OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Trimmers and Brushcutters Four Stroke Trimmers & Brushcutters Honda GX 25 Whipper Snipper

Hi people, I have got a Honda GX 25 w/s, having a slight problem. Will run perfectly while it is cold but as soon as it gets hot it seems to cough and splutter slightly then die ( almost sounds like it is missing and or starving for fuel ). Have cleaned fuel tank/lines, cleaned carby and spark plug and checked timing, all looks good. Still happening. Any ideas will be appreciated. Thanking you Paul.

Some clarifications please Paul. When you say you have checked the timing, you checked the cam belt sprocket timing mark against the exact vertical from the cylinder head? And you are sure the cam belt hasn't jumped?

When the engine begins to falter, have you tried restricting the air inlet, or slowly pumping the primer, to see if that improves the situation?

Did this problem arise suddenly, or gradually?
Have you checked with a known good spark plug?
Have you checked with the muffler removed, in case it, or the spark arrester, is blocked/obstructed?

My first guess is that the fuel pump may not be up to scratch, but we can discuss that after you clarify those points.

Hi Grumpy, sorry I didn't get back to you yesterday, got quiet busy. Have ran through suggestions you gave me one at a time, wasn't a fuel problem, spark plug is correct one and is good order (not burnt out, correct gap , not dirty etc. ), muffler wasn't blocked and spark arrestor wasn't blocked either. Went back to double check timing and noticed both valves open a fraction all the time, reset them both and now running like a new one. Thanks again for your help ( put it all in my memory bank ) , much appreciated. Paul.

Thanks for letting us know, Paul. I can't think how both valves could suffer from reduced clearance without there having been foul play (somebody messed with the adjustment) or a disaster that is in its early stages.

Has anyone been at the valve clearance adjustments previously?

Is there any sign of damage to the cam lobe and/or crud building up under the cam followers?

If it is neither of those causes, it sounds a lot like valve recession - most other kinds of wear cause valve clearance to increase, not decrease. Valve recession should only happen over a very long time (it should take as long as it takes the rest of the engine to wear out), or after long periods of over-revving the engine. (Having said that, lots of engine manufacturers grapple with the problem from time to time, on one model of engine or another.) It would be interesting to know what caused the problem, in case it is a characteristic of the GX25 (and perhaps the GX35 as well).

Hi Grumpy, thought it a bit weird myself. Asked my mate who owns the w/s and apparently a mate of his tried to fix it before me. ( Gave them both this web site and how to register, hopefully help them both ) There was no sign of damage or build up of crud anywhere in timing area ( could of been cleaned up previously ). Thanks heaps again Grumpy, Paul.

So most likely the valve clearance was adjusted inappropriately by the previous tenant, and you've now put it right so all should be good.

One of my tedious stories: years ago my sister's then-boyfriend asked to borrow the workshop manual for a car. Knowing he didn't even own a screwdriver, let alone a car, I asked him why he needed it. He said he and his mate had decided to replace the breaker points in the mate's car, and now it wouldn't start. I asked him what gap he had set them for. He said, "Gap? What's a gap?" It seems they'd just slung in the points and done up the screws, job finished.

Sounds as if your whippersnipper owner's mate did something similar here: "Ah, I can see the problem, these rocker arms are loose, I'll fix that for a start." Most of us do that kind of thing when we first start out, and learn by doing. In this case it did no harm whatsoever, and you can be pretty sure there is one person who will never make that mistake again.

I'll close this thread.