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The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: ShadetreeMotorcycle on November 07, 2020, 06:36:41 pm

Title: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 07, 2020, 06:36:41 pm
My new M94 is here and I have begin to tinker! I want to try more Flywheel weight,....but would like to see the results before turning heavy "tires"....I don't mind making the "tires" but would like an educational guess on just how much More weight might be desirable...I found some Lead tape online, it's common use is to weight tune golf clubs, that might be a more elegant route...but I can not wait to test!... So...my local harbour freight has tire weights for decent price...the adhesive is pretty good, and I washed the flywheels with rubbing alcohol for best bond...but these are designed to go Inside rims where centrifugal force would help them stay in place. In my situation centrifugal force will cause them to want to fly off...specialy after the engine starts slinging oil all about....I don't want to run these very long...just a test...thinking of binding them with carefully applied painters tape, it has a bit of stretch and I am hopeful with the stretching and several layers it will all hold together for a test run!
The engine shipped quite dry...if I hold the exhaust valve open and give it a hand flick it only spins about 3 times around...the tire weights add 8.5oz total...the same hand flick now gives me about 9 times around before stopping, so 8.5 oz should be a noticeable difference! To be continued....

Warning: Tampering with engines can be dangerous! I in no way endorse or encourage activitys in this thread...for informational and entertainment value only! :o
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 07, 2020, 07:41:23 pm
Got the tape bound on And the Soft springs from carbon brushes installed...getting ready to test fire but Thought to take a photo before unless it does not go well, there will be record of what not to do....wish me luck!
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 07, 2020, 07:42:31 pm
I’m really looking forward to your results, will there be a video?
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 07, 2020, 07:47:16 pm
I do Not have a YouTube account...but my cell phone will take video...can I attach a cell phone video?...I have never tryed, but want to learn how!
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 07, 2020, 07:52:32 pm
YouTube has always been the best/easiest way to put videos onto forums. If you need help, let us know... I assume you’re using a smart phone?

At least get a video of tonight’s test run onto your phone and we can help you get the video uploaded later. I’m very interested in seeing it.
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 07, 2020, 07:53:00 pm
And if they weights start flying off, keep recording!
Title: Re: M94 hit n miss Flywheel weight
Post by: RedRyder on November 07, 2020, 08:06:24 pm
Yes, please record this.
And..... if you have access to another person with a smart phone, have them record in slow motion in case the weights fly off. You want to catch that. That said, i don't think you will lose them with the tape wrap.

Gil
Title: Re: M94 hit n miss Flywheel weight
Post by: Adirondack Jack on November 07, 2020, 09:06:37 pm
If you find this idea worthy, someone with a lathe could make replacements for the existing steel rims that are a tad bigger around, perhaps a shade wider as well, to add flywheel weight.  The existing steel rims press off easily with a puller if they won’t come free by hand.
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 07, 2020, 09:32:42 pm
Great News....She held together Just fine!....So in my eagerness to tinker...I never even bothered to to test fire my shiny new engine stock...there was a brief learning curve...first the fuel tank would only except about 2 thimble fills of fuel then an air bubble formed and could get no more fuel in....tryed to start and got pops right away but was sucking air ...probed the tank bubble with tooth pick and now she accept fuel!....a full tank cured my air bubbles....now trying to find best carb setting....she will run from 15% open to 45% open...but so far best running is about 25% open ...just as instructions direct.
   The result of the weight is much slower run....I would guess approx 1/3 the speed of stock....the side affect of this is even though my springs are softer....the rpm is still so low that the weights will not fling open hardly 1/16 inch....in videos I have watched each weight can move outward apox 1/4 inch...So my next move will be to wind some super soft guitar string custom springs and/or make more heavy governor weights....I am going to go back and try just unhook one spring to see if I can get it to miss more just for a test...but want to take the weights to work and ream 2 tiny dowel pins to accept a single spring...I think I am on the right track...but it will be a much more soft spring set up with the lower RPM. The low rpm was no issue for tape to hold weights in place...so when I get my set up dialed I will report!
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 07, 2020, 09:37:15 pm
Great News! Hopefully you get others trying this out too... @Jim get your engine back out  ;)
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 07, 2020, 10:08:03 pm
One thing I forgot to mention...I thought the new engine was very dry...all I have on hand for lube is MM-oil and clock oil...I put MM-oil everywhere I could think of including the piston skirt...ran the engine about 5 min and it has now really free up considerable, I now can hold the exhaust valve open and a stout flick will give me about 19 revolutions with the extra weight....but I wondered what folks like to lube there china engines with in the non combustion areas??
   Also...I only added a few drops of MM-oil to the Zippo fuel...I can Barely see a tint of pink...do I need more?
Title: Re: M94 hit n miss Flywheel weight
Post by: Stoker on November 07, 2020, 11:42:37 pm
You probably don't really need more oil in your fuel mix as it doesn't really burn away and tends to hang around in the cylinder for quite a while I find. As for the other lubrication points, I think most any fairly light machine oil should work fine. I use 3 in 1 (20 wt) with occasional applications of PCL (Breakfree) just to keep the older applications of used oil from getting gummy over time.

Great experiments you have going, and like others I look forward to your eventual conclusions and possibly a video!
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 08, 2020, 12:26:46 am
Well...did a bit more experimental tinkering...I had cut my carbon brush springs in half to get a useable length and now they have to few coils so they stack force to fast...its to late at night to come up with a .010 music wire guitar string...So...looking around For Something suitable I tried some rubber from my rubber band contest model airplanes!... It's much higher quality than an office rubber band and Bingo....my engine was running again! It's not a long term solution as rubber will degrade when in contact with petroleum products...and...it does not look to authentic...but I was happy to have my engine making putt-putt noises and my weights where finally moving like I see them on other run videos!....I am now playing with carb adjustments and the best run I could get tonight was 47-48 hits per min...so I am not really Slower than what others have achieved on the forum....but...it seems to be happening at a little lower RPM. My rubber called Tan Super Sport comes in 25ft length...I have to make a knot and make different size loops to make my rubber spring softer or stronger. I made a loop only 3/16 longer and the engine would not run...to soft...I need to find a way to have greater control almost like a screw adjustment on my tension. I have a fancy rubber splitter so tomorrow I will experiment with thinner rubber bands. I also need to make a solid engine base very soon...i feel with the engine jumping around when it hits prevents me from getting 100% of the power pulse into the flywheels...also the better base may help me tune for better carb setting.
   Part of me wants to go ahead and make a dished piston, I feel I could get the flywheels to coast down a bit more slowly and still carry me thru compression and keep running...but at the cost of a weaker power pulse...I freely admit I do not know enough about hit and miss to know what the best route is....I Did see a engine on YouTube...the owner said it weight was 2500 lb and he won a contest...he had it hitting only 2 times per min! I kept thinking it was no longer running then sure enough...it would hit!
  So...my little engine sure is fun, I feel sure if I keep at it I can get a slower result....please chime in...I would like to know if the general population thinks lower compression would get me running less hits per min With the heavy flywheels combo?

I am enclose a photo of my crude but soft rubber spring
   
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 08, 2020, 12:58:27 am
By my count this guy is down to approx 16 hits per min....he is kicking my butt....

https://youtu.be/ee76fu_bENc
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 08, 2020, 08:13:15 am
Wow! That one in the video is running perfect  8)
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 08, 2020, 01:10:28 pm
One of the down sides of heavy flywheels on a tiny engine is not enough power on the "Hit" stroke to really get them moving...my engine has good compression I feel and I am running Zippo fuel...I have heard of adding a little Acetone in the Zippo fuel to encourage fuel to vaporize...Some spoke of only a few drops of Acetone...just curious how much would be to much...and what is the result of to much Acetone? I don't want to damage my cute little engine. It also occurred to me that I may want to dose my fuel Right before use....we have Acetone dispensers at work used to clean metal, they hold about a quart and if you fill one today and don't use it for 2 or 3 days it will be 3/4 empty from evaporation loss!...even Zippo lighters need to be filled every 3-4 days as Zippo fuel evaporates very well to....I am going to run out for some more engine tuning supply and thinking of picking up some of the small mason canning jars..they make small ones for jelly that may work to store my pre-mix fuel, I can break the seal and quickly grab a syringe full (plenty to play) of fuel and quickly recap mason jar in hopes my addatives stick around....just wondering how others are handling this?
Title: Re: M94 hit n miss Flywheel weight
Post by: tony1951 on November 08, 2020, 02:54:46 pm
I run mine on ordinary petrol. It's cheap and runs perfectly unless I mis-adjust the mixer screw. Mine runs best with the screw just a touch more than a quarter of a turn open from being gently screwed in. If I am not mistaken the manufacturer tests them on ordinary petrol.
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 10, 2020, 07:55:46 pm
Update: had a few min to play some more tonight!...I peeled the tape and added a Second row of weights, putting me up to 17oz of total weight added. It started just fine and ran a bit slower rpm but hit more often because every time you slow the engine the springs need to get softer as less centrifugal force in play....rather than make a new rubber spring....I decided to go BIG or go Home! Added a 3rd row for 27oz! The wheels are getting noticeable larger so they accepted 10 oz on this pass...I made a rubber spring that was quite slack and to my surprise the engine Started!....I am now average 34 to 36 hits per min...but the engine does a double hit about half the time...so if was a Strong hit it coasts quite well....on a double hit cycle the first hit is weak and so the Stronger second hit really gets the flywheels spinning...I am curious if I added a one way check valve in the fuel line if I would get more "strong" hits?...kinda wondering if during the longer coasts I am now getting if the fuel can creep back from the carb a bit...something more to test I guess.
   Think this is as far as I want to go with added weight, unless the check valve fixes the double hit issue. As always advice is Welcomed! I will be trying a deeply dished piston quite soon!
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on November 10, 2020, 08:02:49 pm
This guy (who I don't know) reached out to me on YT and told me to put a weaker exhaust spring in -

https://www.youtube.com/channel/UCItmn6Ly_MtMIY6MoceT75A
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on November 10, 2020, 08:19:53 pm
Hey mate, any chance of a video of your engine running with the added weights on the flywheels?
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on November 10, 2020, 08:26:31 pm
Hey mate, any chance of a video of your engine running with the added weights on the flywheels?

^^^ This right here  ;)
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 10, 2020, 08:39:19 pm
I would Love to share a video of my engine running!....I have Never attached Anything but photos so far....I will consult with the computer guys at work and see if I can get a Video up later this week....I think it's awesome we can share experiments we have tried and the cumulative knowledge may advance the fun had by running these small engines ;D
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on November 10, 2020, 09:02:13 pm
Thanks it would be great to see your experimentation on video. Following along with great enthusiasm here, please keep us all up to date with what you're trying out.

Would you mind sharing your first name? Its nice to be able to address someone on a first name basis.
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on November 10, 2020, 09:34:55 pm
I'm using a urine specimen jar that I turned some ali up for to make it bottom heavy for my Zippo/oil mix.

[attachimg=1]
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 11, 2020, 05:51:16 am
Thanks it would be great to see your experimentation on video. Following along with great enthusiasm here, please keep us all up to date with what you're trying out.

Would you mind sharing your first name? Its nice to be able to address someone on a first name basis.

I don't mind sharing my name at all.....the name on my birth certificate is Benjamin and that is what my mom would call me when she "thinks" I have been naughty....lol...I was never as bad as mom likes to imagine...the guys at work often call me Big Ben as I am 6 ft 6 inches tall and North of 300lb
  Nowadays I mostly go by Ben.
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on November 11, 2020, 02:59:57 pm
Cheers Ben
Title: Re: M94 hit n miss Flywheel weight
Post by: St Paul Steam on November 11, 2020, 03:57:38 pm
Geez...I've seen many good/slow running H&M engines , but this one's got them all beat I believe,  I've never seen one of these run so much like the big ones, the way it winds down before it fires again.
Well done that 🙂👍
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 11, 2020, 05:33:46 pm
Cheers Ben

Cheers Jim!...glad to have fellow enthusiasts to compare notes and ideas with....these are fun little engines and hopefully we will learn to make them even better! I really like the glass syringe you found and will have to Look for something similar over here.
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on November 11, 2020, 08:16:48 pm
Geez...I've seen many good/slow running H&M engines , but this one's got them all beat I believe,  I've never seen one of these run so much like the big ones, the way it winds down before it fires again.
Well done that 🙂👍

The video posted earlier in this thread is not my engine ....but....one I am hopeful to match one day. I do not know exactly "what" was done to it but several have speculated it is well polished and Very Finely tuned plus most believe the compression has been reduced and possibly timing altered.

I put it in this thread as a goal to achieve, but I just wanted to clarify it is Not my work....I hope to get there one day!
Title: Re: M94 hit n miss Flywheel weight
Post by: 70Rcode on November 13, 2020, 07:31:20 am
Hi Ben,...Yes, ...There's almost an addictive interest in trying to slow down the non-loaded rpm & hits per min but only so much can be achieved with flywheel/governor spring & weight mods & the stock firing hit "kick" indicates maybe too much stock compression exists..I ran some engine impulse power output to compression ratio flywheel inertia math numbers & it seems by significantly Reducing the Compression Ratio may be the Key modification to reach the ultimate Low rpm/hits per min goal..Since the sparkplug-cylinder head runs way to cold (even without water) anyway, I'm considering reducing the C/R by using 1/16--1/8" thickness rubber cyl head gasket spacer/thermal isolator to produce a hotter running cyl head cleaner combustion + slower running results...Happy motoring,...tom.
Title: Re: M94 hit n miss Flywheel weight
Post by: Adirondack Jack on November 13, 2020, 05:53:52 pm
Hi Ben,...Yes, ...There's almost an addictive interest in trying to slow down the non-loaded rpm & hits per min but only so much can be achieved with flywheel/governor spring & weight mods & the stock firing hit "kick" indicates maybe too much stock compression exists..I ran some engine impulse power output to compression ratio flywheel inertia math numbers & it seems by significantly Reducing the Compression Ratio may be the Key modification to reach the ultimate Low rpm/hits per min goal..Since the sparkplug-cylinder head runs way to cold (even without water) anyway, I'm considering reducing the C/R by using 1/16--1/8" thickness rubber cyl head gasket spacer/thermal isolator to produce a hotter running cyl head cleaner combustion + slower running results...Happy motoring,...tom.
The head gasket spacer idea is a good thought.  My immediate concern however would be if one could achieve significant reduction with the stock cylinder head screws, (easy enough to use longer screws), and the existing exhaust valve pushrod?   One of our members shaved the piston I think .110”, and dished it out about another .040”, if memory serves. So you’re talking about an eighth inch spacer to achieve similar results?  Nevertheless, I like the idea, especially since it’s completely reversible if results aren’t to your liking.
Title: Re: M94 hit n miss Flywheel weight
Post by: Jim on February 18, 2021, 05:15:51 pm
How did these experiments end up?
Title: Re: M94 hit n miss Flywheel weight
Post by: Nick on February 18, 2021, 05:22:50 pm
How many holes did you end up with in the wall from flying magnets?

Fixed it for you Jim 😂
Title: Re: M94 hit n miss Flywheel weight
Post by: ShadetreeMotorcycle on February 18, 2021, 05:53:19 pm
Sorry guys!...when this engine showed up my shop had me working North of 65 hours a week plus close to 1 HR commute one way plus a bout with plantar fasciitis (foot arch pain) all this caused me to place this project on back burner. Now things have eased up at work but I was bite by a deadly "Steam bug"... Got a couple projects on the work bench then will circle back to hit n miss!
Title: Re: M94 hit n miss Flywheel weight
Post by: RedRyder on February 18, 2021, 07:08:49 pm
Plantar faschitis is truly painful. Sorry to hear this. I have been there.