BrianX128 109 #1 Posted September 18, 2020 Never had this happen before, the wife's transplanted K341 in her 417A when shut down and left for a half hour or less makes 2-3 loud bashing knocks when restarting with a nice black puff. I can only think fuel is leaking in after being shut down but I'm not sure how to fix this or if it's even an issue worth looking into. When you shut it down as it's making it's last revolution the engine makes a sound kinda like someone sipping the last bit of a drink from a glass with a straw like fuel boiling off. It does have a small electric fuel pump on it verses the manual pump. I've had a friends K341 do this on a poorly adjusted carb when you'd rev it from idle to wot quick it would make that "hammer" sound which is what is making me think it's fuel, but the carb is set perfect. Runs great, no smoke, oil still looks new 20+ hours in, engine was rebuilt by the guy I bought it from 2 years ago and everything seems like it was done super well from how good it's been to us since we got it. I just don't want to be damaging anything in there. Share this post Link to post Share on other sites
The Tuul Crib 7,339 #2 Posted September 18, 2020 Dont have a clue but l want to know!! Share this post Link to post Share on other sites
bc.gold 3,406 #3 Posted September 18, 2020 1 hour ago, BrianX128 said: When you shut it down as it's making it's last revolution the engine makes a sound kinda like someone sipping the last bit of a drink from a glass with a straw Could be a faulty crankcase ventilation valve wheezing. Pre-igniton knock could be from carbon build up, again check the PVC valve if faulty excess oil maybe bypassing the piston rings making carbon on the top end. Share this post Link to post Share on other sites
ebinmaine 72,669 #4 Posted September 18, 2020 I like the idea of checking/cleaning the breather. Make sure it's in right before and after. (drain hole). Have you changed anything recently? Is this a slowly arising issue or sudden oncoming? Is it hard to start after a bit like the carb has lost prime? Share this post Link to post Share on other sites
BrianX128 109 #5 Posted September 20, 2020 I can't get it to cooperate for the knocking noise when restarting but I got the hissing noise on video. Share this post Link to post Share on other sites
Rob R 973 #6 Posted September 20, 2020 hmmm carb float, needle valve leaking fuel back..... maybe install a fuel shutoff valve (simple) turn off when shutting down if cures problem.... you gotttem carb issue as mentioned..... Share this post Link to post Share on other sites
953 nut 59,969 #7 Posted September 20, 2020 Have you checked the ignition timing with a timing light? A bit too far advanced could cause some spark knock on starting. Share this post Link to post Share on other sites
