Posts
30
Joined
1/2/2018
Location
CA
I recently acquired a 22 MC250 two stroke, still bone stock. I'm a mild mannered vet rider and have owned several 250 two strokes in my day but have mainly been riding woods bikes and 125s for the past few years.
This MC250 is a rocket and I'd like to calm it down so I don't feel like a squid while riding it. I still want a good hit but this thing has a hyperdrive on it right now.
I'm looking for feedback on what others have tried and their experiences before I dive in.
To avoid throwing money at the problem, I'll start by trying the less aggressive exhaust valve spring and I'll also try the second less aggressive map as well. Any experiences with those?
If I don't find a sweet spot there, I'll research flywheel weights and gearing changes.
Any feedback, solutions experiences are welcomed.
Thanks!
This MC250 is a rocket and I'd like to calm it down so I don't feel like a squid while riding it. I still want a good hit but this thing has a hyperdrive on it right now.
I'm looking for feedback on what others have tried and their experiences before I dive in.
To avoid throwing money at the problem, I'll start by trying the less aggressive exhaust valve spring and I'll also try the second less aggressive map as well. Any experiences with those?
If I don't find a sweet spot there, I'll research flywheel weights and gearing changes.
Any feedback, solutions experiences are welcomed.
Thanks!
Back out the the adjuster 1/2 turn at a time
Should smooth things out
You could also adjust riding style and ride a gear higher
Bike has a ton of torque if you roll on the throttle
Not really wanting to alter the jetting yet either as it runs nice and crisp throughout the RPM range too at the moment.
Opyguy. I'll be trying the green spring first for sure.
You're on to something though about the riding style, I'm probably trying to ride this thing like a 125 right now, my last two seasons have been on 125s or 150s. I forgot how to lug it around, I'll work on that too.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
I pm'd you about jetting, did you get my message ?
I swapped for the green PV springs but after few rides I might go back to the yellow and really spend more time to fine tune
I unplugged the connector under the tank for the more "mellow" ignition setting. Hard to feel significant difference.
I added a flywheel weight, that helped
Gearing like Sandman recommends
Jetting is where you can have the most impact. I used the specs from AJ's on the tech forum, combined with the JD gasket kit upgrade (this will not tame the beast but prevent chasing jetting when/if the gasket fails)
I had a 19 TC 250 and swapping the silencer for the PC 304 (long one, not the shorty), free'd up the rev and actually made it a bit more manageable, smoother.
It's a great bike. I love mine, minus the weird ktm 50's petcock.
I don’t have feedback on the other springs as I’ve adjusted only using the stock spring. I run it 1 3/4 turns in from all the way out with the jetting from the other thread. My bike is really rideable at all speeds depending on what you want your right hand to do. It can lug or it can be violent depending on what you want.
the 17 had a 50 tooth, i went down to 49, it was perfect....I never used 2nd gear, always 3rd.
don't know if you are woods or MX, but literally @ southwick I never used 2nd.
maybe in the woods w/my buddies I would roll 2nd in tight turns, but in general terms 2nd is tooo short and hits too hard.
thx
14/48 gearing
Mellow ignition map
Clutch weigh, 11,75 Oz. Just wanted to try this as it's much cheaper than Steahly fww
Green PV, two turns in from flush
Novice level rider coming from crf250, riding sand mx and some trails
Here’s what I do-
XC or XCW head to reduce compression, reducing the compression tames the power, produces traction and less rider fatigue. The W head has the least compression of the 3. I run the W head on my race bike and xc on the practice.
Green PV spring.
I run 14/48 everywhere, almost went 47 for a recent dez race. Always run heavy twin ring sprockets, aluminum are too light.
Keihin carbs. They run much smoother then the mikuni. Run a yz needle when traction is good and a rm needle at mudders, the yz needle has much more mid range punch. I have a 36 and 38, still testing to see which one I like better, probably will end up having dicks racing oval bore the 36.
Flywheel weight, I like the 11oz, a more aggressive rider would probably want the 9oz.
O-ring chain- additional flywheel effect from the heavier chain.
18” cause off road guy stuff but it does also add a flywheel effect and aid traction.
Xcw cdi - not really worth the money but I got it cheap($40) used, if you see one cheap grab it.
Oh ya basically ignore any xc or xcw riders input on set up, their motors cranks are about 1lbs heavier because of the estart and are totally different animals.
I normally don’t even bother talking about this stuff because it’s normally over most guys head or they think they need more power to go faster(rarely the case)
You can loosen the screws which hold the magneto on, rotate it slightly (counterclockwise, I think...) and get results. No more than about 6 degrees, I'd say.
Dont know if there is any effect to clutch wearing etc (has to grab heavier mass when engaged?)
Somehow I did stall it two times quite easily after adding clutch weigh, which did not happen before.. shouldnt it be the other way?
A flywheel weight is direct on the crank/engine so that would make the engine less likely to stall.
A clutch weight is bolted to the center of the clutch - the hub and the center shaft, all that is 'after' the separation of the clutch plates. So, when the clutch is pulled in, the outer basket is spinning but the center and weight are stationary. When you let the lever out, you are basically applying a heavier load to the engine, making it more likely to stall... just like anything else heavier after the clutch - sealed chain, bigger tire, heavy mud/sand.
Once the lever is fully out and the clutch is fully engaged and you're moving, it should now be less likely to stall and more tractable since the engine, clutch, transmission, entire driveline are 'solid' at that point.
I had a flywheel weight on a previous 250SX of mine and didn't like it at all afterwards so I'll stay away from that for now.
I'm going to start with the 48 tooth sprocket and green spring for now and go from there.
I'll report back after my first ride this weekend.
Pit Row
Still has a hit but a lot more predictable.
I will adjust it to be a bit more snappy as I get more comfy on it.
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