Time for yz300

[Robbyg91]

So I sucked in some sand & dirt..took my cylinder off to do some rings and check everything out. Found a cracked piston - needed a new cylinder - had grit in my crankcase.

Decided to have the crank rebuilt and send the top off to for an EG300 kit

[LAYZ71]

EG295 with mobetta porting is a great option, really happy with mine.

[Robbyg91]

What type of riding do you do? Does the mobetta take away from the 2 stroke power/feel

[shagger]

I don't think it really matters what type of riding you do. If you like more power everywhere, you'll like it. They even seem to rev higher.

 

The EG295 makes a YZ a stronger YZ. The 325 kit turns it into something else. 

[StillSmoking]

The Mo Betta with the timing and jetting right pretty much feels like youre on the pipe from right off idle all the way up. It's linear but its a linear surge. It somehow still feels YZ though not like a KTM.

[LAYZ71]

I mainly ride moto, with some trail riding. Really keeps the same feel just stronger throughout the power curve.

[numroe]

Does the mobetta take away from the 2 stroke power/feel

 

That is such a wrong question.

 

What is "the 2 stroke feel"?

 

Is it that feeling when 4 stroke riders just keep gapping you the longer the moto goes for, while your lap times go up up up?

 

Is it that feeling when the motor falls off the pipe and forces you to abuse your clutch or down shift?

 

Is it that feeling when you come out of a turn and just when you want to lay down some serious power and setup for an obstacle, you need to up shift a gear?

 

If you want a weak blubbery pull down low, then a sudden hit in the middle, and a quick taper off up top. Then forget about the mo-betta porting with correct squish, compression and jetting. You'll hate it.

 

For me, I just love my well tuned EG295 2 stroke. The sound. The instant predictable response. The crisp pull at any engine speed or throttle opening. The ease of starting. The impossibility to stall it (Rekluse). The small 1 thou of piston wear after 45 run hours. The same agility of the YZ250.  It's effectively a cheater bike, in my opinion.

 

Sorry for being so cynical. But as you can tell, I get annoyed when people think a poorly tuned 2 stroke is the way they should be.  4 strokes have proven what is fast ... broad power and less shifting. Peak power matters little.  Two strokes with the same or even less displacement can do it all. Plus they feel so light and are so easy to work on.

 

Lastly, note that a mo-betta EG295 will not perform very well if the squish is too wide, or the comp is wrong for your fuel, or the jetting or timing are wrong.  It's still a 2 stroke, which is sensitive to tuning.  Squish should be 1.2 to 1.5mm depending on fuel quality. Wider than 1.65mm and you are into the zone of fussy jetting and hesitation.  Comp should not be above 12:1 (25cc head vol) on pump gas. Go higher on comp for higher octane fuel. But get the squish in that narrow range and only then can the motor reach it's potential. Same principle applies to the stock YZ250 motor, and KTMs, etc, etc.

Edited December 9, 2014 by numroe

[Robbyg91]

Sent her off today. Should be back in a few weeks. I rode a buddy's 295 with the mobetta porting and I liked it...I went with the mid to top porting and I think I'll love it. With the extra power I'm sure I'll be able to ride it in the lower rpms without hesitation.

Can't wait to get it back

[Josh142]

just got to test my 295 kit out this week. I still cant stop smiling best thing i have ever bought for my 250, just raw power man! surprisingly jetting was pretty smooth for me unlike some problems ive been hearing from other people.

[Robbyg91]

What do you guys suggest a good base starting point for jetting, I usually ride below 1500ft.

When I took my bike apart the piston and plug looked like the jetting was good, I run 32:1 w/ motul 800 and my air screw 1.5 turns out

pilot and power is a 50 and main is 178

Needle is 3rd from the top

[LAYZ71]

I ride mostly at sea level in louisiana's humid climate running 32:1 pump gas mobetta porting.

Running 45 pilot, 172 main, 2nd position from top, air screw 1.5 turns out.

I've brought this bike with the exact jetting to NC, GA, TX, IL, MO and MS with no issues.

[numroe]

I have a mo-betta 295 with 1.3mm squish and 23.5cc head vol (head mods by Dave at TSP). Used with Aus 98 fuel (US 93 or 94) with 32:1 oil premix. At sea level. In temps between 15 and 40C (60 to 100F). Moderate humidity. Boyesen carbon Power Reeds. 

 

Pilot=42, AS=1.3 out. Slide = #8. Needle = J. Clip = 3. Main = 170. pwr jet = #50.

 

Pipe currently a Gnarly. Muffler either Q-Stealth or Stock. Doesn't seem to need a jetting change for the muffler swap.

 

When my squish was 1.60mm, it needed a richer 45 pilot, W needle and 172 main. To get broader power and better roll on response, it was also essential to have the needle clip on 3 (vs 2). At that time I was swapping pipes between the Fatty, The PC Platinum 2 or the Gnarly, and jetting seemed ok unchanged.   Also at this time my head vol was about 19cc, so high comp, and a very aggressive hit from idle.

 

Initially the squish was 1.85mm (double layer head gasket) and the motor was terrible, with a lot of hesitation or else rich burble.

 

Hope that gives you some clues to work with.

Edited December 16, 2014 by numroe

[adam8781]

anything over 1mm is excessive. my stock rm250 was 1.2mm. hell pc sends out pump gas motors at 1 mm.

 

 

I want to ride a 295, i have a feeling once i pick up a yz250 it a 295 wont be far behind.

[Robbyg91]

Well I got it back just before the holidays and I've got 4 hours on it since. I'm totally happy with it! I'm close on my jetting maybe a little rich but I'd rather be rich then lean..

It absolutely rips.

[BRM]

Just as a side note; Athena are suggesting 2.0-2.1mm of squish on their 300 kit.

[numroe]

Just as a side note; Athena are suggesting 2.0-2.1mm of squish on their 300 kit.

Crazy. They must be assuming a really worn out motor and/or maybe their head design has something horribly wrong with it.

[primerib108]

Mid-top porting is the way to go. Might as well get the biggest bang for your buck. I'm happy with with my mo-betta but wish I went the other route now that I am used to it. 

[dbart250]

Did you send your crank to eg too? Im going to need mine done and figured i could send everything in at once. Not sure if people have as good of luck with his crank rebuilds.

[Robbyg91]

I had the crank rebuilt by a guy kinds near where I live. It was 130 for parts and 70 for labor...I haven't heard anything about eg crank rebuilds

[dbart250]

Me either. I just saw he offered it the last time i was on his site