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| blurredman |
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blurredman
World Chat Champion
Joined: 18 Sep 2010
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 Posted: 11:49 - 29 May 2020  Post subject: Just a standard service.. |
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So it comes the time to do some large service to my '90 251 @ 45k.
Quick warning- you migt have to right click and open in a new tab/window unless you have a widescreen/large monitor as i'm not sure how to downsize within the forum, or even if it is a capability.
https://blurredmanswebsite.ddns.net/pictures/bikes/service/1-45k.jpg
I thought it'd be nice to implement a thread for this on the forum as I think we may be lacking picture threads at the minute and I always enjoy pictures ! It's not a re-build, but standard maintenance that should be at least checked often..! Mine coincides to have a lot of things to do at one time. 
Some of the items are hit and miss, and just preference for me- other are overlooked items of service.
My list was thus:
-CHANGE CHAIN + SPROCKETS (?)
-CHANGE REAR TYRE
-DEBLOCK EXHAUST
-EXTEND FUEL PIPE BEFORE RESERVE
-REMOVE OIL TANK ON NEXT AIR FILTER CHANGE
-CHECK REAR BRAKE DRUM ON NEXT TYRE CHANGE
-INSTALL BRAKE CALIPER DUST SHEILD
-CHANGE FRONT INDICATOR FOR 251 TYPE
-CHANGE AIR FILTER
-CHANGE SPARK PLUG
-CHANGE FORK OIL
-GREASE REAR BRAKE PIVOT
-LUBRICATE SPEEDO AND TACHO CABLES
-GREASE WHEEL BEARINGS
-GREASE HEAD BEARINGS
-CHANGE ENGINE OIL?
For a start, As far as I know the front and rear chain sprockets were original. I had previously changed the chain 13,000 miles ago with a 2nd hand one down from my brother which had only 10,000 miles on it. I was replacing one which I had no history on, so I thought it best to be safe with a 10k mile rather than potentially 30k at the time. So that 2nd hand chain is time to go!.
Before that however I started on my rear tyre. It was now at the end of it's life. A Heidenau K33, which I got 7,000 miles from. Not toooooo bad, but I suppose good for a Heidenau.
https://blurredmanswebsite.ddns.net/pictures/bikes/service/2-oldtyre.jpg
Out with the old and onto the pile..!
https://blurredmanswebsite.ddns.net/pictures/bikes/service/3-tyrepile.jpg
I have to replace that old tyre with a tyre I have had before and had 8,000 miles before I got rid of it (only because it got square and not because end of tread life). This is the Duro HF319! It has a nice tread pattern too I think.
https://blurredmanswebsite.ddns.net/pictures/bikes/service/4-newtyre.jpg
Whilst I was replacing the tyre I thought I had punctured the tube, as I could hear a hiss- the tube came out and I pumped it up and it held air, at least visually- I put the tyre tube under-water and saw bubbles coming from through the valve.. I then put the dust cap on and no more bubbles..
I would have changed the tube but I didn't have a spare so tried tightening up on the valve core and that worked. It was older type of valve as the tube had Pneumant symbol on it. So the tube was re-installed, and I just put a bit of thread tape on the valve and put the cap on. Seems fine still as of this morning. I also cleaned up and lubricated the rear brake assembly- including using that grease fitting for a squeeze!
Whilst the wheel was off however, let's go back to that chain! Let's check that rear sprocket.. It is worn, true- but it seems to have a fair amount of life left. If both front and rear sprockets are original- the rear has turned a lot less than the front!
https://blurredmanswebsite.ddns.net/pictures/bikes/service/5-rearsprocket.jpg
And so to the front sprocket- what does that look like? Well.. Like this:
https://blurredmanswebsite.ddns.net/pictures/bikes/service/6-srocketcomparison.jpg
I would have continued to use it, potentially for another 5,000 miles maybe, but I know I have a NOS same tooth sprocket that I purchased in Hungary some years back. But, upon proper inspection there was a crack in one of the tooth, and so- I decided to use my replacement. I must mention that I did purchase an ETZ250 chain, so had to remove a link of the new chain before installation!
https://blurredmanswebsite.ddns.net/pictures/bikes/service/7-oldsprocketchip.jpg
And now- time to replace the air filter. My old one was very dirty
https://blurredmanswebsite.ddns.net/pictures/bikes/service/8-oldairfilter.jpg
and as luck would have it, just the day before my package from MZ-B arrived..! BUT... I have something to do before I install the new filter. I have to remove the air box, this is to remove the oil reservoir. I've never used the oil pump- indeed It's not even installed- so thus off it came. And interesting too.. It seems to have been touching the frame for many years. I should clean that up.
https://blurredmanswebsite.ddns.net/pictures/bikes/service/9-airboxoff.jpg
This has two advantages, one is weight, and easy clean of the frame. Second is foremost to me, and that is to EASILY remove and implement the carburettor. With the reservoir installed it can be a little bit of a hassle. Not a hassle anymore.
An extra thing to mention- When the airbox was off I had a good look inside as it looked dirty, and it WAS. I didn't bother to take pictures as my camera is pretty poor.. But the lower inside was covered in a layer of dirt and debree- slightly oily from presumably carb blow back. The airbox was therefore given a good clean.. It's worth a look if you ever take one off!
Now for the fork oil! I haven't done it for 4 years-which is when I got the bike. Now the seals weren't leaking, so I didn't bother to replace them- I merely took the forks off..
https://blurredmanswebsite.ddns.net/pictures/bikes/service/10-forksout.jpg
Emptied them out!
https://blurredmanswebsite.ddns.net/pictures/bikes/service/11-oldforkoil.jpg
For those thinking "nah, i'll do the fork oil next time". This is only after four years and 15,000 miles. That isn't a lot of mileage, and that isn't really a long time either..!
On re-assembly, I cleaned up the fork stansions, and tree so that crap doesn't fall into the stansion upon re-assembly. I like to assemble the forks into the bike, and then put the springs in, and THEN put the oil in. This way the fork oil doesn't go everywhere when you try to push the forks in!
https://blurredmanswebsite.ddns.net/pictures/bikes/service/12-forksbackon.jpg
One thing to note is that the full amount of each tube was only about 190- they were both equal in oil measure so I suppose that was me who used that figure, but I'm not sure why because the book calls for 230ml...But anyway.. I used ATF myself for the oil. I have a lot of it... 
Some small things more I did, is change the spark plug (Denso W22FSU) and change one of the front indicators- I had previously some years back put a round type on because that was all that I had spare. But these days it bugs me- so it was changed out. And I also put on a replacement front pad dust cover.
Some things I didn't do but I had intended to:
-Grease the wheel bearings: They aren't original- and have actually been replaced by metal dust caged type, so I couldn't really grease them. They were a little grumbly and one was a little loose. But I didn't have any to hand so I will just mark them down as required maybe at 50k interval.
-Grease headstock bearings: An often overlooked item. And this time it was overlooked again.. I didn't have a socket or adjustable spanner large enough to get the tree off the headstock. Maybe next fork oil change..
So it's been a busy day, and there are a few things I didn't have time for..
DEBLOCK EXHAUST
EXTEND FUEL PIPE BEFORE RESERVE
LUBRICATE SPEEDO AND TACHO CABLES
CHANGE ENGINE OIL?
I have already lubricated the clutch, choke and throttle cables about a month ago- but in the want of longevity- I decided I should also add the tacho and speed cable. Next time.
Also next time is to deblock the exhaust.. I intend to do this with caustic soda! I have an issue that I cannot seem to easily get to touch 5k which equates to about 75mph.
Also- I seem to have a bit of clutch slip around 4 to 5k, so intend to change oil to 20w50 mineral(advise me?). Currently in the bike is Semi Synth 10w40.
I also intend to increase the length of the fuel pipe in the tap. Currently reserve is 6 miles and that is NOT ENOUGH. I have run out of fuel many times whilst touring, and a few times run off the last drops of fuel coasting into the petrol station. The Neutral light seems not to work anymore either- I have checked the switch connection itself but I suppose it could be the bulb- it may have taken a knock when the front assembly was removed. Will look into that when I lub the tacho cable!
One major thing I do need to do is to take the barrel off and piston out. The piston is only 5k miles old, but is one of the cheap RAM items and i intend to look for wear... There is a distinctive sound to this bike that doesn't sound too healthy, but despite being on 2nd piston (the old one had a crack in the skirt after 30,000 miles..), and a total rebuild at 40,000 miles.. there isn't anything discernable to be worried about - but I would like the check that piston!
Finished product so far: I must admit that it looks a little naked without the oil tank- but so did my 250 when I removed the one off that. It just takes a little getting used to! Don't mind the puddle. That is my oil, but from months ago.. 
https://blurredmanswebsite.ddns.net/pictures/bikes/service/13-parkedatwork.jpg
Watch this space
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S.
Current: 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (bored to 295cc) - 38k, 1990 MZ ETZ251 - 49k, 1979 Suzuki TS185ER - 9k, 1973 MZ ES250/2 - 17k.
Last edited by blurredman on 20:11 - 31 May 2020; edited 1 time in total |
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| WD Forte |
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WD Forte
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Joined: 17 Jun 2010
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| blurredman |
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blurredman
World Chat Champion
Joined: 18 Sep 2010
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Posted: 20:13 - 31 May 2020  Post subject: |
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| WD Forte wrote: |
I've still got the same ETZ250 fork gaiters on my old thing
and they haven't rot or split like cheap ones |
Yep. It's amazing how long the gaiters last.. Never had to replace them on anybike yet.. Even use a pair on my CX500!
So.. Onwards to to-day's progress. I have oiled the speedo and tacho cables... I like to cut the corner off a plastic bag (the flat type that you might buy washers/nuts etc in), then a small hole.. fit the cable through and zip tie the end... Or I suppose you could use elastic bands.. Sometimes it can take a full day, soemtimes just 30 minutes... When it comes through the other end it's finished.. I just use 2t oil- because I have lots of it.. At the same time I found out why my neutral light didn't work- it was a blown bulb.
https://i.imgur.com/zv3rLwf.jpg
So. Exhaust off. Here is an example of the only original MZ tool I have that serves as the exhaust nut c-spanner at one end, and a tyre iron on the other. I religiously use this item for both requirements and I urge anyone to pick one up if it comes at a fair price..
https://i.imgur.com/dwNV31y.jpg
And with the horn out of the way, the rear mount removed, the whole barrel and assembly can come off. This is more difficult to do with the 250's - the tank has to come off. But with the 251's and the weird banana shaped tank, it means there is fair clearance to get even the barrel up and out.. Interesting to think that all you have to do is take a few bolts/nuts off and you're topless.. 
https://i.imgur.com/UT9XO6F.jpg
So.. I found it difficult to get specs of the caustic soda to water ratio, but I came up with 150grams of caustic soda to a litre of water. I stood the exhaust up straight, put a potato in the end. I measured the soda out, then put water in the pouring jug and just poured it in. It did burp a bit and I even plugged both ends to wash the mix through a bit more to get through to some areas that proved difficult to 'burp'. As of this moment (2 hours after putting the stuff in), the water level does still go down a bit and burps a little so I am just topping up with water now. I will keep it like this for a week and then rinse it out and check what crap comes out.. Give it a good bang... I will decide then whether I put it on the bike and test it, or give it another treatment..
https://i.imgur.com/Z0ErlNE.jpg
And so the engine top end assembly is on the bench..
https://i.imgur.com/R4CBGsQ.jpg
First thing to do is blast through the blocked water drain on the head..... I noticed quite a bit of collection of water/oil up there.
https://i.imgur.com/32z9NMc.jpg
And lets have a look at the head first. It looks fine- there is a witness mark of foreign object though- and this is also evidenced on the piston (a few pics down...)
https://i.imgur.com/pbJwlOt.jpg
The barrel. It looks okay, but there is that line mid way down (just above the ports) where the engine had been sitting for, well, 13 years.. I bought the replacement piston and got the barrel machined hoping in naivity that the rust corrosion would just be machined out, a lot of it was- but not all of it! Maybe a 71.5mm piston...(?)
https://i.imgur.com/2DbxyMg.jpg
The piston itself looks pretty good in my opinion. Very little wear on the side wall- no cracks, no big gauges, you can however see the witness mark of the forign object. It's not too important to me, because it's on the head. I wonder if, whatever it is, came from either the dirty air box (you didn't see how bad it really was), or perhaps something might have fallen in from the top with spark plug replacement/checking..You may also notice a small chunk missing from the cylinder wall in the previous picture of the top of the barrel.. It may be a piece of that.. Cleaning up the head a bit can tell me which direction to re-install it. Also confirms this is a '71mm' piston. The only good thing so far is it looks like there isn't too much blow-by.
https://i.imgur.com/XTI5njl.jpg
https://i.imgur.com/8qGLbeJ.jpg
https://i.imgur.com/WNc3eSi.jpg
So- I checked clearances-- And it isn't very good.. First piston ring gap..
I took the top ring off the piston and placed it half way down the barrel as perpendicular and square as possible. I measured 0.70mm(0.0027in). Specs in the Haynes book is 0.2mm(0.008in) but service limit of 1.6mm(0.063in). That's okay.
The piston was also pushed about half way down the wall- however I can fit a 0.08mm(0.0031in) feeler gauge between the piston and cylinder wall.. That's not so good- esspecially when I had the barrel bored to 2 thou (0.05mm).
This is however somewhat to be expected- This is a cheap RAM piston that I bought for 15 Euros all in (gudgeon pin, circlips, piston rings). I installed this piston 5,000 miles ago. For now it will all go back together. The purpose for this exercise was to check how quickly a cheap piston wears.. The answer = very!
PS: Have also hosted original post's pictures on my own source and re-sized appropriately.
PPS: Have also realised my server cannot hold so many consequtive links .... so have uploaded to a different website for now.
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S.
Current: 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (bored to 295cc) - 38k, 1990 MZ ETZ251 - 49k, 1979 Suzuki TS185ER - 9k, 1973 MZ ES250/2 - 17k. |
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