NX250 Thread -- official ADV owners manual

[mito-nx]

StefanDB
Look at this picture.

This is the engine side of intake manifold.
The restricted versions mainly have a smaler intake hole.
Otherwise look at the numbers on a microfiche, find the difecance between the parts of the ignition system, carburator, cilinder head...

[mito-nx]

When you change a part like this, get the bike tested to make sure the combustion is good and you do not have to make more changes since you are change the airflow.

[mito-nx]

Who can tell me the engine difference...
The NX is a MD21-MD25
The AX-1 is a MD21-MD25
The XL250degree is a MD26, but looks like it is a MD21 ?
Does anyone know the exact difference between the models?

[fikse]

Sambucas

I cannot say anything but: Best of luck

[trailKing]

Thanks for your reply's and welcomes !

Sounds like the overtemp light is pretty bulletproof.

Originally Posted by larry31

Welcome!
I've had my (stock.. unmodified) 1990 NX for just under 20 years. I have had many occasions to make the bike overheat.
It's never overheated and only occasionally will the fan come on. It will go for a full season of riding, 2 - 3,000 miles and not use a drop of oil.
Unless the outside temp. is under 50 deg's, I can start with full choke and drive away. I can usually open the choke as soon as I get moving through the gears. If it's under 50 deg's, I may have to keep the choke on until I get moving around 30 mph.

That was similar to the way my bike was and I thought typical of Honda motors. But with the new CDI, I haven't used the choke once. I'm sure that will change as the temp drops, but it has definitely changed how the bike runs for the better.

" The only issue I have left with the bike is that it "hesitates" pretty consistently between 4500-5000 rpm, any ideas? "
Carb. may need a little cleaning, or carb. cleaner run through it.

Whats the best way to do this? By carb cleaner do you mean the spray can stuff? Ive been hesitant to do that as Ive heard that it can damage some seals or something in some carbs.

If you keep the bike outside, your switches may have some oxidation on the contacts. Try getting some "contact cleaner" and spraying the insides of the switch housings. After spraying, work the switches a few times.

I ended up taking the switch apart and cleaning the contacts with an eraser and re coating in dioelectric grease. works great now!

My fan comes on often during low speed summer travel and my right leg gets hot. Is this abnormal or typical with the rest of your bikes?

[larry31]

Quote: My fan comes on often during low speed summer travel and my right leg gets hot. Is this abnormal or typical with the rest of your bikes?

I've not noticed any excess heat on my legs. However, I ride with jeans and high boots, and normally don't ride in real hot conditions. I may not be using my bike in same conditions as you?

[swg]

hey guys need alittle help with my Honda NX250 ....need to do a clutch adjustment its not slipping but grabs too far out on the release.... some where on the site i saw a download for the owners or maybe it was the repair manual but could not load it , i'm thinking about changing the sprockets and chain does anyone have an idea what tooth sprockets would be best as i am looking for more bottom end offroad, thanks!

[SaDoW]

Originally Posted by mito-nx

When you change a part like this, get the bike tested to make sure the combustion is good and you do not have to make more changes since you are change the airflow.

if you do a change like that you need larger main jet and carb ajustment




After 2 years of work i have finished my baby! !!!





thank you all for helping !!!!!!!!!

[trailKing]

SaDow- Looks great! I like the red/black.

Your seat looks a different shape? Did you do it yourself or have it done?

[Sambucas]

Today we checked the thermostat and the waterpump of the bike that tends to overheat.

Waterpump was fine. Couldn't turn the fan by hand, but it was turnig together with the engine. No damage to the impeller, no pollution, so everything was fine.

Then we checked the thermostat, looked good. Then tested it in boiling water. It opens up perfectly. Actually the thermostat on the bike that doesn't overheat, proved to be working way less better. It only opened up halfway... So this is the world upsidedown. The thermostat of the bike that overheats works fine and the thermostat of the bike that does NOT overheat, only works half...

We also checked the cooling system for blockages by blowing in the hose that is normally connected to the thermostat. That way it goes through the radiator, then through the waterpump and then through the engine itself. Didn't find any blockage, the air came up with full force on the other side.

So we still don't understand why this bike keeps dumping it's coolant. (yes, we use real coolant, so with high boiling point, so it shouldn't be that the bike dumps the coolant, because it is boiling over)

We are clueless, maybe someone else has another idea of what to check or what to do.

(We know of a good motorbike mechanic in Nairobi, so we might look into the bike running lean then...)

[fikse]

Sambucas,

After some brain searching here, I didnt find that much, sorry to say (...)

But!

What about a bad top head gasket? If you have a leak from combustion chamber into one of the cooling channels, Ill guess this could make excess pressure in cooling system...

Actually, when I search my brain a little more, I fixed the pretty much same problem on a KTM Sting 125 (who use a 2-stroke Yamaha DTR125 engine): On these engines it is a common fault that head gasket "blows", and normally this is seen at first as a exessive pressure in the coolingsystem. Well, OK, this was on a 2-stroke, but couldnt this trouble also be seen at the Nixie-engine? The top head gasket both seals the combustion chamber and the cooling system?

Might be a thought

[trailKing]

I 2nd on the head gasket theory. Sounds like a classic symptom, wish I had thought of that. Best of luck!

[CrazyJill]

Originally Posted by trailKing

Hello all,
I just joined the forum but I have been enjoying my 1990 nx250 and this thread for about a year. All this talk about overheating has me wondering, Ive never seen my light come on? Should it come on at startup? Should I test it or is it pretty bullet proof? I dont think I have any heat issues, my fan works great and often in the summer my right leg usually gets hot.

I had the same problem with my right leg getting very hot. We got some heat shield exhaust wrap, and wrapped the headpipe where my leg sits. That cut down on a lot of the heat to the right leg.

[muddyrabbit]

Sambucas, change the thermostat!

[muddyrabbit]

Just realized i botched the explanation a couple of pages back. I said "opens too early" and meant "opens too far". Here's an example i had to deal with recently. Had a Ford f350 diesel (yes it's a truck, but it's still an internal combustion engine) , it would overheat only under severe conditions. Went to replace the thermostat and someone had removed it completely. Coolant was flowing too fast to cool down in the radiator. This COULD be your issue. Not for certain, but possible, plus you have observed a difference in the thermostat of the bike that runs fine compared to the one that overheats. Plus it's a cheap part, worste case your out a few $$ and have a new thermostat.