Planet Minis

reefmuncher

That'll work, though guess grinding burrs must be expensive in Japan cause what's with leaving everything unfinished!?!

I was thinking about ordering one of their 100cc bigbore options, but I'm beginning to think I'll do it myself by ordering some oversize pistons!

NCNSR

I guess the bottom line is Autoboy is mass producing stuff(There stuff is available everywhere)Amazon Japan/Yahoo Auctions/Numerous retail outlets,They are sloppy.As opposed to Lipps which you can only get there stuff through them........RepsolNSR should be getting his Malossi this week and i will suggest he have the auxiliary intake ports done when he sends it out......

johnson05

I don't think you want to do this. The cylinder already sits too high. The base gaskets are .5 mm so it is difficult to lower the cylinder so you are pretty much forced to hit the milling machine. The stock cylinder is not too bad with the thicker base gasket....


But the kitaco overshoots the ports.....



And the athena is even worse...



The old trick of raising the cylinder with a thicker base gasket to get more top end probably will not work in these cases because the cylinders are already way too high.

johnson05

Just some additional information. Almost all the Japanese cylinders are just reworked 50cc boat anchor stock cylinders including the kitaco. The athena is aluminum. Cylinder weights are as follows..
Stock 2.1 kg
Kitaco 1.8 kg
Athena .7 kg

NCNSR

I always thought the Kitaco was Aluminium?

(also great info)

minirazor

Do both heads have the same squish band? and have you measured head volume??

NCNSR

They are totally different,Just by eye the head volume on the Autoboy is considerably less..............There that different,The Autoboy is about as high compression as they come,The head has even been cut down alot more than the Malossi. I took pics from this angle so you could see the Width,Depth and Contour of the combustion chambers,The Autoboy head is on the left

Jeff Lebowski

This is what I was wondering when I asked NCNSR if the Malossi cylinder is a custom piece. It just looks too much like a breathed on stock barrel to be a clean sheet design.

EDIT: Can you explain the timing key included in the kit? (I think we may have spoken about this before.) Will you have to modify the crank and/or the flywheel to accept the key in a different location to therefore change the timing? Are you using a different ignition altogether that can make use of said key?

NCNSR

The key word here is Japanese,The Malossi is Italian,Without betting my children on it i would say the Malossi is a Brand New Casting.There are subtle differences between the two as shown in the pics.I dont know if this is because they are made of a different material,Cast Iron/Steel or because they are both Honda cylinders from a different series GT3/GT4 etc etc.Or because they are in fact totally different?
I think what Johnson meant was Autoboy,Lipps,Burial,Chameleon Factory, Kitaco. I am not so sure about Malossi and Parmakit.

NCNSR

I will post pics of the Key and instructions tomorrow apparently you take out the Honda key and replace it with the new one no modification needed,It appears to be offset by about 3mm.I have a Posh racing CDI,Posh Coil and the kit comes with a NGK ER8EH plug.

reefmuncher

Yeah the Malossi kits are new castings as are many of the other Italian / Spanish brands. It just lets them start with a clean slate and create port combinations which they feel are better for the performance they want to achieve. Not all the time will they be for topend racing performance, some are just to be a cheaper lower cost option, or else a gruntier more lowend option.

Typically the Malossi, Polini, Italkit, Metrakit types were know for racy performance where the Autisa, Eurocilindro, Zeta ones good (and not so good) low cost options. Some of the later kits could be pretty bad with very uneven port heights or have port work which would need to be totally changed to even match a stock block.

I don't know a whole lot about the 50cc engine options, but my Euro friend did mention that the general consensus was the 50cc engine was better in design than the 80cc engine for extracting good performance!? Or at least I think he meant cc for cc? I think it would make sense as if you look at the best twostroke race engines they tend to be square configurations.

So 54mm x 54mm for racing 125 engines and so with a 41.4mm stroke the 80cc engine bore is already 49.5mm and just gets bigger with 53mm and 55mm kits. With portwork designed to flow for a smaller engine the bigbores struggle at higher revs.

If there was some easy way to fit the Italkit 75cc to the 50cc engine, that would be a good combo in IMO as that kit has really awesome precise portwork (like motox cylinder) and is cast aluminium. When I sent pictures to my friends in Japan they were very impressed and shocked at the reasonable price!!

NCNSR

Generally in europe it seems as though for these bikes the Malossi is preferred with the Parmakit Alloy cylinder http://www.parmakit.com/cpz22/jsp/co...TID=0000000226 second......I know the Athena for the ACO8E is considered crap in europe and Racerxxx221 has a Zeta he feels is crap..........I dont think alot of people appreciate the Malossi cylinder for what it is...........

reefmuncher

Yeah Malossi make some good stuff, for the NSR's seem to rule!

Here's a picture of a really old Malossi 93cc for the 80cc engine. It'll be from around 1990 or so. At the time we were blown away as it was so racy and high performance compared to the stock block. I don't know if the 50cc pistons still have slits between the crown and the gudgeon pin, but the 93cc ones still do and that's for the additional port below the transfer ports. I seem to remember many of their kits had this feature, could be possible the old Malossi kits for the 50cc engines had this also?

The current Malossi 93cc kit is basically the same but without this extra set of ports and the exhaust is 1mm lower with a more durable 2 ring piston. Just wished they updated and cast them in aluminium and fitted a bridged exhaust port!!

(note this block was unfortunately butchered, so not much value in it really)

minirazor

The head on the right (MALOSSI) seems to have a bigger bore size, is that so??

fireman_343

I have some pic's of the Athena cylinder transfer ports and intake/exhaust ports somewhere.. I'll have to go look on my desk top and see if I have the pictures on there? I do remember that they were a little bit bigger then the Kitaco cylinder when looking at them side by side.

A lot of great info being passed on here!!

NCNSR

That is because of the Stepped piston in the Autoboy kit........It fits like a glove,I wouldnt dare run this bad boy on anything less than 100 octane.........

minirazor

Is there a stroker crank available for the nsr50?? if there is does anybody know how many cc's a stroker crank and a 63cc kit will produce??

reefmuncher

That'll depend on the length of the stroke!!

I've not seen one, but sure if you pay someone enough money and they'll do it for you!!

NCNSR

The cost benefit ratio isnt there,You would gain so little it is a waste....Racerxxx221(Richie)was already all over that idea...And trust me after working these motors for all there worth for over 25years if it could be done the Japanese would have done it long ago.On another note i just got off the phone with Malossi they are sending me a 47mm piston that i found with a 12mm wrist pin that might be just the ticket to bump the Malossi cylinder to 72cc.Currently the cylinder comes with a 45.5mm/67.3cc, I had it bored for 46.3mm/69.6cc, 47mm is 71.8cc the same as the Autoboy

minirazor

Would't you rather leave the bore size at 46.3, run it for a while then bore it out to 47 ? it seems like the 47mm bore is the max you will be able to go with that cylinder. gods forbidden something goes wrong in the first run with the 71.8cc cylinder. just my .02