choke once warmed up. Plug colour should be light brown or there abouts.

It would help to know what carb you are using the cutaway and main jet. (Needle and pilot settings then adjusted to suit)

I run a 1960 Model 50 engine using a Mk 1 626 carb, No3 cutaway and 210 main jet.  The thing is that these are only guidelines as every bike is different. The engine runs beautifully.

Using the valve lifter to stop the engine was the standard method before ignition switches and mag cut outs.

Your ideal plug is a Champion N5.

To early to say at this stage if your ignition timing and mag are factors, get the carburration right first.

Let us know how you are getting on with more detail.

Good Luck.

 

Re: Model 50 running

Posted by conan_fryer at October 08. 2017

Previously Neil Wyatt wrote:

Previously conan_fryer wrote:

I am new to the club, and am after some basic advice please, from anyone with the knowledge. My M50 '58' is a joy to ride, but I regularly need to change a sooty plug. I am running super unleaded, on full advance when riding with 25% air as she likes best. I am using the valve lift to stop the engine running. Does that all sound correct? Thank you

 

Welcome to the club, Conan,

Another 57/58 single owner / member. How about a decent spares back up, EC? Silence is deafening!

OK, 25% air will be one reason why your plug might be sooting up.  The bike should be set up so that you need no choke once warmed up. Plug colour should be light brown or there abouts.

It would help to know what carb you are using the cutaway and main jet. (Needle and pilot settings then adjusted to suit)

I run a 1960 Model 50 engine using a Mk 1 626 carb, No3 cutaway and 210 main jet.  The thing is that these are only guidelines as every bike is different. The engine runs beautifully.

Using the valve lifter to stop the engine was the standard method before ignition switches and mag cut outs.

Your ideal plug is a Champion N5.

To early to say at this stage if your ignition timing and mag are factors, get the carburration right first.

Let us know how you are getting on with more detail.

Good Luck.

 

Thank you for your welcome and good help.

I will keep you posted. The air setting was advised from an old manual. I may have misread.

Re: Model 50 running

Posted by conan_fryer at October 08. 2017

Previously robert_tuck wrote:

Air (choke) slide should only be used for starting, if its needed to stop spitting back then the main slide or carb body is probably a bit worn, if the choke is used when warmed up or at medium to large throttle openings you will soot up plugs ,once sooted modern plugs can be reluctant to burn themselves clean notwithstanding how fancy or exspensive they are due to the lack of glaze on the insulator (deemed not needed with clean running computer controlled systems that everything now has), WHAT! your not still running a carb are you!!?.Imagine that how old hat.

Thank you :)

Re: Model 50 running

Posted by conan_fryer at October 08. 2017

Previously Neil Wyatt wrote:

Previously conan_fryer wrote:

I am new to the club, and am after some basic advice please, from anyone with the knowledge. My M50 '58' is a joy to ride, but I regularly need to change a sooty plug. I am running super unleaded, on full advance when riding with 25% air as she likes best. I am using the valve lift to stop the engine running. Does that all sound correct? Thank you

 

Welcome to the club, Conan,

Another 57/58 single owner / member. How about a decent spares back up, EC? Silence is deafening!

OK, 25% air will be one reason why your plug might be sooting up.  The bike should be set up so that you need no choke once warmed up. Plug colour should be light brown or there abouts.

It would help to know what carb you are using the cutaway and main jet. (Needle and pilot settings then adjusted to suit)

I run a 1960 Model 50 engine using a Mk 1 626 carb, No3 cutaway and 210 main jet.  The thing is that these are only guidelines as every bike is different. The engine runs beautifully.

Using the valve lifter to stop the engine was the standard method before ignition switches and mag cut outs.

Your ideal plug is a Champion N5.

To early to say at this stage if your ignition timing and mag are factors, get the carburration right first.

Let us know how you are getting on with more detail.

Good Luck.

 

The manual page is attached. It does seem to say run with air open?

Attachments

Re: Model 50 running

Posted by Bob Matthews at October 08. 2017

From the manual you've attached it says this -

(Air Lever.  On the right handlebar.  Close or partly close when starting from cold.  Open as soon as engine will run properly with full air.  Should remain open for normal running.

Air Open, i.e.  the coke is off (fully raised).

Re: Model 50 running

Posted by Neil Wyatt at October 08. 2017

Spot on Bob.

Re: Model 50 running

Posted by John Shorter at October 08. 2017

 If you need to partly close the air lever, with a warm engine, you may have too small a main jet.   Over compensating for this would possibly be the cause of the plug sooting up the plug.

Re: Model 50 running

Posted by richard_payne at October 08. 2017

Perhaps an unneccessary comment, but choke 'off' i.e. normal running is with lever pulled right back (assuming it's on the right hand handlebar) and pushed forwards to let the choke slide downwards for starting.

Under normal running, choke is held off by the tight wire.

Lots of owners used to other systems have been fooled at first acquaintance.

Re: Model 50 running

Posted by conan_fryer at October 08. 2017

Previously Bob Matthews wrote:

From the manual you've attached it says this -

(Air Lever.  On the right handlebar.  Close or partly close when starting from cold.  Open as soon as engine will run properly with full air.  Should remain open for normal running.

Air Open, i.e.  the coke is off (fully raised).

 

Thank you Bob. I am new to this game, being more used to modern bikes. Am enjoying the learning, and appreciate the help.

Re: Model 50 running

Posted by conan_fryer at October 08. 2017

Previously richard_payne wrote:

Perhaps an unneccessary comment, but choke 'off' i.e. normal running is with lever pulled right back (assuming it's on the right hand handlebar) and pushed forwards to let the choke slide downwards for starting.

Under normal running, choke is held off by the tight wire.

Lots of owners used to other systems have been fooled at first acquaintance.

 

Thank you, that's very helpful. It is on the right side, so pulled towards rider is cable tight and open/off = normal running warm as I read this.

Re: Model 50 running

Posted by richard_payne at October 08. 2017

That's correct and in normal running there is no reason to have it other than fully open. It is an 'automatic' carb. If you go back to vintage days, then it was necessary to juggle with air and fuel levers.

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