GX270 Kickback

jshep1102 said:
I wondered that myself but if I disconnect the spark plug, I can pull it over all day without any kickback. As soon as I reconnect the plug, it kicks back when I try to start it. That points me back to a timing issue.
Click to expand...
When the plug is removed, there is 0 compression. To truly test without the plug, use a compression tester in place of the plug. That way you get compression and a reading of how much.
 
SUCCESS!!! Bertsmobile1 win the prize (if I had a prize to give away). I had the original magneto gap set at 0.010". I set the gap to 0.020" and it jerked out of my hand at 1/2 of a pull. I set the gap at 0.030 and it starts every time and runs great. I wouldn't have ever figured that out on my own. This forum comes through again!!

I'll put a label on the engine cover to remind me (or anyone else that may work in this pressure washer in the future) to set the gap at 0.030 to prevent this kickback issue.

Thanks again to all those who offered advice. Thanks most to Bertsmobile1 for figuring it out for me. WooHoo!!
 
With a gap of 0.030" there is something that is wrong.
Illingine is probably right & the timing chip in the coil is bad
But the old saying "If it is working don't try to fix it " comes into play

Have a close look at the exhaust for black smoke and check the plug for soot.
If the spark is too late then you get a build up of soot on the plug & exhaust valve .
You can fix the plug by going one or two grades hotter ( with NGK's ) but you can not fix the valve build up other than by turning the fuel off & starving the engine rather than using the ignition switch .
OTOH mower engines are very low tech lazy engines and will usually run quite happily over a massive range of mal adjustments
Also be watchful for signs of overheating but if it works then go mow .

For those who are unaware , the spark timing vs air gap is an inverse square relationship so 3 times the air gap is around 1.2 deg of crank rotation.
Those of you who play with Runtronics ignitions in your model aircraft will be familiar with this method of timing .
Yamaha also used it on some of their flywheel magneto motorcycle engines till they developed a much better ( thus expensive ) control module
 
bertsmobile1 said:
Have a close look at the exhaust for black smoke and check the plug for soot.
If the spark is too late then you get a build up of soot on the plug & exhaust valve .
Click to expand...

My buddy picked up the pressure washer today and will keep an eye out for these issues. If they appear, we'll order a new magneto and go back to 0.010 gap. Thanks again for all the help!!
 
Update - the pressure washer started fine for a while but recently started kicking back again while trying to start it. My buddy ordered a new ignition coil and set the gap back to 0.010". No change with the new coil. Still kicking back. I think I need to order a book of matches and some gasoline. 😤
 
If its like the GCV200 mower the cam timing is off and there is a video on youtube showing how to adjust this. I had two brand new Honda HRX217HZA's both fail within 4 days of the first mow. Cam not working with automatic compression release so its firing too early. I also talked a honda mechanic that has 35 years and he said even though the service manual says adjust valves at TDC, he said go a hair past that because at TDC sometimes the automatic compression release still won't function. He's repaired dozens and dozens and that is the adjustment he makes. There is also a couple of videos on honda pressure washer valve adjustments.

 
Last edited:
All, the GX270 and corresponding GX390 et al have a compression release issue. There is a new camshaft available to remedy this concern. If under warranty, any capable Honda dealer can replace the camshaft. I monitor these issues daily, so this is a fairly common occurrence.
 
jshep1102 said:
Hi guys, I need your help again. I'm working on a friend's pressure washer with a Honda GX270 engine (GCBGT-2225859) and his complaint is kickback when trying to pull start it. He said it just started doing this a few weeks ago. He has had the unit since new and has not replaced any parts on it. I figured is was a sheared flywheel key that screwed up the timing. My experience is that it's uncommon on a pressure washer and more likely on a mower that has the blade direct coupled to the crankshaft but I told him I'd check. I confirmed the complaint before doing anything.
Upon inspection, the flywheel key was not sheared, the ignition coil looked gapped correctly but I reset it using a business card (~0.010), the valves were a few thousandths loose so I reset them to 0.006 inlet and 0.008 exhaust (at TDC on comp stroke + 1/4"), I can visually see the decompression mechanism burp the exhaust valve on the compression stroke. After reassembly, the engine pulls over normally when the spark plug wire is disconnected but once I hook up the plug wire, it snatches the pull cord out of my hand violently when trying to start it (pressure washer hose not connected so it's not water backpressure causing a problem). In my mind, that confirms a mis-timing issue but hoping you guys have some ideas on a troubleshooting path forward. New coil? Seems like the most likely cause but that's a strange way for a coil to fail (fire early). Picture attached.
Thanks, Jerry
Click to expand...
I am having this exact problem. Mine has always been an easy starter but now I have to practically lift the unit with the pull. cord to get a turn over and then the kick back snatches it out of my hand. I've readt through all the help so far and am not as mechanical as most on here. It sounds like a shop procedure but I'd like to share this info. Any updates like a It was so simple! ??
 
You must log in or register to reply here.
Back
Top