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#828864 11/04/20 4:56 pm
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Hi there, I just purchased an Electrex ignition for the b50mx that I am building up to race in vmx. Can someone tell me if the coil needs to be grounded? Also do I use the stock crankshaft nut without the tab washer? Thanks.

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Which kit do you have?

If you have room for a tab washer, use it, if not, a dab of red loctite and with the proper torque will be sufficient

Coil needs to be grounded


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Originally Posted by C.B.S
Which kit do you have?

If you have room for a tab washer, use it, if not, a dab of red loctite and with the proper torque will be sufficient

Coil needs to be grounded
Thanks you!

The kit I have is STK-010.

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Thanks for the photo

I have the same unit on my T90 race bike

I did ground the coil (negative ground)

If you can use the tab washer use it, if not, a dab of red loctite and torque will be sufficient


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I have the the STK-010 kit in my hands and I'm ready to install it. I bought it from Peter Quick at BSA unit singles and he mentioned that he's had a few customers set it at 35.5 degrees before TDC rather than 34.

I wondered how you set yours and if you have any advice for a successful install.

I'm having a bit of a hard time following the instructions. The best conclusion I can make is match up the blue mark on the rotor with the blue dot on the stator when the piston is TDC on the compression stroke.

How does one go about setting it up for 35.5 degrees before TDC? Would it be aligning the blue mark on the rotor all the way over with the red dot on the staor when TDC?

John

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Originally Posted by EagleLakeWoodworking
I have the the STK-010 kit in my hands and I'm ready to install it. I bought it from Peter Quick at BSA unit singles and he mentioned that he's had a few customers set it at 35.5 degrees before TDC rather than 34.

I wondered how you set yours and if you have any advice for a successful install.

I'm having a bit of a hard time following the instructions. The best conclusion I can make is match up the blue mark on the rotor with the blue dot on the stator when the piston is TDC on the compression stroke.

How does one go about setting it up for 35.5 degrees before TDC? Would it be aligning the blue mark on the rotor all the way over with the red dot on the staor when TDC?

John


Does your unit have degree #'s on the rotor or stator?

If not, you would have to use a degree wheel

Once you find 35.5 BTDC install the rotor on the firing mark


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Originally Posted by EagleLakeWoodworking
I have the the STK-010 kit in my hands and I'm ready to install it. I bought it from Peter Quick at BSA unit singles and he mentioned that he's had a few customers set it at 35.5 degrees before TDC rather than 34.

I wondered how you set yours and if you have any advice for a successful install.

I'm having a bit of a hard time following the instructions. The best conclusion I can make is match up the blue mark on the rotor with the blue dot on the stator when the piston is TDC on the compression stroke.

How does one go about setting it up for 35.5 degrees before TDC? Would it be aligning the blue mark on the rotor all the way over with the red dot on the staor when TDC?

John
Hi John, I did exactly what you described by lining up the blue dots per the instructions. If you set it like this it is my understanding that it fires at 34* btdc at the red dot.
When I fire mine up the exhaust header almost instantly starts to glow red which I am told is an ignition timing issue (firing to retarded). I just purchased a timing light to check that the red dot on the stator lines up with the mark on the rotor when it gets to 3-4k rpm. Peter Quick also mentioned the 35.5* setting to me also. If when I check with the timing light that the red dot is lined up with the rotor as it should be and it is still running hot I will try the 35.5*.
I am not a fourstroke expert so I'm just going by what people have suggested to me.
Good luck
John.

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IIUC the rotor is not keyed to the shaft, there is a very strong chance that when the rotor is tightened it will be dragged round at least a bit this will retard the timing, what happens if you advance the timing with the pick up plate, ie move it clockwise a degree or two.?


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Originally Posted by gavin eisler
IIUC the rotor is not keyed to the shaft, there is a very strong chance that when the rotor is tightened it will be dragged round at least a bit this will retard the timing, what happens if you advance the timing with the pick up plate, ie move it clockwise a degree or two.?
I checked the timing marks after tightening the rotor and adjusted the back plate to suit. May plan is to do exactly as you mention by moving the back plate 1.5*

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As I recall, the stock timing for the B50 was 34 degrees originally. BSA then sent out a bulletin suggesting that overall performance would improve if the timing was changed to 36 degrees. The bulletin went on to suggest that this could be done without a degree wheel by putting a mark on the trailing edge of the pad that the stock timing mark is located on, and timing the ignition to that. If that is uncomfortable, buy a small plastic protractor (no tool kit is complete without one). and use it to determine the additional 1&1/2-2degree advance.

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John, have you had any luck adjusting your timing? Let us know how it's going.

I installed mine, but I have a few more things to put back together before I can fire it up. I locked it in place on the tapered collar by putting a giant socket over the rotor and giving it one sharp hit with a mallet. After tightening the nut, I again checked TDC with a dial gauge and degree wheel and my blue marks were right on, so fingers crossed. But as others indicated, it should just me a small adjustment clockwise on the stator plate to dial it in.

The wire leads on this kit are a bit short for my liking. I wondered where you decided to mount the CDI?

Thanks
John

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[Linked Image]
Originally Posted by EagleLakeWoodworking
John, have you had any luck adjusting your timing? Let us know how it's going.

I installed mine, but I have a few more things to put back together before I can fire it up. I locked it in place on the tapered collar by putting a giant socket over the rotor and giving it one sharp hit with a mallet. After tightening the nut, I again checked TDC with a dial gauge and degree wheel and my blue marks were right on, so fingers crossed. But as others indicated, it should just me a small adjustment clockwise on the stator plate to dial it in.

The wire leads on this kit are a bit short for my liking. I wondered where you decided to mount the CDI?

Thanks
John

Haven't had a chance to run the bike yet as I am waiting for my son to come over and start it (I'm recovering from a knee replacement). I also found another issue on the cylinder head which is outlined in this other thread that I started on here,
https://www.britbike.com/forums/ubb...ngine-expert-in-so-california#Post843420
There is a short video of my bike running on this thread also. I think you will be fine with how you have set yours up. I mounted the cdi/coil under the tank. My wires seem plenty long enough. I'm interested to hear how yours runs when you fire it up!
[Linked Image]
John.

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Great looking bike John!
It really looks like a ripper. That red hot pipe scares the crap out of me, and I hope you get that squared away with your latest changes.

I wish I had room for the cdi to be hidden under the tank, but I have the 1 gallon tank.

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Originally Posted by EagleLakeWoodworking
That red hot pipe scares the crap out of me, and I hope you get that squared away with your latest changes.
John

High temp silicone is a unit single thing. I have a cheapo pipe expanded that helps but still use a smear of the high temp anyway. I do try to hide it by tooling and the use of a heat sink.

I’m pretty sure John left out the smilie face on purpose.

Gordon

Last edited by Gordon Gray; 04/30/21 11:27 am.

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Low temp silicone seems to work just as well, and available in a range of fetching colours to suit your engines mood. The alloy heat sink covers a few sins too.

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I wrapped PTFE tape on my B40 pipe, it worked a treat.


Now let’s all have a beer beerchug

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When I started building this bike up several people told me that the header needs to be sealed well but it's tricky to seal it. I have been using the high temp silicone on my twostroke racing engines for years with no problems. It seems to be working a treat on the BSA as well but time will tell. I'm not bothered about it being visable as long as it looks tidy and does it's job smile

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