questions on boring a cylinder

[jetrail]

Hi ,
im new to the forum . I have a question what is the bestethod to bore a briggs engine? I have been working on small engines for over 15 years but have never learned to bore a cylinder and i am curious and would like to learn more about it . I have a briggs motor ive honed replaced the rings ect and put it all back together and it has low compression 40 lbs. I will have to bore it to use bigger rings right ? What is the best way to bore a small engine Thanks
John

 

[KennyV]

John, 40 pounds is Low... are you sure you are not having valve problems?
Was there any ridge that may have cracked the new top ring... I would look closer at things before I packed it off to a shop with the proper tooling... What B&S engine is it? :smile:KennyV

 

[Rivets]

Personally I would not try to bore the engine myself unless I have a boring machine. I agree with Kenny that you should check the valves and rings first.

 

[fastback]

Yes I agree, I also would check the valves first.

I'm no expert, but I think if you bore the cylinder you will need to replace pistion to the proper size. If you are able to get away with just honing then you can probably get away with a little larger set of rings. Before this happens you really need to inspect the cylinder for imperfections an maybe so some measurement with a snap gauge and micrometer.

 

[Rivets]

I disagree with honing and just new rings. If oil is getting past the rings 90% of the time the cylinder is either worn more than .003 (which is usually the smallest larger ring) or out of round. The only time I recommend honing is when you are doing a rebuild due to internal engine failure (crank, govenor, rod, etc) where you want to install rings in an engine with low hours. Honing and new rings will only solve a oil or compression problem 10% of the time at the most. As long as you have the head off and are checking the valves, take the six measurements of the cylinder as you would for cylinder analysis and see how they match with cylinder specs. This will tell you how to proceed.

 

[jetrail]

Well to give some history on the engine it broke the connecting rod and i decicec to open it up to see how bad the damage was . After checking it out the scoring on tue cylinder wasnt bad i honed it and put in another connecting rod piston and new rings .... i did it mostly to see if i could save the motor but standard size rings arent enough to hold compression now i guess

 

[Rivets]

Did you take any measurements before you installed the new rings. If you did would you post them and the engine numbers. Maybe you can still save it, depending on the measurement, with out a Hugh expense.

 

[motoman]

The tedious method of bore measurement is with a telescoping guage at numerous points. As you may know they are read with a micrometer and easily misread due to not being square in bore. The best is to take it to a motorcycle shop and have someone check the bore with a dial bore guage. This will be accurate and clearly show taper and out-of- round . I am not familiar with small engine repair parts, but many times there are standard overbore piston diameters such as .010" and .020" over. Although there is such a thing as "power " honing for small overbores, a true boring machine is usually called for if enough cylinder wall is present to accept the overbore. Honing is then done to create a proper finish on the cylinder wall for oil retention during break in.

 

[reynoldston]

If the cylinder walls are so bad on a Briggs engine that it needs to be rebored you will need this done at a machine shop. Then you will have to buy oversize pistons and rings. This is if you can find them. If I were you I would check on the price of a new short block or a good used engine. We have our pulling tractors rebored all the time but this is for more power and we also buy custom made pistons and rods to change our stroke, sorry now I am getting into something all together different.

 

[SeniorCitizen]

Hi ,
im new to the forum . I have a question what is the bestethod to bore a briggs engine? I have been working on small engines for over 15 years but have never learned to bore a cylinder and i am curious and would like to learn more about it . I have a briggs motor ive honed replaced the rings ect and put it all back together and it has low compression 40 lbs. I will have to bore it to use bigger rings right ? What is the best way to bore a small engine Thanks
John

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Has this engine ever ran since you did this hone job and re-assembled.? If it has, I have another question.

If you haven't been successful in getting it started since that work was done I have a suggestion.