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Old 06-27-2012, 10:42 AM   #5341
muddyrabbit
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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.
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Old 06-28-2012, 02:09 AM   #5342
fikse
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Quote:
Originally Posted by Keisler View Post
Does anyone have a decent used swingarm chain slipper assy for sale? Mine was missing when I purchased the bike. This is the white delrin plastic piece with the well nuts, and chain stay attached. The chain runs through this just before entering the rear sprocket. Please PM me. thanks
Like this one? :-)
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Old 06-28-2012, 05:55 AM   #5343
xckarlos
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Quote:
Originally Posted by Pavlo View Post
Sorry that i didn't introduce myself on forum.
Welcome everyone :)

I'm Pavlo, I'm from Poland :)

On the Polish market is a few NX 250, but generally they are in poor condition. Thats why I'm looking for something in the neighborhood of Polish, with the exception of Germany or basically from Germany too. Although I checked the ads for mobile.de but maybe someone has a better proposal.
I think Germany is the best place to look for an nx 250. I am from Szczecin (in Poland for all the other nxers) and I got one for my girlfriend last year. I know most of the bikes that come up on mobile.de are in west of Germany, but if you are patient you will eventually find a bike near our border. We got ours for 1350 euro, it's a 1994 bike with 16000kms on the clock.
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Old 06-28-2012, 12:23 PM   #5344
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Roger that, Fikse. Also need the rest of parts. Hoping to find used readily here, but I can break down and buy new.

Thanks for the lead!

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Old 06-28-2012, 12:27 PM   #5345
Keisler
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Quote:
Originally Posted by Pavlo View Post
I'm looking for nx 250 for my wife. Do you have any information about nx for sale in europe?
Hi Pavlo,

There are three NX250 dominators for sale on ebay Germany. Two look like '90 models. The third is a. Series 2, '94 model. That would be the machine to get all other things being equal.

I was writing you a reply last night but fell asleep while typing, so you probably missed on of them already.

Good luck and let us know. I will crate mine up and ship it if you cannot find one.
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Old 06-29-2012, 02:59 PM   #5346
Sambucas
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How to know when your cam chain is worn?

Just a short question: How to know when your cam chain is worn and needs to be replaced?

In a later post I will ask the long version of this question, including the stuff that happenend to my NX250 engine...

Thanks for the answers already! :)
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Old 06-29-2012, 05:05 PM   #5347
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You either have enough experience to know, or you ask someone, or you get a chain wear gauge. Is you chain tension adjustment maxed out?
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Old 06-29-2012, 05:24 PM   #5348
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Quote:
Originally Posted by Sambucas View Post
Just a short question: How to know when your cam chain is worn and needs to be replaced?

In a later post I will ask the long version of this question, including the stuff that happenend to my NX250 engine...

Thanks for the answers already! :)
I have a crankshaft waiting to be removed soon and two bent exhaust valves that probably matches items in your possession.

The chain wasn't worn to the point where I figured there would be a problem, the tensioner still had plenty of tension on the chain. I think the chain wasn't worn, but rather the tensioner failed.
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Old 06-29-2012, 09:34 PM   #5349
scrambler66
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Quote:
Originally Posted by tntmo View Post
I have a crankshaft waiting to be removed soon and two bent exhaust valves that probably matches items in your possession.The chain wasn't worn to the point where I figured there would be a problem, the tensioner still had plenty of tension on the chain. I think the chain wasn't worn, but rather the tensioner failed.
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?

There was an interesting post from mass out, I've tried this, since my engine was rattling the last 28000 km or so - now the rattling is gone, but I guess I really should change the cam chain now

There is something I have to add to Mass out’s consideration. When the rattling became really loud, I tried his fix described below. But at my Nixie it was not possible to turn the adjuster while the engine was running. With the screwdriver at the adjuster I could feel that the adjuster was pushed back and forth by the cam chain while running, so that’s where all the noise came from. Only after shutting the engine off it was possible to turn the adjuster and fix it as described by mass out. BTW: the tensioner was only 28.000 km “old”, I changed it when the rattling began at 70.000km.

Quote:
Originally Posted by mass out
Remove the tensioner and retract the plunger about 3/16" by turning the adjuster clockwise. Hold the plunger firmly in. Place the tensioner (plunger side down) on a bench. Place a 1/2" drive 1" impact socket over the outside (outside is now facing up) portion of the tensioner. Observe how the plunger remains retracted with the weight of the socket. Now do the same test with the socket as a test weight, but retract the plunger close to its most retracted position by turning the adjuster clockwise. You will notice that the plunger spring tension easily overcomes the weight of the socket and the plunger extends.

This test makes clear that the pressure exerted by the plunger depends on the position of the plunger. A more retracted position (new chain) will apply more pressure to the tensioner guide and thus the chain runs with less slack (less noise). A high-mileage worn chain will receive less pressure and will likely whip around and damage the inside of the cam chain cavity or at best will make a lot of unpleasant noise.

I also discovered a few idiosyncrasies about high-mileage NX250 automatic cam chain tensioners (and I think this has already been discussed). The adjuster wants to rotate clockwise (making the chain more loose) in an oscillatory manor during actual running conditions. As soon as I witnessed this behavior, I knew that I had only two options. I would have to buy a new chain and tensioner, or I would need to try the adjuster lock bolt solution mentioned in this thread. I tried the lock bolt, but I discovered that a rough ridge on the end of the bolt was attempting to turn the adjuster clockwise due to friction when I tightened it. I filed the end of the bolt smooth and tried again with a little grease on the end of the bolt for extra insurance. Problem solved.

The next problem was the fact that I needed to know how far to run the lock bolt in. Not enough, and it wont do anything to help the adjuster, Too much and it could break the tensioner housing. It turns out that (at least on my tensioner) the correct amount to thread in the lock bolt is from 1/2 turn to 3/4 turn after first contact with the end of the adjuster. At that point, the plunger is extended outward to its stop, but does not push out with enough force to break the housing. Once you reach a little less than 1/2 turn, pay VERY close attention to a sudden increase in force required to turn the lock bolt. You really need to be paying attention at this point. When you get the bolt right, tighten the jam nut down onto the original aluminum sealing washer (I used a regular washer to protect the sealing washer from the jam nut).

So here is the tensioning procedure I used on this high-mileage chain:
Adjusted the tensioner according to the service manual.
Started the motor with the short stock sealing bolt & washer left out.
Used a 1/4" drive spin handle, 6" !/4" drive extension, 1/4" drive universal, 1/4" deep well socket, and a small #4 slotted head screw bit to reach the tensioner adjuster (a magnet inside the socket will keep the bit from wandering off).
Turned the adjuster just slightly clockwise to get accustomed to the noise resulting from excess cam chain whip.
Turned the adjuster counter-clockwise just enough to stop the sound of chain whip.
Stopped the engine while making sure to hold onto that adjuster setting (remember,a high-mileage adjuster is dancing all over the place).
Ran in the locking bolt and tightened the jam nut as described earlier.

Problem solved (for now).

One thing should be made clear after all of this. I do not think it is a good idea at all to insist on using and old chain and adjuster like I did. Go buy yourself new parts and do the job correctly. You'll have no retarded cam issues and your cam train will be far more reliable, not to mention, you won't have to worry about the chain chewing through from the inside.

Take care....

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Old 06-30-2012, 06:30 AM   #5350
Mass Out
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Hello,

When I first started work on my 1989 NX250, it was making a lot of ugly metallic sounding noise. This noise was not the same as what you would hear with excessive intake/exhaust valve clearance.

I think it is very important for us to do what is necessary to educate our ears as to what different out of spec or failing internal engine components sound like. The sound of excessive valve clearance should have a clear and regular tempo that increases with engine RPM. Timing chain issues, on the other hand, should not have this regular tempo sound characteristic, For me it was an ugly, chaotic, metallic noise.
Excessive valve clearance: Relatively (compared to a slack timing chain) pleasant sounding with even tempo.
Slack timing chain: Dissonant, nerve rattling, metallic, ugly sound.

I would like to comment on scrambler66's post # 5349.
Provided you use the correct tools (I listed the tools I used in my previous post), you can definitely access the tensioner's internal adjustment screw with the engine running. Doing this will give you a great education on the sound of a slack timing chain. It also teaches you how much tension the timing chain needs to run relatively silently. It was more than I thought it would be.

Finally, when insisting on using a somewhat worn and stretched timing chain (not recommended), you will have to seriously consider modifying the tensioner, as even a new tensioner will probably not work well on a timing chain in this state of wear.

Take care.....
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Old 06-30-2012, 06:42 AM   #5351
fikse
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AgriNixie?!

http://www.agriaffaires.co.uk/used/q...dominator.html
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Old 06-30-2012, 07:51 AM   #5352
Sambucas
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Thanks muddyrabbit, tntmo, scrambler66 and Mass Out for your replies! :)

Indeed it sounds like we have the same problem as you have experienced and know about.

So our engine died suddenly while driving 60-70kph with about 5000rpm, after a loud tick and then a series of ticking sounds coming from the engine. It then wouldn't start anymore, even though spark and fuel were fine.

After taking of the valve cover, to check the timing, we noticed that one of the links of the cam chain was broken. (later we found another link broken, so 2 links broken in total on this cam chain!) Also the cam chain couldn't be bended easily, as if all the links had seized up a little in some weird way. A new cam chain is very 'fluid'.





More close inspection revealed the crankshaft timing chain gear was stripped of about 5-6 teeth. (And tntmo is right by stating that this is a stupid design!) Also the cam chain guide (piece of aluminium attached to the oil pump assembly) below the crankshaft timing chain gear had grooves in it and was broken. And the timing was off (2 teeth on the inlet side and 3 teeth on the exhaust side), so my inlet valves are bent.









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.)

But looking at the timing of the cam shafts, I notice that the cam shafts marks are not perfectly aligned with the cylinder head. They are a bit tilted towards the back of the engine, towards the cam chain tensioner. My thinking is that the cam chain might be a bit longer (worn) and the tensioner therefore more extended and therefore the cam shafts marks a bit more tilted towards the tensioner.



Am I right in my thinking and is this cam chain worn and do I need to replace it???

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...)

Thanks for your advice! :)

Greetings from Ethiopia!

Dave and Marly
www.travelin.tk

Ps. This is such a RISKY issue on this bike, somehow we should inform anyone on this forum right away to check for this issue and apply the right fixes! I suggest that we put it on the FRONT page, in a not-to-miss way? Or even create a separate section in this forum, just about this VERY important subject? (ruining your engine, because you are not aware of this, is NOT fun!)
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Old 06-30-2012, 08:06 AM   #5353
Sambucas
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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
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Old 06-30-2012, 08:52 AM   #5354
fikse
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Sambucas,
I wish I could contribute to your challenges, but Im new to this bike/engine (and far from an mecanic), so I just want to give my support by saying: Best of luck, and for your trip :-)

PS: I also have some challenge to understand the tensioner fix. And I'll guess Im not the only and last one wanting to do this. If you do have the opportunity, it would be lovely with some photos from when you apply that fix
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Old 06-30-2012, 12:04 PM   #5355
Sambucas
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Hi guys,

So I have just tried the tensioner fix as first described by Local Machine and later more refined by Mass Out.

I think it should look like this:



So where you normally have the short bolt and washer, just to cover the hole where you can tighten the tensioner with the screw, you now put a longer bolt (30mm) with a nut. Then put the tensioner to the right tension and tighten the bolt manually (so with LITTLE force). Then the bolt is hand-tight, you hold the bolt with a spanner and tighten the nut really well, to fix everything up.

In the picture you can see how the spring in the tensioner is now unloaded, because the end of the spring doesn't touch the wall of it's groove anymore.

Thanks to Local Machine and Mass Out for figuring out and publishing this fix!

(Ps. Here is a link to a document containing the descriptions for this fix from these guys)

Any comments welcome off course!

Dave
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