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Old 03-16-2013, 03:05 PM   #6166
Honda Scoot
My First Gold Chain
 
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Joined: Sep 2008
Location: N.E. Ohio
Oddometer: 361
Each bike is slightly different.
This site with its procedure was very helpful to me. http://www.factorypro.com/tech_tunin...m_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.
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Old 03-16-2013, 08:47 PM   #6167
Orkodelamuerte
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Joined: Sep 2012
Location: Argentina, Cordoba
Oddometer: 80
Quote:
Originally Posted by Honda Scoot View Post
Each bike is slightly different.
This site with its procedure was very helpful to me. http://www.factorypro.com/tech_tunin...m_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 canīt just change the clip position, for there are no other positions to choose..

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

Orkodelamuerte screwed with this post 03-16-2013 at 09:13 PM
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Old 03-16-2013, 10:40 PM   #6168
Honda Scoot
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Joined: Sep 2008
Location: N.E. Ohio
Oddometer: 361
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_tunin...%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.

Honda Scoot screwed with this post 03-16-2013 at 11:01 PM
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Old 03-16-2013, 11:21 PM   #6169
Orkodelamuerte
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Location: Argentina, Cordoba
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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 donīt 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 Iīll 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?
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Old 03-17-2013, 12:11 AM   #6170
Honda Scoot
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Location: N.E. Ohio
Oddometer: 361
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.

Honda Scoot screwed with this post 03-17-2013 at 08:32 AM
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Old 03-18-2013, 05:20 PM   #6171
Ratchdaddy
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Joined: May 2006
Location: 29 Palms, CA
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Gas Tank is in.

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.
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Old 03-18-2013, 06:30 PM   #6172
RebelYell
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Location: somerset nj
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I know this is along shot but will the fmf exhaust or yoshimura for the crf 250L fit our bikes?
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Old 03-18-2013, 08:20 PM   #6173
Honda Scoot
My First Gold Chain
 
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Joined: Sep 2008
Location: N.E. Ohio
Oddometer: 361
Quote:
Originally Posted by Ratchdaddy View Post
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.
Spent some time last month working on Honda plastic. Tried PlastFix, and it works GREAT!

http://advrider.com/forums/showpost....postcount=2708

http://advrider.com/forums/showpost....postcount=2799
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Old 03-18-2013, 08:29 PM   #6174
PTC
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Location: masshole mofo
Oddometer: 258
Quote:
Originally Posted by RebelYell View Post
I know this is along shot but will the fmf exhaust or yoshimura for the crf 250L fit our bikes?
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
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Old 03-20-2013, 08:58 PM   #6175
Ratchdaddy
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Location: 29 Palms, CA
Oddometer: 183
Argghhhhhh

Quote:
Originally Posted by Ratchdaddy View Post
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.
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.
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Old 03-21-2013, 08:57 AM   #6176
Orkodelamuerte
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Joined: Sep 2012
Location: Argentina, Cordoba
Oddometer: 80
Quote:
Originally Posted by Ratchdaddy View Post
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...
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Old 03-21-2013, 09:51 PM   #6177
victory80
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Joined: Jan 2013
Location: sf bay area california
Oddometer: 21
Updates

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


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Old 03-23-2013, 01:26 AM   #6178
danielgraves07
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Joined: Nov 2012
Oddometer: 8
Quote:
Originally Posted by Schimm Schimm View Post
the tires are K671 CRUISER ST TIRES. they work awesome and are fairly cheap. about $100 for the pair. heres the link
http://www.jcwhitney.com/KENDA-K671-...4323_10111.jcw
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!
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Old 03-23-2013, 01:53 PM   #6179
Huck369
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Joined: Mar 2011
Location: Somerset, KY
Oddometer: 83
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
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Old 03-25-2013, 10:17 AM   #6180
muzcuk
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Joined: Aug 2011
Oddometer: 62
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.
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