earlwb

I guess one cannot use the anodized head color to determine if a engine is one type or another, since MVVS used Black, brown, red, green, blue, gold, and no color on their heads for the .40 through .49 engines.
I have a MVVS engine with a green head color but the displacement has been machined off the side of the crankcase.
I would assume that with the 6.5 ground off they made this one a larger displacement then, maybe a .45 or a .49?
I was planning on getting a new cylinder/piston/rod for it, but of course one needs to know what displacement it is.
When I was tinkering with the engine, I found that it was missing a backplate gasket so I made one. It had some remnents of a gasket, but not enough to seal it up good though.
Thanks for looking.

pe reivers

Measure bore/stroke and cylinder outer diameter.
Bore stroke for displacement, cylinder outer diameter and conrod length for eventual replacements.
For the old type 8cc engine (.49) , there are no spare parts available. Maybe Morris ( www.mvvs.com) has some stale stock.

earlwb

Ok it looks like it is a .46, the bore is 0.845 inches and the stroke is 0.83 inches, which works out to be 0.465 cubic inches for displacement or 8cc. I might be a little off though on the measurements.
The outer cylinder diameter looks to be about 0.9865 inches or about 25.057 millimeters.

Pe, Does that look like your cylinder sleeves might fit OK or not?
Thanks

jaka

Hi!
Green head and it's a 8cc (.49) MVVS engine. Red head 7,5cc (.45).
I have spares and engines!
You have the old 7mm carb I see!? All MVVS I have sold have the new 8mm carb. More power that way and no loss of reliability!

DarZeelon

Earl,


Like any European made engine and most Japanese ones, the bore and the stroke are stated in metric units; not in Imperial units.

Also, it is not in units smaller than 0.1 mm.

Both the 8.0 and the 7.5 cc (.45 and .49) engines have a 22 mm diameter bore.
But while the 7.5 cc has a 19.6 mm stroke, like most other .40-.46 engines; the 8.0 cc engine has a stroke of 21 mm.


And Jan is right. I have not seen a 7.5 that had a green anodized head, so it is by all likelihood an 8.0 cc (.49) engine.

You seem to have gotten the stroke measured right, but the bore, I believe, is a bit off for the .49 engine.


EDIT: Correction; .46->.49.

earlwb

Thanks guys. I am in America so we still have a tendency to think in inches instead of metric.

For some odd reason my metric rulers have all been misplaced, and I couldn't find them, I am sure they'll show up now that I don't need them.
Ok I remeasured things, the bore looks like it was coming out closer to 22mm, as I could get about 21.96mm fairly consistently. I measured deeper down inside instead of at the top.
I don't have a depth gauge so measuring the stroke to 0 to 0.4mm difference is not going to be easy. I redid the measurments and using a 64ths of a inch ruler, I was getting about 53/64ths of a inch or a hair over 21mm. My eyeballs just can't see that tiny well anymore. Trying to descern 0.4mm is tough with a ruler much less using 64th's of a inch graduations.

So then all the Green Head engines were .49's or 8cc then? When I was looking for info, it seemed the head colors were more or less random.

Oh yeah, there was not head gasket or even a shim on the head button. Did they run them without a head gasket or shim? I don't have a problem with using no nitro or low nitro fuel.

pe reivers

The 8cc has a 25mm sleeve diameter, and 22mm dia piston, so the sleeves that mvvs still has will fit. I have a 8cc Acrobat sleeve in stock, as well as a cylinder jacket.

earlwb

Thank you very much everyone, I appreciate it.
Earl

fiery

My Feedback: (2)

Earl

I have exactly the same model MVVS, a .49 green head.

It is the best sport glow I have ever owned.

I have wrung it out week end after week end since 2006 ... and it still has good pinch at TDC. A testament to the quality of materials.

It has never been run with Nitro. Also, always 20% lube, mostly all castor, sometimes 10% caster, 10% Klotz synth.

A carb upgrade using the new 8 mm carb, or a "nozzle kit" will really improve throttle transition.

Regards

Derek