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POST 50K KM full engine check

55K views 197 replies 37 participants last post by  Dalap 
#1 · (Edited)
POST 31K miles (50K KM) full engine check

ok after my engine did 50k KM on motul 7100, the crank needle bearing decided to die.
so guy have a taste of the full CBR 250 engine dissembly including full checks and expected engine components life spawn.

for now i posting the pictures and will post full measurements and calculations i a while

have a look on the inside feel free to ask anything
https://plus.google.com/photos/102273974749410979141/albums/5864527495782303249?authkey=CPjH2KrBobDhIg


here you can see the old piston and the new piston compared, you can clearly see that the molybdenum coating of the old piston is worn.
and the piston skirt coating is worn
 
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#41 ·
Man i checked ur pics, carbon deposits galore on your piston top, imo not using top tier fuel did this to your motor because it would have suffered knock (detonation), top tier has cleaners in it to prevent this, also top tier is generally higher octane to prevent knock.
Knock happens very easily if you use low octane in hot weather and lug the motor.
If you're part of the world has less than great quality fuel availability you should be obsessed about running fuel system cleaners regularly to prevent carbon deposits.
Good luck with the new build.
 
#42 ·
Wow,
Didn't think of that.
What Fuel do you have by you in Israel?

Under the subject of being a really warm Climate. Does the CBR have a Radiator FAN?
If so then isn't there a way to bypass the Temp Switch and leave it on Permanently?
To help it Cool on the Slow Stop and Go Traffic? Rather than letting it Heat up and then the Fan switches on trying to Slow down the Rapid increase in head.
I know this bikes Thermal half opens at 85C and is full open at 95C.
Over Heating could of Caused the Soft/Light Piston to deform slightly causing the Blow by.

Let us know when the bike is up and running!
 
#43 ·
Guys let's start with the fact that the bike if fuel injected so it can't knock.
When near knock situation acure the ecu late the ignition.
The late the ignition the less power the engine has, so crappy fuel can only lower the performance.

The second thing in israel we have tropical thermostat it opens on 78 and 87 full open

The last thing, in israel we have 95 octane or 98 . Both crappy so we all using cleaners

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#45 ·
can you describe where the knock sensor is located on the bike. I don't think mine is working and I'd like to get it tested or maybe just replace it if they don't cost too much. Where can I buy one at a reasonable price? I want a good OEM one and not a crappy one that might break right away.
 
#47 · (Edited)
Moto mike I didn't disassemble the top end so no need fro ne gaskets.

The second bike is my Father bike so i can't use it.

Look I rebuilded some engines without do any honing at all and all of them settled the rings properly.

And yes there is different thermostats for different region, there is 2 or 3 types

Deanoh I wilk get home and post where it is for you

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#50 ·
And, how did the OP determine that the valves were OK? Compression prior to opening the engine?

I'm still impressed with what he is doing.
 
#58 ·
The initial post states 50000 KM (about 30000 miles).

The bike is in Israel and I suspect that the owner was doing the maintenance.
 
#59 ·
I think I found the reason for the failure.
I am heavy guy 110 kg, and I was with passenger and gear anouther 65 kg
Was near weight limit, the chain slack was 45 mm.
I was riding very long down hill with massive engine braking.
I think this way I overloaded the bearing and it failed.
I did Service every 6000km for the first 24000 and then did every 12000 as stated by Honda.
I did the service myself
 
#62 ·
i have a 2011 cbr bought in November 2011 i now have 18 thousand miles..90% freeway riding at 80 mph to around 8.5 k rpm . i'll let you guys know when my engine gives out. so far its running strong. plus always been on honda full synthetic oil. Synthetic oil has a lower coefficient of friction than mineral oil, so i dont understand why you guys are saying mineral is better....
 
#63 ·
Regularly changed minerals has given me a far cleaner engine in 4 stroke offroad racebikes, no snake oil for me anymore,
my mechanic proved it to me and I was reluctant to stop using synthetic.
$ saved and better engines.
 
#72 ·
Honda singled out the OP's bike during production, to install one of their special "engineered to fail, but not before 50,000 km" crankshaft needle bearings... yeah, that's the ticket. :rolleyes:

Anyone who believes the OP's crankshaft needle bearing cage story, that it was "defective" from day one... I've got some beautiful land in Florida you should really take a look at... ;)
 
#74 ·
Honda singled out the OP's bike during production, to install one of their special "engineered to fail, but not before 50,000 km" crankshaft needle bearings... yeah, that's the ticket. :rolleyes:

Anyone who believes the OP's crankshaft needle bearing cage story, that it was "defective" from day one... I've got some beautiful land in Florida you should really take a look at... ;)
F'KN lol!

Ive said it before and I'll say it again, you sir have a way with words..
and an ear and eye for the details that matter :cool:
 
#77 ·
I don't disagree with you completely Dan. What is silly... no, complete and utter bull sh!t, is that the OP expects us to believe his story that the so called "defective" needle bearing cage was the source of his engine failure. Look at his photos again... that hardly looks like a well cared for bike. I can only imagine what his air filter must have looked like (notice there were no photos of his air filter). Some of these guys in the middle east think this bike is some kind of Dual Sport machine. And every issue they have, large or small, is Honda's fault. Dan, you are new to these forums... if you dig through some of the older threads in the Problems & Issues forum, you will see what I mean. Some of the guys posting from India are... how shall I put it... just a little over the top. They are all fooking experts on motorcycles, even though the CBR is their first real bike over 50 cc.

Some of us might have been born at night, but it wasn't last night.
 
#78 ·
We can argue about oil, what this engine can tolerate in terms of sustained RPM's, and on and on... If we go back to the beginning of this thread, and look at what the OP started this thread with... to me it looks like just another case of an abused third world bike, operated by someone who doesn't know jack sh!t about motorcycles. I mean come on... he's rebuilding his engine now, with a new piston and ring set, but he can't be bothered to run a flex hone through the cylinder, or just spend another $45 for a new cylinder. But hey, he's the expert here... :rolleyes:
 
#79 ·
Motomike,Sir I will take apicture of the air filter, I chnaged it every 12000km.

I just didn't bothered to take a picture of new filter.

But what curious is your theory of abused bike, how you diceded it? How you dicided that the bike was used as dual sport?
Where you can see poor maintaned engine?
I know how I maintained and how and where I rode the bike, if you think I did something wrong I glad to learn.

Now about the cylinder there is 0.02 wear on the rings working surface, why I should do any honing? The honing grinds more than this, much more than this.

If you saying to Change cylinder why not also replace the carankshaft journals?

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#80 ·
...Now about the cylinder there is 0.02 wear on the rings working surface, why I should do any honing? The honing grinds more than this, much more than this...
Look, this is the last time I will go over this... a Flex Hone, (unlike the way an adjustable rigid hone can increase the size of a cylinder bore, such as the type made by Ammco - http://www.dansmc.com/Hone_cyl1.JPG), doesn't remove enough material when used properly, to change the size of the cylinder. The purpose of a Flex Hone is to give the cylinder a new cross hatch surface, so that the new rings can seat properly. I believe I explained this fairly clearly in a previous post. That you seem to be unable to grasp this concept of what the intended purpose of a Flex hone is, tells me either you actually know little about the procedures involved in properly rebuilding an engine, or that you are just being stubborn for the sake of argument. So, I will say it again... if you install new rings without using a Flex Hone to prepare the bore of the cylinder, those new rings will not seat properly. Period. It's as simple as that... but hey, don't take my word for it, ask some of the other experienced guys here, like BBRMotosports who also has been professionally rebuilding motorcycle and snowmobile engines for many years. Or don't...
 
#83 ·
Motomike, new cylinder comes polished to without cross surface to the rings and every thing seats properly. I rebuilded some engines without honing and every thing seat properly.
If you don't believe it will seat I will post compression measures after the run in of the rings
 
#88 ·
Moto mike.
Btw thank for the link,I will take a look

Nope, just went to the dealer to take a look on new one, just to be on the safer side.
New cilinder goes polished, no any honing at all.
So I not replacing the cylinder I will measure compression after 1000-2000km for you'r good feeling for setteled rings.
Mybe I will even do lab oil test to proove no abnormal gas leaks happening.
 
#94 · (Edited)
These cylinders are not of the "Chrome Bore" type, so they are not "polished" as you say they are.

Do you know what a proper honing cross hatch pattern looks like?
Examples of honed cylinders:

http://www.dansmc.com/Hone_cyl_crosshatch.JPG

http://www.badweatherbikers.com/buell/messages/3842/447956.gif

http://www.atpengines.com/Cylinder_Honing/Sleeve_Honed.jpg

Did you take a look at BBRMotosports rebuild thread?... This one: http://www.cbr250.net/forum/cbr250-performance/9990-my-build-start-finish.html

He has photos of his CBR cylinder after it was honed in preparation for new rings.
 
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