Sprockets

[m in sc]

I did go both ways, was the same either way. fyi... we barely get wind here.

 

[Spydie]

I did go both ways, was the same either way. fyi... we barely get wind here.

What's your elevation?

 

[Migolito]

Yes, I did go with a VX DID 428. So far no issues. The difference in the actual chain is nite v day. The OEM chain is almost bicycle-esq in it's feel and size. Not to mention it's NOT a internally lubricated chain. The VX is substantially more stout. Everything aboust it is bigger/thicker etc-plates, pins, wear resistence, tensile strength. I'll let someone else post up about the actual mechanical tolerences/sepcs. I honestly believe LRD will rust to pieces long before this chain will fail/stretch. Ofcourse I do always carry a spare masterlink.Time will tell. As far as chain clearences with the VX...I have'nt seen any issues. I'll do a follow-up review in a couple of weeks.
I do run a JT front 13T. I'm 200+ gear+ luggage(adevnture luggage full). So, this bike is basically a Donkey. The 13T has noticibly more start off power from a stand still and noticibly more power going up hills. For my weight, it just works. On the road I'm still crusing at 45-50mph which is all Ill ever need.

 

[mars rover]

This forum is not nearly as active as the Adventure Rider forum, but a lot of the same guys are on both.
https://advrider.com/f/threads/honda-ct125-trail-125-hunter-cub.1408707/page-411

Thank you Spydie for the link to the Adventure Rider CT125 section. I have read the Adventure Rider forum for years. I have a Kawasaki KE-100 enduro bike. But did not know that they had a section for the CT125. even though I had looked for one. Muchas Garcias ! LOL

 

[Spydie]

Thank you Spydie for the link to the Adventure Rider CT125 section. I have read the Adventure Rider forum for years. I have a Kawasaki KE-100 enduro bike. But did not know that they had a section for the CT125. even though I had looked for one. Muchas Garcias ! LOL

Da Nada!

 

[m in sc]

What's your elevation?

about 800 ft. however, the pgmfi will compensate. on the grom stock it would correct in the mts from here, did it before I modded it. from 800 to 2500 it corrected within 5 miles of riding.

 

[AZ7000']

I’m probably faster at 7-9000’, the fi still makes 8hp but less wind resistance!!!

 

[Spydie]

about 800 ft. however, the pgmfi will compensate. on the grom stock it would correct in the mts from here, did it before I modded it. from 800 to 2500 it corrected within 5 miles of riding.

The FI compensates for less air, so it cuts back the fuel so you aren't too rich. It still affects the power.

 

[Spydie]

I’m probably faster at 7-9000’, the fi still makes 8hp but less wind resistance!!!

No, FI can't make more hp to compensate for the less fuel it's metering at altitude. If you cut back on oxygen, you have to compensate by cutting back on the fuel or you'll run too rich. You can't beat the laws of thermal dynamics.

 

[m in sc]

afr corrects. I've monitored it with a gauge on this same motor. been the there done it. carbbed motor... different story, on an fi motor at 2-3k elevation from 800 feet, it will correct enough for no depreciatable loss same with my cb1100, ktm 390, and sport classic I had. there are ones I've personally monitored (because I've owned ) at the elevations I speak of. at 4500+ its more notable from my elevation. sorry guys, I've been tuning motors for 25+ years . yes closer to sea level is always better but in this motor, not that big a deal with a 2k swing in elevation. on one of my high strung carbbed 2 strokes, much more sensitive.

I stand by what I said about the gains above with the cam and the perfornance , has nothing to do with headwinds or lack thereof, and weird elevation claims. I'm just trying to help with what I've found on this bike. .02.

 

[Spydie]

afr corrects. I've monitored it with a gauge on this same motor. been the there done it. carbbed motor... different story, on an fi motor at 2-3k elevation from 800 feet, it will correct enough for no depreciatable loss same with my cb1100, ktm 390, and sport classic I had. there are ones I've personally monitored (because I've owned ) at the elevations I speak of. at 4500+ its more notable from my elevation. sorry guys, I've been tuning motors for 25+ years . yes closer to sea level is always better but in this motor, not that big a deal with a 2k swing in elevation. on one of my high strung carbbed 2 strokes, much more sensitive.

I stand by what I said about the gains above with the cam and the perfornance , has nothing to do with headwinds or lack thereof, and weird elevation claims. I'm just trying to help with what I've found on this bike. .02.

We’re talking 4K difference here

 

[m in sc]

I never claimed a 4 k difference. I also stated what my top speed was, and now is. bigger cam = more air. added fuel and to target a 13.2 to 13.5 afr. = more hp. the cam i used also raises the power curve by a few hundred rpm which = higher top speed. the gains at higher elevations will be proportionately the same if that's the goal.

 

[Spydie]

I never claimed a 4 k difference. I also stated what my top speed was, and now is. bigger cam = more air. added fuel and to target a 13.2 to 13.5 afr. = more hp. the cam i used also raises the power curve by a few hundred rpm which = higher top speed. the gains at higher elevations will be proportionately the same if that's the goal.

Well I researched it online and pretty much everyone agrees that you will lose hp at altitude. Your mileage may vary. But that’s not the consensus of most experts in that field. Here is a sample of what everyone else is saying.
“

The bad part of all this is that neither the jetting or the EFI will give you back the loss of power because of change in altitude. You will still see a lose of HP as the engine operates at the higher altitude but it will not be because the fuel air mixture is wrong.

 

[m in sc]

this is basic 101 engine stuff.
However, modern motors are designed to operate well within a
certain range of atmospheric pressure. That's just a fact. while you may get more hp down low, and less up high, I can tell you, you will not feel a significant difference in performance on astock CT125, or any that i mentioned, but especially on these little bikes at a 1-2 k change.

Air basically 'falls' into the motor at a certain rate due to atmospheric pressure. As restrictive as these are stock, even at low elevations you aren't filling the cyl that fast thru that mile long intake and tiny valve. This is also why it will have a much more notable effect on higher performance better breathing motors. I know for a fact on the last series of ecms on the 125's, there were different elevation modes in the ecm that could be set. Look it up. was a dealer setting but mentioned in the manual.

Yes, motors will be less efficient at higher elevations. here's a link showing elevation changes effects on atmospheric pressure. I use a similar one to spec in relief valves at work. (I'm an ME by trade in the valve and fluid power industry).

Elevation Versus Atmospheric Pressure

A table is provided to allow for a quick reference to atmospheric pressure based on elevation in feet. Pressures are provided in PSIA and "HgA.

www.pdblowers.com

basically, in a nutshell, the atmospheric pressure will 'pack in' behind a restrictive intake up to a certain point. that variable here will be the atmospheric pressure. when the intake setup can outperform available pressure (atmospheric in this case) behind it, you will see way more performance loss. .02.

 

[AZ7000']

Turbo!!!

 

[G19Tony]

rode mine yesterday, have a bit over 120 miles on it but had my tb cam & efie in for the last 60, and top speed has increased to 57 tapping 58 indicated with no sprocket changes on flat land. so yes, more HP is needed to overcome it for sure. the intake and exhaust are the real bottleneck but it is what it is. I'm good with that on this bike. IF they ever make a less restrictive replacement intake tube that will fit like an oem one from the airbox to TB i'll probably be on board with that. I wouldn't be surprised if KOSO had one in the works.

Yea, I think in a year or so, there will be some bike specific stuff out there. I'll look into it further, then.

 

[m in sc]

was working on my 2stroke grom over the weekend a bit... as an fyi, 1st gen rebel 250 (rear for sure) sprockets also bolt on with a 520 chain. for those wanting to dirt ride this thing with all the gear, a 520 will hold up pretty much forever on these little bikes, way better than a 428 sprocket. yes it fits with no clearance issues.

I just ordered a 40 rear (428) from JT for this. just to play around. I'm going to wire in a speedo healer and make a new head pipe up to the catalytic converter which is getting gutted when i do this. this poor motor is chocked to death with that pea shooter headpipe.

 

[Migolito]

Thats excellent info! As more folks get these, and start modifying, it will be very interesting to see what 'shared' parts this has.

 

[Migolito]

UPDATE: Sprocket Changes. OEM sprockets are 14T/39T. The updated is 14T/41T.

WHY: One of the first mods I did to LRD was to switch out to a 13T front sprocket from the stock 14T. I did this because I weigh 210 pounds, AND I use the LRD for Adventure riding...which means I carry a lot of luggage, often a lotta miles. I really like the 13T sprocket. It made the throttle response much better from the standing stop, and made hills much more doable with the weight Im asking the bike to carry. The problem is the 13T turns OFF the ABS. IF all I was doing was dirt, thats not a problem. However, I do looong slab with lotsa weight and I likes the ABS.

What: Today I switched out the OEM 39T rear sprocket for a 41T aftermarket Rear sprocket. Spydie provided the link see below. I switched BACK from the aftermarket 13T Sunstar front sprocket to the OEM 14T front sprocket. I added a single chain link to allow for the increase in circumference of the 'chain loop' created by going up 2 teeth. The chain adjustment is excellent allowing the rear axle to sit at the stock location.

Results: I took LRD for a longish test ride. Maybe 3 miles. The bike operates excellent. The 13T front equates to a -7.3%(let me know if im wrong) gearing ratio compared to stock. The new ratio is -5%. So, no I don't get the increase in ration the 13T gave me, however, I keep my ABS. The ABS light did NOT come on a single time. The starting stop feels just as good, and without luggage, the hills seem just as good.



I do have a 1500+ miles adventure ride in May and will be able to do a full review of this gearing set up.

Here is the link to the sprocket I used. It fits perfect. No issues I could see. It bolts right up using the OEM nuts.

(https://www.ebay.com/itm/Dirt-Bike-Pit-Bike-Rear-Sprocket-ACb-41-Teeth-for-428-Chain-in-Black-Color/151150047877?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m2749.l2649).

 

[AZ7000']

Where did you get the extra link? Oem? And now do you have 2 masters?

Thanks