Building the Lynx15

[JimSvarv]

Maybe run it from the crank as waste spark if it would have any advantage.

 

[Vietti]

You've probably noticed the sensor can be removed from the plastic sleeve. It is very small "3/16x3/16" and can be put where needed, pay attention to which side faces magnet. Good luck

 

[Alan's Home Workshop]

Thanks for the helpful suggestions. It hadn't occurred to me that fixing the sensor would prevent adjusting the timing while the engine was running. This may be an advantage of the Nemett rear mounted design as it appears to allow the sensor housing to be rotated. Unfortunately, running from the crank with a lost spark system like the Webster engine isn't possible here as the crank is single sided with no rear protrusion. Also, the valve timing has to be set by rotating the camshaft pulley, so the option of mounting the magnet in the pulley is not on the table in this case. Accepting that I will only be able to statically set the ignition timing, making a cambox lid with integrated sensor mount is looking like the best option. I think it will need to be 3D printed as the instructions urge using an insulated socket, and shaping a tapered socket with a "D" profile with files would be quite tedious. If I do 3D print, I would use PLA-CF filament. This is pretty tough stuff with a softening temperature a bit higher than PLA and the mounting will not be subject to any external bending force.

 

[Eccentric]

The Prefered method is to have a timing ring attached to the Camshaft pulley with a grub screw. This can be made of Aluminum or even 3D Printed higher temp Plastic (PLA-PC polycarbonite or nylon-CF are good choices). A small 3mm round by 2mm deep magnet is bonded into this ring as shown below. The Grub screw allows you to rotate the slip ring and adjust the ignition timing. Marks on both the timing slip ring and the back of the camshaft pulley would help perform timing and insure at a glance that it has not slipped. The PCB has a three pin connector to the ignition module and contains a hall sensor and pullup resistor like the widely available hall sensor boards available for prototyping. As stated above it is important to make cure the correct side of the magnet points outward. The PCB can be any prototyping board cut to size.

Looking good Alan!

 

[Motorman1946]

For me Alan, I would say option 3 is the cleanest, as it also allows adjustments more safely to the pickup. I would also consider fitting the camshaft with a short extension out the back of the cam box and fitting the disc/pickup there.
Chris

 

[Alan's Home Workshop]

 

[Alan's Home Workshop]

 

[JimSvarv]

Thanks for the series, have been fun to watch both the success and failures.
Hope to see a running video soon! But I guess it's up to the postman when it happens.

 

[Alan's Home Workshop]

Thanks for the series, have been fun to watch both the success and failures.
Hope to see a running video soon! But I guess it's up to the postman when it happens.

Thanks Jim.

 

[Alan's Home Workshop]

 

[Eccentric]

Congratulations Alan. You have done an exceptionally thorough job in your build and troubleshooting of the Lynx15. It was great fun seeing the detailed test setups and special tooling you used to build and validate the engine. I especially enjoyed the setups for validating the valve and ignition timing. It's incredibly satisfying to see an engine I designed, built, and successfully run by someone else. You did a great job as the "guinea pig," building to my plans and helping me troubleshoot the design. You provided invaluable feedback, found several errors in the prints, and helped me redesign a couple of parts to improve manufacturability. For example, your tip for easing the alignment of the cylinder to the crankcase was brilliant. There's nothing quite like seeing an engine you've built from scratch in your own workshop, successfully running. And you've done it! Congratulations again.

Greg