WD Motorcycle forum

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Jan 24, 2016 - 5:47AM

M21 timing

Hi all...is the timing procedure, caps etc for the m20 the same for the m21. As I am using a NGK B5ES spark plug is that correct plug for a m21 with alloy head?

Ron Pier

Jan 24, 2016 - 8:34AM

Re: M21 timing

I can't answer about the plug number, but I always prefer Champion plugs anyway. But timing is the same for both M20/21 ie 7/16" BTDC with the lever set at full advance.

Ron

email (option): ronpier@talk21.com

trevor

Jan 24, 2016 - 10:35AM

Re: M21 timing

And I run BP5HS in my iron head M20 so they should be fine in an M21
Try a BP5ES.
The projecting electrode plugs do run better with the sparingly flamable effluent sold as fuel now days

email (option): bsansw1@tpg.com.au

Ron Pier

Jan 24, 2016 - 11:16AM

Re: M21 timing

Don't the ally heads require a longer reach plug than an iron head Ron

email (option): ronpier@talk21.com

Ian Wright

Jan 24, 2016 - 11:35AM

Re: M21 timing

They do...A Champion N5C plug or equivalent for the alloy head...

There is no need to change from the standard grade...I've run the N5Cs in mine for years...

If you are changing from an iron head to an alloy one don't forget the alloy head uses 10 bolts that are the length of the 5 longer ones used with the iron head....Ian

email (option): ian@wright52.plus.com

bryce

Jan 24, 2016 - 12:36PM

Re: M21 timing

thanks for the help

trevor

Jan 25, 2016 - 12:04AM

Re: M21 timing

Ron Pier

Don't the ally heads require a longer reach plug than an iron head

Ron

With NGK's the letter after the number is the length.
ie,-
E for 3/4"
H for 1/2"

email (option): bsansw1@tpg.com.au

Ron Pier

Jan 25, 2016 - 8:51AM

Re: M21 timing

trevor

Ron Pier

Don't the ally heads require a longer reach plug than an iron head

Ron

With NGK's the letter after the number is the length.
ie,-
E for 3/4"
H for 1/2"

That answers that one then. I know little about post war M20's and never studied the NGK plug range as I only use Champion plugs.

Ron

email (option): ronpier@talk21.com

Ian Wright

Jan 25, 2016 - 10:45AM

Re: M21 timing

You're not alone Ron, I share your ignorance of the NGK range..I've always used Champion plugs as well..(apart from a brief period with Bosch)...Ian

email (option): ian@wright52.plus.com

trevor

Jan 25, 2016 - 3:08PM

Re: M21 timing

When Leyland were still making cars down here we had a Champion plug factory at Alexandria and Champion was the dominant brand.
They also made the Motocrafts for the local Fords and whatever GMH were fitting into Holdens.
When Leyland closed, the Champion factory followed suit and all spark plugs were imported.
NGK replaced Champion almost overnight.
I stock all 38 grades of Champions that my wholesaler sells but none are the grades used in motorcycles, despite a motorcycle engine being virtually a lawnmower engine on 2 wheels
However in the 67 grades of NGK's they sell, I can get equivalent to most Champions so thus I run NGK.
The only down side is for any 1 heat gade of Champions there are generally 3 or more NGK's and they are a bit fussy about the range they will work in.

email (option): bsansw1@tpg.com.au