Motovert engine conversion, YX150 into RX125

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motoluver

motoluver

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Ive got a rx125 and its time to upgrade the motor.

I like the yx150cc with the electric start and lighting coil from factory and i know a lot of people have fitted these. But i have also had problems trying to fit these in the past
http://www.miniriders.com/chinese-mini-s/22444-yx-gpx-150-does-not-fit-motovert.html

People who have done these swaps do you have any more tips of fitting these motors in.

Or any other suggestions about another motor to use? Lighting coils are a must and electric start is a bonus.
 
I think the YX150 is a good candidate for fitting into the road reg bikes, due to it coming with the e-start and lighting coil.

I have a pretty easy solution for your problem.
The raised boss area for the breather tube is solid alloy, so it's just a matter of marking it up and grinding or filing a horizontal half moon shaped cutout into the top of the engine.
You can grind or file as much as 10mm (plus another 3mm if you need it) deep in the lowest part of the cutout, and it still will leave between 6mm an 8mm of alloy between it and the breather port


This is the side on view with the case's split, note how much alloy there is between the breather port and the top of the raised section (top picture), the breather port is the one to the left of the top mounting hole.







Tape up any entry point's to the engine so you don't get alloy filings into it, eg intake and exhaust ports, and breather tube.
Mark the raised section for clearance to the frames' tubing with a suitable marker, might not need to go as deep as i have pictured, but will need to be offset towards the breather tube more
Then put on some safety gear on, goggles and gloves, long sleeves etc,
and use an angle grinder with an alloy grinding disc, slowly grind away the centre section deeper in the middle to make it a half moon shaped cutaway when looking from the front or rear.
A normal steel grinding disc is not suitable as the alloy sticks to the disc and gets hot, this can cause the disc to explode.
Grind it down till you are close to your markings, then use a file to finish it off, deburr the edges and your done.


Engine case's, pictured from the rear ( mine doesn't have the pressed in tube for the hose to fit over fitted in this shot)




Engine case's from the front,

 
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Awesome thanks a lot for the info. Looks like ill be doing the yx150 engine swap take 2
 
Yeah just sit the engine in, as lined up and as close as you can get it, and mark the lowest part of the frame against the top of the engine, then centralise your half moon cut out to that marking.
Grind it down say 4mm and try it, if it needs more grind back another 2mm etc etc
 
my67xr said:
Yeah just sit the engine in, as lined up and as close as you can get it, and mark the lowest part of the frame against the top of the engine, then centralise your half moon cut out to that marking.
Grind it down say 4mm and try it, if it needs more grind back another 2mm etc etc
Click to expand...

Yep will do will do. What type of carb should I look into running with the 150
 
Every time i break something on my RX i contemplate doing this conversion... so tempting.
Thanks heaps for the info!
 
im chopping up on a yx160(no elec start) or a 190 anima for my rx build
 
I wish i had the finances for the 190! But alas i am only pondering on a bore kit at the moment... anyone know what kits will fit/work? I have never really dabbled but i am kinda keen to give it a go ;)
 
I am stuck on the 150 or 160. The 150 has the electric start but i dunno... Is there much difference in power between the two and would the 160 support lighting and charging?
 
Just had this puppy delivered for my rx build..along with some tb goodness :) 160cc
f82874171d9622adf838cf69122b00b9.jpg



Sent from my iPhone using Tapatalk
 
Nice,
but is there any reason you went the YX160 over the Z160Ho besides the 5cc difference ?
 
ive had to 3 z155's and they are just a claggy motor compared to the yx160

ive owned 5 yx160's in various bikes and modification and never stripped gears etc

its all down to proper maintence and car
 
hahaha all good
plus i dont like a company who call and 150 engine a 160 :p
 
So you aren't into Brand name bikes, jap bikes etc
They are required to have an actual cc less than their capacity, like the CRF230F 65.5mm bore, 66.2mm stroke
it's only 223cc's,
And the CRF150 57.3mm X 57.3mm = 147cc
 
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oh im into brand name bikes but all in all im not a fan of the z155 and z160
 
Im gonna remove the L shaped rear breather and measure the clearance
Terry from firepower told me to plug it and run a dip stick or valve cover breather if it fouls to much

And ofcoarse drill the top mount out


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