Last week I had a valve seize on the Honda four stroke lawn mower. Not bent, oil good... freed it up, now running fine. So, why the stuck valve? I was wondering if the addition of PURPLE DYE to the gas ( marked gas is available in B.C. for off -road use.. less $) could be the cause of four stroke engine troubles? Any issues here?

 

Just the dye? I don't have experience with BC's gas, but off road diesel here has red dye (not subject to highway tax, but don't get caught with it in a truck).

Lots of tractors, earth movers and what not run with the stuff their entire life with no problems.

I think I'd inspect the valve stem/valve guide very closely to see if there could be a cause there.

 

What octane are you running ? And does the fuel you're using contain ethonol?

Lawn and Garden engines need to use 87 octane unleaded fuel and with a non ethonol fuel , these engines were designed for regular 87 octane pump gas ; so i would have to say yes running a higher octane fuel ( and if the fuel you're using does contain ethonol ) could very well be the cause for the valve sticking !

I would reccomend that you get some regular 87 octane unleaded fuel that doesn't contain ethonol , and get a can of Seam Foam to mix with the fuel and run at least a ffew tank's of the treated gas ; this fuel treatment will clean out the fuel system and the combustion chamber of exccessive carbon deposits whitch can and will cause the problem you had !

You can get the Sea Foam at most all Auto parts Stores as well as your local Walmart Super Centers , mixing directions are on the can this is the best fuel treatment i have found after 20 + years in the Small Engine Service And Repair Industry ; and it has the same money back garrantee that it had when it first stocked the shelves since 1942 .

williebee......

 

Stuck two different valves in two different races this year. Race engine, with full synethetic oil, running quality race gas.

Inspected everything, and then made a call to the machinest that did the head. I had a little "chat" and let him know my dispreasure in loosing two races because of guides set too tight.

He re-did the head and we have not had any issues since.

Lawn mowers are mass produced and not race engines. See my point?

 

Thanks for the ideas gentlemen. Don't think the octane rating or the Red (Purple?) Dye caused any problems as it has only effected this one engine.... now, mass produced lawn mower engines, yeah see your reasoning there Doctorturbo. To be on the safe side Williebee, I'll mix up a batch of your fuel formula and clean out appropriate engines here before the snow flies. Thank you.

 

Using an octane rating lower than the recommendation can cause detonation, but I don't think using fuel of a higher octane would cause any problems, other than adding to the cost of fuel.

Honda power products are indeed mass produced, but are generally of very high quality. I would still say inspecting the stem and guide and mic them out to make sure clearance is in spec would be in order.

I'm not usually a fan of fuel additives, but Sea Foam does seem to be useful. Since it is likely an overhead valve engine, a big build up of carbon could also cause problems with the valves. If there is a lot of carbon, I'd look at either worn rings, or rich mixture (from running with air filter dirty). Dusting from grit getting past the air filter can also cause valve stem issues.