OK Guys I Screwed Up

[bob]

John Deere GT275 with Kawasaki FC540V. Engine was backfiring when starting, so I decided I would do a valve job. Removed Head and I did break one head bolt which I have stripped the thread, so that needs repaired but I thought I could leave that until later. Removed valves and cleaned off carbon and lapped. Reinstalled everything and adjusted lash. Valves are moving up and down. Now it will not start. It has spark and did compression test 120LBs ?? Shooting carb spray down carb but will not even fire. I did try a different plug and shot carb spray down spark plug hole and it down back fire back up carb. That was the closest I got to anything. My only thought is I should have left it alone and lived with backfire. Any thoughts? Do I have a compression problem and need to repair that one head bolt. I thought it would at least attempt to try an start

[KE4AVB]

Well it is unfortunate you broke a head bolt as they are NLA from Kawasaki as it a lot of the parts for this old engine. Even some of the IPLs are not available. Do need the spec number to even try looking up the parts. The last FC540V I worked on had carburetor problem and it was guess work on figuring which parts I needed even with Kawasaki help as there was no IPL for the particular spec I was working and the suggested IPL had the wrong parts. I currently have an unionized PA540V in the shop now with oil leaks.

I have been awaiting over a month on part for it. It was supposedly coming in yesterday but I checked this morning it is now 8/21 as a possible arrival date. Boy is this back ordering nearly everything getting to be a real pain in the rear as my equipment yard is full equipment awaiting parts.

I did look at a couple FC540V engines. One used an igniter and the other solid ignition coil. And I had ignitors to cause backfiring when they start to fail. I even one that shot flames out of the muffler as it would not fire the plug under compression load so it ignited fuel load on the exhaust stroke.

[bob]

I was thinking on just tapping next size up for stripped head bolt. I am more concerned why it will not even try and turn over now. Do you think 120ibs compression is enough to start. This one does not use the igntor

[KE4AVB]

Depends on timing along with good compression which you do have good compression. Timing can be either valve or ignition. With compression at 120 psi I would think valve timing is correct. So it might be that either you losing spark under compression load or it is off one way or the other.

[bob]

Problem solved. I had broke the orginal sparkplug during repair. Orginal plug was a Champion Rn12yc. I replaced it with a Champion RC12yc I think. I tested for spark to ground and looked good but would not fire. Replaced it with BPR5ES form another Kawaski FC540 I have and fired right up. If i had not broke the orginal plug in the first place everything would have fine. Its called learning but it is frustrating. Thanks for help