Orion rxb 250cc
 

Received the bike late last night, no damage to report from shipping. Only thing missing is the two springs that hold the muffler on.

Started this morning assembling, normal stuff like loctite bolts, and make sure everything is tight. Suprised that most all bolts were very tight. Only have one stripped thread on the upper mount for the rear subframe. I lubed front and rear wheel bearings, cleaned both rotors, and will finish tomorrow greasing the shock linkage, swingarm bolt and such.

I pulled all the stickers off, did notice the bike has had a lot of greasy hands on the plastics that haven't been cleaned off. Easy to wipe off, but still it's a new bike you'd figure it would be clean.

Drained shipping oil, added 1.5L of 15W40 Rotella, and adjusted valves on a cold engine, 0.004" intake and 0.005" exhaust. Pulled the carburetor (NIBBI brand), pilot is less than 0.018" (smallest bit I have to check), but not by much, and I left as is. The pilot is marked #40 and the main is marked #120. The stock main jet measured @ 0.045" to 0.048" with the clip on the second notch from the bottom. I drilled it to 0.052", and put the clip in the middle. Stock, the air mixture screw was 4 full turns out from bottom. Ran the engine till warm and set the air mixture screw to 1 1/2 turns from bottom, which was the best idle. I'm just above sea level, it was 90 degrees and high humidity.

So far it starts on a dime, runs smooth and that muffler is LOUD (it does sound good, though). Should get some easy ride time in tomorrow to start breaking in the engine. I'll keep ya updated...

Kirk

Oh, one thing I forgot...you have to pull the intake manifold to get the carburetor out. When I did the gasket was turned the wrong way and partially blocking the entrance to the cylinder head. Flipped it around and fits like it should.

Kirk

Congrats on the new bike. :tup: enjoy the ride.

Yes sir, and thank you.

Kirk

where are the pictures...



..

Agree on the LOUD part. Sounds good, but almost offensive as a trail bike. Very interested to see what alternates I can come up with for mine.

Looking forward to hearing more...glad to see others getting this gem.

Here is a pic of it finally assembled, lubed, and loctited. Got about 20 minutes of limited/easy riding today. It's Sunday, and with this loud bike I thought I would be kind to the neighbors. I have a little hesitation about 1/4 throttle, and plan to move the needle clip down a notch to see if it clears up. Still need to do a plug chop, but plan on it after break-in. Then we can really dial this engine in. Clutch is very easy pull, brakes are pretty good, engine pulls great and runs smooth, and suspension is about right on target with my 225lbs self. Playing with the clickers today, about 5 or so clicks out from full soft on compression on the forks and mid way on shock. Will be working on some kind of spark arrestor/Db killer this week when I take apart the muffler. Also, another missing part I found was the bracket to screw the number plate to. Other than that, it's gonna be a great bike. I'll let y'all know what's up next soon.

Kirk

Attachment 17174

If someone would start importing this type/style of China
bike here I would be temped to get another..

just don't want to brake the frame and twist the swing arm
like my last one.... the motor held togeather...
I did get 7 months out of it...

I keep looking but no one here imports China bikes anymore...
no one will buy them... they f#@&% the market for themselves
by bringing in cheap crap to make a quick dollar...


..

Searching around for some type of Db killer, I found on Cozzoo (never heard of) and AliExpress, an insert that is the same shape as our muffler ends (kind of vagina shaped if you ask me). They are just perforated tube, no spark arrestor screen, but worth a try at $11 or so.
Also you could insert a 51mm perforated tube baffle on the intake side of muffler for even cheaper. They have those types with and without the catalytic substrate in them. The catalysis could act as a spark arrestor, but it chokes the exhaust by a considerable amount. For a spark arrestor on the other you could wrap some fine mesh SS screen around the outside of the baffle and secure it by welding or small pipe clamp. Anyone else find or know of a low dollar fix?

Kirk

Wanted to show a pic of the catalysis which is in some of the baffles I was talking about earlier...


Attachment 17186

This is just a pic showing what some of the baffle tubes have inside them, not the baffle I plan to purchase. That doesn't look too restrictive to me. If it is, I can simply start by drilling holes until I get what is needed. What's your thoughts?

Kirk

Well here's the Db reducer insert I just purchased off Amazon...

Attachment 17188

This one inserts at the intake side of the muffler and is 51mm OD x 120mm. As soon as it comes in I'll let y'all know the results.

Kirk

ps. forgot, it was @ $17 delivered.

Took the muffler apart yesterday, very good muffler packing I must say. The end cap consists of two parts welded together, the shiny end cover and actual end piece. It only has a couple of small spot welds holding it together. The end cap has a small length of pipe that inserts into the 38mm perforated tube. I will say, they missed on a few drilled holes for the rivets when installing the end cap...3 of the six holes are drilled right at the edge with little to hold to.

Attachment 17204

Attachment 17205

The intake side of the muffler is 51mm, but for only about 2" then funnels down to the 38mm perforated tube. Saying this because my Db killer might be too long to insert. I may have to cut off the part of the Db killer to make it work. Was looking for a way to install spark arrestor screen of some type, also. I have a couple of ideas, one involves brazing some funnel shaped SS mesh screen to the Db killer after it is cut to length. The other is buy the quiet core insert for the LEXX muffler that RockymountainATVMC offers and incorporate it into the end cap. I've done the latter on a pit bike muffler before and it worked well.

Kirk
ps. for some reason this camera will not take close ups.

Here's a couple of pics with the cap removed. That was fun getting off, because the shiny cap is pressed formed to fit over the end cap. Had to make a splice in the shiny cap at the bottom edge with a dremel, then tapped it off with hammer and blunt chisel.
Attachment 17209
Attachment 17210
Getting better at the close ups, too.

If I go with the quiet core insert from RMATVMC, I will cut the end cap flush, form the insert edges to match and drill a few attachment holes. Here's a pic of the insert...
Attachment 17211

I might have wasted my $17 on the other Db killer, because I like this option better and it has a spark arrestor, too.

Kirk

Got some time today and installed the quiet core insert. Went rather easy if I must say. End cap material is pretty soft, I for sure thought I would be having to cut stainless, but the band saw went right through.

Attachment 17259

Here it is all put together, minus the high temp gasket sealer.

Attachment 17260

I traced the end cap shape to the quiet core, trimmed the edges with tin snips and finished off with the bench grinder. Drilled three retaining holes for screws and attached the quiet core to end cap. Here's a pic of the finished product...

Attachment 17261

Tried to do a sound clip, but it's not working with this camera. Believe me there is a big difference with this quiet core and its 25mm tip. I will have to do some jetting, lean out what I have now. Gonna start with the needle and place the clip second from the top. Right now idle is great, but when you blip the throttle it is not clean like it was with the open exhaust. That's it for now, I'll let you know how the jetting goes. Have a good one.

Kirk

Did a little rejetting today, first started with a smaller main, 0.049" that I found in my jetting toolbox (from the original main I drilled to 0.052"). Rode it and something felt missing, plus it was popping on decal. Came back readjusted air screw from 2 to 1 5/8 turns out, rode it, no decal popping and almost there...unscrewed top of carb, pulled needle and set it to 4th notch from top instead of the middle and I think I found my sweet spot. Engine sounds good, pulls great getting into the throttle, and I am a happy camper. Today was a little cooler for Texas, @ 80 degrees instead of the upper 90's like it usually is. I'm going to leave this setting alone for a while, well until I do my first plug chop. Then we'll see how close I am once I read that plug.

The bike sound great with the quiet core, almost stealth-like. Sounds just like a stock XR250 I had once, that's the way I like it, too. A few more things I would like to do is add a headlight/tail light and hand guards. Got some cheapo bark buster guards on order already, and the lights won't be too far behind. I'll keep y'all updated as usual...

Kirk
ps. I know the quiet core tip looks a little out of place, but I never look back there when riding anyway.