YSR250

R

Rat_ranger

Over 1,000 Posts
So I've wanted a mini moto for a while, a ysr50 was always my first choice, and a grom was 2nd. Unfortunately a stock grom is scary slow, and I don't want to spend what people want for a used one.

The other day I was able to get a complete, but ugly ysr50. Plans are to swap in a zongshen counterbalanced 250 with a 6 speed. Maybe do grom forks and wheels for a slight update while improving performance.

The goal is a daily capable mini moto that can keep up with the 45-55mph back roads around me.
20260502_143306.jpg
 
ridesolo said:
Looks like a fun project.
Click to expand...
It should be.

I will say the authorized xpro dealer on amazon is kind of a dick. I ordered the zongshen zs172fmm-5 engine from them. I figured amazon would be easier to deal with if it shows up with problems. They wanted to "verify fitment" so I told them I'm getting it for a custom and don't own a xpro. They told me to cancel the order since I don't have an xpro bike. My response was if you refuse to sell it to me then you need to cancel the order, and reported them to amazon for telling me to cancel it. A few hours later I got the shipment notice.

I'll need a few other bits for it, like manifold, carb, and regulator. I'll be sure to order those from a less obnoxious seller.
 
Engine showed up fast. Definitely used the padding for all it was worth, also leaked a little oil out of the breather. But it is new and unused. Should be more than enough power for the little ysr. It's supposed to make somewhere between 18-20hp. And with the 6 speed I should be able to get the sprockets set to cruise comfortably around 55. I'll probably paint the side covers to get rid of the xpro branding.
20260506_184808.jpg
20260506_185334.jpg
20260506_185342.jpg
 
Just curious, was the original engine running and did you get to put a leg over before tearing it down? The only reason I asking is that I'd be curious to know if you are going to have a comparison between the old and new.
 
ridesolo said:
Just curious, was the original engine running and did you get to put a leg over before tearing it down? The only reason I asking is that I'd be curious to know if you are going to have a comparison between the old and new.
Click to expand...
It was running, but not well enough to ride. The amount of smoke tells me it needs crank seals, and it wouldn't idle down. It was also missing a rear wheel spacer, and the brake didn't work. It probably lived a hard life being thrashed by kids.
 
In the 80s we parking lot "raced" those bikes in totally unsanctioned and mostly unorganized events in the Cleveland area. Lots of fun, lots of cheating. The popular engine swaps back then were DT 100/125. The real cheaters used YZ125 engines.
 
Rider52 said:
In the 80s we parking lot "raced" those bikes in totally unsanctioned and mostly unorganized events in the Cleveland area. Lots of fun, lots of cheating. The popular engine swaps back then were DT 100/125. The real cheaters used YZ125 engines.
Click to expand...
A lot of people put blaster engines in, almost direct bolt in. And the right side rz350 pipe with a few inches removed in the right spot is supposed to work great.
 
You must log in or register to reply here.

DTT Light or Dark

  • DTT Light

    • Spread the Love

    Back
    Top Bottom