1957 big twin 35, electric start

[58 chris craft comet]

Brand new to this forum and brand new to 2 strokes.. My issue with my big twin is that there seems to be to much compression, if that's even possible. This motor sat for at least 30 yrs. on the side of my garage, covered, carb drained, cylinders fogged with 2 stroke oil and occasionally turned over by hand. I didn't try to start the motor at first, I did some basic maintenance and soaked the cylinders in ATF and 2 stroke oil. Every day I would give the rope a small tug, the motor was never ceased and after 3 days it hand pulled easily without plugs in.
As of today I have rebuilt carb, replaced impellor, rebuilt gear case, filled gear case with fresh gear oil, new spark plugs. My original pressure gas tank was rusted out so I'm just spraying gas/ 2 stroke oil directly in the carb. I have spark on both plugs. The first attempt to start I got combustion and it ran for about 10 seconds. The next time I got a back fire and now it will only turn over 1/2 revolution and is very hard to hand pull. If I remove both plugs it turns over very easily and hand pulls easily.

Tom

 

[F_R]

The only way it could have "too much" compression is if it has liquid in the cylinders.

Otherwise, are the compression relief valves working (only when hand cranking)?

 

[Scott Danforth]

Brand new to this forum and brand new to 2 strokes.. My issue with my big twin is that there seems to be to much compression, if that's even possible. This motor sat for at least 30 yrs. on the side of my garage, covered, carb drained, cylinders fogged with 2 stroke oil and occasionally turned over by hand. I didn't try to start the motor at first, I did some basic maintenance and soaked the cylinders in ATF and 2 stroke oil. Every day I would give the rope a small tug, the motor was never ceased and after 3 days it hand pulled easily without plugs in.
As of today I have rebuilt carb, replaced impellor, rebuilt gear case, filled gear case with fresh gear oil, new spark plugs. My original pressure gas tank was rusted out so I'm just spraying gas/ 2 stroke oil directly in the carb. I have spark on both plugs. The first attempt to start I got combustion and it ran for about 10 seconds. The next time I got a back fire and now it will only turn over 1/2 revolution and is very hard to hand pull. If I remove both plugs it turns over very easily and hand pulls easily.

Tom

First, welcome aboard

second, sitting outside for 30 years, you cant stop moisture in the air from gumming things up.

as F_R indicated, look at the compression relief valves.

 

[58 chris craft comet]

Thanks for the speedy reply. Me being a complete noob, what and where is the compression relief valve, and can I by pass it and still run.

Tom

 

[Crosbyman]

I think you will find some info on the relief valve adjustments page 535 section 12 of the johnson red book

Boatinfo - 1922-1964 Johnson Service Manual

www.boatinfo.no

you can read up on the whole section as it applies to a starter installation but section 12 syas the releif valves must be adjusted to 0,018 to 0,025 on a cold motor

I hope this will help on your particular issue

 

[58 chris craft comet]

Sorry for late reply, to many irons in the fire. Motor is extremely hard to crank with either starter motor or hand crank until you pull the plugs, then it turns over very easily. There can't be any fluid in cylinders since when I crank it over with the starter motor, plugs removed, everything comes shooting out. The only thing I can imagine is happening is when I "soaked" the pistons I filled the lower power head with too much fluid. Is this even possible? I have since taken the motor to 2 different outboard repair shops in San Diego and they have both refused to do any in depth diagnosis, claiming that parts aren't available. As I said before when I first freed up the pistons, the motor turned over and ran, so the problem must be something I did after this. The only thing I did was add more ATF and 2 stroke oil to spark plug holes. Sorry for lengthy explanation but I'm baffled and so were the 2 San Diego repair shops.

Tom

 

[F_R]

Too much fluid in the "Lower powerhead"??? You mean the crankcase? Yes that is possible, I suppose. There is compression in a two-stroke crankcase. But I've never seen anybody do it.

 

[58 chris craft comet]

Too much fluid in the "Lower powerhead"??? You mean the crankcase? Yes that is possible, I suppose. There is compression in a two-stroke crankcase. But I've never seen anybody do it.

FR:
Yes crankcase. If fluid got into the crankcase would it cause enough compression with plugs in to make it hard to turn over yet when the plugs are removed allow it to turn over easily??? If this is so, how would I remove fluid from crankcase? I did notice fluid draining out of lower unit but this could just be old seals.

Tom

 

[hardwater fisherman]

Are you sure your battery and starter are in good shape? Including clean and tight connections.

 

[F_R]

FR:
Yes crankcase. If fluid got into the crankcase would it cause enough compression with plugs in to make it hard to turn over yet when the plugs are removed allow it to turn over easily??? If this is so, how would I remove fluid from crankcase? I did notice fluid draining out of lower unit but this could just be old seals.

Tom

Just crank it over with the plugs out to blow the liquid out, until most of it is out. You don't have to strive for 100% ejection. Yes, after it has blown out of the powerhead, it will drain out of the underwater exhaust in the lower unit and make a mess.

There is another possibility here. It is entirely possible there is a rusted bearing that locks up when compression pressure is applied to it. That outlook is not good

 

[58 chris craft comet]

Are you sure your battery and starter are in good shape? Including clean and tight connections.

I know my batteries are good and fully charged, I'm using 2 RV batteries in parallel. As for the health of the starter? It cranks the motor over fast with plugs out but can barely move it with them in. I can barely move with rope start in both cases.

Tom

 

[58 chris craft comet]

Just crank it over with the plugs out to blow the liquid out, until most of it is out. You don't have to strive for 100% ejection. Yes, after it has blown out of the powerhead, it will drain out of the underwater exhaust in the lower unit and make a mess.

There is another possibility here. It is entirely possible there is a rusted bearing that locks up when compression pressure is app lied to it. That outlook is not good

I don't like your theory about a seized bearing, sounds terminal. On that note there is another issue I noticed, there is a short lever attached under the flywheel and also to the throttle arm where the carb linkage attaches. This does seem to be frozen. When they are connected, the throttle doesn't move. I think it has something to do with spark advance when the throttle is opened? I may rent a flywheel puller and check if this lever is seized.


Tom