Anybody tried the Athena 125 RR-S Big Bore kit yet?

[Old Plonker]

This Kit has been available for a while, but now Beta carries it (for $699, gasp!). Just wondering if anybody has done this yet, and how it changes the character of the engine.

Also noticed this on Flea-Bay: http://www.ebay.com/itm/NEW-CERAMIC-BIG-BORE-CYLINDER-KIT-180cc-UPGRADE-FOR-BETA-RR-MOTARD-125-LC-4T-/152443617669?hash=item237e590185:g:QzYAAOSw-jhUDY7e&vxp=mtr

I wonder if this is an option? At $112 it looks a lot more palatable.

Edited February 23, 2017 by Old Plonker

[ccullins]

About to put the big bore kit on with a  Scalvini pipe. Let you know in about a week. 

 

[Old Plonker]

2 hours ago, ccullins said:

About to put the big bore kit on with a  Scalvini pipe. Let you know in about a week. 

Thanks, Chris. Looking forward to your feedback. Since you guys seem to all be racers, I can't help but wonder who the 125 is for? And how did it work out in stock form?

Edited February 23, 2017 by Old Plonker

[ccullins]

I'm no racer anymore, I'm a trials rider now.  As well as a trials dealer (not my full time job unfortunately) I do however hop on Ty's race bikes and anything else I can to keep the feel for stuff. 

We would love to have our own 125, they are super fun! But the125 actually belongs to one of my buddy's. He really likes it, just wants to improve it a little more.

I need to get some other bikes setup and another shipped out before I can get to the little RR late next week. 

[vwprostock]

On 2/23/2017 at 4:27 PM, Old Plonker said:

Thanks, Chris. Looking forward to your feedback. Since you guys seem to all be racers, I can't help but wonder who the 125 is for? And how did it work out in stock form?

I looked...and looked...and really wanted the 125 to be the walk up from the CRF150F/KLX140 type bike, reliable motor in a turd chassis with turd brakes and turd suspension. The 125 fit that on paper...water cooled...4 valve...disc and disc, etc.

It missed the mark as its too tall. My local dealer has said thats everyones gripe. For anyone on a 150F or similar, its just too tall.

Thats my opinion of what it should have fit for the demographic...but thats just my opinion...

[Old Plonker]

12 hours ago, vwprostock said:

...reliable motor in a turd chassis with turd brakes and turd suspension.

That sort of describes one of my favorite play bikes of all time, the XR200R. Only, in 1981, everything (except pure race bikes) had turd chassis, turd (drum) brakes and turd suspension.

I was hoping that the 125RR-S would be an updated version of the XR200R. Wheelbase is a little longer, seat height about the same. It's about 10 lbs. heavier and makes about the same power, but at higher revs (the XR would chug down to near idle almost like a 2t). I can only guess from watching YouTube videos, but the suspension looks to be somewhat better than the XR, and adequate for the pace that the engine can generate.

Being an octogenarian, I ride a mellow pace, but still enjoy challenging terrain. I just can't afford to come off at speed and break something. I looked long and hard at the XT, but the capabilities of that bike were sure to tempt me into attempting exploits that would have put me into the hospital. My CRF150RB keeps me honest because, even though it's pretty fast, it's so cramped the I can't really ride standing up, and riding sitting on my ass isn't all that much fun.

So maybe you can see why the 125RR-S poked to 180cc is on my radar. 

[Rubicon79]

Hey did you get that pipe and big bore kit done?  Could you post any jetting changes if they were needed?

 

We're gonna pull the trigger on a Beta 125 for my wife.  She's a beginner but is riding an old clonker xr100 just about to its limits now. 

I feel like the crf150f just isn't enough of an improvement but I'd rather the Beta be an inch shorter.  I'm hoping the Beta will have enough power stock but it's hard to imagine any 125 4t having enough for real offroad work.  

[Old Plonker]

On 2/23/2017 at 0:30 PM, ccullins said:

About to put the big bore kit on with a  Scalvini pipe. Let you know in about a week. 

Hey Chris, did you ever get this done? Love to hear some feedback.

 

Edited April 19, 2017 by Old Plonker

[ohiodrz400sm]

I have read on other sites that the WR125 shares the same basic engine and big bore kits marketed for it can be found for much cheaper. Can anyone confirm that?

[ccullins]

1 hour ago, Old Plonker said:

Hey Chris, did you ever get this done? Love to hear some feedback.

 

Did I say a week? I meant a couple months ?

With my kid getting new bikes, national trials etc. I just hadn't had time to get to it until this week. Fortunately the bike belongs to a good friend so he understood what I had going on. 

So far I've got it all apart. I've worked on plenty of 125's the years, but seeing this tiny 4t piston in the big motor makes me wonder how it had as power as it did! Just looking things over a expect a huge difference. My main concern now is how much of a jetting change to make. 

 

[ccullins]

Also removed a bunch of other junk?

[dstewart]

48 minutes ago, ccullins said:

Also removed a bunch of other junk?

Pretty sure the only reason that stuff is on there is to meet a minimum weight requirement.  Toss it.

[Old Plonker]

1 hour ago, ccullins said:

Did I say a week? I meant a couple months ?

With my kid getting new bikes, national trials etc. I just hadn't had time to get to it until this week. Fortunately the bike belongs to a good friend so he understood what I had going on. 

So far I've got it all apart. I've worked on plenty of 125's the years, but seeing this tiny 4t piston in the big motor makes me wonder how it had as power as it did! Just looking things over a expect a huge difference. My main concern now is how much of a jetting change to make. 

That piston looks significantly heavier. I wonder how much the engine will vibrate because of that. And the piston dome is very interesting. It looks like it is designed to give the squished mixture at the edge of the bore someplace to go, while keeping the compression ratio low enough to run with crap gas.

[ccullins]

1 hour ago, Old Plonker said:

That piston looks significantly heavier. I wonder how much the engine will vibrate because of that. And the piston dome is very interesting. It looks like it is designed to give the squished mixture at the edge of the bore someplace to go, while keeping the compression ratio low enough to run with crap gas.

I really don't think vibration is going to be an issue. Looking down into the motor after pulling the cylinder off, the crank is pretty large as is the rest of the motor. Thing looks built large enough to be a 250! 

We'll see...

[ohiodrz400sm]

I really don't think vibration is going to be an issue. Looking down into the motor after pulling the cylinder off, the crank is pretty large as is the rest of the motor. Thing looks built large enough to be a 250! 
We'll see...

Is there enough clearance to fit a larger carburetor, such as Keihin 32mm FCR-MX?

[Old Plonker]

16 hours ago, ohiodrz400sm said:

I have read on other sites that the WR125 shares the same basic engine and big bore kits marketed for it can be found for much cheaper. Can anyone confirm that?

The engine is built by Minarelli which is owned by Yamaha. The YZF-R125 is injected, the others are not. Here's a video (in German) of an Athena kit, the same as Chris's, being installed in a YZF-R125. You can see that the piston and cylinder are exactly the same as in Chris's pictures above.

Here are a couple of kits from SXParts (I don't know anything about them) but what I notice about them is that, with a flat-topped piston, they appear to have a higher compression ratio than the Athena. Good for a road bike, but I'm not so sure for a rock crawler. I'd want to hear someone's testimony before I sprung for one of these kits.

http://sxparts.com/shop/yzf-r125-r15-fz15-bbk/yamaha-yzf-r125-wr125-r15-big-bore-kit-183cc/

http://sxparts.com/shop/yzf-r125-r15-fz15-bbk/yamaha-yzf-r125-wr125-r15-big-bore-kit-200cc/

[ccullins]

12 hours ago, ohiodrz400sm said:

Is there enough clearance to fit a larger carburetor, such as Keihin 32mm FCR-MX?

I can't say. I don't know how big those carbs are. The stock one isn't small. 

Im not sure I would want to swap carbs. The bike runs pretty sweet stock and I wouldn't want to change those characteristics. We just want to add to it a little.  

[DLUSK]

I installed the 180cc kit sold on EBay (about $120,) about a month ago. It changed the bike so much. More low end pulls from idle, now can loft the front wheel very easily. I experimented with the stock exhaust with and with without baffle.  It is so nice and quite with the baffle yet still runs very good. This motor just revs out so well. I did not feel more power at high rpm, but much more at lower rpms. The Piston weighs 40 grams more than stock.  Still very low vibration. 

[Old Plonker]

17 hours ago, DLUSK said:

I installed the 180cc kit sold on EBay (about $120,) about a month ago. It changed the bike so much. More low end pulls from idle, now can loft the front wheel very easily. I experimented with the stock exhaust with and with without baffle.  It is so nice and quite with the baffle yet still runs very good. This motor just revs out so well. I did not feel more power at high rpm, but much more at lower rpms. The Piston weighs 40 grams more than stock.  Still very low vibration. 

Thanks for the feedback DLUSK. 

On 4/20/2017 at 6:14 PM, ccullins said:

The bike runs pretty sweet stock and I wouldn't want to change those characteristics. We just want to add to it a little. 

It sounds like your experience is just what Chris describes. It's good to know that there is an acceptable and more affordable alternative to the Athena kit. What was your experience with jetting? What grade of fuel do you run now? Any downsides to the upgrade?

[DLUSK]

I seam to have made a lucky guess  on jetting. It has been  runnig very well with 155 main and about 2mm washer under needle. I ran 91 octane for a few tanks, then tried 87, found no difference. I have not found a down side yet to increase in bore. Looking at the thickness of the cylinder walls and the fact that as a 125 it is very under square and as a 180 it is a little over square; I think it was designed as something aroud 200cc .