I MACHINED A HUB FOR A CONVERSION IM WORKING ON BUT IM NOT REAL HAPPY WITH THE OPTIONS. I DONT LIKE THE FACT THAT THE FLYWHEEL SURFACE THAT IT SITS AGAINST IS NOT MACHINED. I HAVE A .750 DIA FLANGE AGAINST THE FLYWHEEL BUT IM NOT SURE IT WILL RUN TRU ENOUGH. I TAPPED THE 8MM SIDE .437 DEEP AND THE PROP SIDE IS TAPPED 3/8-16 ALL THE WAY THROUGH TO THE 8MM THREAD SO I CAN PUT A SETSCREW INSIDE THE HUB AFTER ITS TIGHTEN AGAINST THE FLYWHEEL TO LOCK IT ON. I MACHINED A 1.250 DIA. FLANGE WITH A .500 DIA BOSS ON THE PROP SIDE AND COUNTER BORED THE PROP TO SIT OVER IT TO INSURE PERPECT CENTERING ON THE HUB. IS THERE A PROBLEM WITH HUBS COMING LOOSE FROM ELECTRIC STARTERS? HOW DO ALL YOU EXPERTS DEAL WITH ALL MY WORRIES?
DIFFERENT SUBJECT- DO I NEED THE FLYWHEEL IF I USE A PROSPARK CDI IGNITION SYSTEM?
FARMER TED
PS. IM WORKING ON AN ECHO NOW AND HAVE 2 TORO'S WAITING UNDER THE BENCH

Not too sure on your design. Maybe post a picture or two. If I were to do a conversion with a flywheel, I would make my hub exactly how I make one for my electronic ignition conversions. Those hubs are about 2 inches long or so. It would just seat against the flywheel. If the surface of the flywheel is rough I would face it in my lathe. Do you have a lathe or access to one?

I MACHINED THE FLYWHEEL SURFACE THAT THE HUB SITS ON YESTERDAY AND RAN THE ENGINE. I LOOKS LIKE IT RUNS VERY TRUE. IM STILL CONCERNED ABOUT THE HUB COMING LOOSE FROM THE STARTER AND WONDER IF ANYONE HAS HAD THIS TROUBLE. I THINK THE INTERNAL LOCKING SETSCREW AGAINST THE END OF THE CRANK SHOULD STOP THIS FROM HAPPENING.

When I install the prop adapter, I use a red high strength Loctite thread locking compound on the threads. I haven't found a starter that will loosen it, yet. Just make sure that you clean any oil from the threads before you apply the Loctite. When you need to remove it, just heat the adapter with a propane torch to around 300F, and the loctite will soften and come off. I drill a 3/16" cross hole in the adapter, to insert a rod to tighten the adapter.

Nashcat

I did my hub like you did with the set screw on a poulan 46cc .But when it would backfire it would ring off the set screw everytime. So i put a new screw back on it and then i put RED Loctite on the threads and the taper and let it set 24 hours. That fixed the problem it has never come lose again. I would try that if your scared of it losening up. It should not losen up using a stater because you are turning in the same direction of it tightening up.


Thanks
smallplanes

I MILLED 2 FLAT ON MY PROP FLANGE TO USE A WRENCH TO TIGHTEN THE HUB ON, ILL GO FOR THE LOCKTITE. MY STARTER TURNS THE ENGINE COUNTER CLOCKWISE FROM THE PROP END WHICH DOES LOOSEN THE HUB UNLESS IM RUNNING MY ENGINE BACKWARDS

I use Loctite 620 I think it is. Have never had one come loose yet. I don't use any cross drilled set screws either. I use the prop bolted to the hub to install and tighten. I also use a piece of rope in the cylinder to hold the piston while I use the prop as a "T" wrench to tighten the hub.

I use a piece of rope in the cylinder also when tightening up my hub. I have a piece of 1"wide by 3/8 thick by 1 1/2 long flat oak wood with a hole drilled in it and i bolt it to the hub tru the prop bolt . I then tighten the hub up very tight with the red loctite on it and that seams to work good for me. But i think your rite about the starter it does turn in the same direction that would losen up the prop. But when the motor is running it will keep it tight. Use the loctite it will fix your problem.


Thanks
smallplanes

I too use the red Locktite, nylon cord in head to hold while installing/removing prop bolt into the adapter. I only Locktite about 1 diameter worth of threads and nothing has loosened up yet.

A Loctite usage question: When necessary to remove the prop bolt to replace props, is it necessary to 'chase the interior thread with a tap to clear out old locktite? I have been wire brushing the bolt and chasing the hub threads. Same principle on long shaft Ryobi.

Check it out on the Loctite web site, the strongest Loctite is green, either 638 or 680...It's best to clean off the threads to re apply more Loctite...Loctite sells a primer that REALLY makes it work...
Flying gassers for 18 years, never used Loctite on the prop bolt, even on our 289cc racers...
Just put the (single) bolt in TIGHT and check it once in a while...

I viewed the thread below some time ago and it got me wondering about the pros and cons of this type of prop hub.

I would like to hear the thoughts of more experienced modelers.



RysiuM : If the shaft had a taper for the flywheel, how did you handle engine side of adapter? (BTW Thanks for sharing your work on the Poulan 25cc. Lots of good information.)
Thread: http://www.rcuniverse.com/forum/m_3192059/tm.htm