Installing a magneto in 52 K model

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Re: Installing a magneto in 52 K model

Postby leobrady » Fri Apr 26, 2019 7:10 am

Have a 56 KHK with a Joe Hunt mag. Been running this since 1991. Always starts second kick cold and first hot. Fixed timing with no retard. Sometimes a very small kickback if I am not seriously kicking. Timing is set for best power. 40mm Mikuni pumper.
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Re: Installing a magneto in 52 K model

Postby K Daddy » Sat Apr 27, 2019 5:46 pm

I'm interested in installing a mikuni on my 52 K model.
Is this available as a kit? It seems a lot of parts are needed for this conversion; modified intake, etc.
If no kit, do you have a parts list for this conversion?
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Re: Installing a magneto in 52 K model

Postby jOe » Sat Apr 27, 2019 6:23 pm

Call Kirk at Sportyparts. 714-879-0500. I have two. One on a ‘65 and one on a’62.
The kits are complete. Bolt on to the stock manifold. Air cleaner, assortment of jets,inlet tube and manifold coupling. I think it even comes either the throttle cable.
They work very well, easy to install and work with.
I think it’s the VM38.
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Re: Installing a magneto in 52 K model

Postby K Daddy » Sun May 12, 2019 2:45 pm

wz507
Regarding your recommendations for timing for starting and running, you said
(I would think 10 deg BTDC would be a fine retarded starting position and 25-30 BTDC should be a good running position.)

Wouldn't the timing for starting be 10 deg AFTER top dead center (retarded spark)
and running timing be 25 deg BTDC?
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Re: Installing a magneto in 52 K model

Postby Nitro57xl » Mon May 13, 2019 2:51 pm

Daddy, you are not paying attention! Several people including myself have told you that regarding the spark for starting is not necessary on a k model. Why do you not believe us?
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Re: Installing a magneto in 52 K model

Postby Ferrous_Head » Mon May 13, 2019 5:12 pm

Sportsters are bigger than your 52 K. 750cc versus 993 cc's.They run much higher static compression ratios 8 to 1 Versus 6 to 1.
Yes, a magneto bike is a bit harder to start than battery fed systems. You should be able to kick the K over fast enough to not have a problem with a fixed advance.
The correct timing for an engine is largely a function of the engines efficiency of combustion. The flathead is not a particularly efficient combustion chamber. Neither is a sportster for that matter. That's why the 883's run 45 BTDC.
Is exact ignition timing important ? Well, yes. Too little or too much advance can hurt the engine as well as leading to power loss and orse gas consumption.
With fixed timing you can set the timing using a timing light and get it spot on. It will more or less stay there for a long time after that. With the manual advance systems timing can be a lot more hit and miss.
I would never, ever run a manual advance system like HD's on my race engines, They simply aren't a good idea. The centrifugal advance system is only marginally better and I won't use that either.
"I know only too well the evil that I propose, but my inclinations get the better of me."
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Re: Installing a magneto in 52 K model

Postby wz507 » Mon May 13, 2019 10:20 pm

K Daddy wrote:wz507
Regarding your recommendations for timing for starting and running, you said
(I would think 10 deg BTDC would be a fine retarded starting position and 25-30 BTDC should be a good running position.)

Wouldn't the timing for starting be 10 deg AFTER top dead center (retarded spark)
and running timing be 25 deg BTDC?

No, 10 deg BTDC is plenty late timing to avoid kick-back. 10 deg ATDC would be ridiculously late timing (IMHO) to start the bike.
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Re: Installing a magneto in 52 K model

Postby Noot » Thu May 16, 2019 9:36 am

With all due respect Mr. K Daddy.... Fully retarding the spark on your K with magneto will probably make it more difficult to start than just having your magneto bolted solid in the advanced position. Nitro57xl knows what he's talking about.
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Re: Installing a magneto in 52 K model

Postby Noot » Thu May 16, 2019 9:41 am

....oh, and installing a Mikuni will probably work, BUT - there's so much vacuum and flow with a Mikuni (or Dellorto) that your slide may want to hang up and the rpms won't come down (it will want to run-on at street speeds) You'll think the throttle cable is hanging up - but the problem is the slide spring is too weak to push the slide down. It will snap shut great with engine off - but running it may hang up due to the high flow(suction) of air under the slide. The solution is a stronger (stiffer) slide spring. :D
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Re: Installing a magneto in 52 K model

Postby EKHKHK56 » Thu May 16, 2019 12:38 pm

LINKERTS all other are sacrilegious...There is no need to retard timing before starting. And wanted to say my Joe Hunt Mag is still flawless after 40 years. If you're avoiding kick back do a prime kick or two before turning ignition on. This eliminates lean backfire. Than wind starter crank to just when compression is felt. KHKs and KHs every time... Kick backs are for crooks. And wimpy kicks or lean kicks. KerPow! Erik
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