winter is coming , time to rebuild the engine !?

Hi ,

what is the time table to do the engine top end rebuild and piston change on 2013-2016 Honda CRF450R !? 

if i trust previous owner word , then i have near 60h on my piston . and i dont see any blue smoke when i cold start or running !?  and no extra noises .

but i am wondering if my engine fall suddenly without any warning !? should i do it to be sure for next year !? or just wait !?

 

"If it ain't broke don't fix it."

A lot depends on how you ride. If you are ringing that thing out for everything it's got, you are going to have to rebuild more often than someone just using the power only when needed.

"If you don't take it easy on that thing you're going to dump the gut all over the road!"

Both quotes are form my DAD.

i man run on woods and MX track , but i am not an abuser, and do not over rev.  most of the time i am in Low to mid RPM  and am not using all the bike potential in mid-high RPM . 70% of the time i am in woods and 30% MX

Personally, I have found that even if riding relatively hard, which is a very subjective term, at 60 hours your piston will likely be perfectly fine. However, I'm all about preventative maintenance. Given the fact that you're also going by the previous owners word....I would change the piston and cam chain. Here's a picture of the cylinder off a motor I rebuilt for an acquaintance. Well over 100 hours on the bike. Standard carbon ring from running a a bit rich and obvious wear pattern from the piston skirt. Everything cleaned up with a ball hone run through it for less than 30 seconds. Dial bore gauge indicated the cylinder was still essentially at OEM specs.

Engine Cylinder.JPG

Edited by mxr73
Personally, I have found that even if riding relatively hard, which is a very subjective term, at 60 hours your piston will likely be perfectly fine. However, I'm all about preventative maintenance. Given the fact that you're also going by the previous owners word....I would change the piston and cam chain. Here's a picture of the cylinder off a motor I rebuilt for an acquaintance. Well over 100 hours on the bike. Standard carbon ring from running a a bit rich and obvious wear pattern from the piston skirt. Everything cleaned up with a ball hone run through it for less than 30 seconds. Dial bore gauge indicated the cylinder was still essentially at OEM specs.
5a0448ceae089_EngineCylinder.JPG.67f321f627fe1047f47dd7314eccfea0.JPG

Tanx. Is it better to change the valve and sealing the same time !?
And should go for OEM piston or high compression piston !?

OEM.  Check the valve clearances and shim if needed.  You could replace the valves, but I don't think you need to re-cut the seats at 60hrs.  Take it to a mechanic in you're unsure   My old '13 I replaced the cam chain,  piston, valves, and had the seats cut at 100hrs.  Everything still looked good, but at I wanted to be sure.

I guess you didn't buy the '17?

6 hours ago, mxr73 said:

Personally, I have found that even if riding relatively hard, which is a very subjective term, at 60 hours your piston will likely be perfectly fine. However, I'm all about preventative maintenance. Given the fact that you're also going by the previous owners word....I would change the piston and cam chain. Here's a picture of the cylinder off a motor I rebuilt for an acquaintance. Well over 100 hours on the bike. Standard carbon ring from running a a bit rich and obvious wear pattern from the piston skirt. Everything cleaned up with a ball hone run through it for less than 30 seconds. Dial bore gauge indicated the cylinder was still essentially at OEM specs.

Engine Cylinder.JPG

Race Tech Engine Services strongly recommends avoiding using a ball hone on a cylinder.  Instead, a precision hone with proper stones to provide a diamond finish should be used.

While a ball hone will get any imperfection out to the eye, physically all of the blemishes are still there. A ball hone is flexible and inconsistent. You can ball hone a cylinder and then lightly hone the same cylinder on a precision hone and all the blemishes will show up again until you continue the honing process.It takes a rigid hone that is sharp and precise to truly make sure that all imperfections are gone for a perfect ring seal. A ball hone will not straighten the bore. The ideal goal using a ball hone on a 2 stroke cylinder is to deburr the transfer ports. The same honing process applies on four stroke cylinders, but after you must chamfer all the ports to make sure they are deburred.

OEM.  Check the valve clearances and shim if needed.  You could replace the valves, but I don't think you need to re-cut the seats at 60hrs.  Take it to a mechanic in you're unsure   My old '13 I replaced the cam chain,  piston, valves, and had the seats cut at 100hrs.  Everything still looked good, but at I wanted to be sure.
I guess you didn't buy the '17?

No i still didnt buy it . Looking to get a loan from.a bank and buy it. But anyway i will keep 2013 for a second bike and wood training. That 17 which i look at is so good that i dont wanna destroy it 🤣.
OEM.  Check the valve clearances and shim if needed.  You could replace the valves, but I don't think you need to re-cut the seats at 60hrs.  Take it to a mechanic in you're unsure   My old '13 I replaced the cam chain,  piston, valves, and had the seats cut at 100hrs.  Everything still looked good, but at I wanted to be sure.
I guess you didn't buy the '17?

The totall hour on the bike is 110 and i dont think last owner change the valve and the seats . The honda complete top end rebuild kit is cheaper than other brands :D .

Check the valves and if in spec, don't mess with it. Piston/rings last much longer on 4T engines, and valves wear out much faster

Check the valves and if in spec, don't mess with it. Piston/rings last much longer on 4T engines, and valves wear out much faster

It seems they are on spec .

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