The Honda PCX / Forza / ADV150 / SH Forums

Whip the head off. It won’t cost anything.

Any updates?

I need someone to watch this video..
This is what is happening..

It’s constant (and very loud) only at even cruising speeds..

Here is a video of someone else having the Same problem as i am, mine is a significantly louder, slight engine strain at road speed does it.. Does not do it accelerating or decelerating, only at even speeds Above 20mph

in video- when guy gets to right side of bike

https://youtu.be/5mpvf9xkx7Q

Do you have Video/audio of the issue that you are having?

in This video- when guy gets to right side of bike
https://youtu.be/5mpvf9xkx7Q

Same as me
the motor needs a slight drag on it, so he is fanning throttle
Same as mine

Can hear it echoing off the trees it’s so loud

Spark plug is White in 3minutes

Well now, Looki here..
Undue back pressure Partially plugged up my CAT with Lucas fuel injector cleaner and “Lubricant”
the 2nd part of that injector cleaner, did the bike in..

Well that’s another $500 bucks, it has a catalytic converter in it how nice..

So i ordered a Jug of CATaClean
If that doesn’t work, i am Drilling through the catylst with a long bit
and plugging the entrance hole with a screw or something

Not buying some Loudass muffler to put on it

Wouldn’t excess back pressure make it run rich rather than lean?

Well the CATaClean didn’t work
16oz to 4gal which comes out to 4oz per gallon
Had a gallon in there, stuff Melted the measuring cup almost instantly
10mile hard knocking run, then filled up..

Possibly worse now than before..

The whole Damn bike is NEW PARTS chasing this..
Friggn unbelievable..

was Fine for 5 damn days

Pissed off PCX owner..
And no one is even Looking at that video link of the spark knock..

There is No Way i can recover my expenses and Labor here with this thing

Take the head off. Check for an object in the inlet port and the valves/piston in general.

Bit more mechanics, less fitting.


Then the barrel and you can check the piston and little end.


What is that going to cost?

FWIW . . ..

Maybe something to consider doing first before tearing apart the engine. This will help to determine slop in a crank bearing. Granted the vid is done on a car but similarities do exist between 4-stroke internal combustion engines.

Good luck and may the "Force" be with you. Live long and prosper . . ..

Nope nope and nope again..
Think everyone is looking for Reply points instead of reading..

Nothing.. it is SILENT until enough RPM is achieved, and Only at even road speed..
Silent accelerating Silent decelerating Silent at any rpm doing anything under 20mph

No rod knock
No wiristpin
No Nothing.. ANY of the replies would be noticeable at ALL rpm’s

It’s a SPARK BANG
The plug is White in less than 4min of banging

That’s it
Nothing else..
Everything fuel related has been Replaced with New
No air leaks anywhere
All new sensors

Still spark banging above 20mph
Hot or Cold engine temperatures

Update..
Ordered an exhaust gasket, pulling pipe off and saturating the honeycomb of CAT with CATaClean, after i borescope the thing to see..

Hell i might even pop a wire through it a couple of times..

Then draining fuel tank again, since i put 4oz in the tank

Frign junk PCX

So i purchased a OLED tv to play with over the winter

And selling this two wheeled POS money sucker, to offset the expense

Seems like the machine was cursed from the beginning.

I had a Pontiac that was like that.

After getting for cheap I poured money into it and wish I never did. The OHC 6 cylinder engines they made in the 60's were junk. They'd start to lose compression and burn oil. Aluminum and cast iron have different characteristics when it comes to heat. It was my first car and my last Pontiac.

Money I spent on new tires, shocks, battery, engine work (pistons/rings), exhaust system, and other stuff could have been better spent elsewhere.

FWIW I've read rumors that Honda may be producing a 4 valve PCX with a 157cc ESP engine . . . or something like that. Time will tell in 2021.

Better luck with the TV.

The OHC 6 cylinder engines they made in the 60's were junk.

Ohhhh man, you had one of THOSE ? .... I think they called Tempest "Sprints". Was a powerful in-line 6 for it's day ..... but no durability ..... didn't the Sprints come standard with posi-traction ? Lots of people just swapped it out for a junkyard small block GM from a wreck. But their "regular" in-line 6 was a decent motor.

I think most of us have experienced a least one mechanical money pit.
Like flogging a dead horse my dad would say or your just throwing good money after bad.

Yeah it was crazy, undue everything ya did, still there
Redo all that ya did and then this and that and more of this and that

Everything has been Replaced with new except ECM and CKP
Done with it..

Two months plus Chasing every possible culprit to a spark knock at even speed

Done with it...

I remember the Tempest by the way..

Did you take the head off?

Ohhhh man, you had one of THOSE ? .... I think they called Tempest "Sprints". Was a powerful in-line 6 for it's day ..... but no durability ..... didn't the Sprints come standard with posi-traction ? Lots of people just swapped it out for a junkyard small block GM from a wreck. But their "regular" in-line 6 was a decent motor.

It was just a 2 door Pontiac LeMans with the base OHC 6 (not the Sprint engine), a vinyl top and 2-speed auto. I still have my FM converter I bought for it at Radio Shack. I later transplanted it into my used VW Bug.

The 2-speed automatic never gave me any problems though. Just the engine.

I took off the stock hub caps and just painted the rims silver. I knew I'd never have the GTO or 326 so it was the next best thing.

Hi, I had a kind of noise like the youtube link you posted, on my precedent PCX (PCX 125 2017 V3)

The noise was less than the video, but it appears like you explain : slow speeds no noise, decelerating no noise, full throttle no noise, but metallic rattling at slight acceleration or cruising.

I tried different options, asked many times at my Honda dealer (they said it's perfectly normal...) but no improvements...
So I gave up and "forgot" it during 6000 km , and i took a pcx v4 as soon it was available.

V4 is quite better, wayyyy more silent but if you listen closely you can still hear that small rattle, but not very noticeable.

For information, i hear many of PCXs v3 and Forza 125 in the streets that have this kind of rattle, I agree, the sound is horrible !! But thoses seems to run well tho...