Hey folks, ive been following The 250 forums for about a year now while waiting for the deal i cant pass up on a 250s.. and it happened about 6 months ago.

not to brag but i picked up a bone stock 07 with 8500 miles on it for 1500 bucks. the thing runs like new! and the guy before me must have kept up with maintenance like he had ocd, which is AWESOME. not a scratch on it. ( well he laid it over in the garage before i got it from him and he broke the stock left bark beater.) meh things are ugly as sin anyhow. soo ive owned it for around 2k miles now, had a mechanic i know check the valve clearance, and cam tensioner, ive checked my stem bearings and done everything i feel right doing ( motor mounts, swingarm greasing, axle bearings, oil/filter change) its just tip-top. and i love it.

that being said, I cant believe the wealth of knowledge on these forums.

I have ONE question to you gurus:

At 3000 ft above sea level With the Q4, stock header, the DJ2152, no snorkel ( or lidless), would i be best to use the dj132 main? or should i go a little more rich say, a 134 or 136? ( im not really worried to much about getting every single 1/10th of a horse out of my little shetland, but id like to get a touch more out of her)

thank you guys


Nick

 

As you increase altitude, there are less oxygen molecules per cubic measurement. Approximately a 10% decrease per 3,000 feet increase in altitude. Therefor, the main jet should be smaller with an increase in altitude. At 3,000ft, you may not even feel a difference in performance by rejetting. If you need a little more snap, either use a smaller counter shaft sprocket or larger rear sprocket.

Ride on
Brewster

 

thanks for the quick reply Brewster!

the reason i ask is that I drilled a few holes in the back of the stock spark arrester and took the snorkel off, and added an UNI filter, and cut it at 8/9k to check the spark plug ( a "thing" my other rider buddies have informed me to do ) it seams damn near white as a sheet of paper, so i assume im very lean. therefore, i assume, if i really open up front and back I would need to richen up a fair amount, would the new needle alone do that? say at like the second "notch"?
thanks again.

* afterthought* 13 tooth cs sprocket installed as i ride more offroad/backroad than "highway"

 

If you want to run lidless, you can use the data for the "Dyno w DGR" link below.. You can re-calc DJ140/2N yourself - I recalc'd it for you, guessing at the temp. - DJ140/2N adjusted for 3k ASL @ 86°F = DJ136/2N.

That's a DJ136 main with the needle on the 2nd notch from the top. Both washers on top of the needle.

 

First, welcome to the crew...

How did he "check the tensioner"? If he doesn't know what to look and listen for he didn't check it.

FWIW. If your engine starts or already does rattle from the right side of the engine at 4000-6000 rpm your tensioner is bad. If it rattles while idling it is really bad.

Just making sure you know when you need to replace the part should you have to.

I will defer to the resident DJ wonk, KLXter, on the brass jetting.

But I will mention there is a fuel adder that can compensate for significant altitude change. By jetting lean with the brass, the Dial-A-Jet will supplement the fuel mix with an additional passive injector that will richen the fuel mix when there is need, but in a progressive fashion. It uses acoustic and vacuum wave patterns to do so. Kind of similar to a Mikuni PowerJet, but it mixes in some air for an emulsified partially atomized mix. Big thing with ATV and snowmobile people, not so much with bikes. The newer industries were more open to different methods, bikes seemed to stick with brass only.

Click the link to learn more. Check out the information for general stuff and the tech article for more insight. My brother and I both use it. I've run it on the KLX650 for over 15 years, ranging from sea level to around 5000 ft and from 18-95 degrees F, little noticeable driveability or power changes.

 

You guys are absolutely sick..

I havent ordered anything yet, I just really needed some reassurance that what i am going to purchase is what i need. Klxster you're pretty much there with NW oklahomas summer temperature average, ugghh... its pretty hot out right now,

and KLX678 about the tensioner, I really dont know, and this guy up here, MMI mechanic that i was referred to by other non-certified mechanics.. lol i dont hear any clanking or rattling. i just asked him to check it, and on some faith just let him make the call..hell he probably just listened to it.. regardless im going to get a manual tensioner at some point soon to alleviate any worries that might arise. although like i said the bike sounds akin to the other four strokes ive owned, that ran for years.

well I guess i have my answer, and you guys are awesome.
Thanks Again!


Nick

 

Sure Nick.

If you want to leave the airbox lid on (with the snorkel removed) you go all the way down to DJ128 or DJ132 with needle on 3N. Removing the lid is a "radical" mod because it requires vastly different CVK setups. Don't run a DJ136/2N setup with the lid on!
All this is assuming you are running a Q4+stock header as I have no data on what setup you should use otherwise.

 

No noise no problem. It doesn't fail instantly or catastrophically it just goes bad over a few thousand miles when it does. As I said the experience in general is rattling at 4000-6000 rpm. Again, no noise no problem.

Historically a lot of mechanics tend to figure the noise is normal because they hear it many times.