I apologies for what seems to be such basic questions. Converting these engines is a new aspect of the hobby for me, one that I am very enthusiastic about. I do not posses the extensive background in engine technology as it would appear that some of you do. Therefore I rely on guidance from those of you who kindly share your knowledge. So I too can learn, and like yourself, enjoy seeing a creation take flight.

open the muffler with another 1/2" hole, take a dremel or chainsaw files (takes longer, but works) to the exhaust port, trim the top of the port until you get the 140-150* exhaust timing you need to make power.

I tore down the engine to match the transfer ports to the crankcase and change the timing on the exhaust port.

One thing comes to mind about grinding the exhaust port. Isn't the cyl. chrome lined and won't grinding the port cause the chrome cyl. to chip and peal as the engine runs?

I've never had problems with the chrome peeling after porting. Just go slow so that you don't take too much off, (check often), and make sure to lightly chamfer the port edges so that they don't damage the ring and/or piston.

To realize more benefits, you are really going to have to add more muffler outlet area. Hopping up an engine is a coordinated effort, and doing one thing without attending to another leads to disappointing results. I once bought an aluminum after market muffler for one of my Homelite 30 engines. It had two tubes, but the outlets were about 1/8" smaller than the home made muffler I had been running. The engine lost 400 rpms....

The object is to get as much air to flow into, and out of, an engine as possible for max power.

AV8TOR

Would a fine grinding stone in a Dremel be appropriate for grinding the exhaust port?

There seems to be allot of emphasis on changing the timing. What about port area? In the process of trying to educate myself, I have done some reading (much of which, is over my head) of some well known texts that says, port area is also a significant consideration in improving 2 stoke engine performance. My Homie's exhaust port appears to taper in on the sides as it goes to the cyl. leaving room for expansion at the sides. The texts I read said, a port can be up to 50% of the width of the bore Dia. Going that wide isn't my goal but straitening out the sides I may concider, if that has been found to be of benefit without consequence.

One thing I do know about engines is: You can't put a double quad, tunnel ram intake on a stock V8 engine and expect great performance. I have seen others do it though. Mis matched parts definitely can lead to disappointment.

I do straighten the port walls a bit when I port the Homeys, but I don't widen the port where it enters the cylinder much. Just a little to blend everything in well. The main improvement comes from getting the timing up to around 150 degrees for operation below 8000 rpms, and 160 or so for operation above 8000. The timing is important and you will see good results from going to 150 degrees if your carb and muffler are up to the task. Keeping the port fairly close to stock size keeps the flow velocity up and the timing does the rest in this case.

Stones don't work very well on aluminum as they clog up almost instantly. I use carbide cutters. Once again, be sure to chamfer any port edge you have touched, and be sure you go slow with your porting. A small amount makes a pretty big change, as it makes the port open earlier, and also close later. So you effectively get a "double" timing increase for each increment you grind out. I have a tiny little flex light that I insert into the spark plug hole. Makes it real easy to see exactly when the exhaust port opens and closes while looking into the port.

AV8TOR

P.S. If you want to pm me your e-mail, I will send you a nice degree wheel that you can print out...

Ooops!! Anybody looking to match the crankcase to the transfer port look out! In the front port the case material is very thin at one spot. Before I knew it I had ground a hole in the crankcase. I hope JB weld will fix it. Next time I will fill the depression with JB on the front of the case first.

Clean that area with acetone and then fill that cavity with JB Weld. Let it dry thoroughly and I bet it never gives a problem.

AV8TOR

I am going to heed strong advise and add a second outlet to the muffler. I had to purchase another muffler though, because adding a second outlet to my existing one wouldn't be the right configuration for the test stand or a plane. My intent is to install an 11mm carb on an enlarged intake and message the cyl. port to match as well. So everything should be up to the task.

Just so I'm crystal clear, because now I'm real nervous about grinding on the exhaust port, after goofing up the case. Is the cutter pictured the type of carbide cutter to use on the port?

Yeah, that looks fine and similar to the one I use. Just use a light touch as it will remove material quickly. By the way, where did you get that one? Mine is about due to be replaced and I've had it so long I can't remember where I got it.

Now if I could just talk you into going to a Frank Bowman ring too, you would be set...

(The Christen Eagle on the degree wheel has one of my hopped up Homelite 30cc engines on it. It turns an APC 16 x 8 prop at 9400 rpms.)

Have at it!
Take care,
AV8TOR

I can't remember if the cutter is from Micro Mark or I found it on the Dremel display at Lowe's. I've had mine awhile too, but now, it's getting some real use.

No convincing necessary. I am definitely going to get a Bowman ring too. I like to go through a progression of steps with these engines (this is my third), rather than do everything at once and then wonder what the actual results, of the given changes were. I guess for me, its not so much just the destination, but also the journey getting there. I know, I know, some results are contingent on several factors and I take that into consideration. Some things I learned on this engine compels me to re-visit a past engine.

If I can get close to 7400 or somewhere north of that with all the improvements and a 18 x 8. I will deem the project a success.

I do understand the wondering what each step is actually worth, but as you said, you "Can't put a dual quad tunnel ram on a stock engine". All the mods work together. A larger carb does no good if the increased air available can't get out of the engine due to a restricted exhaust. Increased port timing does no good unless the rest of the engine can "breathe" well enough to take advantage of it. And any engine that isn't sealing well due to poor rings, valves, or what have you, will not respond well to performance mods. All this makes it difficult to do quantitative, step by step improvements. Engines just don't work that way; they are a combination of all factors, as I believe you well know.

Have fun, and I think you are well on the way now. I hope no offense has been taken; all I hope to do is share my experiences and knowledge, and help people out.

AV8TOR

Hello everyone.  I am new to converting engines, just ripped out a homelite 30cc with a Zama carb and got all the bulk stuff taken off (screws, plastic casing from the trimmer, etc...).  I got to the point where it's time to take the fly wheel off but I'm having lots of trouble.  I know it's held on with friction, and all the techniques I've read online have you hit the drive shaft with a hammer to loosen things up,... am I not hitting it hard enough do you think?<div>
</div><div>Also, I'm new to these forums, so if this belongs somewhere else, can you point me in the right direction?  Thank you all very much.</div><div>
</div><div>-hotelmode</div>

Wedge two large screwdrivers 180 degrees apart between the crankcase and the flywheel, putting some pressure against the flywheel. Don't get crazy and damage the case, just get some firm pressure going from two sides. Then screw the nut fully onto the shaft so you don't wreck the threads, and give the end of the crank a fairly good whack with a hammer. It should pop right off. If it doesn't, heat the center of the flywheel up real well with your Monokote heat gun, and try it again.

AV8TOR

Hotelmode
Use an oil filter wrench to hold the flywheel to loosen the nut and then firmly tapping all the way around the flywheel with a large plastic handled screwdriver. I have found this technique requires less than three hands.

av8tor
No offense, maybe disappointment for a short while, but that has passed.
Thanks for your help.

Thanks guys, I guess I just wasn't trying hard enough.<div>
</div><div>One more question, though, I don't see a nut.  The slip clutch (it came off a weed wacker) held everything on, and there aren't any other nuts.</div>

Yep, that clutch IS the nut. You can screw it on to protect the threads while you whack the crankshaft end. Screw it on until the top of the clutch is flush with the threads on the crank if it will go that far without actually touching/putting pressure against the flywheel. Later, your prop hub will screw onto those threads where the clutch once was.

AV8TOR

Boy this thing is stubborn.  I have hit this thing with all my might and the flywheel just won't budge.  I tried some WD-40 to see if it would penetrate and loosen things up but that hasn't worked.<div>
</div><div>What about holding the engine with the nut facing the table, and slamming the whole engine hard on the table?  Would the weight of the flywheel make it come loose?</div>

Oh man, you shouldn't have to hit it that hard. Are you sure you are getting some good leverage/pressure on the flywheel while you are hitting the crank? Maybe someone put Loctite on it. Heat will break it loose, but don't go crazy with a torch or something and ruin the bearings/seals.

Usually they just pop right off with a medium smack on the nut if you have good pressure against the flywheel when you hit it. Try the heat.

AV8TOR

Just for S&Gs, make sure there is NOT a retaining ring in a groove just in front of the flywheel. I don't remember (CRS) where, but I did have to take out a RR at some time in a gasser teardown. Just a random thought, usually they pop right off for me.

I finally got it off, guys.  Thanks for all your tips.  What did it in the end was heat and a hammer.<div>
</div><div>I used a blow dryer on it for a good 45 seconds, made sure it was hot to the touch, turned it upside down and gave the crank a whack with a hammer.  One medium whack was all it took, no screw drivers or 3 hands holding things.</div>

Usually I carefully wedge the screwdrivers between an unimportant/about to be removed part of the crankcase and the flywheel, and that free's my hands up to give the crank a smack with the hammer.

I figured the heat would work. Glad you got it off. Now you can get back to "work"...

AV8TOR

It's time to order the conversion parts, probably from wackerengines, but I don't know if it has a long or short shaft.  Measured from the bearing the shaft is 3" long.  Measured from as close to the case as my tape measure will go (where the back of the flywheel would be close to), it's 3.75", which makes me think it's long.

I just gotan email from hotelmode:

"I just got off the phone with Pete at wackerengines.com and someone close to him is dealing with a medical situation. He won't be able to make any parts for a little while, he told me he hoped to be back up and running in a couple weeks, but until then he referred me to Dave at carrprecision.com.

Thought I would give anyone who was planning on doing business with Pete a heads up.

Does anybody have any experience with carrprecision? It's a little more expensive."


Read more: http://www.rcuniverse.com/forum/m_97...#ixzz0mu5Wfa00

It's a long shaft. The short shaft measures about 1 3/8" from the bearing to the shaft end.

AV8TOR