Mikuni VM30 ?

[akirasan]

When i got my ETZ last year and rode it 30 miles home it was surging on the over run like a bucking bronco.

So I turned the tickover up and changed the standard airfilter for a K and N in the airbox

I bought a panel filters and bent it to fit round inside the air box.

No more surging with the standard carb.

[burudi]

high flux air filter round, the same but inexpensive at alliespress.

http://mzclub.forosactivos.net/t1409-fi ... z-250#7246

[philt77+]

The settings determined by Derek Pickard were

150 main jet
6DH3 needle mid-notch
P-5 needle jet
2.5 slide
Pilot jet 30 or 35


These settings take into account the comments from arthurf

If in Australia you can get the Mikuni VM30 plus the MZ kit for about $200 from MikuniOz. About 110 quid. This is probably cheaper than a genuine Bing or genuine NOS BVF if you can find one.

[burudi]

thks philt77+ !

[dirtsurfer]

Dear All, Recently I have been speaking with Derek Pickard (out here in Oz), and he mentioned that his article on the VM30 had one error - the size of the pilot jet - it should be 30 or 35, not 40.

Now however I cannot get onto the "Realclassic" site to write down the specifications/jetting/and conversion process and would like a bit of help from all/any of you in this area.

My BVF carb is quite worn (the slide can be "rattled" from side to side within the carb), and occasionally sticks and does not return the carb to "off'''.

So I am looking at using a Mikuni. Which Mikuni model has the spigot mounting (so that I can use the existing manifold)? Can anyone supply pictures of changes to both the manifold and the air box connections?.
Many thanks, Arthur

Hi Arthur
The spiggot mounting model is: VM30-83 30mm Mikuni VM Carburetor - $143.00 from MikuniOz

You can also get the jetting and needle kit : VM30-83 Mikuni Tuner Kits for 2-Stroke Engines - MZ '84 ETZ 250 for a few dollars more
I wound up buying a twist grip and cable as well.
I don't have pictures, but to mount your mikuni, you will need to reduce the O/D of the MZ manifold slightly (I used fine grit abrasive paper) and increase the I/D of the airbox connection (I used a stanley knife) If your airbox rubber is old and hard, you may have to soften it up in hot water or pay $3 for a new one
good luck

Max

[burudi]

alibaba (and the 40 thieves) is full of bing carburetors and BVF as well as the extinct front brake pump. EVERYTHING is Chinese copy!

[Puffs]

But of course they are. On Mr.Ma's money machine you can find some original items, but very few, and then they're actually more expensive than elsewhere. If you buy in China, you buy Made in China. But that's not necessarily bad.

Earlier in this thread there was focus on 'high flux air filters', either from K&N or others; and I was wondering: how on earth could that help? IMO, if the bike runs better with such a 'high flux air filter', it just had wrong jetting for the standard filter.

Yes, any air filter will cause a (small) pressure drop, which influences the pressure downstream of the filter: inside the carburettor. So the jetting is chosen to fit the air filter that is used. Change the filter --> change the jetting. If you want to minimise the pressure drop, just use no filter at all (as done sometimes in road racing), together with adapted jetting. Of course without a filter, the engine will wear much faster.

My concern with these 'high flux air filters' is that their reduced pressure drop (= increased permeability) comes with less effective filtering. Hence more wear, particularly in a two stroke. So instead of getting the maybe 0.123 HP extra from using a 'high flux air filter', I just use the standard paper filter, and replace it when it gets dirty. (Which takes a very long time, because of the effective inlet tract.)

[burudi]

Dear All, Recently I have been speaking with Derek Pickard (out here in Oz), and he mentioned that his article on the VM30 had one error - the size of the pilot jet - it should be 30 or 35, not 40.

...............................

I agree in opinion. With a Chinese 35 I am doing very well.
thanks !

[klemmy]

The settings determined by Derek Pickard were

150 main jet
6DH3 needle mid-notch
P-5 needle jet
2.5 slide
Pilot jet 30 or 35


These settings take into account the comments from arthurf

If in Australia you can get the Mikuni VM30 plus the MZ kit for about $200 from MikuniOz. About 110 quid. This is probably cheaper than a genuine Bing or genuine NOS BVF if you can find one.

pretty old topic, but anyway...

Is it possible to get 2 stroke kit from Mikuni somewhere in Europe?

[burudi]

yes.
deutchland mikuni

uk mikuni.

[klemmy]

They dont offer 2 stroke kits, only spare parts separately. The main question is what jets are in these https://www.guesi-motorradteile.de/inde ... ing=mikuni and which they should be for ETZ 250. There is only main jet (150) and idle jet (45). In this configuration my bike is running like a crap.

[burudi]

error-error-hit-error-hit......
I think more than one is affected by the heat