99 135cc GCV135/160 mower engine problem ? - cheddar

I have previously totally reliable 1999 Honda mower powered by a GCV135 4.5hp engine, there is a GCV160 5.5hp version of the same unit so any knowledge / experiences would apply though the later GCV135 3.5hp, GCV160 4.1hp and GCV190 5.1hp may be mechanically different.

The engine still starts first pull and appears to run perfectly though every now and then the revs die and it pops and bangs, spitting back through the carburettor, if it is immediately put back to idle it can be caught before it cuts out completely. Then if throttle is applied it with pop and spit unless left to idle for a minute or so after which it will operate as normal for a while until the next episode.

When it is running normally the governor lever resists any pressure on it however when the revs die and it pops and bangs there is no resistance on the governor lever perhaps indicating a problem with the govenor. I have yet to invistigate the workings of the governor fully.

Any thoughts and ideas?

99 135cc GCV135/160 mower engine problem ? - cheddar

Any mower experts ?

99 135cc GCV135/160 mower engine problem ? - Steptoe
Rather than leave you reply-less I will offer the solution that worked for me (this was for a Briggs & Stratton engine but so long your petrol tank is below the carburetor the operating principles may well be the same)

The carburetor is made in two bits with a rubber diagraphm sandwiched between them. This diagraphm performs all the important duties like float level and mixture but can get wrinkly and possibly develop splits over a period of time.

In my case the symptons were that the mower would start and idle but not give any power at all whatever position the throttle was in. After replacing this diagraphm not only does it run as well as new again but the petrol consumption has halved. IMRC I initially got the info from the BR
99 135cc GCV135/160 mower engine problem ? - cheddar
Thanks Steptoe, from experience with inlaw's old Briggs & Stratton they have a very simple carb enabling constant speed operation where as the Honda has a conventional carb rather like a car or motorcycle enabling variable speed operation though with a govenor to maintain constant revs under varying loads.


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