4 stroke Honda Service Intro


Earth Mechanic


Hey folks, Im posting this thread as the first in a series of posts that will hopefully help guide me and anyone else through service of their new 4 stroke motor. This thread relates explicitly to the Honda GXH50 4 stroke.

The pics are a general introduction to the motor and motor casing, carb and carb adjustments, and preliminary observations about the motor after 100 hours of use. I know there are many experienced riders / mechanics out there, so I hope this will be useful and not trite. The next post will be valve clearence adjustment where im going to space the exhaust and intake valves at top dead center (tdc) to hopefully get rid of the ticking noise which is robbing my motor of power, could potentially cause a bent valve rod, and just plain annoying.

1. Non Drive Side
2. Carbonized Exhaust
3. Carb Diagram
4. Head Cover Removed



  • Painted Plastic Casing.jpg
    Painted Plastic Casing.jpg
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  • Carbonized Exhaust.jpg
    Carbonized Exhaust.jpg
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  • GXH50 Carb.jpg
    GXH50 Carb.jpg
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  • Top of Motor.jpg
    Top of Motor.jpg
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great info

great info.
looking forward to hearing all you have to say. Im not mechanical at all. but im trying.

ive got the heushen 4 stroke engine. but it seems quiet similar. and one day i plan to upgrade to the hona motor.

btw. how fast do you get on this motor? (w/ what size sprocket?)
How fast you say?

Well, I have a heavy, but sturdy, bike. And i get up to 35 mph. I have the 56 tooth sprocket installed now, but also have a smaller sprocket. I pedal start my bike because it bogs down the motor otherwise, but i dont want to change to the smaller gear because i think it will limit my top speed (and its a bugger to change those dang sprockets!!!)
limit ur top speed

limit your top speed?

dont you get more top end speed with a smaller sprocket??
wait, wait...this is too good a topic to distract with off-topic...let's keep this as clean as possible, please, as it looks like future wiki-"owner's manual" material...

stowaway: i don't wanna squash your question, tho...feel free to jump in on an existing ratio discussion, or start a new topic specific to the 4-strokes...with pics, of course :)

Earth-Mechanic: everyone at MBc appreciates this kind of contribution, and i'm personally grateful for your involvement...please do continue 8)

ps-i don't think you can rate your own topic...anyone who wants to give kudos to a good thread, just click on "rate this thread" at the top of the topic.
I wondered about that. actually, the gasket from my exhaust manifold to the exhaust pipe crumbled when i took it all apart. Thankfully i have another gasket, and will replace when i put this mofo back together. Do you think this could have caused the pinging? Thanks for the reply vintageOG!
An exhaust leak can be the cause of weird noises.
Even can cause popping or backfire type sounds, usually on deceleration.
I agree. An exhaust leak, especially right at the port, has a very sharp sound that does not sound like the roar when a leak is further downstream. I would check the valve clearance, adjust if neceesary, then put it together with the new gasket to see what she sounds like.