Flywheel machining question
 

Im playing around with a 27cc stihl engine for a boat and after some searching i noticed that some of you guys on here are using that engine so i thought id post this here. Anyway I thought id try and lighten the flywheel a little, wasnt going to go too crazy, just going to cut the fins in flush to the rest of the flywheel to reduce some drag. So I went ahead and done that and when i got the fins cut down, i noticed that the casting was out by about 30 thou, meaning i had about 30 thou of fins left on one side when the other side was clean. So i decided to take another cut and face it all off the same thickness and i ended up hitting something steel. Im guessing its a part attached to the magnets to hold them in place. Once i hit this i stopped, so one side now the fins are still noticable but their almost cut flush.

I'm kinda nervous now about this thing comming apart. Alot of you plane guys run lighter flywheels right? How dangerous is it maching them down? Heres a pic of my flywheel (steel part is between the holes in the lower part of the flywheel), what do you guys think? Should I try and pick up another one?

RE: Flywheel machining question
 

I would get rid of the flywheel...and possibly use a $25 electronic ignition. Capt,n

RE: Flywheel machining question
 

I see what you mean now.A few of the more expensive engines dont use a full bodied cast flywheel.They use a solid steel center and then pour the cast around it.Huskys do it this way,and you found out stihls.I had an olympic that was the same way.When i turned it it looked like yours but when i screwed my hub on it covered that area up so nothing could come apart.I sent ya a pm with some info.I see youve turned down the top of the cylinder round where the fins where.Is this for the water cooling jacket to fit.I woudnt use it like that unless you could somhow tighten a flat piece of aluminum up against it that was large enough to cover at least a half inch over the whole center sectiion.

RE: Flywheel machining question
 

You may need the flywheel as a flywheel. On the planes, the prop acts as a flywheel.

RE: Flywheel machining question
 

That is very true...you will need a flywheel....but not that one. If you got a lathe or know some person who has....make a flywheel that would have a v groove for a starting belt. You could then elecric start it. Also have a magnet installed for electronic ignition! Just A idea. Capt,n;)

RE: Flywheel machining question
 

Hey Cap.. where do I get this 25$ ignition system?

RE: Flywheel machining question
 

tstotts: I think the data for the $25 ignition is in the gas engine forum. Go to the gas forum and ask same question. If you do not find the place.....P.M. me. Capt,n UPDATE Try this link http://www.rcuniverse.com/forum/m_7430878/tm.htm

RE: Flywheel machining question
 

Hey guys I couldnt find a new flywheel anywhere so I made a mandrel for this one and tested it (safely) at 30,000 rpm for a few minutes in a router and it held together so I figured it would be fine.

I got the engine running and its working great. Its modified but it really rips for a trimmer engine. Heres a link to a video of it in my boat: http://www.rcuniverse.com/forum/m_7638502/tm.htm

RE: Flywheel machining question
 

mmyurray70: Thats a good fast running boat you have. You did a good job on doing the kind of stuff that makes em go!!! I had a boat once and ran it on a river that was only 70-90 feet wide. I kinda had to be carefull not to hit the banks!!! Best Regards Capt,n:D