I posted this in the engine forum.. got a lotta looks, but no knowledge.. I figured I try here...

Maybe they just didnt know.....

I just switched my motor on my longtail from a 16 to a 21. Hoping it'll carry loads in my boat better. Now on to my questions. When I first got the motor, I could barely turn it over with the pull start (forget the starter)due to high compression. I pulled the spark plugs and when plug was out of cylinder on left facing the motor it turned over freely, so I ended up redoing the valve lash, set it at 0.005 (they were way off). Now it'll start but it still seems there is too still a little bit to much compression. Once I do get it started it runs fine for a random amount of time no shorter than 5 minutes, and shuts off... So questions are:

1. After redoing the valve lash, still harder than normal to pull start (do I need to redo the adjustment again? or other ideas?
2. Random shut off after alotted time. Card rebuild? some other problem? I did notice fuel sitting/collecting in the bottom of the carb intake (not sure if thats normal or not for as vtwin)

Thanks in advance.

Briggs engines are notorious for the the valve lash being out and high on compression, this relates to the compression release built into the camshaft - I've seen quite a few of my competitors sell people new starters when valve lash is the only problem (sometimes though, they have burned the starter up trying to start it with the valve lash being out of specs, resulting in 2 problems to fix...)

The easiest way I've found to adjust valve lash (without pulling the flywheel cover, or spark plug to find TDC) is to turn the engine over until 1 valve on that cylinder is all the way down - set the lash on the valve that is up - repeat the stroke until the other valve on that cylinder is down and adjust the other valve that is up .... do the same for the other cylinder.

Occasionally, I have found the compression release on the camshaft had gone out - which requires replacing the camshaft, but from what you describe, I would recommend checking your lash again.

Thanks for your reply... at least one person.... yeah!

I have checked the valve lash again, and it is set a 0.004. Still high too on the compression for the starter. I have a friend of a friend who owns a lawnmower repair shop and hes gonna look at it for a 12 pack of beer. I am gonna let him tell me which direction to go.... But the back of my head keeps telling me I might need a new cam. Here's hoping not, but if I do it'll be a good time to go do some mods.

Ill keep you updated.