What are you building for, is it for all-out top end speed, pulling hard to accelerate or something else? Until you have a real target for the build & your expectations, it's not going to be what you want. Light flywheel is fine, but it might shake a bit at different rpms as you get there. If you aren't racing in a "class" against other similar motors, it doesn't really matter.
The iron flywheels are made to help reduce vibration & dampen the effects from a single cylinder's inherent "out of balance" running. Really enjoying this thread by the way, just keep going!
Yep the light flywheels I've seen recommend balancing the rotating assembly.
Now I'm kinda leaning towards the 2.7 lb 34 degree Ambush Flywheel.
I've asked my favorite engine builder at ARC for advice on ignition timing for my application.
"Looking for ignition timing recommendations. NR285-0211 Cam (should pull from 4000 - 7500 RPM), 4k Clutch engagement, 24mm Flat side carb, Ported - Milled (0.040") Big Valve (28.5/25mm) Hemi Head, 37 lb valve springs, 0.027" Head Gasket, +0.020" Con Rod (0.005" In the Hole) Robertson 3 stage exhaust, AR3910X spark plug, 11:1 CR, 100 Octane race gas.
I'm not racing, so should spend most of the time between 5k and 6.5k RPM, but will be over 7k RPM for short periods of time. Testing the HP and RPM limits of a 30 series torque converter on a minibike with this engine.
I need help deciding 28 degrees,30 degrees, 32 degrees, 34 degrees,....
Looking for middle of the road, not too advanced for 5k, but not too retarded for 7k.
Trying to avoid the PVL system, so I get that timing will retard with higher RPMs.
Any input is much appreciated. BTW thanks for these video. I've learned so much from you here and on the forums."
The exhaust is ordered, now the flywheel is the only thing left.
Unless I decide to follow instructions and break in the cam with the stock springs. Then I need to order the retainers for the smaller valve springs.
---------- Post added at 03:00 PM ---------- Previous post was at 02:38 PM ----------
I'm impatient so I called ARC. Jody says 32 degrees would be around perfect. And says the stock springs may float around 3000 RPM with my cam. He doesn't like to break things in that way, but says if that's what the instructions say, then go ahead and let it run for a few minutes with the stock springs at low RPM.
Don't really want to take the head off, I have everything cleaned and put together and torqued. It is sitting waiting for the exhaust. And waiting for me to order a flywheel.
I still may get a top plate, even though I don't need the throttle linkage or a place for a fuel pump, I want it for the bracing on top. TC backplate will provide bracing on the PTO side and maybe I'll add a plate on the flywheel side. People said 3/16" Aluminum plate works nicely.
---------- Post added at 03:04 PM ---------- Previous post was at 03:00 PM ----------
The head I ordered did not come with exhaust studs.
I'll wait for the header to arrive then decide if I can pull the studs from the old head and use those or just get some bolts to use instead. Not sure if the exhaust comes with bolts, or if I'm supposed to use the stock studs. I'm guessing either should be fine, but some times the flange is tight and normal nuts are too big to fit on the studs because they hit the base of the pipe.
---------- Post added at 03:30 PM ---------- Previous post was at 03:04 PM ----------
Flywheel ordered.
But I hate that it is going to be covered up by the stock blower housing and recoil starter.
What the point in being safe, if I can't show off the bling while doing so?
