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Colt 1.2hp rebuild

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s2sailorlis

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Getting started on a first-time total rebuild project - 1986 Colt 1.2hp. Factory service manual is on order...

At this stage, main task is to clean engine block and gasket surfaces. Please see attached. I am thinking of using carb cleaner and scotchbrite/plastic scraper for gasket surface. And carb cleaner for exterior. My concern is getting carb cleaner into the cylinder area - would this be an issue? Guess I could stuff some rags into the cylinder area. (carb walls look good - cross-hatching still visible - piston looks good with no blow-by past the rings. Also, can I re-use the rings (not sure they make them any more...)

Note that this engine is for ocassional use on a 9 foot dinghy when I am lazy and not wanting to row..
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Just use a large fine flat file to clean up the surfaces just use smooth strokes careful not to gouge the surface. Do a quick deglaze on the cylinder wall with a cylinder hone and try to achieve a 45 degree cross hatch just use lots of oil with a slow drill and pull the hone out before you turn the drill off. You can soak it with carb cleaner and blast it with high pressure water just be sure and dry and oil the cylinder it will begin to rust immediately if not protected.
 
I also use a sharp wood chizzel to scrape the old gasket material off also careful not to gouge the aluminum. I surface the head and the head surface on the block with 220 grit on my tablesaw you can use a glass table. Just swirl it in a figure 8 pattern until it all shines the same.
 
You do need to be careful with the needle bearing you dont get metal fragments and dirt in it just stuff a clean rag in it until you get the rest all cleaned up.
 
http://www.ebay.com/itm/OMC-Tankdec...049399?hash=item3ace49d937:g:XWEAAOSw8gVX81e2
I have been searching for a new gas cap for the plastic tank for three years and finally found one in germany. Looks like the fat O-ring for the vent is a bit cheaper.
When you get to adjusting the points use a timing light. On the side of the points plate is two marks and a single mark on the flywheel. just tighten the flywheel nut finger tight and point the light at the two marks on the points plate and spin the flywheel by hand. just leave the spark plug out and rest it on a good ground. you want the single mark on the flywheel to be in between the two marks on the plate. Then you can torque the flywheel nut to spec. That will make it a one pull start motor. You can connect the timing light to any 12 volt battery.
 
New rings are not cheap and I highly recommend breaking in new rings the engine will idle alot better. Seaway marine has them for around $45 #0395596 as well as any other parts you need except the gas cap. For the first 8 hours of operation mix the fuel 40:1 and run it at variable speeds up to 3/4 throttle. You can run short bursts at WOT but keep it at lower speeds for the break in period to seat the rings. Then you can mix 50:1 and run all day on less than a gallon of fuel.
 
Post #1 stated can i reuse old rings, Crosshatch can still be seen, How many hours are on engine, approx.? Title says total rebuild, Are you rebuilding engine from ground up s2sailorlis. keep us posted!
 
Kimcrwbr1 thanks for the input. The motor was running fine but it was overheating...In my quest to figure this out I managed to disassemble the entire bloody engine. The water flow was blocked where the tube ties into the top of the housing, thus never making its way to cylinder head. The head water channels were completely blocked too.

Once I got started ripping things apart..My hope was simply to remove block from housing, unfortunately the drive shaft was seized onto the crank..So I could not separate block from housing...So to ckntinue...Rest is history.

I am eternally cheap and won't use the motor much, hence hesitation in buying new rings..But it probably makes sense to do it....
 
Johnny, good question. Here is history of motor as I purchased it from original owner (who died and son was selling it...).

It's a 1986 that was used as a tender to sailboat. I purchased it in 2013 along with a sailing dinghy for $800. I resold dinghy for $1000, so engine was essentially free!

The dinghy and engine sat in a garage for 16 years prior to my purchase, so it has 10 years if what appears to be very little use, it's in quite nice shape....Or was...;).

The motor is COMPLETELY disassembled..Totally in pieces....

I'll post updates as I get time to work on it, given my schedule I'll prob get it done this fall as I have to get my big boat in the water in the spring....
 
It is my experience the cheapest way is to do it right once. Just guessing but looking at the block it is a salt water motor that was never flushed properly.
 
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