1988 ETZ125 - a few questions!

[mr_luke]

Hi all, last weekend I acquired a 1988 MZ ETZ125. It's been off the road since 1999, and the guy I got it from had had it for quite a few years, but hadn't been able to get it running. I managed to get it fired up the same afternoon, but turned it off after about 20 seconds due to the horrible noise it made! Turns out the big end is completely goosed, so I'm now halfway through stripping the engine... It came with a spare engine in bits, which looks as though it was allowed to fill up with water before it was dismantled. There's a rusty tide-mark on the flywheels which looks as though it just came up to the bottom of the conrod, but didn't quite get into the big end bearing. I'm planning to stick this crank in for now, even though I know it probably won't be incredibly long-lived, on the basis that I may feel a bit more like spending some money on it once it's on the road!

I've also bid on a complete engine on ebay. This engine appears to have an oil pump fitted, which mine hasn't got. The bike is in theory for my good lady to learn to ride on, so I think it would go down quite well if she didn't have to mix her fuel. Also, looking at the figures in the MZ manual, it would appear that the oil pump delivers a fuel:oil mixture of around 43:1, compared to the 50:1 recommended for pre-mix. Added to this the fact that the oil is delivered straight to the main bearings and big end, and I think the lubrication must be improved? (Assuming it works!)

This engine doesn't come with the oil tank or anything else. Is there anything special about the tank, or will pretty much anything do? I see from the manual that the pump is actuated by the throttle cable. How does this work? Would I need a different twist grip?

I think the only other question I have at the moment, is whether there should be a tool box anywhere on the bike?

Thanks,
Luke

[djsbriscoe]

The throttle has two cables going into it for the oil pump version. If I was you I'd put the oil system back to the OEM arrangement or go pre-mix rather than rely on some kind of "special" lubrication system. There is no tool box, just a small tool roll that fits under the seat.

David.

[mr_luke]

Hi, thanks for that. The engine is now built back up with the spare crank, and is running really quite sweetly.

As far as I am aware, this bike was never fitted with any form of oil pump - the primary chain case is the flatter version, with no space for one - and has always relied on pre-mix. I'm not planning to do anything very radical, but was more wondering what would be involved in fitting the oil pump which was fitted as standard to other ETZs. If I win the engine on ebay I will have the first bit of the jigsaw (the pump itself) but was wondering what else I will need to source and what I will need to do?

[djsbriscoe]

It might be usefull to join the MZ_RIDERS group

http://groups.yahoo.com/group/mz_riders ... =330951138

There are a lot of experienced 2 stroke owners on there who should be able to help.

David.

[Louis Mair]

I'm not too clued up on the ETZs, but I thought they all had oil pumps. The TS was the previous model which did not have an oil-pump. It also had a different frame and cylinder head/frame mounting. Your engine may be a little 'special' already!
I hope this helps.
Louis

[mr_luke]

Definitely an ETZ, and definitely wasn't fitted with an oil pump from new. As I said, the primary chaincase/clutch cover is much flatter, without the "bulge" for the oil pump to sit behind. It also doesn't have a rev-counter, and has a drum brake on the front. Definitely the poverty-spec model!

The ETZ 125/150 service manual which I found on the Hungarian MZ club's website recommends a 50:1 for mixing in the fuel tank, and has a small subsection towards the end for "models fitted with an oil-dosing device". My engine does have the drillings in the crankcases to carry oil to the main bearings, and to the "weir" for the big end, so I hope it will be possible to fit a pump fairly easily.

[djsbriscoe]

The oil from the pump (a Mikuni) is injected just behind the cylinder block on the EM251 (ETZ251 engine). Is there any evidence of any flat casting areas where a brass injector can be fitted? The oil might be injected into a transfer port in the base of the cylinder block. I'm just going off memory as it's around 7 years since I had an ETZ251.

[Louis Mair]

My apologies if I have inadvertently caused confusion amongst the ET Zedders. A little research has revealed that ETZs come in both persuasions, with oil pumps and without oil pumps. The with oil pump persuasion has a threaded hole in the left crankcase that lets the oil in. If the no-oil-pump bike has a blanking plug at the left rear corner of the crankcase mouth then a conversion should be straightforward. No plug = no threaded hole.
Typing of ET Zedders has reminded me of an old joke:
How do you know ET is a Rangers fan?
He just looks like one.
I guess it loses a lot in the translation.
If you can't find a plugged hole in your 125 do not despair. You'll soon get used to mixing fuel and oil as they did 'in former times'. You will also be able to feel good because your carburettor is getting some oil as well!
Louis

[mr_luke]

Thanks for that, Louis. I seem to recall reading somewhere that early ETZs had all the drillings inside the crankcases. I wasn't entirely sure what that meant at the time (!), but I seem to recall that the dismantled spare engine I have (the one which has donated the crank) has a threaded hole into the clutch area, next to where the pump would go, which looks as though it goes through to the oil drillings. I didn't pay very much attention to whether this hole was present on the engine in the bike, but there's hope! I'm fairly sure there isn't one on the outside of the engine, as you describe.

This is by far the most modern two-stroke I've had, so I'm quite happy with the idea of mixing the fuel every time I fill up, but the bike is eventually intended for my better half, and I think she'd sooner not have to bother!

I'm hoping any differences between the two engines will become more obvious when the ebay one arrives - I'll probably have even more questions then! As far as the bike itself goes, I'm in the frustrating position of having it ready for MOT (bar a v5, a battery and a coil), and having no money to insure it and nowhere within easy reach of the road to keep it!

[webhead]

hi you can fit the bits that are missing easy enough then have a nice oil pump ,its easy buy parts fit better than mixing the crap all the time and always put a tiny blob in your petrol tank as it will help keep rust away,

i use my etz everyday to work and i go 15miles a day and i fill up every 2 weeks so well worth it, and if you want more power

fit a 24 mm carb off a 150 and lift the exhaust port up 3 mm then your see how she goes put a 115 jet in aswell ,if your going to foam filter it put a 120 in.

it will rev more and get to top end better and make sure you got a 15 tooth sprocket best 1 to use if you do exhaust port..

have fun, they are great fun to ride.

[mr_luke]

Well the bike passed its MOT yesterday with no problems! The only issue I had was being used to the Voskhod and forgetting I had indicators and brakes which worked on the way over there..! The tax starts on the first of October so I am being a *very* good boy and not using it until then.

So far I've got petroil mixed at 40:1 in the tank. I know this is more oil than suggested by the factory but 50:1 strikes me as *very* lean and I am conscious that the main bearings are the same ones which were fitted when the big end self destructed....

The plan is to run it for the foreseeable future on premix with the original engine, until either the engine gives up or my wife starts making more serious noises about her CBT - then I'll look at sticking the spare engine in complete with oil pump. I've sourced an oil tank so now all I need to get hold of is a twist grip and some cables.

[Trogolodyte]

Think what you have is an ETZ125std the first basic etz 125 model, came with hub brakes all round (no disc up front), no rev counter & no oil pump, just an oil measuring thing under the petrol cap, at 50:1 it was basicly one capfull every 4.54 litres (imp gallon), if your petrol cap doesnt have one then they are easy enough to find. DO NOT run anything other than 50:1 too much oil & it will run too lean and too hot and eventually the bore life will be seriously reduced and piston damage will result, either by nipping up and stopping at best (and as the piston cools down and contracts it'll release and run normally again but it will do damage), or at worst it'll seize solid or hole the piston. same thing if you run it with too little plus you run the risk of burning out the main bearings, bottom end and damaging the small end (gudgeon pin bearing) wich is a total lump drop and strip