Madrid Motorcycle Alpha 301 Kit

[borus]

So how much material must come out of the case?

I would take a good 250 top if you find a trade!

the 290 cylinder wall thickness is 3.5 mm and the 301 cylinder wall is 2.5mm, so i removed 1mm, a very small amount, it didn't take that long once i got the nerve up to do it. it's jsut the ledges that the cylinder butts up against.

(i couldn't control the 290 caby with stock timing, it simply had expolsive power in that setup).

so, i decided to put the timing back to stock by advancing it 2.5mm. well, the 301 has more power and grunt but still controllable. i've put about 5 hours it now, i;m starting to feel it beginning to run in and the timing will be staying stock. most of what i've read over on the gg forum about comparing 300's to 280's and 250's is true. large power and grunt with loads of traction but controllable. i'm finding my practice obstacles and sections easier to ride, i think i'm finding alot of confidence in the bike.

cheers

[copemech]

the 290 cylinder wall thickness is 3.5 mm and the 301 cylinder wall is 2.5mm, so i removed 1mm, a very small amount, it didn't take that long once i got the nerve up to do it. it's jsut the ledges that the cylinder butts up against.

(i couldn't control the 290 caby with stock timing, it simply had expolsive power in that setup).

so, i decided to put the timing back to stock by advancing it 2.5mm. well, the 301 has more power and grunt but still controllable. i've put about 5 hours it now, i;m starting to feel it beginning to run in and the timing will be staying stock. most of what i've read over on the gg forum about comparing 300's to 280's and 250's is true. large power and grunt with loads of traction but controllable. i'm finding my practice obstacles and sections easier to ride, i think i'm finding alot of confidence in the bike.

cheers

I think you lost me there on the thickness thing!

So you did require a mill setup to bore the cases?

[borus]

I think you lost me there on the thickness thing!

So you did require a mill setup to bore the cases?

i used a dremel to grind 1mm away to leave a thickness of 2.5mm. it's the inside ledge that is reduced to allow the piston to lower into the case, not the outside casing. to limit the grindings from falling to the case i drained the oil and flipped the bike upside down by partially hanging it from the swingarm by the garage joist. a very small amount of grindings actually made there way into the case but they're smaller than the normal metal swarf you would see on a new bike run in.

cheers

[borus]

Cheers Borus, just done the maths! Every year they print the same old figures don't they.

So to downsize from a 290 to a 250 is it simply a barrel, head and piston change then.

update, from my dealer and ryan young - the 290 cylinder and piston will fit on the 250, a 290 head will be required, the 250 head won't fit.

cheers

[copemech]

update, from my dealer and ryan young - the 290 cylinder and piston will fit on the 250, a 290 head will be required, the 250 head won't fit.

cheers

That seems correct, as the 2.5 head is a different part number. I still like the 2.5 much, although one was not available when I got the current 2.9, I can well live with a 2.9 with a proper dellorto and the Boyesens.

We did some comparisons a few weeks ago with a '08 Beta 270 and mine is much gentler off the bottom. Greater mid hit it seems. A Beta will chug lower it seems, they seem to have a bit more flywheel.

I have ridden the 300Gassers, the "torque pig"! It works too. Sounds like a fun bike to ride.

You do realize which side of the "I cannot do what they do on 125's" POWER CURVE you are on now, don't you?

[nigel dabster]

i used a dremel to grind 1mm away to leave a thickness of 2.5mm. it's the inside ledge that is reduced to allow the piston to lower into the case, not the outside casing. to limit the grindings from falling to the case i drained the oil and flipped the bike upside down by partially hanging it from the swingarm by the garage joist. a very small amount of grindings actually made there way into the case but they're smaller than the normal metal swarf you would see on a new bike run in.

cheers

Drained the oil?