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Throttle governed engine.

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  • Good --- what about the coil demand from running two plugs ?

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    • The coil is off a 2 cylinder snowmobile engine. It has two separate take off wires that fire simultaneously. It is working alright.
      Brian Rupnow

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      • and your powering the coil with the exact voltage and supply you used long ago when the engine ran good? what do you gap the plugs at Bri?

        its a shame cuz i did see the original vid of long ago and the little guy seemed somewhat happy in the higher RPM range...

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        • Here we have two new cylinder heads, which almost entail a full days work. Notice that the sparkplugs have been moved a lot closer to the side of the head which the manifolds bolt to, which places them high above the bottom of the cylinder bore. I still have to make valves, valve guides, rocker arms and brackets but I'm happy with these. I never noticed how dirty the business end of that sparkplug was until after I had taken the picture.
          Brian Rupnow

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          • That's just so fast Brian - you no more than think it and it's built... kudos

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            • Originally posted by A.K. Boomer View Post
              That's just so fast Brian - you no more than think it and it's built... kudos
              That's kind of what I was thinking.........he dreams about in his sleep, and wakes up and.....poof, there it is !!!

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              • Originally posted by Ringo View Post

                That's kind of what I was thinking.........he dreams about in his sleep, and wakes up and.....poof, there it is !!!
                It's what makes him the most prolific builder on any of the home shop forums, and if you noticed, he's active on most of them.

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                • This mornings offering to the machine Gods is four brass valve cages. These cages get Loctited and very lightly pressed into the cylinder heads. The 0.125" thru hole and the 0.25" hole are both put in in the same set-up to guarantee concentricity. The one on the left was about .002" undersize so I knurled it lightly, which increases the diameter by about 0.010", then turned it down to the correct dimension. After the Loctite sets up (preferably overnight) I will use my George Britnel inspired valve seat cutting tool to put the 45 degree chamfer in the area where the valves seat.
                  Brian Rupnow

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                  • I spent the afternoon making the main bases of the rocker arm support brackets. Tomorrow I will have to build a welding jig to hold all of the vertical legs of the brackets in the correct place before silver soldering the brackets together.
                    Brian Rupnow

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                    • Just had a very valvey morning. I leave the long end unturned to act as a handle while I am lapping them. Then I drill the cross holes,then I part off the handles.
                      Brian Rupnow

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                      • So, the valves, valve cages and valve spring retainers are finished. The valves have been lapped with #320 then #400, then #600 lapping paste and have been match marked to their specific place in the heads so that I don't mix them up. I'm coming down to the exciting strokes now. I will first design and build a fixture to hold all of the parts of the rocker arm bracket in the correct relationship and silver solder it together.
                        Brian Rupnow

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                        • Looking good Brain --- a performance note; (since your going to be trying to actually get work done with this thing)

                          Your valve stems are twice the size they need to be - very restrictive when you look at the already small valve seat I.D. and then imagine that colossal stem in there,,, you could still use everything as is and just turn down the business end by the valve head to a much smaller diameter --- at least for the dominant valve (the intake) the exhaust will find it's way out regardless but it too would help...

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                          • This should make a good welding fixture to hold all of the rocker arm bracket parts in the correct relationship for silver soldering.
                            Brian Rupnow

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                            • Boomer--You're not wrong on that. It's a matter of scale. The valve stems are only 1/8" diameter----and the valves are all lapped. The most I could take off the stems is .025" of diameter, and then the heads would move enough to require lapping the valves all over again.
                              Brian Rupnow

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                              • Is the reason for all this major rework just to place the spark plugs where they have less tendency to get fouled by the combustion products? My guess is that this is only a minor component of the overall problem, which I think is more likely the valve timing and perhaps ignition timing. Perhaps I just approach failure analysis in a different way, by actually measuring the parameters and comparing them to other more successful and less problematic systems. Of course, I would also try using electronics and computer control to tweak the ignition system, at least, which (for me) is much easier (and more fun) than a major machining effort. I'll be following the progress closely, and hopefully there will be shouts of "Eureka!" when the problem is solved. Good luck!
                                http://pauleschoen.com/pix/PM08_P76_P54.png
                                Paul , P S Technology, Inc. and MrTibbs
                                USA Maryland 21030

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