2015 PCX 150 sounds like a Rod Knock

[MichaelGee]

So I drive from MI to Tennessee to get a PCX -then back 13hour drive
No sounds at all Clean and quiet, a week of zipping around Zero noises

Then
Change the oil, spark plug, air filter, and open the case to look at the dry rot cracked drive belt. Case air vent plugged with grass, cleaned that all up and flowing air again.. ordered a belt and Dr Pulley 14g slides figuring the rollers are probably shot at 13k

Next Day-
Cruising even at 50 mph heard some rattling reflecting off a guard rail “?”
Home checked oil, that’s good, Now i start paying attention..

Started hearing it at 30mph, then 20mph.. Now Every EVEN speed above 15mph is the Rod Knock sound.. Now I’m freakn... Check the oil i bought, full synthetic 10w30 Walmart stuff.. bought a manual, says HP4M Moly oil, oh shit Bearing caps are shot now

Overnight RUsh air delivery a quart of HP4M, think it’s too late for me and this PCX still knocked.
Dr Pulley and belt came in, so i did that anyway already paid for em along with clutch kit and bell (I was doing a Full tuneup), some people say “oh it’s the variator rattling” yea okay.. Never had rollers or the plate rattle Ever in any of my scoots, all 7 of them -silent

Still rod knocking at any speed above 15mph even keel on the throttle
Silent at idle..

Pulled variator off and started engine, revved it up a bit and held even, that’s Zero strain and shoot i can’t remember the noises (I’m old), what the heck, I’ve done So Much to this thing

Spark ping? Put regular pump junk in it, Then find out 91 + only
Pssssht it’s at 97mpg on the dash, take forever to burn up the fuel.. Octane booster, no change, 4hrs of saddle sore riding at 15mph circles around sub to get rid of some gas to put Clean premium in it.. still rattling.. so I used a straw and a shot glass and pulled 4 shot glasses of oil out to put 4 shot glasses of Motor Honey in, took almost 3hours to do this, my back Hurts.. Still rod knocking

And Don’t put gas in at a gas station, 1st gallon or so is Regular unleaded before Premium starts flowing, i ask someone around me if they want a free gallon of gas before putting the handle in my can or bikes

Freaking out Hardcore here Ready to dump it to Craigslist for sale..
And i still have a new tires on the way “?”

[MichaelGee]

Remembered an old Acquaintance that had a 2015 PCX
asked him if his rattled, he said he Thinks it rattled a bit at 50 miles an hour ya only live once rip it up..

We old fart grandpa’s call these people, Kids..
the “it had air in the tires when i bought it” kind of kid

For most of those out here claiming this is Normal to hear buzzes and rattles as the nature of the beast, i Highly Disagree.. it’s a Honda, and all Honda’s are fairly silent compared to anything similar..

This PCX did not buzz rattle creak at all for the 1st week of zipping around, Nothing.. plastics are Tight , motor was tight, exhaust is tight, Literally silent other than the puffs coming out of the exhaust..

Could still hear while revving at idle, that tight whining sound in the engine that all Honda engines are known for, I can still hear this at idle

Anyone have any ideas?
No rod knock noise accelerating or decelerating
Only even keel speed rod knock sound “?”

[fish]

Mileage on the engine?
Mileage since last valve check?
Fish

[MichaelGee]

13k
No valve train noises at all prior to “fixing“ things

oil
Plug
Air filter
And cleaning case air vent on cvt cover
Then began to rattle

[springer1]

Change the oil, spark plug, air filter, and open the case to look at the dry rot cracked drive belt. Case air vent plugged with grass, cleaned that all up and flowing air again.. ordered a belt and Dr Pulley 14g slides figuring the rollers are probably shot at 13k

A few worthless thoughts; 1) If you still have the old spark plug, reinstall it. The knock may not be mechanical, but rather related to preignition (knock) that the new plug is somehow aggravating. If that doesn't eliminate it, 2) plug up the cases's air vent. If the knock still exists, I'd 3) check the timing anyway.

[Old Grinner]

Loose spark plug?

Maybe you thought it was tight when you installed it but maybe it wasn't or became loose and started to back out a bit? Did you notice if the plug had the crush washer on it?

Info found previously on forum here . . ..

https://www.hondapcx.org/viewtopic.php?f=19&t=3119

Maybe something in the exhaust flange came loose?

You were in the middle of hand tightening the plug when you got a phone call and forgot to go back and finish the job?

Sorry . . . couldn't help myself.

I sincerely hope it's not bearing related which gets expensive to fix.

It seemed to have run OK until you futzed with a few things. Check the spark plug. Also make sure it's the correct spark plug. As mentioned above try putting the old one back in to see if the problems goes away. Double check to make sure there's a washer.

Good luck and may the "Force" be with you!

[Old Grinner]

I still have my spare plug from my 2017 PCX. It's brand new . . . still have the original box. It came with a crush washer already on the plug. I think your 2015 model takes the same plug (CPR7EA-9). FWIW I think the new 2019/2020 model PCX machines take a different spark plug.

I'm not one to work miracles but I'd be willing to bet your problem is a loose spark plug that started to back out or it didn't have the crush washer on it . . . or it just wasn't installed tight enough (proper torque) to begin with.

100_7122a.jpg

100_7123a.jpg

I've only had a spark plug loosen up once on me in all my years of riding . . ..

[WhiteNoise]

"Very interesting, but stupid!" (some "Laugh-in" humor folks - Arte Johnson)

Seriously, I do find this topic very interesting. I'm entering only to mention that I have a 2015 USA Model and my fuel requirements (per pg 35 of owners manual) states, "Your scooter is designed to use Pump Octane Number (PON) 86 or higher. Tank capacity: 2.11 US gal (8.0 liters)."

Michael, welcome to our forums I hope you resolve your "knock" pronto as it must be nerve wracking. Members are offering great advice and you're capable of making it right. I'm sticking 'round for this one like a fly on...

Just do us one favor, add your location "in" your profile so we know what we're talking about in our responses (now and down the road). Did that make sense? No? Alright then, pour me another cup of coffee
(Ezy directions to complete yours is just below my post)

@ OldG: Yes that is the proper spark plug for a 2015 model. You guys are Great!

[MichaelGee]

Hilarious break in the monotony
All great responses, Thank you.. just might have had a phone call or the many questions these grandkids of mine pose, it’s like exercising 123 123..

I’ll check the spark plug in a few minutes, just wanted to touch base here..

Been going through anything that may or could rattle under this thing with my grandson, found some interesting things underneath, like a Stick wedged into center stand and such.. as I said previously grass and weeds packed into the cvt cover air vent..

It was an insurance claim PCX
Stolen busted out ignition and it looks like it slid for a bit on its side, well That’s a labor bill insurance wasn’t going to pay so they totaled it..

Then it became mine, got it in East of Cincinnati, don’t know why I typed Tennessee “?”
I completed the new ignition install last week, all new panels etc..

Have it out with a blanket and tools, Going to check plug, if tight reinstall old one and be back for an update but I think I need a quick nap, all 4 grandkids just got picked up..

[Gil]

Did you check the oil level before your first ride? If it fell on it's side, oil could of gotten into the air box or spilled out. My scooters original engine got rod knock due to low oil, I didn't check it often enough when riding more often. The rod knock will be more pronounced from the CVT side of the crank. The drive face of the variator will act like a speaker. You can better locate the sound by using a long screwdriver, while placing the plastic end on your ear, prod different parts of the engine block with the metal end to find the source of the noise.

The rod knock started with a faint sound when riding close to the sidewalk and highway dividers and got progressively louder until it was the classic clank clank sound.

Good luck, and check your oil everyone.

[MichaelGee]

Zipping all over the place 1st 5 days not one single abnormal sound
it’s After oil and plug and filter and cleaning cvt vent that the rattle started..

Update on spark plug
Yes i tightened it..
But look what the heck this plugs been doing

Plug Left is original, Plug Right is what I put in
Darn thing is Burnt or burning something in the fuel

Could spark Ping be loud enough to duplicate a rod knock?
Isn’t a rod knock Consistant all the time knocking?
If that’s spark ping- i am burning a whole in my piston

Haven’t tested old plug yet
Wife asking me to cook

[Gil]

Forgot to mention that when the timing chain tensioner goes out, it also makes a rock knock type sound. I bought my scooter used with "rod knock", it was the chain tensioner. The sound of it is like this youtube video.

[Gil]

Here is another video of the noise the failed timing chain tensioner makes.

[mymitzi]

Just want to vouch for the Walmart full synthetic 10w30 oil. Many trouble free miles. Understand you wanting to "go by the book" now though. Hope it turns out to be something else [minor]

[you you]

If it started knocking after the work you did I’d reverse or go through each item in turn.

[MichaelGee]

Oh god no to tensioner
This thing is Silent at idle, even that 1st bike sounded worse than this, I heard a little rattle near end of video clip

So our variator acts like a Speaker was a Correct way of putting it..

Pulling all fuel out of this thing
(Look at Plugs- that was now Today)

[MichaelGee]

All fuel is out, and i saw the Low Fuel flash for the 1st time, that’s cool..

Super Clean fresh fuel is in..
Let it idle for 5min, then shut it off for about 15min

Fired it up and went for a 10mph ride for a mile or so around our sub, this thing really Sips the gas so, i know it’s going to take a bit for Real fuel to be flowing solid. Punched it a couple of times to push fuel in, but short streets right to deceleration.. didn’t give it a chance to even speed rattle, pulled in and shut it down..

A little leary with that new plug looking like that, whether or not I fried my o2 sensor, any thoughts on this “?”

Engine management will advance retard spark based on content sniffed, this thing may have went on the offensive timing side with additives in fuel (see 1st post), added shot glass of Lucas fuel injector cleaner lubricant at plug oil filter change, since i didn’t know what happened prior.. Then knock or pings slowly started happening.. Then 3 shot glasses of octane booster.. fuel looked cloudy Yellow

Really thank everyone for responding, means a lot to this old fart..

So I’ll take it out tonight for higher even speeds with my ears turned on, and post results

I know it’s going to take quite a bit for closed loop fuel/timing management to start managing the maps correctly..

i just hope the piston isn’t too far pitted, the bearings aren’t toast, the o2 sensor isn’t fried.. Sounds like I’m cooking dinner again.. Your posts along with me re-reading mine, really helps out on possibilities.. So i am hopeful..

Thanks for the heads up on Walmart synthetic oil being fine to use.. Still can’t believe it was $53 bucks to overnight ONE quart of HP4M

[MichaelGee]

Mileage on the engine?
Mileage since last valve check?
Fish

All prior history is unknown, carfax only shows my data entries
So it looks like I’m going to learn how to do a valve job

At least this bike will have a fresh point of maintenance
Nothing really left to work on, other than the new front tire stuck in the mail somewhere

Hey if anyone knows how to see more history than I can here’s the vin RLHKF1808FY001540, maybe y’all can tell me what was done to this machine, all I know is it had a busted out ignition and insurance totaled it..

[MichaelGee]

Okay another form of reasoning..

IF the valves were out of spec
THEN the valves would be ticking at ALL rpm’s

Right?

Here’s a video of some guy and his valves




That’s not my problem then..
only at Even throttle “at speed” above 15mph does it rattle..

At idle it is Silent..
Riding upto 15mph, it is Silent..

Noticed something-
Rattle per second does not increase with higher road speeds, it’s fairly constant..

In other words, at any given speed, the rattling is the same..

I’m telling ya, it’s pulling my hair out..
Reversed all that i have done, even took air cleaner out and drove it..

When there is No acceleration Strain on motor, its a Rattling..
It’s silent at idle
It’s silent upto 15mph, no matter what I’m doing with throttle
It’s silent when fuel cuts-off decelerating from any speed
It’s silent accelerating to 60mph

Mechanic stopped by last night
“it shouldn’t be doing that” as he scratched his head

The math just doesn’t add up without an rpm change in the rattling “?”

[MichaelGee]

EDIT “it seems” as though it is not changing..

Anyway, a new Faster way to check valve train;
Remove seat bucket
Drop the shocks, BooM swings right into view, remove fan/radiator and voila There it is to work on.. I remove spark plug to rotate easier..

Can’t see 14 procedures to Get Too the valves..

Anyway my two cents, haven’t done it yet, but thatsa whatta ima gonna doo