Honda 5 horse with stuck valve

[BTDT]

Here is a pic of my tiller (18). It's a 5hp on an old White's tiller. Engine has run fine for 3 years, this year it wouldn't start. Blowing back through carb. So I pulled valve cover and intake valve was stuck open. I removed pin to take off rocker arm, removed valve keeper and spring (after getting piston to TDC so if it dropped it wouldn't go down into cylinder). Clamped vise grips to top of valve and worked it up and down to get it freed up. Put back together and it cranked up and run fine. Today it wouldn't start again. So I repeated process, only to find rocker arm had cracked. I can operate valve with my thumb (push down and it comes back up). Don't know why it cracked, you can see crack in picture (kind of blurry). Will repair as soon as I can find replacement part.

 

[Fordlords]

A highly likely cause of all the above problems is a weak valve spring. I'd replace both valve springs along with the broken rocker arm. Also, did you properly set the cold valve lash clearance with a feeler gauge after you took it apart? This is very important. Don't use vice grips to free a valve that might be gummed up in its guide. (A very common small engine problem.) Instead, put penetrating oil or Marvel Mystery Oil around the top of the valve stem, and start lightly tapping the top of the stem (with spring in place) with a plastic faced hammer to free up the stuck valve. Once running, add a little fuel system cleaner to the gas tank to clean the valves and top end up.
-Fordlords-

 

[BTDT]

Thanks for the tips. I'll keep that in mind when I go back together with it. I wouldn't doubt the weak spring theory. I was kind of suprised at how cheap all the parts under the valve cover looked (plastic cam, pressed steel rocker arm, very thin belt to drive cam). Not at all what I expected from a Honda engine, but then again, maybe I was expecting too much. Kind of like the difference in the old Briggs engines--cast iron vs aluminum.

 

[BTDT]

Well, I got the new rocker arm. It was made a little different than the original. Parts guy says "I sell a lot of these." I said then it must be a manufacturer's defect. He kind of paused with a stupid look on his face, then "no, I don't think so". He said he thought it was caused by a lack of oil reaching valve. So I get home, tear rubber valve "seal" off of metal seal holder, and put unit back together. If it wasn't getting enough oil to valve, I bet it can now. (Will post pics later in week). Unit cranked right up and runs fine. $9.00 for part. Easy fix.

 

[Fordlords]

Just watch to be sure it doesn't consume a lot of oil without the valve stem seal in place. -Fordlords-

 

[BTDT]

Update on tiller. The parts guy made the comment that these engines don't oil well at the valves. The first pics (#3 & 4) is of tiller sitting on level ground, so if it already has trouble getting oil to valves, this rearward sloping of engine might add to problem.

 

[BTDT]

Next is the redesigned rocker arm. New one is on left (intake), old style on right, (exhaust). Pic 5. Pic 6 and 7 are my redesigned valve seal. I think the wiper with spring was keeping valve too dry, so I tore it off and reinstalled. Seemed to work ok. We'll have to wait and see. Next option, pic 8, is to do away with splash shield to allow more oil distribution (may not have to go this far).

Disclaimer: These modifications are mine and I don't recommend them to any one else as a fix. This is how I chose to address this problem.

 

[Molerj]

Maybe your fix will work, but I am a little hesitant about altering the design. Especially on a Honda engine. My guess is the problem resulted from using old fuel, which is very common in a seasonal item like a tiller. The old fuel will leave a residue on the valve stem which when cool will cause the valve to stick.