Keeway, Vento, CPI parts vs Minarelli Parts

[Deleted]

Hi all,

Have a Yamati qj 1e40qmb motor that came off of a Eurojet RX8i, pretty much same as Keeway, that I am putting back together and I'm trying to figure out crankshaft options. I keep running into versions of cranks that are labeled 12mm minarelli horizontal and then other versions that are labeled 12mm minarelli for keeway, Vento, CPI. In many cases, the differing versions are made by same company, but there really isn't much explanation in way of difference and prices seem to fluctuate as well.

From a look at the photos online, they seem the same. I've also seen some of the parts for Keeway, CPI, Vento referred to as minarelli Euro 2, but again I seem to keep hitting dead ends as far as explanation. Is there a major difference between these two versions?

[190mech]

Brent has this article in the tech section;
49ccscoot.proboards.com/thread/2422/minarelli-1e40qmb-wrist-pin-sizes
I have seen all the mixed up combinations for these cranks over the years..The Jog type have small spline,small taper,10mm pin,,which will fit that engine with a piston,variator,& flywheel change,but I prefer the bigger Chinarelli type crank,,Can post some pics on Jog and Ch'relli side by side if that helps..The 2stroke market is slowly going away and parts are getting harder to find,another option would be to put a rod kit on your old crank..

[Deleted]

190mech oh yeah I totally get the wrist pin measurements. The issue that I'm running into is cranks of the same wrist pin size at 12mm but different labels. One group being specifically labeled for Keeway, Vento and others just labeled as Minarelli. Trying to find out if there's really a difference between these 12mm cranks or if they are interchangeable.

Reading through, like you mentioned, I guess it's an issue of the 13mm vs 16mm shaft? I'll see if I can dig up some examples.

Edit: I got it now!  took a closer look and it looks like shaft diameter and there a few minor differences on the stator side of the crank.

Thank you!

[captincvmn]

I’ll eventually re-crank my Keeway F-act. I’ll head down that rabbit hole in spring. My concern is small end bearings.
I bought a bearing that was identical to the stock one. The width of a 70cc bearing seems like it should be wider though. Why don’t cylinder kits come with rod bearing?

[Deleted]

captincvmn It seems like the Yamati, CPI, QJ, Keeway all use the same parts more or less, so I'll be happy to pass along anything that I find as I'm digging away. It seems like a lot of the cranks do come with small end bearings.

I also saw that Stage6 makes a 12mm to 10mm reducer. Not sure how good it is, but perhaps someone around here has used it before. www.dynoscooter.com/products/stage-6-reduction-bearing-12mm-to-10mm?variant=17999548165

As for kits with small end bearings, here's a couple examples below.

www.racingplanetusa.com/crankshaft-naraku-racing-keeway-china-stroke-p-210440-1.html?backcPathco=295&cPath=802_25072#.X7PfnshKiUk

www.racingplanetusa.com/crankshaft-racing-full-circle-high-quality-12mm-piston-p-209396-1.html?backcPathco=295&cPath=802_25072#.X7Pgn8hKiUk

Not sure exactly how this case is going to hold up and I don't want to tear up expensive crank or cylinder, so I'm going with standard parts and a mild 72cc kit like the Naraku or NCY.  Also, there's the learning curve to consider.  This is first time around for me, and if I muck things up, I'd rather do it to something I can replace fairly cheaply.  If everything holds up, will likely switch to something with a bit more oomph down the road and mothball the stock parts as spares.

[fugaziiv]

Nov 17, 2020 7:43:15 GMT -5 captincvmn said:

I’ll eventually re-crank my Keeway F-act. I’ll head down that rabbit hole in spring. My concern is small end bearings.
I bought a bearing that was identical to the stock one. The width of a 70cc bearing seems like it should be wider though. Why don’t cylinder kits come with rod bearing?

Depends on the kit, but generally lower end kits don't to keep the cost down. Conversely at the higher end, the Polini Corsa kit does come with a bearing.


Matt

[190mech]

The Naraku crank "looks" correct in the pic as its got the big spline and flywheel taper..Heck!That case will handle a bad-a** 100cc+ build,,they have thicker cases than the Yam motors..Make great big cc cases!!

[Deleted]

Nov 17, 2020 9:58:03 GMT -5 190mech said:

The Naraku crank "looks" correct in the pic as its got the big spline and flywheel taper..Heck!That case will handle a bad-a** 100cc+ build,,they have thicker cases than the Yam motors..Make great big cc cases!!

That's what I'm thinking too.  Just going easy with this first build and then transplanting this engine on the scoot while I rebuild the one that is currently on it.  That one is going to get the heavy treatment for sure.