Two questions piston and gearing?

[Xcfjohn]

So I thought its best to do one post for both questons I have the first is on my 2012 KTM XCF 250. Inthe owners manual it says I need to replace the piston and check valves after 50 hours. I'm about that maybe over do I need a new piston now? Do you guys do everything to the manual? Second question should I change my gearing for maclean creek im still on 13/50 my bike bogs in second. Mainly because I'm not a fast rider so im normally always in first. Like today I rode swanys ridge I only got into second a few times on some of the climbs and straights.

[cedric]

I'd say check the valve clearances, they are likely fine. If the bike is burning oil or blowing oil into the air boot you may need rings.

[boland]

Gearing is personal preference. You could try a 52 on the rear so you can get into 2nd more but there is nothing wrong with riding in first gear, you will use more gears as you progress. I rarely got out of first gear when I started riding single track(still don't some days ).

[Xcfjohn]

Gearing is personal preference. You could try a 52 on the rear so you can get into 2nd more but there is nothing wrong with riding in first gear, you will use more gears as you progress. I rarely got out of first gear when I started riding single track(still don't some days ).

Thanks boland how have you been I can't believe how far I have come since my first ride with you. I rode swanys ridge by myself last week and rode it again today with a friend. Did the single track back down had a good day today.

[AJRJ]

Those recommendations from the manual relate to assumed use. Bikes like the 250 ( and all MX bikes really) are expected to spend a huge portion of their time bouncing of the rev limiter. Off road, most people rarely ever take it that high. A lot of the web chatter would have people going twice the recommended interval, but obviously you have to be somewhat careful. Keep that air filter clean, and I'd wait to 100 hrs. I'm going to do mine this winter, mainly because I'll have the time. I'm at about 80 hrs.

[thirtyseven]

What AJRJ said, and gearing is a funny thing. Odds are on the 250 XCf if you are "bogging" in second, you have 6000 unused rpms left in first.

when you experience this, go back and do the section again but when you feel it's time to click up a gear, instead just twist that thing on the right and let the rpms climb.
The 250f has a modest amount of torque and at your stage of the riding game you can get trapped into just riding it at that band of comfort rpms.

You can't get much better than stock gearing in modern XCs, and to improve it you need to be a great rider with empirical evidence (lap times), and the result will be very specific to that terrain (lap).

Prior to any gearing changes make 100% sure you are using all of first prior to going up to second. It will take a conscious effort, sadly we are all limited by what's going on between the ears. This is most notable in engineers, followed by Nova Scotians.

[trailguy]

The XCF 250 is way over geared, I went 13/52 and this seems perfect. I can run 2nd in the tight stuff and 3rd in more flowing singletrack and 6th gear still has tons of top end speed. I really only get into 6th on roads ( other than the Warp factor 10 cutlines they had in the Marble Mountain XC ) I ride alot of Moto and 13/52 is great there as well. I've ridden a friends XCF 250 with 12/50 and it was way to low - shifting constantly like a 125 2T. ( 1 tooth drop on the front is approx. 3 1/2 teeth on the back ).
If you've been diligent with your air filter maintenance and are changing the oil before it gets really dark you should get 100+ hours out of the top end. I would check the valves at this point.

[cerealkiller]

I've run 13-50, 12-50 and 13-52 on my 350F. Although it's a bigger bike, I would echo trailguy's comments.

I'm not fast enough to run 13-50 in our terrain without a lot of clutch-work. 12-50 was nice when things were really nasty. I could crawl along in first gear without worrying about the clutch. Too often however, I found myself stuck between revving-out second or lugging in 3rd.

I'm presently running 13-52 and I'm quite happy with it. While you could hold first longer to close the gap to 2nd, I generally like to keep the rpms as low as possible. My theory is that it helps the suspension work better. That may not work as well on a 250f.

Keep in mind that keeping the rpms "low" is a subjective measure. If you're bogging in second, that certainly sounds like you're shifting too soon.

[cedric]

I'm using 13-51 on my older 250 XCF. I think it's a good compromise, but I think I could get along with 13-52 too. As you know, these bikes like to sing, and chugging is not their strong point, lower gearing is your friend.

Everything I've read about the RC4 engine is that the valve train and bottom end are really tough (think hundreds of hours trail riding) and the main weakness is the rings need frequent replacement. I haven't logged enough time on mine to say yet, but I did check the valves once and everything was in spec.

[WRocks]

All good comments above...

I run 13-52 gearing on my 350 XCF and really like it. For the tight trails we have here in Ghost and Mclean, is a good fit to get more out of 1st and 2nd gear.

As for top end service. I'd agree the 50 hours to replace piston/rings is for severe service.
There will be lots of differing opinions on this one, but I plan on running much longer before doing that service.
Agreed, check the valves and be mindful of oil consumption.

[350scott]

A suggestion on playing with gearing. Don't get too caught up in the rear sprocket, try different fronts. The fronts are cheap compared to the rears and you can almost always use the same chain with a 12, 13 and 14 front. Changing the rear sprocket by 2 teeth is about a 4% change. If you can really feel a 4% (i.e. 5000rpm vs 5200rpm) change in engine speed, well you should be a test rider 'cause you've got real good feel. Contrast this to a 1 tooth change in the front which is about a 7-8% change in engine speed.

[RJHenry]

A suggestion on playing with gearing. Don't get too caught up in the rear sprocket, try different fronts. The fronts are cheap compared to the rears and you can almost always use the same chain with a 12, 13 and 14 front. Changing the rear sprocket by 2 teeth is about a 4% change. If you can really feel a 4% (i.e. 5000rpm vs 5200rpm) change in engine speed, well you should be a test rider 'cause you've got real good feel. Contrast this to a 1 tooth change in the front which is about a 7-8% change in engine speed.

Scott is right, though you can sometime get away with flipping the axle blocks to try a larger rear - particularly if you are able to borrow one before you commit to $200 in sprockets and longer chain.

If you would like to try a 52, I have a stock aluminum that you are welcome to borrow and try for one ride.