NX250 Thread -- official ADV owners manual

[Sambucas]

One more question...

If I would like to replace my cam chain, I need to remove my clutch (been there, done that) and the primary drive gear.

The manual states that I need a 'gear holder' to hold the gears when I remove the primary drive gear lock nut.

I don't have a gear holder, what can I use instead???

Just a piece of soft wood between the gears?

The last time I remove this nut, my cylinder head was off, so I put a piece of wood between the piston and the frame, but now I don't have the cylinder head off and I don't wish to take it off.

Thanks for any advice! :)

[tntmo]

Originally Posted by Sambucas

One more question...

If I would like to replace my cam chain, I need to remove my clutch (been there, done that) and the primary drive gear.

The manual states that I need a 'gear holder' to hold the gears when I remove the primary drive gear lock nut.

I don't have a gear holder, what can I use instead???

Just a piece of soft wood between the gears?

The last time I remove this nut, my cylinder head was off, so I put a piece of wood between the piston and the frame, but now I don't have the cylinder head off and I don't wish to take it off.

Thanks for any advice! :)

A small wooden dowel might work, I usually use a piece of aluminum between the gears. I've also heard of people using a penny.

As for your other post of riding on tight valve clearance....it probably won't hurt anything. Probably. Usually tight valves will make a motorcycle more difficult to start. If the clearance gets worse, you may overheat and burn a valve. With the numbers you listed, I would feel confident to get to your destination. What about robbing some valve shims from the broken motor? Might be able to mix and match some to make it work.

[scrambler66]

Originally Posted by Sambucas

The strange thing is that when I compare the cam chain with the broken links with a brand-new cam chain, the length is identical (although it is not 'fluid', like mentioned before), so I presume that the cam chain is not to blame, but that we became a victim of the dreaded cam chain tensioner problem. (which I knew about before, I just didn't consider it critical enough to do something about it. (apply the cam chain tensioner fix.))

Now I have a complete replacement engine (engine 2), to replace the first broken engine (engine 1). While engine 1 only had 45.000km, this engine 2 has 85.000km. Looking at the cam chain, it doesn't look like having 85.000km, so my guess is that it has been replaced at least once and so maybe this chain has 30.000km (?). I am not sure about the tensioner, but I will look to apply the tensioner fix, as recommended in this forum. (altough I don't fully understand the fix yet, but I will try it and get back to you if it doesn't work out.)


Basically I have 2 options:
- Leave this cam chain and applying only the tensioner fix.
- Replace this cam chain with a brand-new cam chain and applying the tensioner fix. The problem is that dismounting the old cam chain and placing the new chain (one piece) is not totally without risk. (removing clutch, crankshaft output gear and oil pump...)

Maybe the problem is not the cam chain, but the wear of the guide A and the cam chain tensioner (see below). If those wear out, it would probably have the same effect as a lengthened cam chain – the rod of the tensioner (even if it’s a new one) will push forward to the point, where the tensioner lifter is not able to apply enough pressure to the cam chain. If that is the case, changing the cam chain and the tensioner lifter will not solve the problem. When I finally overhaul my 100.000km engine I will take a close look at those parts and will replace them anyway. And I will measure the length of the old cam chain and compare it to the new one.

Ok, but that wouldn’t help you with your two options to choose . But if I were you … if engine 2 is running without any inappropriate noises, I wouldn’t touch it – I totally agree with you that replacing the cam chain is a risky operation – that’s why I tried Mass out fix - and it worked fine so far for the last 2000km. And given the considerations above, it probably wouldn’t help anyway - a guy from our German NX250 forum also changed the cam chain because of the noise, but found out that afterwards the noise continued – I have to ask him if he noticed any wear of the guide and the tensioner.

Anyway, this wearing out issue is apparently a slow process (mine was increasingly rattling the last 28.000km to a point where I couldn't ignore it any longer) so I suspect that the sudden breakdown of your first engine has probably nothing to do with it. Did you check the lifter operation as described in the manual (see below)?

[Sambucas]

Originally Posted by scrambler66

A worn cam chain will rattle softly at first, after a few 10000km, the rattling will become stronger. If the tensioner failed, it will make a lot more of unpleasant noise - was that the case, just before the engine died?

Maybe the problem is not the cam chain, but the wear of the guide A and the cam chain tensioner (see below). If those wear out, it would probably have the same effect as a lengthened cam chain – the rod of the tensioner (even if it’s a new one) will push forward to the point, where the tensioner lifter is not able to apply enough pressure to the cam chain. If that is the case, changing the cam chain and the tensioner lifter will not solve the problem. When I finally overhaul my 100.000km engine I will take a close look at those parts and will replace them anyway. And I will measure the length of the old cam chain and compare it to the new one.

Ok, but that wouldn’t help you with your two options to choose . But if I were you … if engine 2 is running without any inappropriate noises, I wouldn’t touch it – I totally agree with you that replacing the cam chain is a risky operation – that’s why I tried Mass out fix - and it worked fine so far for the last 2000km. And given the considerations above, it probably wouldn’t help anyway - a guy from our German NX250 forum also changed the cam chain because of the noise, but found out that afterwards the noise continued – I have to ask him if he noticed any wear of the guide and the tensioner.

Anyway, this wearing out issue is apparently a slow process (mine was increasingly rattling the last 28.000km to a point where I couldn't ignore it any longer) so I suspect that the sudden breakdown of your first engine has probably nothing to do with it. Did you check the lifter operation as described in the manual (see below)?

Thanks for your answer, Scambler!

To answer your first question of a few posts back: Yes, the engine was making strange noises, already for a long time:

http://advrider.com/forums/showpost....postcount=3648

http://advrider.com/forums/showpost....postcount=3659

But the most common answer was that it was nothing to worry about, although a few people mentioned the cam chain.

http://advrider.com/forums/showpost....postcount=3665

I didn't have enough practical mechanic experience to understand the sound was the cam chain (if it was that sound).

Now I know...

The cam chain tensioner / lifter works according to the manual. I actually played around with 2 different tensioners before we started this travel, so see if I could make the sound go away. But it was all with the same half-worn chain, so same result, obviously.

My cam chain guides seem to be OK and not too worn, except for the damage that the broken cam chain link did, now they are scrap. But they didn't seem to be so worn out as to lengthen the cam chain.

I will run the replacement engine with the current cam chain and see how it sounds and then decide to change the cam chain or not.

[fikse]

Originally Posted by Keisler

Hi All,

snip

FRONT Suspension Upgrade
Is there a definitive or best upgrade for the fork springs? Part number, supplier?
And what is the best oil to run? weight, supplier?

snip

Cheers!

Shafi

Im also into suspension, both front and rear. Most probably I will go for Hyperpro all way. Most expensive, but also seems to be first class. In meantime, when raising funds (flirt my wife for some months...) I'll go for an ultracheap ($40) yellow SV650 and Hyperpro progressive in front. I talked with a Hyperpro dealer, who wrote excactly this: "It is just regular SAE40 fork oil, with a air gap of 150mm on this bike".
So, SAE40 is a new one (for me), and air gap is 107mm as standard... That's a new twist in making better suspension! Maybe this 40-oil and 150 gap is something worth to try even on OE springs?
Regarding oil brand/supplier, I have yet to see any neutral / objectively review. Personally I'll stick to well-known brands, who get's good results in motor-oil reviews. Until anyone convince me there is something brilliant better product than what i.e. Castrol/Valvoline does

[scrambler66]

Originally Posted by Sambucas

To answer your first question of a few posts back: Yes, the engine was making strange noises, already for a long time:

http://advrider.com/forums/showpost....postcount=3648

http://advrider.com/forums/showpost....postcount=3659

But the most common answer was that it was nothing to worry about, although a few people mentioned the cam chain.

Hmm, that was before I joined ADV . That shrieking/ticking sound at higher revs is irritating, sounds like something got loose inside the engine. It’s totally different from the noise my NX was making before I applied mass outs fix, it was a rattling sound strongest at low revs, and vanished at mid revs. Big Question: which noise is typical for a worn out cam chain? My guess is that the centrifugal forces at higher revs apply more pressure to the cam chain and the noise vanishes. So I guess that your shrieking sound is due to something else, in any case it’s probably best to remove at least the cylinder head cover / clutch cover and look for the source of the noise. Maybe its just a loose screw.

[thirstybuck]

Totally non-related to the cam chain /tensioner debate.

How would I find out if the wheels from a 82 cb650 would fit on the NX without buying them first? Front is 19 the rear is 18. I ask because a pair came up for sale locally with new rubber, but I hardly see any bikes on here with different wheels other than the 350XL or related 17" swap.
Thanks.


TB

[Keisler]

Originally Posted by fikse

Im also into suspension, both front and rear. Most probably I will go for Hyperpro all way. Most expensive, but also seems to be first class. In meantime, when raising funds (flirt my wife for some months...) I'll go for an ultracheap ($40) yellow SV650 and Hyperpro progressive in front. I talked with a Hyperpro dealer, who wrote excactly this: "It is just regular SAE40 fork oil, with a air gap of 150mm on this bike".
So, SAE40 is a new one (for me), and air gap is 107mm as standard... That's a new twist in making better suspension! Maybe this 40-oil and 150 gap is something worth to try even on OE springs?
Regarding oil brand/supplier, I have yet to see any neutral / objectively review. Personally I'll stick to well-known brands, who get's good results in motor-oil reviews. Until anyone convince me there is something brilliant better product than what i.e. Castrol/Valvoline does

Hi Fikse,

The Hyperpro front kit includes the fork oil. I just got my kit Friday.
I picked up the later SV650 shock because it has a lower spring rate and I wanted to make a smaller change, check it and go from there. Found some blue fork gaiters/boots and fork seals from Pyramid Parts on fleabay. Looking forward to getting this suspension upgrade in place.

[fikse]

Originally Posted by Keisler

Hi Fikse,

The Hyperpro front kit includes the fork oil. I just got my kit Friday.
I picked up the later SV650 shock because it has a lower spring rate and I wanted to make a smaller change, check it and go from there. Found some blue fork gaiters/boots and fork seals from Pyramid Parts on fleabay. Looking forward to getting this suspension upgrade in place.

Lucky you
If I buy Hyperpro from another country, they cannot include the oil. Import regulations bla bla. That's why I got the oil viscosity and air gap from the shop :-)
Hopefullly this odd combination of oil and air gap can be adapted succesfully to OE setup
Yes, I have seen the later SV shock is a tad softer. If you cut the lower fork and makes a new hole for the bolt on the old SV-shock, this will be a tad lower than the newer.. So, its a choice, either way

[scrambler66]

Originally Posted by muddyrabbit

Well, Jill found the answer, since we're not really interested in ripping the airbox out, if anyone wants a very nice GSXR rear shock let me know. $30 shipped.

Yep, that stupid air box - there would have been a perfect, highend showa for the NX250 if it wasn’t for the air box. The shock from a XL650V has adjustable dampening; the right length and the mounts diameter are 25/30mm, the same as NX250. And since the XL650 is also a dual purpose, the dampening should fit much better than a shock from a street bike such as SV650 or the like. And the XL650 has been sold by the thousends (at least in Europe), you can get the shock for a few bucks at ebay. But the problem is with the piggy back dampening extension, on the right it collides with the manifold, on the left the air box is in the way. I guess I will have to try sometimes (when I get a second airbox) if its not possible to modify it for a XLV shock

[Local Machine]

Originally Posted by Sambucas

Just another short question:

The replacement engine has a bit tight valve clearance. The clearance should be 0.23 +- 0.03 mm and on this engine it is about 0.15 mm.

The problem is I don't have shims and they are not available in Ethiopia. My plan is to drive to Nairobi, Kenia, which is about 2000 rough kilometers with this valve clearance. In Nairobi I should be able to find shims to adjust the valve clearance properly.

Would it be very harmful for the engine to drive 2000 km with a valve clearance of only 0.15mm???

I suspect it should be OK, but I am not sure...

Thanks again for your help!

Dave and Marly

You could drive your bike safely only if that's the clearance of the intake valves.
If the exhaust valves are under the same specs, there's a big chance they'll be scorched along the way.
Just sayin

[Navek]

Originally Posted by Local Machine

You could drive your bike safely only if that's the clearance of the intake valves.
If the exhaust valves are under the same specs, there's a big chance they'll be scorched along the way.
Just sayin

there is an old saying, "I would rather hear them than smell them", ie loose is better than tight. You are looking for burned valves with exhaust clearances so tight especially on a long trip like that where the valves don't get chance to cool,
Kevan

[muddyrabbit]

Hondascoot mentioned he did a spacer in the stock forks to raise the front enough to clear a 21 wheel. I could accomplish the same thing by getting a set of custom wound springsthat are slightly longer, and get whatever spring rate we want at the same time. I'm weighing the cost benefit ratioof doing that versus swapping the forks with xr250 forks. Yes the xr forks are slightly larger diameter, but it's only 1mm. Either way I'd want to go through the forks and replace oil and seals, so that cost will be the same. The other advantage to the spring swap is we could do it in stages, springs first then the 21 wheel later. Thoughts?

[CrazyJill]

Hi Everyone!

I've been lurking for awhile, but I thought I'd finally introduce myself.

My name is Jill, and I am a pretty new rider, and my NX is my first bike. Muddyrabbit taught me everything I know about riding so far, and is now helping me fix my bike up. Prior to this, I knew nothing about working on motorcycles, but I am learning slowly!

Thanks to tips from this thread, we were able to replace my old shock with one from an SV 650. What a difference it has made!

My future plans include swapping that rear wheel to a 17'', and swapping the front forks/ wheel, as well.

[fikse]

Welcome Jill-the-Crazy