I recently rebuilt the engine on my 98 XR250 where I installed new piston rings and had the cylinder honed. I used a mineral oil for the engine break-in and have run the bike for about 3 ten minute rides. My questions are: 1) How soon should I change the oil? 2) Is it ok to use a synthetic oil now, or should I use mineral oil again for a while? Thanks.

Change it now and check the oil for particles like gasket pieces, gasket cement, glistening aluminum, etc.  Also change the filter.
That will give the engine a clean system for the rest of the break in period.

I don't know when to change to syn oil; some engines come with syn oil when new, some say wait until after breakin.
I switched to syn oil at 20 hours, probably could have done it sooner but I wasn't sure what syn oil to use. These air cooled engine can run very hot so high temp stability is important, IMO 30wt dyno oils don't have the high temp stability of 40 and 50 wt oils.   This why 40 and 50wt oils are used in air cooled engines . Harley rear cylinders can run very hot in traffic which is why they run 50wt oil. Most syn oils are only 30wt but checking spec sheets I found Mobil 1 0W-40 has very good high temp rating so I've been using that.

If it was me, I don't believe I'd switch to syn just yet, with only 30 minutes on the engine. Doesn't have to be mineral oil, just a regular non-syn conventional oil. Put 100 miles on it, then switch.

Fresh dino oil to start
1. Warm bike up to normal operating temp then shut down and let it cool naturally back to ambient.
2. Warm bike, take it for a 10 minute ride, don't go more than 1/2 throttle and don't stay at one throttle position.  Let cool to ambient.
3. Warm bike, take for a 10 minute ride, vary the throttle up to 3/4 open, with occassional blips WOT (not in top gear).  Let cool to ambient.
4. Change oil to fresh dino oil
5. 1 tank of gas, 20 minute rides, never stay at the same throttle, try to do many brief WOT runs with cooldown between.  WOT ok in any gear.
6. Change oil again to fresh dino oil
7. Ride normally
8. Switch to synthetic only after 1000 miles

That's how I've always done it and my top ends last forever.

Edited by wallrat, 20 May 2012 - 07:42 AM.

wallrat, on 19 May 2012 - 06:40 PM, said:

That's close to what I did on my last rebuild but no WOT until the second tank.  
I did oil changes at #4 and at each five hours until switching to Mobil 1 0W-40 at 20 hours. I then abused the well used clutch and had to replace the plates so I also changed the oil  again. I don't have enough time on the engine to determine if 20 hours was OK to switch to syn, but it sure runs good and the clutch is smoother than with the dyno oil.
I was riding normally at 10 hours but with very limited time at WOT.

I have a Vapor on the bike and it was interesting observing the decline in peak head temps during breakin. This Powroll build does seem to run hotter than the stocker did but it does produce a lot more power.

Does it need to be Motorcycle oil or can you use any 10w-40w oil?

bonesxr, on 20 May 2012 - 02:32 AM, said:

Automotive oil is okay but it needs to be changed more often.  If you're OCD about oil changes like me and do them too frequently regardless of what's in there then its no big deal.  Also you can't run any auto oil with 'friction modifiers'.  I finally had to switch to MX oil after running auto for the last decade or so simply because the only auto oil I can find locally that doesn't have those friction modifiers costs just as much as MX oil.

In regards to WOT on a new engine:  In order to properly wear in the rings you need to run the engine to its maximum potential without allowing it to overheat.  That's why you allow for adequate cooling time between WOT runs.  Babying it and avoiding WOT is actually detrimental since it can lead to glazing and you won't get as good of a break in.  It seems counter-intuitive to run a new engine hard but that's exactly what you need to do for the rings to wear in properly.  By the second tank glazing has already occured and you missed your opportunity.  There's still beneficially increased wear post break in which is why you want to continue to run dino oil for a good 1000 miles or so.  Syn is too slick and prevents this wear in so switching too soon will lessen the life of the engine.

I edited my other post.  Forgot to mention that you shouldn't do WOT in top gear until after the 1st oil change.

Myths about synthetic motor oils
http://www.mobiloil....tics/myths.aspx
  

ramz, on 20 May 2012 - 08:18 AM, said:

But our low tech, old tech, air cooled engines of the XR don't conform to "current engine manufacturing technology".

Trailryder42, on 20 May 2012 - 02:02 PM, said:

Exactly.  On a new vehicle I switch to synthetic on the 1st oil change @ 1000 miles.  Could do it the day you buy it but kind of a waste of money since you should still change the oil at 1k to remove any shavings worn off from the new engine.  Believe it or not this:




Does not equal this:

Edited by wallrat, 20 May 2012 - 06:57 PM.

So glad I read this as I'm about to do the rings on the xr400 and hadn't really thought much about a break in period and also wasn't going to rehone the cylinder even though it looks a little glazed.

Are you replacing the filter at each of these oil changes?

And, apologies if this is a stupid question, but in step 5, do the 20min runs need to be immediate after the cool down or can they be done on different days?

Cheers.

Brian1980, on 19 May 2012 - 03:18 PM, said:

You don't need to run dino oil at all, although it makes for a cheap first change.  The break-in period benefit is found with the cam and crank, not the piston or cylinder.  Temp cycling is also unnecessary since that is really for seating crank bearings.  For just a top end, I do a single temp cycle (warm up at idle then cool completely), then a 10 minute easy run with varying throttle and cool completely, then I warm it up again, and take it for a blast around the block, snapping the throttle between full-on and full-off the entire way.  That seats the rings and at that point, it is ready to be beat on.  Then it's ready to take for a short ride in the trails, and I make every effort to beat the hell out of it as much as possible, then change the oil.  It should get changed after no more than a few hours of total run time simply because there is extra blow-by with a new engine until the rings seat, which doesn't take very long.

I don't use synthetic oil - I change it too frequently derive any benefit.

JayC

Michaeb, on 21 May 2012 - 01:02 AM, said:

- Its very important to do a hone anytime you change the rings.  The rings won't wear in correctly if you don't.
- Yes oil and filter need to be changed.
- Different days is fine.  It took a good 3+ hours for my garaged bike to return to ambient so really its not possible to go through a tank in one day when you're limited to 20 min runs followed by hours worth of cooling.

The heat cycling is to limit run time so the components are not damaged from overheating, same for WOT operation. And IMO the big issue is the rings/piston.  Lot's of variations in piston/ring/cylinder materials and fit so there is no one way to break in engines. The problem is ring/piston fit to the cylinder; I've rebuilt Diesels using factory matched liners/pistons and put the engines on a dyno for a twenty minute run to record max power, but I would never do that to an engine using rebuild components and machining from several sources.

Brian, hope you dont mind me jumping in on your thread

Chuck, I've just fitted a new as in new Honda cylinder/piston/rings/clutch/crank bearings/cam chain; I'm a tad confused with all the recommendations all over the net regarding run in methods etc. Came across one where the chap says to ride it like you stole it kind of thing http://www.mototuneu..._in_secrets.htm

I'm not saying this is what I'm going to do but could I ask you chuck what you'd recommend for my 85 XR250? Cheers.