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26 hp briggs only running on one cylinder (I pull one plug wire and nothing changes) new plugs any ideas??

Check for spark on the cylinder that is not firing. If you have fire then check the pushrods to make sure they are still in place and straight.

ILENGINE said:

Check for spark on the cylinder that is not firing. If you have fire then check the pushrods to make sure they are still in place and straight.

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its has spark and the pushrods/rockers seem to be normal when cranking with cover off !what next??Thanx

spanky324 said:

its has spark and the pushrods/rockers seem to be normal when cranking with cover off !what next??Thanx

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How did you check the spark and what is the compression on the cylinder not firing? There could be several reasons for this, compression, spark, fuel, timing, you will find one of these things missing with the last two not that likely but not impossible. I might add plugged exhaust.

don't have a compression tester but I checked for spark by cranking it with a plug touching ground --great spark-I could hear compression though--valve adjust maybe??

ILL borrow compression tester tomorrow any special procedure that needs to be done?Like both plugs out or squirt oil in cylinder ?Its been awhile!

spanky324 said:

don't have a compression tester but I checked for spark by cranking it with a plug touching ground --great spark-I could hear compression though--valve adjust maybe??

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The proper way of checking spark is under compression with the plug in the engine with a tester and also make sure the spark will jump a good 1/4 inch. As for myself I find its impossible for me anyways to check compression without a compression tester or a leak down test. Just don't have a feel for it. I am doing this work on customers equipment in my shop also and have all the tools to do this. Not that hard to check for a tight valve with a feeler gauge so that may be your next step ?? Buy a new spark plug they are very inexpensive.

ill check out the valves --I got two new ngk plugs too!

spanky324 said:

ILL borrow compression tester tomorrow any special procedure that needs to be done?Like both plugs out or squirt oil in cylinder ?Its been awhile!

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Both plugs out, throttle WFO ( not choked ) dryI like to
I like to do it by jumping the trigger on the starter solenoid, so the ignition is off thus no spark.
You can do it again after squirting a little oil into the cylinder and revolving the motor a few time to distribute it. called a wet compression test.
Only old farts like me do this. A difference of 10% or more = bad rings.
You need something better than 75 psi for the engine to fire even allowing or decompression.

You might like to try shoving the piston down with a stick while you rotate the engine to check the rod & crank are still together

bertsmobile1 said:

Both plugs out, throttle WFO ( not choked ) dryI like to
I like to do it by jumping the trigger on the starter solenoid, so the ignition is off thus no spark.
You can do it again after squirting a little oil into the cylinder and revolving the motor a few time to distribute it. called a wet compression test.
Only old farts like me do this. A difference of 10% or more = bad rings.
You need something better than 75 psi for the engine to fire even allowing or decompression.

You might like to try shoving the piston down with a stick while you rotate the engine to check the rod & crank are still together

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My thoughts also, you could have broken rod and valves would still work.
With spark plugs out you can put your thumb over hole with good compression it will push your thumb off (you still need to do compression check) if you don't get this on dead cylinder you need to put screw driver in hole go till it touches piston bump starter or roll over by hand to move engine if piston doesn't move you will need to open engine up to see what happened.

I inherited two B & S V twins with the stock of used bits from Bert when I bought the business, marked "OK needs new rod"
After pulling them down I could not believe what I saw.
Both had dropped the cap off the end of one con rod and the cap was sitting happily in the bottom of the engine.
Both owners had been using the mowers all the time and did not realize they had been running on one cylinder.
These pistons would move up & down as the engine was cranked due to nothing more then crankcase pressures.

bertsmobile1 said:

I inherited two B & S V twins with the stock of used bits from Bert when I bought the business, marked "OK needs new rod"
After pulling them down I could not believe what I saw.
Both had dropped the cap off the end of one con rod and the cap was sitting happily in the bottom of the engine.
Both owners had been using the mowers all the time and did not realize they had been running on one cylinder.
These pistons would move up & down as the engine was cranked due to nothing more then crankcase pressures.

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They were saying I wonder why this thing is low on power :confused2:

spanky324 said:

don't have a compression tester but I checked for spark by cranking it with a plug touching ground --great spark-((I could hear compression)) though--valve adjust maybe??

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If the piston isn't moving I don't think he would hear compression?

reynoldston said:

If the piston isn't moving I don't think he would hear compression?

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Yep your right , I missed that :confused2:

I have found that the valves were way too tight I loosened them and it runs great !!im now trying to find out how to adjust them the right way as the previous owner must of done this !!Anyone that can tell me how to adjust them right??Thanx Guys for all your help!!(26hp intec twin cyl)

This is fight material.
B & S tell you to do each cylinder on the firing stroke 1/4" past TDC

Others will do the inlet when the exhaust closes and the exhaust when the inlet just closes

bertsmobile1 said:

This is fight material.

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Who cares

With engine cold on compression stroke get piston to top dead center then turn right 1/4 inch so you get past compression release.

loosen the jam nut take a feeler gage on the intake .003 to .005 inch exhaust .005 to .007 inch.
put feeler gage between rocker and top of valve tighten nut till you feel resistance but can steel slide gage back and forth tighten nut and jam nut and re check, I usually go with .004 on intake and .006 on exhaust.

once you get one cylinder finished do the same on other cylinder.
it kinda takes a good touch to get right so don't get discouraged if you need to adjust several times.

good luck :thumbsup:

Sorry to seem stupid but which is exhaust and which is intake thanx again guys!!

Inlet sucks so it opens as the piston is descending.
Exhaust blows so it opens as the piston is ascending.
Usual practice is to put the hotter port ( exhaust ) at the top when it gets the cooling air first.
Always worth while to check with a soft rod poked down the plug hole.

After adjustment turn the engine a few times by hand to check the inlet opens slightly just before TDC.
This is to release the compression for starting.
If it does not do this tighten the valve lash a little more till it does.

I had a Briggs do this.
It was a dirty carb. Not letting gas get to the left side.