2018 RR300 rings

[Gibnut]

Anecdotally, I’ve heard a lot of Beta 2-t owners have left their top ends for up to 120 hours between changes. I read yesterday of a bloke in Europe with 300 hours on a top end and 600 hours on the motor, a ‘13 RR300.

After checking with a very well-regarded motorcycle mechanic mate I ride with (P.C. Gas Gas) & having never left a top end for more than 55 hours, I thought I’d open the bike up and have a look. It was recommended I check the piston spec & ring gap. It was said fresh rings at least would enhance the service life of the bore and maintain performance.

As some Beta 2-t owners have had oi malfunctions & some just don’t trust the system, I was most curious to see how the oil injection had left my piston, rings, barrel & crank after 60 hours.

After removing the head* & barrel, I was pleasantly surprised. The barrel is in top shape, clean as a whistle. The power valve had minor carbon build up that came away easily. The head had a tiny amount of soft carbon on it, too - it wiped off with a rag.
I then measured the piston (‘B’ size) on the mike & using the manual’s instructions; 71.95mm - in the middle of the manual service measurements. Then the ring gap - 0.4mm; at the end of the recommended service life. The rod has zero up & down play and the crank is lubed nicely. I use Motul 710, 98RON fuel.

Other stats - squish; was 2.04mm, base gasket was a 0.6mm.
The new base gasket is a 0.3mm, giving me a squish of 1.74mm. I should get a smidge more bottom end (all I use, really).

Outcome - I just replaced the rings this time. They are $75AUD per pair & a Beta top end kit is $294AUD. I will do a piston & rings at 120 hours. Torqued it all up, coolant in, head stay on, seat & tank on, fired up first stab. Love that feeling

I’ve had 2 xRR300’s now & I find the Beta’s easy to work on, really well put together & reliable. Just what a 2-t is supposed to be! I am also REALLY happy to report my oi appears to be functioning as per design so far.

* Due to Euro 4 restrictions, the head has 1 x 6mm security hex bolt. As the frame clearance wasn’t enough to get my impact driver onto the bit, I got creative by inserting the 6.3mm drive end of the security hex bit into a 1/4 inch socket ($5), and then onto the torque wrench.

[aj_mariner]

71.95mm is the OEM Vertex sized A piston. I have seen a 71.94mm called the “A” but don’t remember where.

Edit: Found that the Pro-X site lists the A as 71.94mm

[Leon_RR250]

What? What? What am I really reading here? This is non-sense! This cannot be implied by "simple logic" rules! Beta engines with OI should seize! Must seize! It is so stupid how the factory implemented the OI solution! Come on! You must have been hiding something.....

P.S. I am fully with you on that! I acknowledge that some bikes, especially 2017 models, had the problem due to corroded capacitors but personally I had no problem on a 2016 300 for 110 hrs until I changed the bike during a very very wet season with also lots of cold driving on snow (-5 to -15 C), around half of the 110 hrs with only the usual snow/ice protection for the carb. Have we been the only lucky ones??

[Gibnut]

Ha ha! Leon, we must the fortunate ones..

Rode the bike a few days ago & the change to a 50t rear cog from a 48t (for my terrain 14/48 was crazy-tall) and dropping the squish has pepped the bike up very nicely - builds power a little quicker through the mid-range and has more bottom end punch for sure.

I tried to factor in the factory dropping the primary drive slightly for ‘18 when keeping the 14t on the front - the bike is now geared pretty close to my ‘14 RR300; which was spot on for me.

Merry Christmas from the glorious Southern Highlands near Sydney, Australia. Sunny & 24c. Riding tomorrow with my mates in one of my favourite spots - Meryla State Forest, 600m from where I am typing. Happy holidays!

[Hurky]

* Due to Euro 4 restrictions, the head has 1 x 6mm security hex bolt. As the frame clearance wasn’t enough to get my impact driver onto the bit, I got creative by inserting the 6.3mm drive end of the security hex bit into a 1/4 inch socket ($5), and then onto the torque wrench.

That's interesting, I wondered why the Betas do have a few security bolts on the engine, there's the one on the head and some little ones on the right side power valve cover and another one on the intake flange. What's the reason for this ? To avoid the hobby mechanic touch the engine ? I will change mine out once I need to dig into those parts..

Cheers !

[Hubert Carpet]

EU Nanny State regulations. They don't want people to touch their own property. I had noticed the security screws on my new 2020 200RR. They will go in the bin when I need to remove them.

[Clearvu1]

The MY 2016 bikes (can't say for certain on later bikes) used 2 - .3 base gaskets sandwiched together to get .6 total. If you happen to have the old gasket you could try to peel it apart to verify.