Author Topic: Lauson LA build  (Read 13676 times)

Offline gbritnell

  • Full Member
  • ****
  • Posts: 1795
Re: Lauson LA build
« Reply #165 on: July 06, 2018, 08:39:35 PM »
Dang! it looks like the real thing!
Talent unshared is talent wasted.

Offline Roger B

  • Full Member
  • *****
  • Posts: 3483
  • Switzerland
Re: Lauson LA build
« Reply #166 on: July 11, 2018, 08:32:07 PM »
Catching up with this build again. Excellent work and looks almost ready to start  :praise2:  :praise2:  :wine1:

I was looking back at your points setup and wonder if your closed (dwell) time is too short. The points need to close for enough time for the magnetic field to build up in the coil. I think there is also a video missing in post 137  :headscratch:
Best regards

Roger

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 267
  • Raleigh,NC. USA
    • Lauson small engines
Re: Lauson LA build
« Reply #167 on: July 11, 2018, 10:17:06 PM »
Cletus, Kirk, Allen, Brian, Rodger, George: yíall are too kind; thank you for your complements.

Well, it runs: sort-of  :o

The above is an edited video of the more successful (fits and starts).  I still have a few issues to address (like getting it to run dependably and the gas pouring out of the carburetor) but Iím thinking my remaining issues are confined to carburetion.  Iíve come across LOTS of problems in the last week or two, trying to coach some life out of this thing.

This little guy has proven to be one of the more problematic models Iíve built.  I will occasionally build a model (like the Debolt Star) that ran great the first time I cranked it over; but not this little guy.

I would never call myself an ďexpertĒ model engine builder, :Lol: there are some folks on this site that work at a caliber of which I can only dream of aspiring to; but I have built four of these Ĺ size Lausons.  The previous three run pretty well and I have no doubt that this one will too once I get the few remaining problems solved.  Iím going to document the highlights of the problems Iíve dealt with over the past two weeks so that some of the less experienced guys on this site can see that even someone who you would think ought to know what he is doing by now still can create a raft of problems to sort through.

My first problem occurred pretty early, like when I first turned this engine over with the starter.  You might remember that this engine, like the full size, has a mandrel threaded into the front of the block.  The hollow camshaft rides on this mandrel.  When I spun the engine with the starter, the cam mandrel, even though it had a locking nut on the outside of the block, promptly screwed out of the engine block and fell into the crankcase, taking the camshaft with it. :o   Drilling the locking nut (effectively turning it into a castle nut) and placing a keeper through the hole corrected that problem.

The second problem was that even though I had checked this earlier, the inside of the flywheel was dragging on something on the magneto.  I ended up using marker dye and spinning the flywheel, then disassembling to see where the problem occurred.  Fortunately, there was a little extra ďmeatĒ on the flywheel at the offending spot to remove and correct this problem.

Thirdly, the exhaust valve was leaking.  It wasnít when I lapped and tested the valves but it sure was now.  More lapping and a stronger spring corrected that problem.

Fourthly, and Rodger had scoped this out up thread, but after I found it; I had spark at hand cranking speed but no spark when spun with the electric starter.  As Rodger suggested I increased the dwell time and corrected this problem.

Fifthly, the timing seemed to have shifted a bit to the ďlateĒ side, maybe due to ďFourĒ above.  This was a mystery and since the timing collar had no adjustment (just like the original) I ended up redesigning the timing collar so that the timing could be adjusted; then re-timed the engine.

Now about a week had passed, and I had as yet to hear one solitary ďPOPĒ from this thing.

In frustration I removed the carburetor and squirted a little gas into the intake valve area, spun the engine, and POP POP POP three good successive fires. :ThumbsUp:  An inspection of the intake manifold showed it was completely blocked. :noidea:  Well, I had glued the five parts that make it up together, hadnít I checked to see if it was blocked?  Apparently I had not.  I managed to fish out the blockage with a bit of stiff wire.

After that things improved dramatically and I thought Iíd make this video to show it probably will run once the remaining kinks are worked out.

At this venture it seems to be starving out as it runs, but opening the main needle seems to flood it out.  With the construction of the needle, anything over three turns probably wonít make any difference. It either wants a VERY critical needle setting or I have some porting wrong in the carburetor.  Iím thinking more toward the latter and Iíll have my thinking cap on over the next few days about addressing that.  I also need to figure out from where the gas is pouring out of the carburetor; probably the float valve needs some attention and if this is the case, fixing this will probably correct the flooding problem; this has been a critical issue with the other carburetors Iíve built.
 
Then of course, in concert with getting it running better, there are lots of items to address to complete this model: the blower housing, fuel tank, and kick start mechanism to name a few.

All in all Cletus, time to sit back and open a beer to celebrate.
Craig

Offline Admiral_dk

  • Full Member
  • ****
  • Posts: 1011
  • SÝften - Denmark
Re: Lauson LA build
« Reply #168 on: July 12, 2018, 10:51:36 AM »
Congratulations on a fine (if not completed) runner  :cheers:

I feel confident that you will iron out the last problems too  :ThumbsUp:

Offline gbritnell

  • Full Member
  • ****
  • Posts: 1795
Re: Lauson LA build
« Reply #169 on: July 12, 2018, 11:55:55 AM »
Craig,
Congratulations to this point are certainly in order. From your explanations let me offer you my two cents worth. First I don't think the porting is an issue. I have engines with porting of all different sizes and shapes and as much as you'd think there would be a problem, there's not.
Carburetors in these sizes can be very sensitive so that could might be an issue.
The thing I'm suspecting is the ignition timing. It's hard to know exactly where to start. I usually begin between 10-15 degrees. Once the engine is running I adjust it to find the sweet spot. With your ignition timer buried that makes it more difficult. Once you get the carb sorted out I would play with the timing a little. It's amazing how just a couple of degrees will change the whole character of the engines performance.
gbritnell
Talent unshared is talent wasted.

Offline kvom

  • Full Member
  • ****
  • Posts: 1719
Re: Lauson LA build
« Reply #170 on: July 12, 2018, 04:02:05 PM »
Wondering why you've built 4 of these.  Addiction?   :shrug:  :noidea:

Offline Johnmcc69

  • Full Member
  • ****
  • Posts: 344
  • Erie Pa., USA
Re: Lauson LA build
« Reply #171 on: July 12, 2018, 06:35:02 PM »
Been following along silently Craig, but must say this is a beautiful build. Very well thought out & executed. Very nice work.

 Thanks for pointing out your trials & tribulations in getting the bugs worked out, good info to digest & as usual, great responses from the community here.

 Can't wait to see it finished & a family shot of the others with it.

  :ThumbsUp: :cheers: :popcorn:

 John

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 267
  • Raleigh,NC. USA
    • Lauson small engines
Re: Lauson LA build
« Reply #172 on: July 12, 2018, 10:05:00 PM »
Thanks for your encouragement, yesterday was a discouraging day. 

George- thanks for your advice. Iím going to look at the timing as you suggest but in post following this one youíll see that my major problems were, chiefly, fuel related.  I might be able to tweak the timing some, resulting in the engine being able to run through abrupt throttle changes.  Any insight regarding that would be appreciated.

Kirk- I wasnít clear regarding building Lauson models; Iím not building four of these things.  I have built three different Lauson engine models (this being the fourth) which I posted a while back:

http://www.modelenginemaker.com/index.php/topic,7500.0.html
http://www.modelenginemaker.com/index.php/topic,7501.0.html
http://www.modelenginemaker.com/index.php/topic,7502.0.html

Along with building models, Iím a Lauson small engine collector and over the years I have managed to collect nearly one example of each of the different types of air cooled engines that Lauson produced.  I maintain a website (http://lausonsmallengines.org) for use by other Lauson enthusiasts to assist them in their collecting and restoration of these engines.  Iíve been using a few of the engines from my collection as a basis for these models.   
« Last Edit: July 12, 2018, 10:27:44 PM by Craig DeShong »
Craig

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 267
  • Raleigh,NC. USA
    • Lauson small engines
Re: Lauson LA build
« Reply #173 on: July 12, 2018, 10:25:38 PM »
A better day today.  I tracked the carburetor leak down to a blind passageway that hadnít been plugged properly and once plugged the leak was stopped.  This also had the benefit of allowing the pressure differences in the carburetor passageways to work as designed and the result was a MUCH better running engine.

I spent the morning working on a spring in the governor cap that allows the governor to regulate the speed of the engine.  I had limited success in this because abrupt throttle changes just seem to stall out the engine while it seems to tolerate slow changes pretty well; it actually has a decent idle when the throttle is closed slowly.  Iíll need to think on this a while, maybe Georges suggestion on tweaking the timing might address this and Iím open to other suggestions if anyone wants to volunteer any. :help:  I didnít design/build an idle circuit in the carburetor so this doesnít surprise me.

By noon I had pretty much killed my ignition battery and I was having intermittent problems with air getting in a siphon I was using to draw fuel from my temporary fuel tank.  I did manage to make this short video to redeem myself from the one I posted yesterday.
Craig

Online Tennessee Whiskey

  • Full Member
  • *****
  • Posts: 3623
  • Springfield, Tennessee. USA
Re: Lauson LA build
« Reply #174 on: July 12, 2018, 11:45:46 PM »
Now that just sounded so darn good that Iím going to drink a beer or three for you  :cheers:  :lolb:. Great job Craig.

Cletus

Offline zeeprogrammer

  • Full Member
  • *****
  • Posts: 6277
  • West Chester, PA, USA
Re: Lauson LA build
« Reply #175 on: July 13, 2018, 12:34:52 AM »
 :pinkelephant:

I'd been following along. Very happy to see your success.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
"To work. To work."
Zee-Another Thread Trasher.

Offline Craig DeShong

  • Full Member
  • ****
  • Posts: 267
  • Raleigh,NC. USA
    • Lauson small engines
Re: Lauson LA build
« Reply #176 on: July 24, 2018, 08:52:42 PM »
With this little Lauson running now, A few more issues have come up that need a resolution. 

Some of the J B Weld glue joints are releasing from the aluminum; especially in the kick start area.  This is area is saturated with crankcase oil and the oil appears to be working under the epoxy and lifting it; Iím thinking J B Weld probably isnít the best material to use in this area.   

When I lessen the tension on the governor spring, the governor will close the throttle as the engine speeds up, just like itís supposed to; unfortunately, when this happens the engine just cuts out.  Iím thinking this engine would benefit greatly from a low speed circuit designed into the carburetor.  This can be done, but it requires a carburetor re-design and re-fabrication.

Iím also being plagued by a points problem where, as the engine runs, the engine timing changes.  Some alteration of the points is probably in order.

Rather than just plow on with my first devised immediate solution to these problems, Iím going to set this project aside for a brief period while I think about the best way to address these problems; then after careful thought Iíll get back on this project.

Meanwhile, I have a few other projects that have been awaiting my attention far too long.
Craig