honda small engine issue

[moobeast2]

Been a long time since I was on this board, not sure if this is proper spot, but here goes; recently bought a hot water pressure washer, it's a MiTi-M branded as John Deere. It has a Honda GX390 recoil start gas engine; the engine is a bear to start. First few times it started ok, now it has a terrible recoil/kickback issue. All 3 of my employees have had it kickback enough to hurt hand or wrist a bit. Took it back to dealer; they said we needed to make sure we're going through start-up procedures properly, like holding wand handle open, backing off the pressure adjuster etc. No kidding. You need to pull rope until it hits a spot where it sticks and can barely pull it through a turn, then pull it again until you hit another spot that is hard, get it just past that then you can give it a good yank and hope it fires, otherwise have to repeat. I don't find this acceptable We disconnected the pump; it's not the pump. Pulled flywheel and cam cover off, nothing obviously loose, broken or out of adjustment. I've looked at adding an electric starter to it, I think our model requires some modification to make one fit. Haven't found out yet if can add the Honda starter to it, they make a model with electric start.
Any suggestions for what I may be missing? Or for adding electric start to this particular model? I don't want to blow money on a starter and have something break if it's a problem with engine. Thanks for any advice. Andrew

 

[lilredex]

Sounds like the "Automatic mechanical de-compression system" is malfunctioning.


https://engine.honda.ca/gx/horizontal_crankshaft/gx390/features

 

[Boilerhouse]

I had this issue on a g300 Honda that I volunteered to overhaul for a neighbour. It had a number of issues, but the kickback problem was caused by faulty value clearance. Once I got the clearance issue back within spec, it pulled over fine.

 

[Jking24]

Compression release issue pull the valve cover back off and look at it closely rotate the engine by hand looking at the rockers and its usually pretty obvious Edgar's supposed to be happening

 

[nadogail]

Thanks for adding to my education

 

[Mick56]

I believe if the flywheel key is partially sheared it can throw the timing off, too. That can create a kickback.

 

[oldmxracer]

I had this issue on a g300 Honda that I volunteered to overhaul for a neighbour. It had a number of issues, but the kickback problem was caused by faulty value clearance. Once I got the clearance issue back within spec, it pulled over fine.

First thing I would check ! Repaired one for a friend about 5 months ago, it was just a valve clearance issue ! Very simple fix !

 

[driftpin]

I have the same GX390 engine on my 4,000PSI pressure washer, but have yet to encounter that particular problem. I don't have a lot of hours on it, mine starts without any issues, quickly.

I did have a Yard Man lawnmower with a Honda engine, I bought new from Costco. It quickly developed a problem starting, I found that a valve was seizing in the guide. It was an easy temporary fix, I would pull the valve cover, and use a bit of carburetor cleaner on the valve stem, and work-it until it un-stuck. I took that machine back for an exchange of a new one, and damned if that one did the same-thing after a bit, too! I liked the design because it had a stainless steel deck and a Honda engine, but that ^%$#! valve sticking was a pain in the ***. I went-out and bought a riding lawnmower, a Snapper 28" Hi-Vac, which I actually enjoy using.

I'm gonna file-away this thread tidbit, in-case I have any issues with my GX390 engine.

 

[greg13]

Valve rocker adjustment, common problem usually overlooked.

 

[gnpenning]

You said you recently bought it, should be under warranty. If they won't fix it return and go somewhere else. If they won't service you now it won't get better.

Or you can do there job as already suggested.

 

[Iron Beaver]

I would say the decompression system is not working. Or the valve clearance as others have mentioned

 

[Ryanmk]

I would say the decompression system is not working. Or the valve clearance as others have mentioned

I just found this thread while searching the internet. I am currently having this very problem on my Honda gx340 on a BCS tractor. I adjusted the valves to the proper clearance and it started fine and ran for about a day then the next morning I went to start it and it was happening again. I found a repair manual online with a troubleshooting section, it said in there to check the decompression on the camshaft if the recoil is hard to pull. Does this mean the decompression mechanism on the camshaft is somehow dysfunctional? I'd be grateful for any advice you guys could give me to get this thing to start....

 

[joseisen]

I just found this thread while searching the internet. I am currently having this very problem on my Honda gx340 on a BCS tractor. I adjusted the valves to the proper clearance and it started fine and ran for about a day then the next morning I went to start it and it was happening again. I found a repair manual online with a troubleshooting section, it said in there to check the decompression on the camshaft if the recoil is hard to pull. Does this mean the decompression mechanism on the camshaft is somehow dysfunctional? I'd be grateful for any advice you guys could give me to get this thing to start....

Exact same issue here, except on a grillo tractor with a gx340. It almost ripped off two of my fingers seriously bruised my wrist last time I tried to start it. I have to adjust the valves almost every time I use it. Bought new November of 2020, has less than 60 hours on it even now, in November of 2022. I'd use it a lot more if I didn't have to take it apart every single time I needed to use it. Just got a shop manual and I'm going to try to adjust the decompression mechanism.