4-Stroke Engine Life Expectency.

Strouble

Strouble

PR Addict
I have an '08 Honda 450 with about 10 hours on a full motor rebuild. It has a JE High Comp. piston, Kibble White Valve set-up and a Stage 2 Hot-Cam. Uses hi-test pump gas.

What can you expect from a motor in non-racing conditions for your average decent rider presuming proper maintainance is kept up?

How often should you check valve clearance?
 
You don't need check valves until the bike is hard starting. I use to check them regularly and never caught one just under spec. when the bike is hard to start that is when I would look at the valves. The biggest way to take out the intake valves is to suck a little dirt from a bad filter. On Hondas its almost always the throttle side intake valve that goes out for some reason.
I just rebuilt an 07 crf450 for a kid, who never checked/changed the oil. He rode the bike mostly on the roads wide open for over a year. When I drained the oil about 100cc of tar came out of it. The head, valves, piston, cylinder all looked good. the valves were still in spec. The only thing I found was the connecting rod bearings were seizing. the bottom end bearing was the worst. I'm sure the bike would have fired up if I would have tried. I would say regular oil changes and air filter changes would be all you need to worry about.
 
If your valves go out of spec, Don't try and shim them back to spec. Replace the intake valves, seals, and springs as a set. The longer you try to get out of the valves by shimming them the more wear you are putting on you head. You could eventually drop a valve also. Just my 2 cents.
 
I bought my bike new.. (2010 crf450). It recently started taking more than 2 kicks to start @ 62 hours. I change the oil & filter every 3-5 or so hours.
 
This info is very helpful. Thank you! I have heard all kinds of things. Some folks told me to do a rebuild at 40 hrs...I am thinking that can't be right for guys like us. When I got the bike home, it fired up first kick. It blows a little smoke initially when cold...I think it is just excess unburnt gas. It has a full FMF power-bomb titanium exhaust system and a K&N air filter. Thinking the jetting might need tweaked or just leave it alone. What do you think about the smoke?
 
MXCrusader617 said:
Some folks told me to do a rebuild at 40 hrs...I am thinking that can't be right for guys like us. It blows a little smoke initially when cold...I think it is just excess unburnt gas. What do you think about the smoke?
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Not sure with the high compression piston, but I have rebuilt mine with a full season of hare scrambles, and some moto and the top end still looks like brand new. I think the smoke when started is because it not up to temp. yet.
 
Bill480 said:
I bought my bike new.. (2010 crf450). It recently started taking more than 2 kicks to start @ 62 hours. I change the oil & filter every 3-5 or so hours.
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I would check the idle first. the fuel injection bikes are sensitive to the right idle speed. don't forget the idle adjuster is backwards from carburetor.
 
C Hudak said:
I would check the idle first. the fuel injection bikes are sensitive to the right idle speed. don't forget the idle adjuster is backwards from carburetor.
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Idle RPM hasn't changed as per tach.. I have been putting it off forever but I plan on checking the valves (for the first time lol) this weekend and shimming if necessary.
 
I had just under 300 hours on my 09 YZ 450 and one valve was less than one shim size off.
My RMZ has 97 hours on it. I havent checked the valves but it still starts and runs perfect.
Treat them right and you wont have to worry at our level of riding.
 
hershey said:
I had just under 300 hours on my 09 YZ 450 and one valve was less than one shim size off.
My RMZ has 97 hours on it. I havent checked the valves but it still starts and runs perfect.
Treat them right and you wont have to worry at our level of riding.
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Wow! Yami's are known for being tough. Sounds like all I need to think about and do is...ride!!! Thank you for the help!
 
Finally got around to checking the valves on my bike.. 64.8 hours in and my valves were all spot on the manuals spec. One intake valve was .007 and the spec was .006 +- .001 so that one is still within spec. The rest were dead nutz.

So not really sure why my bike doesnt take 1-2 kicks to start anymore (it's more like 4-5) :dunno:
 
Bill480 said:
Finally got around to checking the valves on my bike.. 64.8 hours in and my valves were all spot on the manuals spec. One intake valve was .007 and the spec was .006 +- .001 so that one is still within spec. The rest were dead nutz.

So not really sure why my bike doesnt take 1-2 kicks to start anymore (it's more like 4-5) :dunno:
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Bill480, even though your tac. is still showing the same RPM I would try turning out the choke knob to raise the idle. If that doesn't work, Did you recently change your air filter oil? I learned the hard way 4strokes don't like heavy filter oil. I was using the old Bell Ray blue filter oil and the bike was very hard starting. I started using the PJ1 spray on oil and cleaner and the bike started 10 times better. Just make sure your filter isn't to heavy with oil.
 
C Hudak said:
Bill480, even though your tac. is still showing the same RPM I would try turning out the choke knob to raise the idle. If that doesn't work, Did you recently change your air filter oil? I learned the hard way 4strokes don't like heavy filter oil. I was using the old Bell Ray blue filter oil and the bike was very hard starting. I started using the PJ1 spray on oil and cleaner and the bike started 10 times better. Just make sure your filter isn't to heavy with oil.
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Turning it out raises the idle? I turned it in a click or two last night and that seemed to bring the idle up. Not sure if it made any difference in starting.

I've been running no-toil pre-oiled filters since the beginning.. haven't noticed a difference and when I oil them myself I don't go very heavy either.

Maybe fuel filter or fuel related? I hope not
 
Bill, I just went out and double checked the manual so I wasn't telling you the wrong thing. Its counterclockwise to raise idle speed. Also don't pull out the knob when adjusting the idle. Has the bike just been harder starting since its cold out?
 
C Hudak said:
Bill, I just went out and double checked the manual so I wasn't telling you the wrong thing. Its counterclockwise to raise idle speed. Also don't pull out the knob when adjusting the idle. Has the bike just been harder starting since its cold out?
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Ok thanks. I'll re-adjust next time I mess with it. Knob might have been out when I was turning it last time... woops.

And no it was acting the same way for the second half of last summer as well. Feels maybe a little down on power? Hard to tell.
 
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