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May 12, 2015, 10:50 PM
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I've already re-routed the hoses to not cool the exhaust jacket. No, it's not a system that dumps the water directly into the exhaust...aka a wet pipe. It's just a jacket that is fitted around the pipe at the base. I think it's intended purpose is to keep the rubber connector from burning up but I don't use one anyway on this engine. I have a fiberglass wrap system that I use. It's not as "oil spray" proof as a rubber sleeve but it seals pretty well and won't burn up.

The engine started life as a 32cc two stroke Sears Brushwacker. It's actually a pretty nice donor. It has a four port transfer system, a reed valve intake system and dual ring piston so you have a choice on better seal or lower friction. The draw back to it, is that the crank is only supported on one end. It began as a two bearing support system but i added a third bearing and lightened the piston so its pretty rugged....especially since it cost me ten dollars at a yard sale and I do all of my own machine work. (It's amazing how many weed trimmers get destroyed by somebody backing the car over them!!) The neat thing about it, is that the spark plug is dead centered in the top of the head. It makes building a water jacket so much easier. I cut away all of the excess stuff...brackets, mounts, etc. I tossed the flywheel and oem ignition system and machined out a new flywheel with built in starter pulley and a neodymium magnet for the hall effect sensor.

The CDI ignition system supposedly has an auto retard feature that's supposed to hold the timing down at an idle and let it increase as the rpm's go up. But, that part doesn't seem to work as advertised. I used a timing lite to verify the auto retard/advance and it's nothing at all. So, I built a servo controlled advance system. The Hall effect sensor is on a slider so I can rotate it on the mount. I control it from the radio via a knob and also have it linked thru a mix with the throttle servo. More throttle = more advance. I can adjust it from about ten degrees advance to thirty degrees advance. I haven't field tested that system yet so it's still questionable.
Ok, sorry for rambling on about my boat engine. Once I get started on it, I have trouble stopping!!
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May 12, 2015, 10:59 PM
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I like the way all that sounds.There are still some records held in IMPBA with modified homelites which I think are similar to what you have. Unfortunately these engine builders do not post very much in forums for some reason. With the lawn engine set up that way I wonder could a machinist modify it to some type of rotary induction? What do you think it would take? Are you running pullstart or have you machined a flywheel?Ramble away..... if you actually machine your own stuff and are smart enuf to actually use your radio mix for something useful on the performance boat Id like to hear about some of the other ideas and things you have. Its your thread.....

Hugh
Last edited by Xfactor940; May 12, 2015 at 11:27 PM.
May 13, 2015, 12:18 AM
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Yes, I think this engine could be modified to run a rotary valve induction system. The backing plate has the intake tube and carb with the velocity stack mounted on it but nothing else. A new backing plate is fairly easy to machine. You'd have to tie it in with the crank/rod pin to make it spin. That could be done by putting in a longer pin. But, then you'd have to do some heat treating for the backing plate and rotary valve and I'm not set up for that.

I did some port smoothing on the intake tube and have a large carb mounted on it with a two inch velocity stack. I replaced the Stainless steel reed valve with a fiberglass one from Boyeson. It is a little more flexible than the oem one but more importantly, it's "digestible" in case the engine eats it. With all of that, I'm satisfied that it's ramming about as much as it can into the crankcase. I haven't stuffed the crankcase yet but that's on the list.

One other neat thing that I've built into my boats for many years, is a radio controlled mixture adjusting system. A servo linked to an arm on the high speed mixture screw controlled by a knob on the radio can make a world of difference in getting the engine dialed in. I can rich or lean the mixture by about a 1/4 turn while it's running on the lake.

Yes, I machined a pulley starter belt system onto the flywheel. It's all one piece. There is no pull starter, all done thru a belt on the pulley. I gave up on my old Sullivan starter though. It just wasn't powerful enough to spin it over. I ended up getting a starter motor from a Kawasaki motorcycle. (1000 cc, $10 shipped) I had to work a while to figure out how to attach a pulley to it but it works great now. Electrical power is from a lawn tractor battery. It does spin the engine over nicely! The one change that I'll make the next time I pull the engine out, is to make the groove on the pulley deeper. When the engine starts to kick, it spits the belt off before it's really started. Then I have to stop, put the belt back on the crank pulley, etc. No big deal but it's a nuisance. One thing about the belt. The old sewing machine type belts won't even last for one start up on this engine. They shred really fast. I took a short automotive type multi groove belt and split it lengthwise with a razor blade so it's about a 1/4 inch wide. One car belt gave me two boat starter belts. I've been using the same belt for quite a while with no signs that it's getting ready let loose.

Yeah, I do all of my own machine work. My shop is pretty well equipped with a lathe, mill, a couple of fancy drill presses, band saw, surfacer, sanders, etc. It's not a business or anything like that...I've just always liked to tinker and build stuff so I bought the machines to do that. I have a great wife of many years who's attitude is: What the heck. It keeps him at home. W.
May 13, 2015, 01:20 AM
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Well I think you know what is next......

photos please
May 13, 2015, 08:47 AM
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The real truth came out A Homelite motor would be better than a Sears trimmer any day. I run Homelite 30cc too and use a wet exhaust So dump the water in the pipe. A Zenoah G320 is way faster than a sears trimmer. I bet the
Sears motor is the same as a Mcculloch or Ryobi trimmer. I was real suspicious about him not posting pics rite away. A 32cc motor is a odd ball. I had it figured for a trimmer engine. Zenoah just came out with the G320 not long ago so I new it wasn't that. Homelites were the best motors in the day to use if on a budget.
May 13, 2015, 09:18 AM
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I dont see why anyone would be ashame to show photos of things they machined themselves because that is more impressive than a zen 32 to me so Im not suspicious. Not trying to be funny but without quite a bit of mods they're referred to as "paperweights".Falling apart over 16k. That's the real truth. If you're running water actually through your header full time you might be helping the engine by running like a longer pipe less top rpm more torque at a safer rpm. That engine has some issues so I was actually quite pleased to hear he was working on the trimmer and doing some machining.Not saying its any better but its actually worth its low price. Also seem to consider metallurgy with the hardened pin idea for rotary induction. For me that all means I want to see his photos with great interest and no doubts that its something very nice.Reed valve engines make good power as I understand but the reeds have their limits like he is talking about. I think I have seen some carbon fiber ones but I dont know anything about reeds but that they can make good power. The ryobi I have here with reed induction is a 30.5cc . If it is a 32 zen there are several threads currently on improving the engines mechanical reliability at higher rpms .

Here something I just found that is quite interesting about the type intake and carb bore relationship. Oh wow. This was taken from www.dragonfly75.com . I dont know how much stake you can put in it but its interesting. Ron did you machine youre own stack?
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Last edited by Xfactor940; May 13, 2015 at 09:50 AM.
May 13, 2015, 10:02 AM
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Quote:
Originally Posted by txt killer
The real truth came out. I was real suspicious about him not posting pics rite away. A 32cc motor is a odd ball. I had it figured for a trimmer engine. Zenoah just came out with the G320 not long ago so I new it wasn't that.
WOW! Sorry for not sitting here at the computer to post those photo's right away. I have other things to do besides allay your suspicions that I'm making this all up. So here ya go. The first one is the old housing off of the engine. See the 32cc? The others should be self explanatory. The second one shows the details of the adjustable timing system with the pulley that I machined for it. The last two are photo's of part of my shop....just so you don't get any suspicions that I'm exaggerating that! Yeah, I machined the velocity stack, the head jacket, the intake spacer and the intake manifold. No, I'm not going to take the engine apart just to prove to you that I also machined the piston to make it lighter or matched the transfer ports nor am I going to show you how I balanced it all. Yes, I am positive that there are faster and more durable motors out there. However, I doubt that you can get one for less than ten dollars and get TWO 1/4 drive shafts with it! Also, here's a link to Boyeson's reeds. http://www.boyesen.com/
May 13, 2015, 10:17 AM
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Ron,
I see the majority if not all the pieces have been fabricated by U. down to the bell cranks and brackets. Nice To have a shop with tools and a brain. I had no suspicions only great curiosity. I have great confidence now we can have great off board discussions about different ideas. I hope you have great success with the dry pipe setup but it certainly appears you are advanced enuf in your thinking and execution to run a water injection setup. Anyone with an open mind can apprecaite the ramblings of Lohring Miller. Im glad I shared it with you.

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Thank you very much for the photos and ramblings...... hope you do more.

Oh yeah I see the crank pickup...... nice!

I was also told this would be a friendly board. U can not learn anything if it is not......... your ignition advance idea could be utilized with different engines. Do you have a tac pickup? How fast you turning that thing? What prop are you pulling?


Hugh
Last edited by Xfactor940; May 13, 2015 at 10:43 AM.
May 13, 2015, 10:40 AM
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Xfactor940...Thanks! Like I said earlier...I haven't done any field testing with the adjustable timing system yet so I don't know how it'll work in "real life". It does seem to work fine while running it in the shop. Yeah, I've been giving some thought to the wet pipe system. The problem with this engine is that the exhaust port faces forward so I had to make an exhaust manifold that bent around backwards. My pipe tuning length is right at the maximum and I can't make it any shorter. From what I've read and researched, the wet pipe system simulates a shorter pipe. In effect, the engine would think the pipe is shorter than it really is. Also, sorry for the way my boat interior looks! It's pretty dirty. I had a leak in my crank pressure driven water pump and it squirted oily gas all over.
May 13, 2015, 10:52 AM
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Quote:
Originally Posted by wolfiniron
Xfactor940...Thanks! Like I said earlier...I haven't done any field testing with the adjustable timing system yet so I don't know how it'll work in "real life". It does seem to work fine while running it in the shop. Yeah, I've been giving some thought to the wet pipe system. The problem with this engine is that the exhaust port faces forward so I had to make an exhaust manifold that bent around backwards. My pipe tuning length is right at the maximum and I can't make it any shorter. From what I've read and researched, the wet pipe system simulates a shorter pipe. In effect, the engine would think the pipe is shorter than it really is. Also, sorry for the way my boat interior looks! It's pretty dirty. I had a leak in my crank pressure driven water pump and it squirted oily gas all over.
Cooling with water should actually make the pipe appear longer.A multi chamber pipe with a properly designed stinger could help you with length problems.Keep at it. Use a gps and tach to get a feel if what you do is actually giving you more speed. You can also load the motor with a carbon airplane propeller on a rigid test stand and look for more rpm with your mods. Since you have the shop u can build these things.... The limits will be the mechanical integrity of the bottom end. Garden equipment is not designed to run 19k for several minutes at wot. Neither is a zenoah 32 cc from the way things look so I definitely agree with you about price.
Last edited by Xfactor940; May 13, 2015 at 11:08 AM.
May 13, 2015, 11:51 AM
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As far as I concerned am concerned I will take a Zenoah or Homelite any day than modify a Craftsman / Mcculloch. I do my own work on my Homelites. I have tried those engines with no success in work. They just don't have any tongue like the Homelites.
May 13, 2015, 01:25 PM
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Last edited by sleepwalker; May 13, 2015 at 06:31 PM. Reason: deleted post.
May 13, 2015, 04:16 PM
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See I dont see how this is something that happens on a friendly board. What a gross picture that no one needed to see to discuss a tuned pipe. Are you going to follow your own advice. Just curious.


".......Let's keep this site about r/c and not turn it into your personal battle ground with someone........."

But then produce a post like above what is the metric and purpose of it? What does it have to do with cooling the tuned pipe? or will it start a personal battle?

I dont know whats going on here Ron. It makes no sense to me..Ill pm you my ideas its already getting silly for no reason.
Last edited by Xfactor940; May 13, 2015 at 04:27 PM.
May 13, 2015, 04:28 PM
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Xfactor940...Yup, you're right about the water and the pipe length. I got it backwards. Oh well. As far as I'm concerned, building the thing and making all of my great ideas actually work is most of the fun.

Here's another photo of my boat but look at the strange curved thing over it. I'm disabled so I was having trouble with the launches. My engine has a clutch so all I have to do is to set it down in the water but the problem is that the water is a foot below the concrete dock. I've almost fallen in several times. So I built the "recovery bow". Yes, that's an old Marine Specialties dual rudder setup on the stern but it's been honeycombed so it's really light.

Pssst. ....Can somebody please tell me what an "engine having tongue" means? I built race engines and transmissions for many years for Kawasaki and have heard a lot of engine related expressions but never that one.
May 13, 2015, 04:33 PM
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Im not touching any of that about a tongue. I dont think it will generate friendly discussion about a model boat. Imma sit back and watch that silly seed that has been planted grow.




I already asked the mods to remove the post that have nothing to do with cooling the tuned pipe or your boat. I dont care what kind of board this is supposed to be. You gotta practice what you preach before you can tell someone else what they need to do.


I mean thats crazy.....
Last edited by Xfactor940; May 13, 2015 at 04:48 PM.


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