NX250 Thread -- official ADV owners manual

These are the links to the items..

http://www.partzilla.com/parts/detail/honda/HP-64520-KW3-670.html

http://www.partzilla.com/parts/detail/honda/HP-64530-KW3-670.html

enjoy!

That if you were in my area, ill probably buy your fairing... It's painfull for some of us to see a good bike parted out..

I understand the pain, but the reality is what it is. I have had scads of DR350's. The last one was the best DR350 most people had ever seen. It even had a Scotts Swingarm! Ran tight, strong, handled great, but it was an old discontinued bike. I felt like I got top dollar when I sold it (which was $1500 as I recall like 4 years ago). With shipping and eBay I figure the bike is worth 2x what it will fetch as a rider. Perhaps I am wrong. Who is buying a decent 1989 bike for $1500? Maybe I have the market all wrong. I found one that looked showroom new in Chico California for $2200. Mine is not that nice. I am open to ideas. I can always ride it! I do have the DR650 bug pretty bad.

Bike sold W/O this box and a half of spares, take a look.
http://www.advrider.com/forums/showthread.php?t=865037

So i´m having some hard time with the carb...

As previously posted, I bought some new stuff to my bike including new jets...

After opening the carb; I found a #135 jet on main. Still, I intalled my brand new OEM #138 jet.

That being said, I started the bike; everything ok, untill attempted to go high on revs.. when I go for the throttle, it will sometimes fail to explode.. Thought I might be getting too much gas, so I went for high revs, killed the engine, pulled over and took out the spark plug. It was wet in the base (on the thread) and with soot on the head... That means I have too much gas in there right?... If so, maybe is due to the main jet swap.. right? And if so... is there a way to correct the flow of gas without putting the #135 jet back? like something than can be adjusted to let less gas inside the mixture...

Each bike is slightly different.
This site with its procedure was very helpful to me. http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

My NX250 uses:
OEM air filter and screen with the top of the air box opened
Stock exhaust with the header welds filed down and the carbon clean out port in the can opened slightly and screened.
145 main jet
stock slow jet
0.056" washer under the stock needle
air mixture screw turned out 2.5 turns from closed
Cleaned the carb over and over making sure ALL those little holes are clear.

Starts easy, pulls hard from 4K to 8K rpm, but only gets 62 MPG now.

Not so sure, but I think I saw a small washer under the needle. If it where there, and if I take it off, will that mean there will be less gas in the mixture?

Now, If that washer is just my imagination... any ideas? I do recall that the needle did not have those indents that I remember seing on other carbs.., so I can´t just change the clip position, for there are no other positions to choose..

By the way... what is the pilot screw for?

Removing a washer from under the needle jet's head, or moving the needle clip closer to the needles head, if so equipped, will allow less fuel to pass through the main jet circuit at any engine rpm.

Check the emulation tube for a round hole. This is the longer brass part that the main jet screws into. If it or the needle are worn, this condition will allow excess fuel at any engine rpm.

Pilot Screw adjusts the fuel at:
idle
cruising - constant speed with small throttle opening
decelerating - high rpm with closed throttle
http://www.factorypro.com/tech_tuning_procedures/tuning_pilot%20jet,%20affect%20of%20size%20on%20idle%20and%20cruise.html

If the bike pops / back fires on closed throttle deceleration, the engine is lean.
If you operated the bike at high elevation it gets richer the higher you go.

Mine as described above works well from 600 to 5300 Feet above sea level were we live.

Your 138 main jet has a 1.38mm hole, and the 135 jet has a 1.35mm hole. Tiny changes make a difference through out the whole carburetor. I had the carb out of the bike probably 8 times to get it right.

So, I did found 2 0.032" washers under the needle. Took them out, started the engine, went for a 10 minute test-ride.. and so far so good. I don´t have that running failure anymore.. It idles good as well

Still need to check the sparkplug to see if mixture is good.

Too tired now, but tomorrow I´ll check on that brass holder you said to see if there is any wear. I did saw that the valve throttle was a little scraped. Hope thats not too important. The needle seemed perfect, but it does not have that clip position option.

By the way, I didnt get any backfire or pop on close throtle deceleration. Hight here is 2400 feet. I dont know how to add that one to the maths though... all I know is that when I got that #138 jet, everything got f***** up.

Thanks for the assist!

Will update.

edit: So I guess that if this thing worked, I can use that pilot screw to set the right mixture up, correct?

Those washers were holding the main jet circuit open by 0.064" further at any throttle position allowing more gas into the engine.

Plug chops are always good. When the engine warm do the plug chops at idle, cruise, and wide open throttle just to check all the possibilities. This being done at YOUR ALTITUDE will tell you what you need to know.

Your scratches on the valve throttle are probably from dirt / dust getting past the air filter.
Also make sure your air filter is clean as a really dirty filter will cause the engine to run rich as the air flow is restricted. Stupid mice nests have been found as well.

No pop on deceleration means you are still rich enough(getting enough gas) = good, since you removed those washers which leaned the engine (getting less gas than before the washers were removed).

Yes, adjust the pilot jet screw at idle to get the highest rpm with a closed throttle. Do not turn the pilot screw out more than 3 turns from closed as the spring tension may be lite to the point where the screw could back out from vibration. Once the highest rpm is determined, then set your idle rpm with the big thumb screw on a short cable.

With any luck she will be on the road tonight and my fuel and carb problems will be a thing of the past. Now I have to figure out how bad the plastics are after being on a shelf since 09.

I know this is along shot but will the fmf exhaust or yoshimura for the crf 250L fit our bikes?

Spent some time last month working on Honda plastic. Tried PlastFix, and it works GREAT!

http://advrider.com/forums/showpost.php?p=20666845&postcount=2708

http://advrider.com/forums/showpost.php?p=20800287&postcount=2799

The nx exhaust is a structural Frame member. Lots of things would work, but you would have to connect the frame after to prevent collapse

Put the new tank on last night. She was hard to start but eventually started. I rode her around for about 10 miles of trails and some road and fell in love with this bike again. It is so well behaved and easy to ride.

Then I tried to start it later and it would crank but not fire. I figured maybe I was still having fuel issues even after cleaning the carb and putting on a new tank.

Well tonight I checked for spark and NOTHING. I have one of the ebay CDI's and my original and neither one will give me a spark. I guess I will be gettin out the multimeter and troubleshooting now.

Check also the ignition coil...

Nx'ers,

Here are some updates on my supermoto build. Still have to mount the acerbis sm fender and tackle the muffler swap but it's coming along. Now for some pictures!









Chopped up crf450 fender

Hey can u help me out? Wondering how and where u got the rear fender on. Also i like the front fender. Any info would help!

Sold my NX250 a few months ago...got a few things left from my parts bike.
Would prefer local pick-up, but might ship items.

What I've got:

Good Front Wheel, with worn tire on it
Good Rear Wheel with like new Tire on it
Motor with 15k on it ran, but needed a new head gasket.
Carb with 7k on it, but would need to be gone through, been setting for years.
Set of front forks
Rear Shock

If someone wanted it all, and can come pick it up, I'd make a good deal to them. (Actually have most of a parts bike...could even get it back to a roller if needed)
All the plastics are gone or trashed.

All located in Somerset, Kentucky Zip 42501

Make offers here or via PM's

Hey guys!

I have finally restored my bike to working condition. It runs and shifts perfectly and I am breaking it in now. All the problems with shifting were appearantly due to a small piece of aluminum (0,5 cm cube) bouncing around in the transmission.

Now I have a new problem. It pulls to the left when I let go off the handle. I did not notice this before because the forks and the front rim were all messed up. Do you think this could be anything other than the chasis? What should I check..?

Has anyone attempted to correct a bent chasis? I rode this bike for about 5000 kms with bent forks and a wobbly front rim, so I know I can compensate but I would like to fix it if at all possible.

Any advice is greatly appreciated.