ES150 will not run right!!

[dave47]

I looked at a youtube video for an es150 engine restoration and a very competent looking person was using a 13mm gauge (12.97), rather than 16.1mm.
Checking further, there are two mz manuals for the es150, the early one says 16.1 and the later 13mm.
The Haynes manual wrongly copies the details from the earlier manual for both ES and TS, although the accompanying photo seems to show a vernier on 13mm.
This may relate to two different engines, both fitted to the ES, the early engine with a single chain, and the later one with a duplex.
If yours has the duplex, it might be as well to go with 13mm?????

[ScotBob]

I looked at a youtube video for an es150 engine restoration and a very competent looking person was using a 13mm gauge (12.97), rather than 16.1mm.
Checking further, there are two mz manuals for the es150, the early one says 16.1 and the later 13mm.
The Haynes manual wrongly copies the details from the earlier manual for both ES and TS, although the accompanying photo seems to show a vernier on 13mm.
This may relate to two different engines, both fitted to the ES, the early engine with a single chain, and the later one with a duplex.
If yours has the duplex, it might be as well to go with 13mm?????

Interesting; mine is a duplex, perhaps thats why I struggled for so long to get it set up, as previously mentioned I ran out of adjustment and could not attain the 16.1mm setting, 13.3 is certainly attainable.

[Blurredman]

Perhaps that means it has a TS engine instead of an ES engine? Interesting. And also, good to know, for youself I mean, for the future.

[dave47]

If the TS150 was introduced in 1972, and the ES150 only discontinued in 1977, and if the engine was modernised in this period, the early TS150s would get the old engine and the later ES150s would get the new one. This seems likely, as youtube shows ES150s with single and double chains and the Haynes manual shows a single chain engine, which is stated to be a TS150.

[ScotBob]

Right, back at it; new seals in and all new bearings fitted, cases reunited without drama which makes me suspicious somethings not right.

Crank turning super smooth, well centred and not touching anything, so that’s good. Only issue is the new brass bush for the layshaft is tight so shaft cannot be spun by hand but will turn ok with the sprocket on so hope it will loosen off.

New piston fitted too.

[Puffs]

Fingers crossed...!

[ScotBob]

That’s the engine back in the frame final assembly to go and nearly there.

[ScotBob]

Even closer now:

[ScotBob]

That's it done; starts easily hot and cold, idles nice, revs cleanly through the range, pulls like a train and going better than it ever did. Running it in a little richer with the needle up a notch until it beds in then i'll drop the oil and see how it looks, but to be honest i'm delighted with the result it's like having a new bike, well worth the effort.

[ScotBob]

That’s it fully assembled, running sweet and cleaned up ready to go, thanks to all for advice and comments.

[Puffs]

Ooooiihh...! It looks gorgeous!

Congratulations with the result & your work.

But: what was it? Which of the issues you found caused all the hassle?

[Blurredman]

Congratulations! I bet you can't wait to go for a ride.


Question: Is that left rear shock on the correct side of the swingarm at the lower mount? I often see people put it this way you have (or previous owner has) but it looks a bit odd to me- surely it should be mounted on the outside of the swingarm, even on this model of bike?

[ScotBob]

Ooooiihh...! It looks gorgeous!

Congratulations with the result & your work.

But: what was it? Which of the issues you found caused all the hassle?

Hmm, therein lies the question?

Crank seals: one was badly worn and both not seated correctly, neither were flush with the casing both were angled and not flat( ie one end protruding up above the indent for them in the crank case.

Bearings: significant movement in the layshaft bush and all gearbox bearings hence the gears contacting the casing (swarf). Evidence of the crank bearings spinning in the casing i.e loose, in fact the surface needed a bit of finishing to remove a lip that had formed. New bearings fitted with bearing glue to ensure a tighter fit.

Evidence of the crank contacting the casing but I do not believe this to have been during my ownership as I’m sure I would have heard / felt it. It may be the noise stopped after the groove had been worn? Crank looked to have been running off centre I’m guessing this maybe caused the bearings to go off centre and work loose potentially partially dislodging the seals? I measured and checked the crank before it was reinstalled all looked good.

There was partial plugging of the crank vent but I would have thought it was insufficient to cause the overpressure as I checked this with an airline before disassembly and there was clear passage of air but perhaps insufficient?

There was some scorching of the piston skirt so a new piston kit was installed, piston and bore were still to the original spec.

I can only surmise a combination of the above caused the issue, engine unable to breath fully, mixtures wrong due to loose bearings and unsealed crank seals and potentially a timing issue from an off centre crank?

But to be honest I am delighted with the end result and it really does go well now, so it was worth the effort.

[ScotBob]

Congratulations! I bet you can't wait to go for a ride.


Question: Is that left rear shock on the correct side of the swingarm at the lower mount? I often see people put it this way you have (or previous owner has) but it looks a bit odd to me- surely it should be mounted on the outside of the swingarm, even on this model of bike?

Good spot, it’s mounted in that manner as the bike does not have the original rear subframe. The subframe fitted is from an MZ enduro, the bike was a standard ES built to look like an enduro rep. The mounting was changed to keep it in line with the new subframe.

[Puffs]

Thanks for your review Bob. Sounds like it's a very good thing you took it apart to rectify previous assembly issues!

Should be great this summer, now that Nicola seems to slacken the reins.