Couple of questions......

[difflock]

Firstly, I see various people change the air filter setups, including modifying the airbox for more flow.


but I've seen some of the racing MZs fitted with cone filters directly onto the carbs.

has anyone done this on a road going MZ?

I've been thinking about it, simply so I could alter the airbox and battery tray area....
the plan I had, was to make a new battery bracket (a bit bigger for a wider choice of batteries), and move the coil, indicator flasher, a bit further down.

then the airbox side could be modified for a nice storage box.....





secondly, has anyone fitted a 'boost bottle' to an MZ?

[dwc]

Hi,
I cant answere any of your questions, but I have seen an MZ with a boost bottle on you tube. What does it do?

DWC

[Trogolodyte]

Erm just what do you mean by "boost bottle"?

do you mean a big blue N02 bottle, as in nitrous oxide gas injection....?

if yes then your answer is
Nitrous oxide is a gas the drag racers inject into there engines for a Power increase of up to and over 100% for very short periods ie 2-3 seconds, it works because
N02 is a very oxygen rich compound that allows your engine to burn more petrol per revolution than is possible with normal atmospheric aspiration,
which is why with N02 you need to re jet your carbytooters to allow more fuel into the engine when on gas and to allow it to run normally when off the gas.
The downside of running nitrous oxide is that there engines have a major tendancy to blow up due to the MASSIVE loads that running gas puts on an engine.

Not such a good idea on small capacity singles

[Trogolodyte]

Also if you get caught running a full gas bottle on the street without informing your insurer then it is very likely that they will refuse to cover you should you have an accident because it is a VERY serious performance modification, if they will cover you then they will state that the bottle remains empty when being used on the street, because a full nitrous bottle that has 2000 psi+ in it, is a mobile bomb, Eg:- I used to have an air gun that used a 300cc air bottle that had a working pressure of 2500 psi of compressed air, they estimated that much compressed air had the explosive capacity of a single stick of dynamite, putting a 2000cc bottle full of nitrous oxide gas at the same pressure on a road going motorcycle that is susceptible to road traffic accidents, is a MAJOR accident waiting to happen

[billr]

Hi,
I cant answere any of your questions, but I have seen an MZ with a boost bottle on you tube. What does it do?
DWC

Haven't modified the air box and wouldn't want the extra intake noise I've noticed when servicing the bike and running it with the snorkel removed...

A boost bottle scavenges extra fuel mixture from the intake when the piston closes off the intake port.
Boost bottle write-up #1
Boost Bottle write-up #2

I thought they were only used on 2-strokes, learn something everyday.

Bill R

[difflock]

I mean on a 2 stroke! :p

I've got an MZ ETZ251



yes, a boost bottle stores the overly rich mixture that occurs when the engine throttle is shut.
it stores the fuel mixture in a small bottle (off a stub in the intake manifold).
then when the engine speed increases/throttle is opened, the mixture can be drawn into the engine, so the engine will always be closer to the optimum mixture.

I wondered if the MZ 2 strokes could be improved by fitting one......



as for the air filter/etc, induction noise doesnt bother me.....I prefer a bike to run spot perfectly, than sound good....



I posted this thread in the tech talk of the main forum, as I thought more people would read it :p
perhaps should of mentioned 2 stroke in the title :p

[billr]

Nah, I shouldn't have assumed that "MZ" meant a Skorpion...
Those are some cool looking bikes.

Might be an interesting experiment.
Bill R

[basser23]

heyBill look up Mz racing,think there were some cool videos from UK on the 2 smokes racing....

[billr]

heyBill look up Mz racing,think there were some cool videos from UK on the 2 smokes racing....

I did a bit of searching for the MZ 2-smokers. Lots of You Tube video.
Those 251s and 301s sound nice. Much better than the ring-ding motocrossers I'm used to.
Have to check out the racing videos, too.
Bill R

[Trogolodyte]

have never heard of a scavenging boost bottle before, I ( my personal opinion) don't think it would have any measurable effect without some form of valving system to controll the flow of fuel/air mixture into the bottle and out of the bottle at the right times, but surely a properly made and tuned harmonic expansion chamber exhaust would have exactly the same if not, a better effect?

[difflock]

have never heard of a scavenging boost bottle before, I ( my personal opinion) don't think it would have any measurable effect without some form of valving system to controll the flow of fuel/air mixture into the bottle and out of the bottle at the right times, but surely a properly made and tuned harmonic expansion chamber exhaust would have exactly the same if not, a better effect?

when you shut the throttle on a 2 stroke, the air supply to the engine is restricted, but some fuel still flows into the engine.

which can cause lurching/juddering....

when you open the throttle, the engine then can deal with the extra petrol/oil and all is OK again.



in a reed valve 2 stroke, when the throttle is shut a similar thing happens, due to the reeds not opening/closing as often.



the boost bottle basically stores that excess rich mixture until the engine revs start to rise/throttle is opened.
it then just gets burnt properly during acceleration.


a better exhaust could help the initial pickup when the throttle is opened, but the mixture will still richen up.......



all of this is academic for my bike at the moment

its deciding that it doesnt want to charge at less than 18v.....which is especially annoying, considering I've fitted a different mechanical regulator that I cleaned up and set the gaps correctly......
so I'll have to get an electronic regulator and see how it goes....

its being a bit of a pain to start at the moment though.......


oh well....