Fix'em all 49 #1 Posted December 3, 2017 Hi all, I would appreciate any advice please. I have an Alko 5000 with a Tecumseh Bvl198 5 hp engine. It is so hard to pull over that it only turns 1 cycle & stops before completing compression a second time. Yesterday it would spit back through the carb or nearly wrench your arm off with a vicious recoil. I checked for a partially sheared flywheel key & it was fine. I took the head off and noticed the inlet valve was not sealing probably due to wear on the head so I took the valve out & ground a bit off the pushrod end of the valve. This sorted the inlet valve but now the compression is so high you have to ease it on compression and pull as hard as you can. I have removed the drive belt so there is no resistance there. I know some of these older 5hp engines were designed to open the exhaust valve very slightly on compression but this doesn't. Share this post Link to post Share on other sites
Fix'em all 49 #2 Posted December 4, 2017 Checked the compression tonight & only 45psi so must be something internal causing this. Not a big fan of Tecumseh engines so might be time to fit another motor Share this post Link to post Share on other sites
the showman 4,074 #3 Posted December 4, 2017 Try spinning it over with the sparkplug removed, your soon know if something is binding up on the crankshaft Share this post Link to post Share on other sites
Wristpin 400 #4 Posted December 5, 2017 If it’s something binding, it’s unlikely to cause a kickback , but if is, disregard the following . For reasons unknown we used to see more Tecumsehs with kick back caused by incorrectly gapped valves than any other brand. Excessive valve clearance leading to an inoperative decompressor was nearly always the reason. The gaps should be checked / set with the piston a quarter of an inch down the bore on the power stroke, or, if you prefer after TDC - same difference! Grind lots off the stems to achieve clearance when “ on the cam” and you’re in trouble. Share this post Link to post Share on other sites
Fix'em all 49 #5 Posted December 5, 2017 Snowman, I did spin it over without the plug a few times on Sunday. It turned over a lot better as you would expect but was probably not as free as it should be. Wristpin, originally the inlet valve was partially open on all 3 strokes when it shouldn't be & this was why it was spitting back through the carb. I only took a bit off the valve stem so I don't think the clearance will be excessive. Not touched the exhaust valve so not sure why it does not partially open on compression. I thought about putting an extra head gasket on to reduce the compression. Do you think this may help. The machine has not run for a long time so if I could just get it to start it may loosen it up just through running. Share this post Link to post Share on other sites
Wristpin 400 #6 Posted December 6, 2017 If the inlet was open when it shouldn't be it is more likely that it was partially seized in the guide . I've seen valves that hung open but while one watched, slowly close! Bit worried about the " bit off the stem" , how much and what was the resulting clearance? One of my favourite small engine books has the following to say about valves - IN BOLD PRINT! "Technicians who are valve critical will always have a better record of repair success than those who take a near enough approach" Time spent fiddling with ignition and carburettion , is time wasted if the valves are not right. Share this post Link to post Share on other sites
