Viral Interlude

[Puffs]

OK, so I understand that you have some oil in the crankcase. It could come from a (previously) leaking seal, or just remnant oil from a rich pre-mix or so. You say you have not set the oil pump yet, but are you sure it doesn't work = pump oil into the crankcase? I ask this because if it's still there, and if there's oil in the tank, that pump will pump oil into the crankcase, so then, in conjunction with a 1:50 premix, you might be lubricating at double the rate.

Regardless, some oil in the crankcase is quite common after a bike has cooled down & been standing for a while, and causes some puffs of smoke the first time you accelerate full throttle. After that the smoking should stop.

I'm starting to wish I had a platform for the bikes too, but maybe you can mount the bike, when still on the platform in it's lowest setting, and start it with the LH leg? That's what I always do anyway, after many years of bikes with the kick on the LH side. Of course watch out you don't fall off.

As an aside, I'm not sure you need to take the engine apart to replace the clutch side main seal. I'd surely try to just take off the clutch & pry out the old seal, with the engine still in the frame. OK, you'll ruin the old seal (watch out not to damage the bearing behind it!), but you'll put a new one anyway.
But I'm confused: didn't you just replace those seals?

On the carb connection, not quite clear where you'd put that 'O'-ring, but if if you manage to get a suitable seal with rubber that's fine & more convenient when you take the carb off.
I never actually used sealant on the ETZ carb, as my original manifold fits fine onto the BVF; just some grease. The Chinco carb got a rubber muff on another manifold.

Best of luck & please keep us posted!

[AlanJ]

Hi Puffs,
I have changed the main seals (twin lip) so no problem there, I am hoping that the excess smoke is the oil I forgot to remove from the sump, it probably will need a run to get rid of it. I am running with the BVF at the moment but if all goes well as I now have the 2 new carbs from China I will look at the Mikuni and at £25, I just don't know how they do them at that price they look superb, incidently the flat slide was only £17. I have just looked at your reply and to answer, the pump looks ok, there is no oil in the oil box and once I have cleared the smoke, I will fill up with oil and perhaps an MOT, anyway.
stay safe Alan.

[AlanJ]

Hi Puffs,
I forgot the o ring, I pushed it, a tight fit into the tube area where the male part of the carb slides into the manifold and if you push the carb tightly to the manifold and tighten the 2 bolts then the o ring becomes a seal pinched between the 2 items.
Alan.

[Puffs]

Alan, riding it might become a problem, with banning all non-essential travel now being back on the cards. And of course winter is coming. But tomorrow we, here in the Ardennes, should get a sunny window amidst weeks of rain.

Smoking is better than no oil at all, and I guessed that, with the 'O'-ring, you had done it like that. Keep an eye on it, that might not be very reliable on the long term.

And with the plurality of carbs you have you'll need another manifold anyway!

[AlanJ]

Hi Puffs,
Just out in the garage, with a reading on the battery, bike not running 12.68V. with bike running, no lights ( forgot o turn them on) 14.44V. Trouble is
I had to get you know who to hold the multimeter ( don't have enough hands). The good bit is it's charging and I didn't fall off the stool.I will try again with the lights on and the wife is a bit happier with me. This bike business sure has it's problems.
Alan.

[AlanJ]

Hi Puffs,
Have now got the whole picture. Tickover 12.68V. Good throttle no lights (normal running) 14.44V. Normal running main beam and indicators and brake light 12.68V. Tickover main lights 12.1/2V. The way I have it set up seems to be ok, no discharge whatever. Thanks for your thoughts on this Puffs, GREAT!!!
Alan.

[Puffs]

Good on you Alan!
Then you can use that charge light the same way I do on the Jawa: if it shines bright --> charges well. Shines weak --> poor charge.

[Puffs]

Alan, I forgot to mention that IMO 14.4V is a bit high and might fry your battery in due course (normal charging should stop around 14V), so also for that reason it's best to always ride the bike with your lights on.

[Blurredman]

Alan, I forgot to mention that IMO 14.4V is a bit high and might fry your battery in due course (normal charging should stop around 14V), so also for that reason it's best to always ride the bike with your lights on.

I've come accross various machines that have charged in different ways..

Some charge at 14.5(ish) volts ALL the time, and this is just the upper limit, so that when all appliances are turned on and the vehicle is greater than idle, it normally gives about 13v. Some vehicles, just like the MZ's, don't charge at all at idle, one of my cars drops to about 10.5v at idle when the lights, rear defogger and wipers are going... and then when the car is in motion it runs at 13/13.5v.

Some cars charge at only 13.5v regardless as to whether lights are on/off, and it seems in that case a computer is controlling the output of the alternator in addition to it's voltage regulator..

Of course.. modern cars, what with the computer too and lack of incandescent bulbs can make sure that the charge is at 14/14.5v regardless of engine speed or the load put on it by appliances.

[AlanJ]

Hi Guys,
Thanks for the info, as it happens I am using a gel type battery, which I believe should not be charged too highly, so, thankfully as I always run with
my dipped beam on, I should not have a problem with the charge rate, thanks Puffs for the reminder. I am just about there with the Saxon, I have some air in
the front brake, it's not quite hard, change the speedo for the right one (showing 19k ) which will stack up with the MOT info, put some Loctite on the 3 stator
screws and put the cover on, give it a run on premix and set the oil system, then the MOT, but of course the next problem Covid lockdown.
Stay safe All Alan.

[AlanJ]

Hi Guys,
The Saxon is at last complete and finished, the build that is, but I need some thoughts on the smoking problem. As I mentioned earlier there was oil just touching the bottom of the flywheels, which looked like gearbox oil, and I thought it might have got there via the clutch side main seal (I have had that happen before) and I will siphon it out, stupidly I forgot and completed the rebuild and as expected a reasonable amount of smoke when running, now the question is, is there any other way that gearbox oil can enter the crankcase area other than past the main oil seal? because if there is then that may well be the problem.
Stay safe guys Alan

[Blurredman]

Hi Alan,

Yes, I have also heard that batteries that are not traditional lead-acid can have unhappiness in regards to the fluctuating charging/discharging that older charging systems exhibit.. After all, you can be 10.5v at idle (with several loads on), and have up to 14.5v on a run without any load.. That is a lot of variation, and lead-acid is the only battery I read that is capable and 'happy' with such variation.

Cars computers these days means that they can easily control the componants and regulate the voltage much better and keep it at a steady 14.5v with full load on or off, and whilst idling or going at any speed.. So the new batteries like this.




In regards to smoking, I have seen it on this forum that someone missed out the 'black rubber circle/bung' that goes between the two crankcase halfs. This can be a point of entry..Do you remember installing this ?


If I were you and you do syphon the oil from the bottom of the crankcase.. just smell it, and feel it- from the smell and consistency you should be able to tell what kind of oil it is... And if you are gaining transmission oil to the crank.. then you would see A LOT of smoke.. Like someone running off 10:1 I should imagine.


I would perhaps measure the trans oil too.. Drain it.. measure how much you have- and either put it back in through a strainer (or put new), and do the same test in a week or two.. It might simply be that you ride around town a lot and don't get much chance to do more than 40mph??

[Puffs]

On the batteries, I understand Lithium dies if exposed to anything above 14.6V.

On oil: I'd suggest to observe the level in the gearbox with use, if it leaks into the crankcase, it should go down, clearly.
Other than that, smell & looks, as BM says. The 2T oil I use is red.

Missed: I cannot remember, it's been quite a while since I had my MZ apart. Have a look in the (Haynes) manual. I remember only sealant.

(Famous last words...)

[AlanJ]

Hi Guys,
Thank you both for your reply, the battery is a MotoBat which is a gel-filled ( not Lithium) as we said earlier running with a dipped main should solve any overcharge (i hope). I was hoping to run the Saxon on premix to get rid of the smoke but I am concerned that with the nick Nicks with the Covid problem could be trouble. As I said earlier the main seals could have been the problem before I bought the 7 boxes of parts etc, most of the time you don't know the history
of what you are buying, so, I was taking a bit of a chance with the engine, incidentally, it is the right engine for the original bike showing on the V5C, but I, of course, don't know why the previous owner did the dismantle bit As far as smelling the oil etc. sadly I have had sinus ops in the past and I can't smell a thing, can be a problem with petrol, anyway take care guys.
Alan.

[AlanJ]

Hi Guys,
When I bought the Saxon, from Leeds, in the midlands, apart from the complete Saxon and all the boxes with all the parts for the dismantled one + all sorts of MZ parts, there was also paperwork, ie Haynes manual and more importantly, an ETZ service manual from Zschopau translated in English, and I must say
absolutely superb much much better than Haynes, and of course, there is u-tube with it's 250/251 engine stripdown, wonderful. To be honest, with all the info
there is on the Mz engines most guys should be able to strip an engine after all the only must-have is a clutch puller you can improvise on all the rest. When I read the post for JawaandMZ and the cost involved, especially if it was just the main oil seals for £650, I felt sad for him seeing that. One of the items that came with the Saxons was a 251 engine. It doesn/t have a piston but I think it is otherwise complete, so, during this shutdown I will redurb it if I can.
Wish you well Guys Alan.