Bandaid-ed No Start Solution-Thoughts?

[Mek-a-nik]

Customers JD Sabre w/ a 406777 0115-E1 991117YH Briggs V-Twin Intek.
Would not start when cold w/o a shot of carb spray. Starts warm, no problem. Runs good once running.
Choke flap is operating correctly. I flushed the gas. Adjusted the valves. Went through the carb. Still no start.
Then I did compression and leakdown tests.

Compression:
#1- 75 psi #2- 105 psi

Leakdown:
#1- 65% #2- 45%
Air leaked past rings and exhaust valve on #1, just the rings on #2.

Plugs weren't perfect, but no oil fouling.
My theory is that it won't start because the compression is too low for the gas to be sucked into the airstream. The choke flap doesn't cover the throat completely, so I made a new flap that covers the opening better and it started cold. Only once, so far. I want to test it several times.

I'm going to tell the customer that his engine's seen better days.

Think this is an okay way to bandaid it for a while? Also, I made mine out of steel. The original is brass. I wonder why? Brass costs more, there must be a reason.

EDIT: I just tried starting it again this morning; no go.
I wonder if I repaired the exhaust valve leak on # 1, if it would start?

[KE4AVB]

First if you haven't already done it, I would adjust the valves as compression release can throw your measurements off.

If the valves are adjusted correctly and you getting these reading then either cylinders are worn heavily or you have a partially blown head gasket(s). The cylinder are out balance by more than 10% so there definitely something wrong and with the age of the engine it probably seen better days. These engines with the flat panel filters tend to an issue with poorly installed filters. I have had to replace several engine where the filter was installed incorrectly and the cylinders were ate up by dirt.

As for the choke butterfly it is probably because steel tends to rust and can cause sticking problems. As far changing the choke design several of us have in the past on Tecumseh carburetor soldered up the holes so an engine could start. I just recently had to modify the choke butterfly on a brand new Ryobi leaf blower carburetor as it was causing the engine to flood out and it would not start. The choke had to be closed for it even hit a lick but then it immediately flooded out.

[Mek-a-nik]

I just edited my post to include more info.

[KE4AVB]

I actually needed to edit my post too. Difference between cylinder compression is to be no than 25% per the service manual instead of 10% but I tend to use the 10% around here.

As fixing the exhaust valve leak it won't hurt; Although I have seen these to start on just one cylinder with the other cylinder having a blown head gasket.

I haven't had with a leakdown tester that gives the percentage of leakdown as I only have the homemade leak tester but those numbers does sound quite high; maybe, Brian will chime in and give us a better idea of the numbers we should see on the tester.

[bgsengine]

If you did a leakdown test that shows those % numbers, did you take a couple more minutes to find out *where* the air was going? that would tell the tale for you (and make sure the valves were fully closed when doing the test - if you do it a little before TDC the compression release may be "on") listen for air out the dipstick tube and/or breather , if no air coming out intake or exhaust or around the head, the only other place that air would be going is through the crankcase, and I would be willing to bet you have blown head gasket(s) On the briggs tester gauge - 20% to 40% is the "normal" range. at 40% and air coming out crankcase, I would tend to say worn rings.
Anything more than 40% is not good, indicating either severely worn rings or blown head gasket or a leaking valve (and use your sense of touch and hearing to find where it leaks)

[Mek-a-nik]

First, I went out there after I posted that it wouldn't start this morning and tried it again. It started.

I've seen that air cleaner sealing problem on these engines. It was sealed and clean on the "clean side" when I got to it, but it could've had problems with that before.
I considered the (steel) choke flap rusting, but the shaft and the screws are steel. I'd like to fix the problem, (if it isn't too costly) and re-install the original flap.

I adjusted the valves- .005" 1/4 ATDC. Also, I listened to where the air was coming from during the leakdown test with a stethoscope. (See first post.)

BUT, I completely forgot to consider the piston position (MCR) for the leakdown test. I had them right at TDC. But, I believe the MCR is on the intake? If so, my findings are still accurate (And because the compression test results jive up with the leakdown test results). The exhaust valve is leaking on #1, and the rings are pretty well shot or as BGS suggests, the head gasket(s) are bad.
I'd like to do exploratory surgery. I'm going to pull the heads and look around.

[Mek-a-nik]

I pulled the heads. The exhaust valve in #1 (the worse of the two) leaked solvent when poured. I lapped it until it stopped. It seemed to have carbon under it. Both heads and pistons had some carbon build-up. Removed that.
The gaskets don't look too bad. The twin has a head bolt in the spot where the single usually leaks.
I'm waiting for the gasket kit. I'll re-take the leakdown and compression tests. I'll also shoot some oil in the cylinders for the compression test to see if it point towards rings. I think it will. There's a pretty good ridge on the cylinders.

[Mek-a-nik]

I put this back together Thursday. Several cold starts- okay.
-Number 1 improved to about 95 psi compression (had leaking exhaust valve). Leakdown to roughly 45%. Went to 125 with oil in the cylinder.
-Number 2 had about the same compression. Leakdown remained at 45%. Went to 130 with oil in the cylinder.
I told the customer that the rings were the culprit. He seemed happy with my new choke flap idea.
I checked my records, when I first worked on it earlier this year, the air cleaner was not installed correctly and dirt was entering the engine. He told me the folks who rented the house where the tractor is kept, were responsible for cutting the grass. They destroyed the house, also. If I rented a house out, I would not let the tennant use my lawn mower. This is the second customer I have with equipment problems because the renter uses it. Let them supply their own mower!
Thanks for the ideas-----------