Can’t top out past 43ph

[Mntnmike]

So I read all these posts about people WOT at 50mph on flat land and holding that for awhile. No problems.

I have a 2023 that I’m the third owner, but I got it with 78 miles on it. I weigh 185lbs, it’s stock tires, sprockets, everything. Only mods are accessories, like milk crate, phone holder, usb, etc. Nothing of any weight.

Where I live it is nearly all hilly with paved road speed limits of 35 or less. But in some areas the limit goes up on flat sections. One downhill section I regularly try to see how fast I can get the bike going.

And I never, ever can get it above 43mph. The engine is screaming, WOT, no wind, downhill, and it’s like I hit max power red line on it. (And I still regularly get between 135-145mpg.) Everything is vibrating intensely as you can feel the bike straining.

I seriously doubt either of the two previous owners did a sprocket change as they were both older and couldn’t ride it anyways.

I did an oil/filter change on it at 200 miles (as I didn’t know how it had been ridden) and I’m only up to 1100 miles total on the bike.

I never really have any other power issues with it, as far as I can tell. I don’t have anything to compare to. It’s happy speed is between 35-38 in 4th, but if I don’t have speed up on a hill or I’m stuck behind a slowpoke holding at 35mph, I’m down to 3rd quickly.

I’ve adjusted the chain (do it regularly) and will be switching out the stock chain soon. But also putting 244s on (2.5 front, 3.0 rear) so that worries me about more power loss.

Any ideas? I haven’t explored the plug but that doesn’t seem like it. Just out of ideas.

Thanks for any suggestions or ideas.

Cheers!

 

[Cpd419]

It’s not set to kilometers is it? Or am I thinking opposite on the numbers?

 

[BergyPatty37]

It’s not set to kilometers is it? Or am I thinking opposite on the numbers?

KPH would read even faster. 50 MPH is 80.4KPH

 

[BergyPatty37]

What your indicating does sound like regearing. Take pictures of the sprockets and then count them to see how many teeth. Stock gearing on the 2023 JA65 is 14/38.
The other thing is it almost sounds like you aren't getting into 4th gear. Because 43mph is about redlining it in 3rd.
That is very strange if you are indeed stock gearing and getting all 4 gears.

 

[BergyPatty37]

What you could do is buy one of those cheap dirt bike tachometers, that the wire wraps around ignition wire. Then get a reading of the engine RPMs and report back.
The only other thing I could thing of is if you have a brake that is slightly grabbing and causing you to not be able to get more speed. Put bike on center stand and make sure both wheels spin freely with no resistance.

 

[Mntnmike]

What your indicating does sound like regearing. Take pictures of the sprockets and then count them to see how many teeth. Stock gearing on the 2023 JA65 is 14/38.
The other thing is it almost sounds like you aren't getting into 4th gear. Because 43mph is about redlining it in 3rd.
That is very strange if you are indeed stock gearing and getting all 4 gears.

Thanks! Yeah, redlining in 3rd, that’s what it feels like but I am clearly in 4th.

Note: I have had difficulties getting it to shift sometimes. The person I bought from included an “extra” used shifter that he got from the previous owner. On close inspection it was bent so it must have laid it down bad in its short life. I recently bought the reinforcing bracket for the shifter and that should help, but I don’t see how this could be the problem. But I also don’t understand how the clutch-engine interaction in the motor actually works, unlike regular clutches.

I will go and count the sprockets later today. I seriously didn’t think that either of the previous owners did that but it would make sense.

And the wheels do spin freely, so not a brake issue. It’s clearly the engine straining. If the sprocket counts are correct, I will be back on that downhill stretch on Thursday and will get some video from the phone mount this time, doing gear count and hearing it maxed out.

 

[Mntnmike]

I should also add that the whole time the bike is staring by in the low 40mph, in still trying to shift to the phantom 5th gear as it feels like that. But it’s 4th.

 

[Texan]

I was having a similar issue recently. I just replaced my fuel filter and it helped.

What altitude are you at? Currently running around just over 5000’ and losing that whole HP feels pretty noticeable compared to when I’m riding at sea level. Definitely seeing a reduction in top speed.

 

[BergyPatty37]

The bent shift lever and harder shifting is leading me towards you might not be getting 4th gear. Perhaps one of the shift forks got bent and its not engaging all the way into 4th. Down hill you should be able to get way above 43mph even at higher elevation.
I would start with just doing the clutch adjustment which is super simple. See if that helps.
Here is thread on doing clutch adjustment: https://hondatrail125.com/index.php?threads/clutch-adjustment.3697/

Lets see what @dmonkey has to say.

 

[Mntnmike]

I was having a similar issue recently. I just replaced my fuel filter and it helped.

What altitude are you at? Currently running around just over 5000’ and losing that whole HP feels pretty noticeable compared to when I’m riding at sea level. Definitely seeing a reduction in top speed.

Ahh, good point. Most of my riding is at 4000’ with some riding up to 6000’ but the downhill flat straight is down to 2,500’.

 

[Mntnmike]

The bent shift lever and harder shifting is leading me towards you might not be getting 4th gear. Perhaps one of the shift forks got bent and its not engaging all the way into 4th. Down hill you should be able to get way above 43mph even at higher elevation.
I would start with just doing the clutch adjustment which is super simple. See if that helps.
Here is thread on doing clutch adjustment: https://hondatrail125.com/index.php?threads/clutch-adjustment.3697/

Lets see what @dmonkey has to say.

Forgot to include in original query that I do the clutch adjustment about once a month, or maybe 3 weeks?

So it could click into fourth, i can rev up in the new gear, but it doesn’t fully engage? Now that makes some sense.

One thing I haven’t done is put it up on a jack stand and run through all the gears to max rpm each gear. Or would the lack of friction/torque on the rear wheel make that irrelevant?

 

[Texan]

One thing I haven’t done is put it up on a jack stand and run through all the gears to max rpm each gear. Or would the lack of friction/torque on the rear wheel make that irrelevant?

It won’t be super informative without load, but it might not be a bad peace-of-mind check.

Any reason not to do it on the center stand with the front weighed/strapped down?

 

[BaldRider]

Even geared down, you shouldn’t be redlining at 43 in 4th unless it is gears really low. Elevation wouldn’t cause this, either. Even at 7k+, on flat ground, you should be doing better than 43.

 

[BergyPatty37]

Even geared down, you shouldn’t be redlining at 43 in 4th unless it is gears really low. Elevation wouldn’t cause this, either. Even at 7k+, on flat ground, you should be doing better than 43.

Im thinking unless its gear down significantly like 13/50. Im almost positive he isn't getting 4th gear.

 

[Mntnmike]

It won’t be super informative without load, but it might not be a bad peace-of-mind check.

Any reason not to do it on the center stand with the front weighed/strapped down?

View attachment 14067

No reason, really. I’m out of town but will do that tomorrow.

Also, I’m a woodcarver so your Safety Third gave me a good chuckle.

 

[Mntnmike]

Im thinking unless its gear down significantly like 13/50. Im almost positive he isn't getting 4th gear.

I’ll be back home later this afternoon and back to the bike and I’ll be doing a sprocket count first thing. I’ll also put it on the stand and run through the gears and get it on video.

Thanks everyone for helping me solve this!

 

[BergyPatty37]

@Mntnmike Ive thought about this a little more. Even if you had the bike regeared short (smaller front and or bigger rear) the speedometer still reads off the countershaft. So your Speedometer would be very innacurate but would still read up to like 60+mph down a hill. I know on mine with 13/42 gearing I have hit 70mph on the speedometer, which was 59-60 MPH actual GPS reading.

The speeds you are giving above of 43mph maxx, is that with the factory speedometer or actual GPS reading?

Perhaps there was a reason there was 2 owners before you in only 78 miles?

 

[BaldRider]

That’s a good point. I have also lost some power but haven’t had a chance to dig in and find out why.

Also worth pointing out that with a 39T rear, I managed to hit 67mph (GPS) downhill and still didn’t hit the rev limiter.

 

[Cpd419]

KPH would read even faster. 50 MPH is 80.4KPH

Yea I’m mph all the way. I never learned nor do I ever intend to learn much of anything metric.

 

[dmonkey]

To me it sounds like a prior owner changed at least one of the sprockets. The factory front sprocket will read 14T on it so you don't need to count the teeth, just wipe it clean to read. The factory rear sprocket has a harmonic ring fastened to it to reduce chain noise, which also makes it easy to identify if it's been swapped to an aftermarket replacement.
Pics of a JA55:

Note that your 2023 JA65's front sprocket is a little more work to get to than the earlier JA55.

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