Just finished the breakin on my 2009 klx 250s its my first 4 stroke. I was hoping for some oppinions on running it at high rpms for long runs on highway. Will it damage motor to run at 7000 rpm for long runs of hour or two. I have rejeted carb and slip on fmf q4 and removed slorkle. Should i be woried about causing any damage.

 

Hey mate

I've been wondering something similar. I haven't even finished running my engine in yet - only done 300km's odd. With how much the engine has loosened up already I would be surprised if there is any wearing in significant enough to cause damage left.

From chatting with the dealer, the running in is more to allow the bearing and everything to loosen up as opposed to the "old days" where the rings were extremely tight in the bore due to poor engineering tolerances. With modern technology and the accuracy they bring, I reckon you'll be alright.

I have started to ride the bike a little more aggressively already, and would be happy riding it at highway speeds. But that's just be with a pretty uninformed opinion. *shrug*

 

Got 1100 miles on bike now and just woried about causing damage to motor on long highway rides its an hour and a half to 2 hours to the nerest decent offroad riding. All my previous riding has been strictly offroad and on 2 strokes this is my first 4 stroke and not sure bout long runs at high rpms with my 2 strokes i blew up more than 1 motor running long high rpm runs on fire roads

 

4 strokes aren't prone to seizing like 2 smokes are. That said, it's still a good idea to give the engine a rest every hour if you are running constantly high RPM like that.

 

With the redline set at 10500 I don't think holding it at 7k is pushing it too hard. 7k also happens to be the torque peak, it's quite common to gear a bike to 'cruise at or near it's torque peak for best roll on performance.

Know what you mean the 7k does seem spinning pretty fast. Maybe the best thing to do it cover the tach so you cant see it, and just ride on? the old motto "if it can't take it, it deserves to die", LOL.

 

I'm currently in the "Engine Breakin" period at this time as well. The owners manual states that you should keep the engine at 4000 rpm or below for the first 500 miles. I don't even think that is possible and sounds rediculous to me.

I've been keeping the rpm's at or below 6000 rpm's. What does/has everyone else done for the first 500 - 1000 miles?

 

Engine Break in, What's that? I ran mine slow for the first 50 miles. After that I didn't look.

 

Its possible, I done it with both my KLX's, means you cant go over 40mph-ish for 500 miles & then its 60mph-ish until the 1000 mark..

Also, UK bikes cant do over 72mph, meaning that you cant get the Rpm above 7400ish anyway due to the limiter in the fuel injection, so Id say its ok for the bikes to sit at those rpm's as Ive done it.

Ed.

 

I pretty much used the Mototune break-in method after recently installing my 300 cylinder and piston. Modern engines just don't have the bearing, friction, and clearance issues like old-time stuff had. The break-in of the piston and rings is the critical part today. The Mototune method clearly explains how/why this is done on a more modern engine, and I think it's the right approach. I think the factory recommended rpm max is kind of silly.

 

I tried to respect the 6000 rpm limit during break in except when cruising at high speed in top gear when you need to be around 7000 just to stay safe. The 4000 rpm limit was a joke in the manual.

Figure, the fast idle with the choke set is at 4000 rpm so what's wrong with doubling the warm up idle? The high rpm high speed stuff isn't really loading the engine, the high rpms mean that the loading is very spread out. Everything should like the high rpm except the valve train and the P&C. Cooling and lube flow are excellent at high rpm.

Now 2 hours at 65 on this bike has got to be rough on you. The bike isn't smooth like a cruiser so 2 hours of slab, off-road for a few more hours, Don't forget to fuel up, and the 2 more hours of high speed to get home? You'll be worn out.