TS150 tune-up help / idle problems

[Agronski]

Hi all,

New member, 'new' MZ owner - my previous 2-wheeled-engine-thing was a Puch Maxi, but it doesn't like hills so I've tripled by engine size and bought a late '70s TS150. Lovely machine, engine seems sound but doesn't run very well; after kick-start, it idles okay for a couple of minutes, then starts to bog unless I blip the throttle - takes a while to return to idle, then usually bogs down and dies. Also sounds like it's 4-stroking a lot, not getting the nice clean '2-stroke ping' sound.

Things I Have Changed To Get Her Running:
- Points (new set, gapped to 0.4mm and timed to 2.8mm BTDC)
- Condensor
- Spark plug + HT lead (getting a nice reliable spark, but not always a fat blue *zap*, sometimes more a white crackle)
- Piston + rings (original had a 10mm crack/bite out of the intake-side skirt!)
- Paper gaskets (cylinder gasket was _welded_ to the face, had to scrub for weeks to remove it all)
- Carb settings (returned to stock, original jets clear, needle sharp, everything clean)
- Air filter, air hose (currently haven't got the rubber seam between the filter cover and the panel - is this a big deal?)
- Exhaust tube and muffler (ooh, shiny!)
- Battery

I've got a blade-fuse holder on order and a 6V electronic regulator ready to be installed once I bother to take the old one off.

Things I Have Adjusted to try and Get Her to Idle/Run Properly:
- Idle screw (3 turns out, 2 turns out, 1 turn out - all the same effect)
- Throttle cable Bowden (adjusts the idle okay, but doesn't seem to make much difference to the problem)
- Fuel mix (put in some fresh 33:1 to run in the rings - again, doesn't seem to change the way she runs)

The seal between the exhaust and the muffler puffs smoke and leaks a very little half-burned fuel-mix, and I idled for 5mins then took the head off - very wet with browny-coloured fuel-mix. Haven't had a chance to do a proper plug-chop yet, but I guess it's running rich - sometimes doesn't like starting unless I hold the throttle half-open.

I'm not sure what to try next. Can anyone tell me what to try/adjust/replace?

[radiograf]

Is the choke closing properly?

[Agronski]

I'm pretty sure the choke is okay - I stripped the choke lever, removed the 30-year-old crud, and repacked it with new lithium grease. Cable is also free and slides easily. Rubber stopper at the end of the choke piston is good, seats and seals well I think. The return spring is firm and the cable Bowden is adjusted so it sits right down over the starter jet when the lever is in the 'off' position.

[Agronski]

Update: I think I've solved one problem, only to find at least two more

When I got the bike I replaced the HT lead and spark-plug with brand new parts, but re-used a spare plug cap I had - didn't realise it was a 5K resistor cap. The new spark plugs I bought are BR7HS, so already have resistors, so with the cap resistor I was getting next to no spark. I have tested with a bare wire and get a nice blue spark now, so I will buy some non-resistor plugs and see how they go. However...

The seal between the exhaust and the muffler started spitting thick, mud-coloured oily stuff, which I think is crankcase oil mixed with my fuel. I took the exhaust off, and it dribbled out about 10ml of the stuff. I flushed the exhaust out with raw petrol, and looked into the cylinder while the exhaust was off - and as I crank the engine, I can hear hissing and see bubbles on the piston, which looked like it was covered in pre-mix, even the skirt. Not sure if this is normal or not, but I can't imagine it is...

I'm pretty sure my (brand new) rings aren't sealing properly. The new piston/rings hasn't been run in yet, so they might just need bedding down, but maybe someone can tell me if it's just that my engine was too cold to seal properly, or if I need to re-bore and move up a piston size?

I'm now also really worried about my crankcase seals - is there any way of replacing these without having to crack the case?

[Old Dog]

OK, I don't want to teach anyone to suck eggs but this is a two stroke and there is no crank oil, the fuel oil mix is drawn into the crank via the carb and the transfer ports see to the rest.
Check the gearbox oil (change it) and if it stink of petrol then your seals have gone and you need to take the motor out and strip it or call me and I'll make you a suitable offer of a tiny amount of cash for the bike.

I would take off the entire exhaust system. If you want to be sure replace the silencer, they are pretty cheap but they do clog up, unless of course you know the provenance of the bike. Put the system back together making sure that it all fits neatly and lines up, I use a little HT silicone on the down pipe/silencer joint. Then...and this is the big one.

Get on it and ride it, get it warm and then ride it hard, they will spits a bit of unburned but the more you ride it hot the quicker this will settle down as the carbon seals everything.

Sitting it on the stand on idle for minutes is not helpful and in my experience they don't like it.

They are better on the throttle, have fun, and remember you have no brakes

[arry_b]

Apart from very early 150s, the crank seals can be changed with the engine in situ and without splitting the crank cases. If your engine has a needle roller small end bush, you've got the later 150 and can do a happy dance.

The crank seals are in carriers under the clutch and the dynamo that come out to change the seals.

Like Old Dog says, don't baby it. Don't use too-good oil while you're running it in either, a decent mineral will get the running in over faster and more effectively than a semi-synth.

[Agronski]

Thanks for the input - will give the bike a workout soon as I get a non-resistor spark cap. Have changed the oil - slight smell of petrol, but that is probably due to the oil being 30 years old and looked like mouldy treacle. Nice new half-litre of ST90 and the kickstart feels smoother already. As for crankcase lubrication - I was getting confused by shared oil system between gearbox and clutch. Happily, I have a needle-roller bushing [happy dance], but even happier since I think the seals are fine. Good to know I can change them if I need to easily enough, though.

Before I changed the oil, the clutch was slipping a bit - now it's a bit worse and doesn't disengage completely even with the lever right back to the handlebar - hopefully just need to adjust the worm. Any suggestions/hints?

---

Update: Bike now running okay - Haynes Book of Lies forgot to mention that needle clip settings are numbered from the TOP of the needle. Have changed to clip 3, adjusted the air screw and throttle cable Bowden, and also given it a bit of throttle - seems TS really doesn't like low revs. Have run it around a bit - not yet really wrung it out yet, but just enough to get it warm. Will take it out for a spin sometime soon, really open her up and do a plug chop to check the carb settings and mix. As for the clutch, it disengaged properly once I'd got the revs high enough and knocked it into gear, so I guess it just needed to be loosened after a long time sitting doing nothing.

I do still need to get the front forks sorted though - don't think there's any oil left in them at all. And someone once told me to put about 10 pennies/coins in the forks to make them stiffer - can anyone shed some light on that?

[Agronski]

Hi all,

A quick update, and a few questions that neither the Big Book of Lies nor a very thorough search of the forums will answer. Update first: she runs!
Clutch is a little squishy, will occasionally not disengage fully until engine revs high enough to knock it loose - not sure if this is normal, age-related, new oil bedding in or something else. For now, not really a problem.
What is a problem, is my generator/electrics have crapped out. I have stripped, checked, cleaned, probed and dismantled damn near every component and I can't see why my battery isn't charging when the engine is running - not at all. Just running my battery down all the time, and I'm getting tired taking it off the bike to recharge it before I want to ride!

Things I've checked:
1) Wiring/loom - all looks fine - wires where they should be, contacts cleaned, continuity good.
2) Carbon brushes - a little worn, but contact onto the commutator is good, low resistance.
3) Commutator - no shorts between segments (after gently scraping out the old carbon gunk from between contacts). Haven't yet checked each turning or ground shorts yet.
4) Field coils - fine, resistance 1.7 ohms, no obvious shorts to ground , but might be intermittent or.....
5a) Regulator - have checked the old mechanical reg, no obvious shorts, coils intact, contacts clean; even tried wedging the contact between the arms to take the field-resistor out of circuit: no effect. Haven't yet tried to get it to switch manually, though - might have failed open circuit?
5b) Tried to connect a 5-terminal electronic regulator - doesn't seem to work at all, but I might have the connections wrong. Anyone have any experience with this type? http://www.mz-b.net/index.php?page=shop ... &Itemid=87
The connections on that reg don't match the mechanical one, but I know that 'B+' and '51' are the same, and that (theoretically) 'D-' is just ground. Hopefully the others are just the same...
6) Field resistor - intact, resistance 4.7 ohms, contacts clean, but seems to be shunting the field coil all the time, even without the regulator connected - at least, that's what I see on my multimeter. Field coil voltage is really low (1 volt max!) when the engine is running, even if I take the resistor off completely and rev it up to 5K!

So, I'll continue debugging, but if anyone has any hints I'd appreciate it. I'm usually pretty good when it comes to electrics, but this has got me stumped. And yes, I'm well aware of PowerDynamo....but I'm a stubborn SOB, and I want the 6V system to work before I gut it and replace it with $£250 worth of new kit.

Second, I'm replacing most of the bulbs with LEDs so that there'll be more juice for my spark; already have a nice set of indicator 'bulbs' and I'm brewing my own solid-state flasher...but I cannot figure out how the hell to get access to the speedo and rev-counter bulbs! The rubber boots don't seem to have any joins in them, and they seem to have been made inside the handlebar mounts. There must be a trick to getting the clocks out of the rubbers...any special tool/technique [scissors? ]

Third (and final): TS doesn't have any mirrors yet, but I have some bar-end types waiting. I can get the clutch-side handlebar cap off, but not the throttle-side, since there doesn't appear to be a grub screw anywhere. How do I get the cap off the throttle-side handlebar off?! Have tried brute force, but it's held in tight with something and I don't want to snap it.

Thanks,

A.

[arry_b]

<snip> I cannot figure out how the hell to get access to the speedo and rev-counter bulbs! The rubber boots don't seem to have any joins in them, and they seem to have been made inside the handlebar mounts. There must be a trick to getting the clocks out of the rubbers...any special tool/technique [scissors? ]

Third (and final): TS doesn't have any mirrors yet, but I have some bar-end types waiting. I can get the clutch-side handlebar cap off, but not the throttle-side, since there doesn't appear to be a grub screw anywhere. How do I get the cap off the throttle-side handlebar off?! Have tried brute force, but it's held in tight with something and I don't want to snap it.

Thanks,

A.

Speedo and rev counter bulb access: Remove the spring clip from the bottom of the rubber boot where the speedo/rev cable passes through it (if it's still there). Then simply push up on the cable and the instrument will slide out of the rubber boot from the top.

Throttle end plug: Take a good look at the outer end of the throttle grip, around 1/2 inch from the end. You'll find a hole around 10mm in diameter in the throttle "pipe"- it may be covered by the rubber of the grip. Undo the 10mm nut (or 6mm allen key on some bikes) which clamps the throttle housing to the bar, this allow the throttle grip to rotate around the bar. Rotate the grip while looking through the 10mm hole in the throttle pipe, and you'll eventually find a slotted head countersunk screw. Undo and remove the screw, and the end cap will pull out of the end of the bar.

[breakwellmz]

http://www.themzshop.co.uk/category/905/

http://i.ebayimg.com/t/MZ-ETZ-SPEEDOMET ... ~60_35.JPG

The speedo pushes out!

[cabi3]

how on earth does the CArriers Come out?

[Agronski]

cabi, mounting carriers/boots should just pull out once the clock is removed. Don't forget the retainer clips at the bottom by the tacho/speedo drive.

TS is running okay now, but did a quick plug-chop the other day after 15mins riding around the block, going up and down the gearbox but not pulling very hard. Plug looks okay but ash-grey, not nice tan. Think I'm running a bit hot/lean - not very hard running, head was too hot to touch and the gearbox/bottom end was warm. Carb is set up as new, float heights are good, needle clip position 4 (richest), plug is BR7HS, airmix screw is 3.5 turns out, idle is about 2500RPM when warm. Premix is Castrol 2T Power-1 @ 33:1

Air filter and cover are new, but couldn't get the rubber seal so cut along a length of fuel line and pushed over the edge of the filter cover - seems air-tight enough, but I don't know - side-panel rubber plug is still sound, too. Wonder if the carb air intake (new) is letting in some air, because it doesn't seat over the carb throat very well.

I suppose 2T newbies are always scared of how hot they get, but I don't want to seize my shiny new piston/rings unnecessarily

Any thoughts?
___

[arry_b]

A new piston and rings will get a little hotter than normal while they bed in, but I'd be looking at improving the seal between the carb and the air trunking. Any excess air drawn in there will cause a lean condition. Check by spraying soapy water around the joint while the bike's running and looking for bubbles, or by spraying carb cleaner or easy start around the joint and manifold gaskets while it's ticking over and see if the engine speed changes.

Your tickover seems high, I'd be looking at getting that under 1500 rpm, also, 33:1 is too oily for a 50:1 bike. More oil = less petrol which won't help with a lean running engine.

If your carb is a 24N1-1, the settings in the factory book are:
Needle - 3rd from top (4th for running in)
Slow running screw - turned out between 2 and 3 turns.

It IS very warm at the moment though, it could just be getting hotter than usual as it can't dissipate heat through the pot and head as fast as it normally could, I seem to remember something about dissipation being proportional to the 4th power of ambient temperature in degrees kelvin from college physics years ago. So your engine will get disproportionally hot when the temperature rises.

'arry

[Agronski]

I set idle at 2500RPM because when cold, anything lower than about 2000 and the engine struggles, and below 2000 TS bogs down and guts out.

Running at 33:1 because of the new rings - same with the needle-clip and airmix screw. Although the oil might displace some fuel, running 4th clip should make it rich, not lean.

Assumeing the bike is set up for running in, what could cause it to run lean/hot?
- New piston/rings bedding in - okay, will keep an eye on this as I run in. Haven't yet got 100mi on these rings yet...
- Too much oil in premix - not sure this is a big problem, will see.
- Air mix - will check carb for leaks/excess air intake.
- Ambient - damn hot summer here!


As for bogging down below 2000RPM - only thing I can think is running too rich! Maybe combine 4th needle clip with 50:1 oil mix? Is there anything else that would make TS need a high idle to not bog/gut out?
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