Author Topic: Rebuilding an unknown 4 stroke single.  (Read 8677 times)

Offline Stuart

  • Full Member
  • ****
  • Posts: 1724
  • Tilchestune UK
Re: Rebuilding an unknown 4 stroke single.
« Reply #15 on: June 23, 2014, 07:21:46 AM »
I do not qualified to make a judgement, but my only resavation based on my other build and reading
Is the CI liner in a Ali fined outer is the thermal expansion would not the Ali move away and leave the cylinder uncooled ?
The CI head would be ok

Note I have yet to build a IC engine but have built many live steam locomotive ,many other modles over many many years, but alas the locomotive have been sold :'( due to mobile problem I am on crutches and have work the lathe and mill sitting down , but I get round the problem so no worries

Stuart
My aim is for a accurate part with a good finish

Online Jo

  • Administrator
  • Full Member
  • *****
  • Posts: 12010
  • Hampshire, england.
Re: Rebuilding an unknown 4 stroke single.
« Reply #16 on: June 23, 2014, 07:47:13 AM »
CI liners in Aluminium cylinders work just fine  :ThumbsUp: The liners normally have a shoulder on the head end to keep it in place.

My Anzanis  ;D both will have steel cylinder heads and cylinders, my Kiwi will have the Cast Aluminium head and all steel cylinder. 

Jo
Usus est optimum magister

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #17 on: June 23, 2014, 04:38:56 PM »
The old/present assembly is a steel liner in Alum. I was thinking maybe machining off the Alum and reusing the liner. All just to reuse as much of the old as possible. I was intending using the old valves and rockers also.
Alum is definitely easier to work with, so the "fins" may be a no brainer.
For the head assembly, is brass or bronze better for the valve cages?
PatO
I started out with nothing, I still have most of it left.

Offline Jasonb

  • Full Member
  • *****
  • Posts: 6168
  • Surrey, UK
Re: Rebuilding an unknown 4 stroke single.
« Reply #18 on: June 23, 2014, 05:44:44 PM »
Whats the piston and does it have any rings? If no rings then I would probably go for a steel liner in alloy cylinder and a iron piston. If you are running rings then steel or iron liner will work with alloy piston and CI rings.

If you do the head from iron you don't really need cages the valves can seat on the iron. If its an alloy head then bronze cages.

J

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #19 on: June 23, 2014, 08:33:32 PM »
Thanks for the head and valve info Jason. Yes the piston is alloy, forged by the look of it with 2 rings. The sleeve is steel.
PatO
I started out with nothing, I still have most of it left.

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #20 on: July 07, 2014, 04:03:45 PM »
OK, so I have started the rebuild in earnest now that I have a lathe again.
The first item on the agenda was the spacer to align the cylinder into the crankcase.
After that was done and fitted I remachined the fins on the cylinder barrel to a more even and "finished" appearance.
The next piece was the head. I did not have a piece of cast iron on hand to suit, so I opted for the aluminium 6061-T6. I machined it to size, cut some fins, and after numerous cuts and settings on the rotary table and cutter and drill changes, I had a head replacement.
The valve cages are next.
PatO
I started out with nothing, I still have most of it left.

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #21 on: July 15, 2014, 01:04:19 AM »
The valve cages were made, valves seated, installed into the head, drilled the ports and tapped them 1/4-32, made up an inlet manifold/tube, and put the whole thing back together. There was not a lot of compression, so I pulled it apart and machined .040" off the bottom of the alum. barrel to close up the deck height. Now it does have compression.
Next I setup a 1966 Honda 90 coil, a B&S condenser, and a 4 pack of 1.5V AA's and checked if the points work. They do and it sparks at the plug.
Next I need a gas tank and a bit of setting up, a drive dog to crank it with and see if/how it runs.
 
PatO
I started out with nothing, I still have most of it left.

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #22 on: July 15, 2014, 01:09:09 AM »
I picked that carb up at a model swap meet about 25 yrs ago. My research shows that it is similar to an ETW design. It was rough, and did not have a spring under the vacuum operated valve. I have added a light one into it, and when you turn the motor over by hand you can feel , see and hear it opening.
PatO
I started out with nothing, I still have most of it left.

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3712
  • Switzerland
Re: Rebuilding an unknown 4 stroke single.
« Reply #23 on: July 15, 2014, 05:37:56 AM »
I was confused, why would Brown and Sharpe make condensers, then it clicked Briggs and Stratton  :facepalm:

Looking good. Hopefully not long to the first run  :ThumbsUp:  :ThumbsUp:  :popcorn:
Best regards

Roger

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #24 on: July 29, 2014, 04:58:45 AM »
I have not fired it up yet, I am having spark trouble, among other things!!! The drive dog needed remakeing, the flywheel came loose after it backfired twice, etc etc. I am picking up a new spark plug tomorrow, maybe try running before end of week.
PatO
I started out with nothing, I still have most of it left.

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #25 on: August 09, 2014, 04:32:34 AM »
Well, I had it firing, as long as I had the drill attached. Soon as I removed that it stopped. I played with cam timing ignition timing, compression ratio, fuel, and then built a larger flywheel. Well it ran for 2 seconds, and seized up solid. The crank had seized into the main bearing. I had attempted to keep plenty of oil in the case but it blows out pretty quick.
I lowered the compression by adding copper washers to the spark plug. The bigend of the rod is also screwed. so a new rod, a new front main and some more rethinking as to why it will not just run!!
PatO
I started out with nothing, I still have most of it left.

Offline HobbyNut

  • Full Member
  • ****
  • Posts: 307
  • Surrey BC
    • What I do
Re: Rebuilding an unknown 4 stroke single.
« Reply #26 on: September 26, 2014, 04:37:20 AM »
Actually the rod was OK, it was just the main bushing that was shot. It was cast iron?....I made a bronze one and reassembled it. I am going to make a new carb, maybe a Fellows or Rupnow type.
PatO
I started out with nothing, I still have most of it left.

Offline Roger B

  • Global Moderator
  • Full Member
  • *****
  • Posts: 3712
  • Switzerland
Re: Rebuilding an unknown 4 stroke single.
« Reply #27 on: December 16, 2014, 12:21:03 PM »
Have you got any further with this one?
Best regards

Roger

Offline fidlstyks

  • Full Member
  • ****
  • Posts: 51
Re: Rebuilding an unknown 4 stroke single.
« Reply #28 on: February 01, 2015, 04:19:03 PM »
as far as identification,  I had a similar model and  have seen several others , some on ebay, all a little different. It was my understanding they were a design that the blue prints  of had been published in a magazine like Popular Science . Some were made as school projects. They run as good as their builders !