I've had two Honda OHC engines but neither mower had a 'clutch' (I guess this is the blade control). The first was a GCV 160 and now I have a GSV 190. I have not heard any knocking from either one. They do have a little 'pop' at low speed like an OHC bike engine - maybe that's what you're hearing. I'm sure if it were a serious problem like excessive bearing clearance it would get worse when hot and under a load. Have you checked the blade nuts and engine mounts? I might also be inclined to check the flywheel nut if it's really making noise. You might be able to reach up under the shroud and see if you can detect any play in the flywheel with the blade blocked.

I am really tired today running between all the big box stores. At the end, I didn't option the lawn boy because I really can't justify the extra cost vs sears promo today. Plus, a technician at Rona's service center gave me a friendly warning about the Tecumseh engine, the supply of the parts might be good for next 2-3 years but can't promise anything at long run. I still have a thought that a good mower should last me 10 years ironed in my head... However, I really like the design of the lawn boy 10684, everything seems very well design and build quality is better than others. If it's around $350CND range and none self-propelled model, I would pull the trigger, no question ask. I went back to Sears and ordered the Craftsman 36933 model (3-in-1 with bag, side discharge, mulching), which has B&S 850 platinum engine (8.5 ft/lb torque), no choke and no primer needed. The price is just what I am aiming for, 289.99+taxes. The engine seems pretty well build but the rest of the parts are very standard, a regular every week lawn mower...

@tomplum I sent your description to the original shop's owner to let his tech review what you'd suggested. It makes sense to eliminate the cause(s) of problems starting with simplest up to most complex. I'm not sure how much time's been applied to winnowing out the non-culprits. A hearty "yes and amen!" to the point about focusing on fixing things. There was a comment in another online thread about how some feel that dealerships back away from servicing older high-quality mowers despite their reliability and long-lived function. If the mower's known to stay trustworthy, and a few part replacements keep it running merrily along, then it has to be an "anti-customer/pro-profit-margin" attitude which will blow up on the dealers in the long run.Seems foolish to alienate the folks you sought to attract with your product line by claiming it was better than the competitor's, but when time proves the claim was true, slamming a door shut! @ericwi I know it's true shops don't want to burn up their tech's hours on a mower with that many years on it. But when someone assumes responsibility for fixing one thing, and inadvertently messes up another in the process, does the customer need to eat that mistake? I don't think so. The original shop has shown quite a bit of graciousness so far, and as long as they do that, I respect them for honoring the customer and having integrity. The dealer has been more dodgey in the situation than I was led to believe they'd be from speaking with them a month ago. Not a good way to persuade toward a possible future sale. Okay, why do I hang on to the HRM215? Because it's been proven as a quality machine, it's been for the most part extremely reliable, and mulched like a dream. As a middle age, single-again mom with three young adults at home (two in college) and not much income, I absolutely have to find ways to minimize chaos in my life. There's not enough energy to go around the day as it is! Buying or sticking with solidly-made house and yard goods is essential. I don't have the luxury of spare time/cash to keep replacing cheaper items every few years. But of course the days are fading where manufacturers vied with each other to have the best product and a good reputation, versus a flood of trashy throw-aways out on the market. Where the few companies DO continue to make something of value, that's where I'll end up putting my hard-earned dollars! I did take your good point about used mowers, though, and that's still an acceptable option. So thanks for mentioning it. And I'm glad your Yardman has stood you in good stead so far (fyi - I wear earplugs when I mow, so nothing dorky whatsoever about saving one's hearing).

Thanks Weed Cutter I have download the file and going to read it later tonight. That ok about the model airplane, this is more fun and useful. I can play with the motor and get something done. Believe it or not, this is cheaper than the model plane engine stuff if you get into the real fancy brand. I bought some used glow engine on ebay cheap and open it up, I know what you mean about gum. The ring stuck in the grove, ball bearing balls don't run at all!!! Yes I actually went on Navada Walrus (Bob's) page and look at his history, very interesting. How about you, are you very involve in this field also. I am surprised that people in this business like Bob, Canguy, they been in this field for so many years and still have the interest to get on this kind of forum and help people ( newbys) like me. I am an electronic engineer by trade, into gas engine as hobby( model planes cars and now lawn equipments) Anything smell gas, I like it!! I gave my wife all the excuses to buy the best toy for a tiny little 5000sqft yard!!!! BTW, to everyone: I start to do the experiment of putting 30:1 ratio in both my Echo HC150 hedge trimmer and my Shindaiwa EB3410 4 cycle blower. I pull out the plugs and inspect it. I'll do it again after 2 months and see whether it foul up or not and I'll post the result. I am using Shindaiwa One with Sta-Bil in 91 Octane Gas from Chevron. We'll see. I heard about too lean a mixture on 2 cycle or hybrid 4 cycle will hurt the engine because of high temperature and lack of oil in lean mixture. Then the ones with separate oil like Honda trimmer will fare a lot better if the mixture is too lean because the oil supply remain the same and oil will carry heat out even the mixture is too lean. Is this true from your experience? Have a nice evening