Is 150 PSI a Good Compression Number?

I've got a 12.5 HP Intek (model no. 219907, manufacture date of 2005) on an old-style Snapper rear-engine rider. It's not running smoothly, & I'm trying to zero in on the problem, so I performed a compression test on it. B&S doesn't publish compression specs. Instead, they recommend that you take the engine to a service ctr. for a leak-down test. That would be a hairy hassle for me, plus $ I don't want to shell out, plus who knows how long the service ctr. will have it? As stated in the title, I got a reading of 150, & I was wondering if an experienced person here could tell me whether that's good, bad, or merely acceptable.

Also, a little bit of gas leaked out when I unscrewed the hose from the adapter in the spark plug hole. Is that a big deal?

MonkeyCam said:

I've got a 12.5 HP Intek (model no. 219907, manufacture date of 2005) on an old-style Snapper rear-engine rider. It's not running smoothly, & I'm trying to zero in on the problem, so I performed a compression test on it. B&S doesn't publish compression specs. Instead, they recommend that you take the engine to a service ctr. for a leak-down test. That would be a hairy hassle for me, plus $ I don't want to shell out, plus who knows how long the service ctr. will have it? As stated in the title, I got a reading of 150, & I was wondering if an experienced person here could tell me whether that's good, bad, or merely acceptable.

Also, a little bit of gas leaked out when I unscrewed the hose from the adapter in the spark plug hole. Is that a big deal?

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IF you bring the engine in and ask nicely most will do a leak down test on the spot.
I charge $ 30 Aust as it takes around an hour to do properly and you need compressed air so there are costs involved.

B & S do not publish compression figures because they all have a decompressor of some type so the results will vary according to the condition of the cam , the amount of valve lash & the speed of rotation
So if you want to do a meaning full one you need to open out the valve lash such that the inlet valve does not reopen.
Somewhere around .020" usually works.
However without the decompression most starters will not be able to crank over TDC
Catch 22
Thus the leakdown test
GO on You tube there are a dozen videos showing you how to make one cheap

FWIW Kohler have a lower limit of 160 psi

If the engine has a fuel shut off solenoid, it needs to be unpluged before you do the test

Just be aware that the 160 lower limit on the Kohler is for the Command series only, which doesn't use a decompressor

Well . . . I guess I'll have to see if I can borrow a pickup truck to take it to the service center. Crap. :frown:

Well "not running smoothly" is a bit vague
If you describe what your problem is as if you were talking to some one who had never seen a ride on mower before then there are people on this list who could be of great help.
Inteks have a habit of eating head gasktes and "not running smoothly" is one of the initial symptoms.
It is also a symptom of a blocked carb, worn governor, shorting out ground, terminal badly adjusted valve lash etc, etc, etc.

For what it's worth the 150 reading is what I have always gotten on my Intek 24 V.

"Just be aware that the 160 lower limit on the Kohler is for the Command series only, which doesn't use a decompressor"

??

Walt Conner

If I get a reading of 150 on a compression test that is good reading. Your very first step would make sure you have all new filters, fresh fuel, and plugs. If you have gas running out of the compression tester adapter you have a fuel problem such a bad carburetor float or needle valve.

bertsmobile1 said:

Well "not running smoothly" is a bit vague
If you describe what your problem is as if you were talking to some one who had never seen a ride on mower before then there are people on this list who could be of great help.
Inteks have a habit of eating head gasktes and "not running smoothly" is one of the initial symptoms.
It is also a symptom of a blocked carb, worn governor, shorting out ground, terminal badly adjusted valve lash etc, etc, etc.

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OK, so maybe I won’t bother w/ taking it in for a leak-down test, since a couple of people have chimed in & said that 150 PSI is probably a good compression number. One reason I tried a compression test in the 1st place is b/c in my surfing around to try to zero in on the problem, I came across some info. that Intek engines have a tendency to blow head gaskets.

I’ve already done all the tune-up stuff like changing the oil, spark plug, air & fuel filters, & making sure it has fresh ethanol-free fuel in it. I found out that the valves needed to be adjusted & took care of that, too.
I also rebuilt the carb by following along w/ a professionally-done YouTube video by RepairClinic.com that used the identical carb (Nikki, part no. 590399).

The problem I’m having is that after starting, as I move the throttle lever from the turtle icon to the rabbit icon, the engine clearly increases in RPMs but then suddenly dies before I get to the rabbit. If I suddenly back down w/ the lever, the engine will usually run rough for several seconds & then recover. The engine also seems to lack power, which is another thing that made me suspect a loss of compression due to a blown head gasket. The last time I was working on the engine, I had the mower parked in the concrete driveway, & when I engaged the blades, I could tell it was a strain on the engine.

Maybe the carb is getting too much gas & flooding the engine. The only 2 adjustments I know of making to the carb are the idle fuel mixture screw (which has a plastic cap on it, the purpose of which is apparently to prevent it from being tampered with) & the idle speed screw. Assuming this actually is a carb issue, which screw should I adjust, & in which direction should I adjust it?

Sorry for such a long post, but I wanted to, as you suggested, describe the problem as fully & clearly as I could. I appreciate the help.

This is not twitter.
Long posts with lots of information is soooooo much better than a short post with not enough information.
First of all does the mower have a throttle & choke or just a throttle ?
If it is the latter you are most likely going past the full throttle position and engaging the choke.
What you describe is exactly what happens when the choke is engaged.
Also check that the cable has not come loose in the anchor point and engaging the choke .
You can slip your finger in the carb throat and check the throttle butterfly for movement when you move the throttle.

Double check the valve lash .
Remember the grub screw is the lock nut and the big nut is the adjuster.
It is not a good system & I oft have to do it several times to get it right.
While the rocker cover is off check the movement of the valves.
They should both sit at the same height above the floor of the head ( nice mix up there isn't it ) and move the same amount.
If not one of the cam lobes could very well be worn.
The cam fitted to inteks is not particularly any better than it needed to be and some wear quite badly, particularly if the DPO ran the mower across slopes which causes reduced lubrication of the cam.
Pull the exhaust off and check for carbon blockage and bugs / rodents etc reducing the flow thus choking the engine