High Country rid-n with the 4-strokers

[TxTechRedRider]

In the spring, I have been invited to go riding in the high country, say up around 12000 feet above sea level.(Goose Lake New Mexico and surround area, and back country fire roads)
Going with an older buddy with 4 stroke crf450.  He already gives me grief about my cr125 and 2-stroke & the whole business.
I need to make sure I put in a strong showing for all us 2-stroke guys when I go.
I am thinking of things to get my bike ready for the ride.
It will include some mountainous trails, some valleys in which to haul a$$, some meadows to haul a$$, some tricky
agility trails, no real brush to speak of, but some big tree root areas.
We have visited this area before and, unfortunately, I was riding an xr500, so this riding is catered to the thumper, so, at least, I dont want anything going wrong with my 2-stroke and it becoming an issue for a bad ride, no stop and go instances with spark plugs changes. I will really have to do my jetting homework.
So, here are some things I am thinking about doing to my 07 cr125 to get it ready.  
1.) more rear sprocket tooth.
2.) along with jeting, probably a jd kit for the needles.
3.) perhaps a little more rubber in the back tire (size)?
4.) rad valves
Any other mods & or suggestions, welcome.
Keep on, keeping 2-strokes

Todd

[factoryX]

meh, wrong bike.

[riffraff]

meh, wrong bike.

x2 on that. At that elevation you'll lose around 25 percent of you're horsepower, not good for a 125.

[SachsGS]

Borrow a CR500.A 125 4T wouldn't even run at that elevation.

[Marco810]

Borrow a CR500.A 125 4T wouldn't even run at that elevation.

agreed and tell him its your 125 with new plastic/graphic kit

[TxTechRedRider]

"miles and miles and miles of water all around me and not a drop to drink"......

[bearorso]

If you're used to the 125, and can ride it well, go for it.

His CRF will loose the same percentage of power. And CRF Rs (if that's what he has) haven't a  rep  for being great in tight stuff.

When I read high country, I thought of technical riding,( so I thought straight away of a trials tyre - which is what I use on my 500) but , by your post, it seems the usual cow trailing / fire roading that so many blokes do, is on the agenda.

Just make sure the bike is fresh and well prepared. Make sure you've enough jets to set it up - and Demand of you fellow riders the time to set up the jetting.They too would probably benefit from a few changes in jetting, if it's high up.

Gearing - you might be able to set up gearing so you can do a quick change of the front sprocket, dependant on conditions. I've got my chain/ sprockets set so I can go 1 tooth (14 to 15, or vice versa) so I can quickly change gearing. Takes me about 3 to 4 minutes, and I've worked out the adjustment change at the axle, which comes out to 2 full turns and 4 spanner flats, either way I go.

Something to think of is fitting some fans. A pair of computer fans, with an RC car battery ( seems everyone's got access to RC stuff) will keep things from boiling. It would cost you bugger all to set them up, and really help you from killing the little engine. I've used computer fans now since 2006, and even though I thought they'd cark it instantly, I'm still on the same pair, despite a few drownings in muddy rivers, and constant exposure to Australian dust.

[Coop]

I can't help with that crazy high elevation, but I trail rode a 125 in very nasty and tight PA trails for a long time. They can perform quite well if you know what you are doing. I remember seeing a CR80E in a mountain ISDE once in the 90's, so a 125 can make a good trail bike. I think with your mods you will be able to have fun. Don't get discouraged if your bike seems a little low on power or if the 4T's are leaving you behind with all their extra power.

[TxTechRedRider]

Thanks for the great information.
I plan to up at least one more tooth in the back sprocket for some lower end power if possible, but, Bearorso, you think I may need to change out the front also?
If I am up at least one more too in the back, then for any more possible low end I would add or lessen the teeth in the front? and this would help in the narrower
and steeper trails? Which direction would I go in the front sprocket for more low end as possible?
And no disrespect intended, but the computer fans located near the front of the rads would keep my bike from over heating because of the less speed and less air traveling over the rads? would that be the intention? I remember the temparture only getting to the high 80's.
My friend and his son have crf450x's.
The trails we rode a few years ago are awesome, some tight and twisting, some very very steep, some rocky with large and small rocks, some meadows and wide open trails and old mining, loging and fire roads, its an awesome ride. Its very fun picking the lines in the trails and making it thru. And the views and scenery is just incredible.
I do plan to be close to a "jetting master" if possible, by the time of this ride.
One other thing I plan to do:
5.) remove the carb and check the float height, I have heard this has been an issue to many 07 cr's as it was set too high or too low on these bikes from the factory.
I need to make sure all variables are certain so that there are no un-knowns that would create speculation when it comes to the jetting.
Thanks again for the information and please feel free to add any thoughts.

Thanks,

Todd

[MyckMcClung]

more teeth for tighter stuff less teeth for more open stuff. it is much easier to change the front sprocket than the rear,
1 tooth+/-up front = 2+/- in the rear
the computer fans work better, and are more out of the way, mounted to the rear of the right radiator (the one with the cap) pulling air through. it is also possible to power them from the throttle position sensor curcuit since they are such a low voltage.
If you have read any of my posts to other threads concerning boosting the bottom end of any two stroke, install a torque spacer from Moose Racing, $30, best money I ever spent for a performance mod. it goes between the reed block and cylinder to lengthen the intake tract, thus changing the power characteristics to favor the lower rpm range.

[bearorso]

TX Tech,

Just a suggestion on the gearing , that's all. I'm thinking along the lines of perhaps you're going to be doing a bit of open stuff, were you might benefit from 1 tooth extra on the front - roughly equal to 3 on the rear), then, if you get into really nasty stuff, quickly change the gearing for low work. I recently changed to 14 / 52, with 15/52 for when I do more open stuff - the 15/52 brings the 500 back to the equivalent, std 14/49 gearing, whilst the 14/52 gives me crawler gearing where I can use 2nd in most of my tight stuff, with 1st available in really silly sections.

You know how your bike works, so just give thought to what your doing. Coming from OZ - we just don't deal with such high altitudes - though it comes down to the altitude range you're riding in. I don't think you'd be going from sea level to 12000ft, are you? I think that range would be a nightmare even for EFI equipped bikes.

Yes, fans can pretty much eliminate boiling / overheating - the higher altitude you go, the more likelihood you have of boil overs. despite ambient temperatures.Without the fans, my bike still boils over mid winter, and in the once or twice riding in the snow here.It snows a few times each year in the Blue Mountains, 100km from the centre of Sydney, which even most locals don't realize. Here's a pic of my mounting - I do it properly, mounted to my rad cages that I make, but plenty of people just simply cable tie them directly on their rads. Connect them to a battery (as I said, lots of people have RC car batteries and their related charging systems) - you can get 6V, 12V comp fans for less than 10 dollars each, a couple more dollars for some wire and fittings and off you go. My 500 is a steamer of epic proportions in my near trials type terrain , I tried multiple solutions, such as full alloy water lines, to increase fluid capacity and 'radiator' surface, all types of fluids (not Evans - I did not want to just let the bike run hotter and hotter), 1.8 rad caps, 2 catch tanks etc, etc- with the fans - no more problems. Ever. I've a stator system to run them, but to me a RC battery pack would be very easy to set up.

[TxTechRedRider]

That fan setup is very cool. We will be around 10500 up to 12k something, theres a trail/4 wheel jeep road that leads up to the lake.
Then there are trails & 4 wheel jeep roads that branch off and go to some the most remote places. Last time we went up this one trail and didnt see any animals, but, on the way down we saw evidence of a huge animal had been by, pretty spooky.
Thanks for the suggestions, I think possibly the front sprocket sound like the way to go.