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Heavy compression

bench

Registered
I have heard that you can remove a ring to lower compression and make it easier to turn over and it also helps with letting engine run slower.
Is this true or not,I have a 12hp pattin I would like to roll thru in the running direction to start and not kick start.
Let me know if any of this is true or not.
Thanks
 

con-rad

Registered
never heard of that. I don't see anything wrong with bump starting an engine, it's how they were supposed to be started. you can even bump start with a friction wheel starter if you have physical limitations.
 

Kirk Taylor

Registered
I have heard that you can remove a ring to lower compression and make it easier to turn over, and it also helps with letting engine run slower.
Is this true or not? I have a 12hp Pattin I would like to roll through in the running direction to start and not kick start.
Let me know if any of this is true or not.
Thanks
What ignition does your engine use? If it is hot tube, you need the compression to effect ignition.
Why do you not want to back-tramp the engine? Unless there are extenuating circumstances, an engine of that size would be easier to tramp than it would be to pull it over the top.
Removing the top ring probably will make no noticeable difference in the compression. Nor will it allow the engine to run slower. Assuming you are running spark plug ignition, you could put a compression release valve on the engine. All you need is a quarter-turn ball valve or plug valve plumbed into the combustion chamber. If the engine has a tapped hole going to the combustion chamber, that's perfect. If not, you could put a tee at the spark plug and use that. Also assuming that your engine is a four-cycle, open the valve and bring the engine to inner dead center. With the valve closed, roll the engine through the intake stroke to pull in fuel. Open the valve and roll the engine until the piston is about two-thirds of the way up the compression stroke. Close the valve and pull it over the top. If the planets are all aligned, it might fire hard enough to make it through the next compression stroke and start. However, doing it this way, you don't "get a running start at it" the way you do when you're tramping it, so it's all muscle and no momentum.

Kirk
 

bench

Registered
What ignition does your engine use? If it is hot tube, you need the compression to effect ignition.
Why do you not want to back-tramp the engine? Unless there are extenuating circumstances, an engine of that size would be easier to tramp than it would be to pull it over the top.
Removing the top ring probably will make no noticeable difference in the compression. Nor will it allow the engine to run slower. Assuming you are running spark plug ignition, you could put a compression release valve on the engine. All you need is a quarter-turn ball valve or plug valve plumbed into the combustion chamber. If the engine has a tapped hole going to the combustion chamber, that's perfect. If not, you could put a tee at the spark plug and use that. Also assuming that your engine is a four-cycle, open the valve and bring the engine to inner dead center. With the valve closed, roll the engine through the intake stroke to pull in fuel. Open the valve and roll the engine until the piston is about two-thirds of the way up the compression stroke. Close the valve and pull it over the top. If the planets are all aligned, it might fire hard enough to make it through the next compression stroke and start. However, doing it this way, you don't "get a running start at it" the way you do when you're tramping it, so it's all muscle and no momentum.

Kirk
KIRK,
Some very good ideas thanks for the info.
You gave me some good ideas.
Thanks
 

IronworkerFXR

Subscriber
Last Subscription Date
09/06/2020
Kirk is right,
and if you want less compression you be better to add head gaskets. I do not see how removing the ring would help reduce compression, it WILL give blowby , and a poor ingition with little power . there are much better ways , , and I get it ,, it can be a B*$ch to start them at times ......
Keep us in the loop on what you end up doing .
 

bench

Registered
Kirk is right,
and if you want less compression you be better to add head gaskets. I do not see how removing the ring would help reduce compression, it WILL give blowby , and a poor ingition with little power . there are much better ways , , and I get it ,, it can be a B*$ch to start them at times ......
Keep us in the loop on what you end up doing .
I will let you know what I come up with to help start this old girl.
 

Lou Quirch

Subscriber
Last Subscription Date
03-09-2020
When I ran into the original owner of our 16hp SM Jones, he told me thy had taken a ring out to lower the compression when starting.
I've had this engine for 15 years and I run it for many hours at 3 shows. It does have a little blow by, but you can't hardly see it.
John Neagley and I were going to pull the piston and check, then unfortunately John past away. It keeps running fine.
Lou
 
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