Cogsy Builds Rupnow Engine

[Swifty]

That would just be the West Australian version, the Victorian version still runs well.

Paul.

 

[gus]

The Singapore Flied Chicken Lice spinning but not hitting and missing yet.

After the Burma Bank Fishing Trip,same engine will be ''hitting and missing''.

Now busy retrofitting my DIY cheapy deep sea rod holder which the swivel base busted.

 

[Cogsy]

I'm back, admittedley with my tail between my legs for being away so long.

Events have conspired to keep me from engine building, or even viewing the forum for quite a while (I know it sounds like I've been in prison but I haven't, I promise).

So without further ado, I'll bring you up to speed on my Rupnow build, if you're still interested.

With all the pops and bangs I was getting, and the increased compression I could feel, I suspected fuel was my issue. As Swifty suggested, I was lacking a vent hole in my fuel tank, but as it was a thin, flexible platic bottle, I didn't really think that it would be much of an issue. Eventually, I built an intake manifold and adapter to take a model plane carby and put that on, still without making much difference.

I played with the mixture till I was blue in the face and eventually had it firing consistently, but it wouldn't self sustain. Then I lifted the 'fuel tank' above the carby and it took off running perfectly! I was so very happy, for about 60 seconds or so. Then it siezed up solid :wall:. I was mildly upset at this point, but I did refrain from using my 8 pound sledgehammer on everything in sight before I locked the shed and walked away.

When I did get back to the shed a couple of weeks later, I stripped the motor down, everything seemed good, but it appeared the rings had grabbed. All I could think was that I hadn't cut the ring groove in the piston quite deep enough and as the rings expanded they had no room to grow. I chucked the piston in the lathe, deepened the ring grooves slightly and widened them a poofteenth. Reassembled everything and it felt perfect again.

I reinstalled my original carby (made to Brians' plans) and it started and ran no problem at all! Victory at last!

I then made up a fuel tank and bracket , but I do need to revisit it and make a bigger one.

This is where the story ends though, as circumstances beyond my control took over at this point. I'm back on track now, and I've just ordered my first ever plans and casting kit for an engine. I won't be starting it for a while though, as I still have to finish off my Rupnow engine, including making the hit and miss mechanism for it.

My apologies for such a long break in communication, I'll try and do better in the future. For now, I've got 6 months worth of posts to read so I'd better get started.

 

[Brian Rupnow]

Cogsy---I am so happy to see you back on board, and to hear of your success. Did you get the hit and miss system working? We would love to see a video.---Brian

 

[gus]

Hi Cogsy,
Congrats.You got it going.

In about two weeks there should be two Nemett-Lynx Engine about to spin. And at least another two more too.

 

[Cogsy]

Thanks guys. I haven't built the hit and miss mechanism yet, but I will be starting tomorrow, as long as the wife lets me. I will post a video of the running engine, hitting and missing, just as soon as it's done.

 

[gus]

Thanks guys. I haven't built the hit and miss mechanism yet, but I will be starting tomorrow, as long as the wife lets me. I will post a video of the running engine, hitting and missing, just as soon as it's done.

The valve and ignition timing must be spot on. Good indication is easy starting
at every spin start. Engine speed at medium.The governor arm sub-assembly and the trigger lever must be smooth and well oiled. You may have to play around with the main spring.
Have fun. ( My darling boss thought Gus gone bonkers staring at a crazy engine that just won't run steady for hours!!!)

 

[Cogsy]

Time for a quick update so you don't think I've disappeared into an abyss again.

I built a new fuel tank but haven't made a bracket for it yet, and then tried to start the engine again. Nothing. For 2 days. It would pop now and then but refused to run. I played with ignition timing and reset the valve timing. Actually, I don't remember Brian recommending anything on valve timing. Maybe I missed it but I've just used my best estimate. Then I adjusted the fuel needle 7.2 million times. Then I changed back to the RC carby and fiddled with the needle a further 6 million times. Pops, sometimes a couple in a row, but no running.

Eventually, I removed the spark plug and checked spark, even though I knew it was sparking from the random pops. No problem there, turning the crank by hand I had a big, fat blue spark. Then, as I had no compression with the plug out, a quick spin of the crank showed - No spark . Turn the crank slowly and there was good spark. Turn it fast and nothing . Spin it with a drill and there was the odd random spark (hence the random pops) . I'm using a CDI ignition that's supposed to be triggered by a hall sensor, but I've changed it to points as I killed all my sensors. I figured I'd killed the unit somehow, but it turned out... drum roll here...the 4 AA batteries that power the CDI were flat :wall:. Changed them, VROOM, instantly. Oops.

So since then I've been having greater success. The governor stem post assembly is complete. Now I need to work on the bracket and the shaft, spring adjuster and latch. Hit and miss day is approaching slowly.

 

[Swifty]

Hi Cogsy, glad to see that you got that problem sorted.

Paul.

 

[Cogsy]

Thanks Paul. I can't believe how long it took me to find out I had flat batteries. Lesson learned though, from now on I'll double check all the easy things before I start searching for gremlins.

Progress might speed up a bit soon - I think I'm about to find myself 'between jobs' for a while.

 

[Path]

Hey Cogsy ..

Great update ...

Fat blue spark who would of thought batteries .. not me, but now we
know! Thanks.


Pat H

 

[Brian Rupnow]

Cogsy--Don't feel too bad. I can not count the number of times that I have been tuning an engine, when suddenly it would trail off and quit for no reason. After checking about a dozen things that could have potentially gone wrong, I discover that it has run out of fuel!!!---Brian

 

[gus]

Wish You All Success to the H&M happening!!!

Now busy upgrading the RT to get rid of excessive back lash which cause chattering when profile milling Con-rod big/small ends. Just graduated the hand dial. Cam cutting for the Nemett-Lynx Engine begins soon as the engraving cutters arrive.

 

[gus]

Will soon be Gus's turn to mess around with the electronic CDI.
Hopefully the CDI won't get fried. Can't make ''Fly Lice'' aka Fried Rice.

 

[Brian Rupnow]

Gus--Whatever you do, don't trigger the Hall effect sensor without a well grounded sparkplug in the circuit. That is what fries them.---Brian

 

[gus]

Gus--Whatever you do, don't trigger the Hall effect sensor without a well grounded sparkplug in the circuit. That is what fries them.---Brian

Will connect earth first. Is this battery +ve or -ve?

Thanks.

 

[Brian Rupnow]

Gus--I believe they are negative ground, but I am certainly no expert. You will have to ask whoever you purchase the ignition components from. I know my way around ignition points and coils very well, but not CDI ignitions. I am sure of what I said in regards to not firing the ignition without a well grounded sparkplug though.---Brian

 

[SixSixSevenSeven]

positive earth is very rare. Almost all electronic components are negative ground (earth isn't a phrasing used so often in electronics although the 2 can be interchanged). Of course as always check the documents beforehand to confirm, but it should be earth/ground on negative.

In theory, hall sensor triggering without a grounded sparkplug shouldnt do anything odd, I can only assume the hall sensor itself was not properly grounded. Still, might aswell ground it anyway, better safe than sorry

 

[Cogsy]

So I've been slogging along making parts and it's been going pretty well. I somehow managed to manually resharpen a broken 1.5mm drill bit, even though I couldn't actually see the cutting edges. Then I turned the smallest part I've ever made - a locking pin with a .057" diameter shaft. I don't know about anyone else, but for me, that's a small part.

Here's a pic of my completed governor shaft. It was fun to make and my wife and daughters are very impressed with the movement of the weights and shaft.

Here's a shot of the 57 thou pin I was talking about. I didn't say it was pretty, just that it was small.

I'll end this post now to save it becoming a long one. More to follow very soon.

 

[Cogsy]

At this point I had to disassemble the engine just to drill and tap the mounting holes for the governor mechanism. I hate to pull apart a running engine but it had to be done. I drilled and tapped the holes without drama and managed to get it all back together again.

To try and start it, I decided to go with the RC carb, just so I could be reasonably certain the carb would work properly (nothing against Brians' design, it's my building skills I don't trust). For ignition I have a Chinese CDI coupled up to a set of automotive points. It works, but timing is challenging and ends up being a lot of trial and error. I will be changing to a different ignition at some point but I haven't decided what sort yet.

Valve timing was set by guessing and hoping, but I doubt it's too far off.

I was able to test the governor mechanism by spinning the engine over with my electric drill and it worked just as well as I hoped it would.

1/2 an hour of spinning it over, tinkering with the carb needle and resetting the timing had the engine making all sorts of promising noises and then ---- it started up! Then promptly started missing...then firing...then missing... and so on. It still needs a lot of tinkering with the carb (I'll change to the one I made before long), ignition timing, valve timing and governor settings, as well as a fair amount of breaking in, but I'm over the moon it's running.

Once it's all sorted I'll strip it down again and clean and polish it all up, then it's mount to some sort of base and present to my father as a long overdue gift.

Below is a low quality video, but before you watch it there are some things I need to point out. 1. Yes, my work bench is atrocious. 2. Yes, the engine is filthy. 3. Yes, I filmed the clip with a potato, in the dark. and 4. Most of the fasteners you can see will be replaced with the correct size and style before the engine is finished, I just cobbled together what I had to get it going.

Also, just FYI, when I reach over the engine I'm adjusting the governor spring tension, not the carb.

Enjoy!

[ame]https://www.youtube.com/watch?v=jpeieS9NJvE[/ame]

Thanks for looking.