Tire Pressure: How Low Is Too Low?

[MrKymco]

Hello Fellow Agility 125 owners

I am trying to do everything "by the book" so far as my Agility is concerned, but figure their is room to improvise sometimes. My latest foray is into setting the tire pressure on the OEM rubber that came on the scoot.

I bought myself a tire pressure gauge and tire air pump. Checked the pressure this morning and found both tires under inflated  by several psi each. According to the owners manual the front tire is to be set at roughly 28psi, the rear at 32psi. So I set the air pressure according to spec.

But holy cow what a negative difference in ride quality. The ride went from compliant to hard and feels jittery even over smoother pavement. It hasn't felt like this in the nearly 1200 miles I have put on the scoot, or after the first service when the tech adjusted the tire pressure.

I keep reading about how it's important to keep the tires properly inflated for the sake of handling, safety, top speed, and fuel mileage. But is this a hard and fast rule?  I don't think the tires being hard as they are at spec and the ride given on account is something I can live with. If this is the way its supposed to be, maybe I can get used to it, or find a happy median? I think I would rather find a happy median or just simply set them as low as they were before I gave them more air.

Right now I have both tires set 4psi below spec. I think they were lower when I checked before, but figure I'll give this a try.

So, is this ok, and where do you set your own tire pressure? If you aren't running with the OEM tires anymore, how did you find them when you first got your bike, and where did you set them?

Any advice or suggestions is much appreciated. Even if you ride something other then an Agility.

Thanks

[Cortez]

No idea about PSI (and no time to do the math now) but the manual says
1,75 bar front and 2,0 rear, and up to 2,25 bar rear under heavy loads
(topcase, passanger).

I've always got a lot of stuff with me and a 35l topcase so I keep the rear
at 2,1, just a bit OVER recommendation for 1up riding, but I've been keeping
the front a bit lower at 1,6 to 1,7 bar, since I've had some front tire grip
issues with the OEM (crap) tires.

With a better front tire the 1,75 works great, but I've always ridden underinflated
by just a bit on all 3 of my bikes and with various tires.

I wouldn't underinflate the rear since it has a rather dramatic effect on acceleration
and top speed, and I'd imagine the fuel consumption too.

If you're on stock tires, I'd keep them underinflated at all times since they'll grip a
bit better that way but try to get rid of them ASAP.

With proper tires there's no need for that.

[marioG]

please, change tires = aka plastic bags on wheels.....makes big difference...

happy new year!

[ShaunMalik]

I've always got a lot of stuff with me and a 35l topcase so I keep the rear
at 2,1, just a bit OVER recommendation for 1up riding, but I've been keeping
the front a bit lower at 1,6 to 1,7 bar, since I've had some front tire grip
issues with the OEM (crap) tires.

I wouldn't underinflate the rear since it has a rather dramatic effect on acceleration
and top speed, and I'd imagine the fuel consumption too.

Wait, what?
You notice all that "dramatic effects" due to the 0,1 increments in the rear tire pressure, but the temperature, air moisture, air/gasoline mixture, wind, weight fluctuation, and (transmission) oil viscosity plays no significance whatsover? Wow.

Haaave you met Paranoid Parrot?
http://images1.memegenerator.net/ImageMacro/4845328/tire-underinflated-for-01-bar-dramatic-effect-on-acceleration-top-speed-and-fuel-consumption.jpg?imageSize=Large&generatorName=Paranoid-Parrot?imageSize=Large&generatorName=Paranoid-Parrot

[axy]

It is true that tires have to be properly inflated, but it is interesting that underinflation raises consumption just marginally.
Recently I have read American Automotive Association's 200-page study whose conclusion is that 30-40 % underinflation (which is quite a lot) causes on average at most 1.7 % raise in consumption, which is marginal and not noticeable by drivers.
However, it can have a significant impact on the national fuel consumption, tire wear, braking distance and cornering stability.

So, while it is true that under inflated tire may cause in theory higher rolling resistance and larger consumption, it has almost no noticable/measurable effect on it.

[MrKymco]

thanks for the responses, guys.

as it turns out i was in fact over inflating the tires and this was the reason for the hard ride. i was following the first spec table in the service manual which stated the front tire at 1.75 kg/cm (28psi) and 2.25 kg/cm (32psi), respectively. but that is in fact for "two up" riding, as Cortez pointed out. this is pointed out further along in the manual. so the proper inflation is indeed 21.4psi front and 28 psi rear. glad to get that worked out

so far as the stock tires being junk, i am pleased with them myself. they haven't caused me any perceived problems with handling, even on wet roads. i have read this (junk) on various different forums, however. and while i will be replacing them with different tires, i plan on getting as much out of these as possible before swapping them

next up is an oil change. plan on doing it myself at around 2000km (2200 for mine) as required in the owners manual, and although my dealer says use 10W40 i think i will go with 15W40 motorcycle oil (synthetic) as stated in the manual, and by fellow Kymco owners. i will also be changing or cleaning the air filter element

what is the size socket for the oil drain bolt? i would rather buy one quality socket as needed for my jobs, then a set of cheaper ones i may never use

[MaryK]

Buy a quality 3/8" drive socket set or if you have SAE tools already, buy a metric set of sockets.
Craftsman at Sears are usually on sale and as good as needed, with a lifetime warranty.
Lowes sells Cobalt and Ace hardware also has lifetime warranty tools.

Scoot Safely,

[MrKymco]

thanks MaryK

would something like this be perfect for my scoot?

http://losangeles.craigslist.org/lgb/tls/2138999989.html

[old mod]

My new scoot came with warning stickers, which stated pressures for front and back 2.3 bar, whereas the manual states 1.75 front 2.3 rear, i rode it home from the dealers, who had set it at the sticker levels and found it skittish to handle. i have since dropped the pressure to manual levels and find it much better. in PSI that's 25psi front 32psi rear.
                Regarding oil and breaking in, i posted a link on "breaking in" which addresses, the oil to be used, and i agree with it. Hope this helps?

[MaryK]

thanks MaryK

would something like this be perfect for my scoot?

http://losangeles.craigslist.org/lgb/tls/2138999989.html

No, those are American (SAE) fractional inch sockets.  You need metric (millimeter) sockets.

LIke this, for example:

Minimal:  http://www.sears.com/shc/s/p_10153_12605_00934554000P?prdNo=6

More expensive:  http://www.craftsman.com/shc/s/p_10155_12602_00934866000P?vName=Tools+%26+Equipment&cName=Hand+Tools&sName=Tools+Sets

There are other choices, but you want 3/8" drive, 6-point metric sockets with sizes ranging from 6mm to 18mm approximately.

If you buy quality with this first purchase, then you can add to it later as your needs grow.

Most Japanese motorcycles use a 17mm nut for the oil drain... to answer an earlier question... but I am unsure of the other Asian bikes.

A set of combination metric wrenches would be the next purchase; from 6mm to 17mm.

Wait for a Sears sale and don't bite into their new/improved styles of wrenches which cost more and may not be as useful.



Scoot Safely,

[MrKymco]

^ awesome! thanks for the suggestions, you've been a big help. i thought decent tools were much more expensive then this. i can even get Craftsman!

i'm new to all this so this is great info in helping me understand what i need and what i don't. thanks once again!

[Cortez]

so far as the stock tires being junk, i am pleased with them myself. they haven't caused me any perceived problems with handling, even on wet roads. i have read this (junk) on various different forums, however. and while i will be replacing them with different tires, i plan on getting as much out of these as possible before swapping them

They're fine until about 7000km on the clock, then start loosing grip rapidly.
I have better grip on wet roads with the new front tire then I EVER had with the stock front even when it was dry.

[axy]

I had a good experience with OEM Agility tires and with OEM People tires (still on the scoot after 12.600 kms, will replace them at 15.000 kms or so).

Had no problems whatsoever with A125 OEM tires, except for the fact that they are flat and do not have somewhat roundish profile, making leaning over feel quite awkward.

[MrKymco]

No, those are American (SAE) fractional inch sockets.  You need metric (millimeter) sockets.

LIke this, for example:

Minimal:  http://www.sears.com/shc/s/p_10153_12605_00934554000P?prdNo=6

More expensive:  http://www.craftsman.com/shc/s/p_10155_12602_00934866000P?vName=Tools+%26+Equipment&cName=Hand+Tools&sName=Tools+Sets

There are other choices, but you want 3/8" drive, 6-point metric sockets with sizes ranging from 6mm to 18mm approximately.

If you buy quality with this first purchase, then you can add to it later as your needs grow.

A set of combination metric wrenches would be the next purchase; from 6mm to 17mm.

Scoot Safely

well i was at Costco today and picked up this set. only it wasn't $80 like this guy is selling it for, but $20. i can't really find this brand much around the internet. here and there. apparently the parent company is AllTrade, and they make a bunch of tools under different names. including some for Snap-On and other pro brands, i believe.  these are made in Taiwan, just like my scooter  (ok my scooter is made in China but whatever lol). from what i could dig up its said these are good for the "home mechanic"  but aren't really suited for day in, day out pro work. fine by me

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=110627610498+,110627610498&viewitem=

seems reasonable quality, meets ANSI standards. which i think is supposed to be a good thing. i opened up the package before hand to feel the weight of the ratchet and it had some heft to it. the short sockets are the "star' style or whatever. but the longer ones are the recommended 6 point

good enough, i suppose. at least they're colorful

[sparko]

'' these are made in Taiwan, just like my scooter   (ok my scooter is made in China but whatever lol)''

ftp://ftp.nhtsa.dot.gov/mfrmail/ORG4576.pdf

you can reference your VIN against this chart to see where your agility 125 is made. Mine is from taiwan, yours probably is as well. Hope you find a nice set of wrenches that will last a long time. The link above was provided by Rianna (thank you Rianna). I'm sure the chinese can make a great scoot but I know for sure the taiwanese do. thanks for an interesting thread Mr.Kymco. I agree with Axy, I am satisfied with the oem tires on the agility. I keep mine a little overinflated but I have a tendency to ride slower than most and don't take too many chances. I am still a novice. Someday I will get some better tires but they ain't broke so I won't fix 'em.