Davinci856
Forum Newbie
- Joined
- Oct 25, 2019
- Threads
- 1
- Messages
- 3
Hi All.
Before anyone asks why I'm going through all the below...this is sort of personal now. I like working on engines, even small ones, because I find it relaxing (usually), but this is bugging the heck out of me.
I have an old (as in 1973) B&S 8HP engine on a Snapper rider (B&S model 190702-0867-01) that worked well for years, but has been sitting for about 4 in a garage after I got a new mower. The new one blew up (threw a rod) so I wanted to use the old rider again for a while rather than the pushmower. It was stored out of gas, so I made sure the air cleaner was in good shape, changed the fuel filter, put new gas in it and it started. Problem is that it ran very fast - (estimate 4000 or so) so I shut it down immediately and looked for a linkage problem. Everything was clear, checked the governor by moving the throttle to fast, saw the governor arm move all the way over, even loosened the locknut after noting where the shaft was, saw the governor shaft smoothly moved through travel from one end to the other, then ended up rotating it in the same direction of fast while the throttle was open all the way and tightened it in the same place it was originally.
I next verified that all the throttle linkages were again in the right places, the butterfly moved correctly with the throttle, I noted positions of the high and low speed mixture screws and then set to a starting point as per the shop manual and started it again. Not as fast as before because it was slightly out of adjustment, but still really fast, so shut it down. Then I got some WD40 to look for what I thought must be an air leak around the carb, but when it was running nothing changed the speed no matter what I soaked with WD40. I found that if I held the throttle with my finger about all the way closed, it will idle sort of normally, but it's not too happy because it's pretty much on choke that way. If I come off of closed with it running even a tiny it (I mean so that you could barely fit a toothpick under the butterfly if you could get it in there) it is off to the races again.
I then thought that something internal must be messed up, but didn't know what. I ordered gaskets and tore the engine down completely. Governor looked to be in good shape, valves were so/so, so I cleaned/lapped/adjusted to spec (which wasn't much different) and decarboned the piston top and head, which were fairly cruddy. I thought maybe something in that carbon might have been the issue, or maybe at least the new gaskets would seal a leak I couldn't find. I even honed the cylinder a bit, but surprisingly could still see shadows of the original hone marks after all these years. After putting it back together, exactly the same situation. It thinks it's a Ferrrari. I remembered that I'd rebuilt the carb not long before storing it, but said since it was really old and a new one was cheap, got a new one and put it on. Still the same.
So, this is where I am now. I know the governor is right, it's got a new carb, and it still races.
Anyone got any ideas?
Thanks.
Before anyone asks why I'm going through all the below...this is sort of personal now. I like working on engines, even small ones, because I find it relaxing (usually), but this is bugging the heck out of me.
I have an old (as in 1973) B&S 8HP engine on a Snapper rider (B&S model 190702-0867-01) that worked well for years, but has been sitting for about 4 in a garage after I got a new mower. The new one blew up (threw a rod) so I wanted to use the old rider again for a while rather than the pushmower. It was stored out of gas, so I made sure the air cleaner was in good shape, changed the fuel filter, put new gas in it and it started. Problem is that it ran very fast - (estimate 4000 or so) so I shut it down immediately and looked for a linkage problem. Everything was clear, checked the governor by moving the throttle to fast, saw the governor arm move all the way over, even loosened the locknut after noting where the shaft was, saw the governor shaft smoothly moved through travel from one end to the other, then ended up rotating it in the same direction of fast while the throttle was open all the way and tightened it in the same place it was originally.
I next verified that all the throttle linkages were again in the right places, the butterfly moved correctly with the throttle, I noted positions of the high and low speed mixture screws and then set to a starting point as per the shop manual and started it again. Not as fast as before because it was slightly out of adjustment, but still really fast, so shut it down. Then I got some WD40 to look for what I thought must be an air leak around the carb, but when it was running nothing changed the speed no matter what I soaked with WD40. I found that if I held the throttle with my finger about all the way closed, it will idle sort of normally, but it's not too happy because it's pretty much on choke that way. If I come off of closed with it running even a tiny it (I mean so that you could barely fit a toothpick under the butterfly if you could get it in there) it is off to the races again.
I then thought that something internal must be messed up, but didn't know what. I ordered gaskets and tore the engine down completely. Governor looked to be in good shape, valves were so/so, so I cleaned/lapped/adjusted to spec (which wasn't much different) and decarboned the piston top and head, which were fairly cruddy. I thought maybe something in that carbon might have been the issue, or maybe at least the new gaskets would seal a leak I couldn't find. I even honed the cylinder a bit, but surprisingly could still see shadows of the original hone marks after all these years. After putting it back together, exactly the same situation. It thinks it's a Ferrrari. I remembered that I'd rebuilt the carb not long before storing it, but said since it was really old and a new one was cheap, got a new one and put it on. Still the same.
So, this is where I am now. I know the governor is right, it's got a new carb, and it still races.
Anyone got any ideas?
Thanks.