Author Topic: Magneto puller for BS 50 Sport  (Read 5830 times)

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Offline CL-100

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Magneto puller for BS 50 Sport
« on: May 24, 2015, 05:50:53 PM »
I'm looking to purchase a magneto puller that will fit the magneto flywheel on a Bridgestone 50 Sport.  I've checked the forum and can't find anything on the 50.  Looks like a 27mm left hand thread puller works on the 90/100.  I've checked part numbers for magnetos on the 50 and the 90/100's and they differ. 

Anyone know what size puller works on the 50 and if it's also left-hand threaded?  There seem to be a lot of combination pullers that are both 27mm and 24 mm.  The 27 is left threaded, the 24 is not.

Thanks for any and all help.

Rowland

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Re: Magneto puller for BS 50 Sport
« Reply #1 on: May 25, 2015, 10:39:23 PM »
Rowland,
When you have some time send me a picture of your flywheel.
I have all the pullers but i have never worked on a 50 Sport.
Thanks.
Steve.

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Re: Magneto puller for BS 50 Sport
« Reply #2 on: May 26, 2015, 06:13:38 AM »
Hi, Rowland,

Yes, the puller screws into the flywheel on  a left-hand thread - although I'm not sure of the exact diameter. The same type of magneto was, however, used on pretty much all the Japanese fifties back in the day. The Honda C100 Cub and its derivatives used the same mag, as did the Suzuki M12/M15/M30 and the Suzuki AS50/A50 series, (The Yamaha YF1 and YG1 most likely used the same mag, but I've got no personal experience of those bikes so I can't be sure).

Pullers suitable for the C100 and M12 are available here in the UK, so I guess they should also be obtainable in the US without too much trouble.

Hope that helps,

Graham

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Re: Magneto puller for BS 50 Sport
« Reply #3 on: May 26, 2015, 07:28:51 AM »
Steve and Graham,

Thanks for your help.  I'll post a picture of the flywheel later today.  Last night I got my caliper out and tried to measure the threaded opening in the center and it appears to be 27mm.  I'm not sure why I didn't think of it earlier but I'll also measure the magneto on my 100 and see how that compares. 

The 50 has a real weak spark compared to the spark on my 100 and the points look burnt.  I'll also test the coil and the condenser to see what I come up with.  I hope the condenser is OK.  They look like they'll be hard to find. 

I'll have a magneto picture posted this afternoon. 

Rowland

Offline disc_valve

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Re: Magneto puller for BS 50 Sport
« Reply #4 on: May 26, 2015, 11:14:11 AM »
It's me again, Rowland!

I've dug out my BS50 puller and measured the thread - it's 27 *1.0mm pitch, left hand thread. The puller body screws into the flywheel and there is a long 10mm bolt in the centre of the puller that tightens against the end of the crank. If the flywheel hasn't been removed for a few year, it might be a bit tight. Tighten the puller central bolt and if the flywheel doesn't want to  shift, try giving the bolt head a few whacks with and engineer's persuader (i.e a hammer) to jar the flywheel free from the taper.

The flywheel used on the 90/100cc engines is a different design. There are three 6mm threaded holes around the edge of the flywheel centre. The puller consists of a thick circular plate (in my case, about 1/2" thick) with three bolts around the edge that locate in the threaded holes in the flywheel. There is then another 10mm bolt in the centre that bears against the tip of the crank. The only thing to watch here is, don't screw the 6mm bolts more than about 3 or 4 turns into the flywheel - otherwise they could poke through and damage the magneto coils.


Graham

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Re: Magneto puller for BS 50 Sport
« Reply #5 on: May 26, 2015, 02:22:32 PM »
Thanks Graham (aka BS guru).

I appreciate the time and effort you spent researching my question.  I had started looking for a 27mm puller when you posted your latest reply.  I took the points cover off of my 100 and saw the three 6mm holes for the puller.  I bought one of these pullers a long time ago and forgot that I had it in my parts bin.  As you can see from the picture I've attached, the BS50 flywheel is different (as you stated) which helps me understand the differing part numbers as well as the need for a different style puller.  I also happened to notice that the points and condenser on the 50 and the 100 are placed differently on the timing plate.  The condenser looks the same for both bikes and has the same green, blue, and black wires attached to the condenser. 

Steve, I've attached the picture of my flywheel for you to see the differences between the 50 and 90/100 flywheels.  It looks like the puller you recommended in an earlier thread (on a 90 I think) is the one that also works for my 50.

I'll be shopping online this afternoon.  They're only about $15.  Less if you want to wait for one from China.

Thanks again to you guys for the help.

Rowland


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Re: Magneto puller for BS 50 Sport
« Reply #6 on: May 29, 2015, 06:54:47 AM »
Yes, that looks just like a BS50 Sport magnetos! The points and condenser are both the same as the corresponding 90 parts, and are also the same as M12/K10 Suzuki parts should you come across any of those at e swap meet.

I hope you soon have the little beastie popping away - it's no ball of fire, but the 50 is a sweet little motor and fun to ride - as long as you don't try riding more than 30 miles or climbing too many mountain passes!

Cheers,

Graham

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Re: Magneto puller for BS 50 Sport
« Reply #7 on: May 29, 2015, 02:00:00 PM »
Graham,

Thanks for the info on compatible condensers.  I hope to get it running well and then tear it down for a good cleaning.  It's in pretty nice shape for a 50 year old bike.

Rowland

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Re: Magneto puller for BS 50 Sport
« Reply #8 on: May 29, 2015, 02:37:21 PM »
I just got my 50 Sport (1965) back together and running about 2 weeks ago. I've been meaning to get a few pictures and post them now that its done. It runs great after a full motor rebuild. It hits 40 mph pretty easy on flat ground with 200 lbs of rider on it. No speed records but its fun to run around on.
1966 175 DT and 1968 350 GTR

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Re: Magneto puller for BS 50 Sport
« Reply #9 on: May 30, 2015, 09:11:04 AM »
That sounds about right on performance, and it's down to 32mph in 3rd gear up a steady grade. Who needs ton-up machinery?

Graham

 


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