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Discussion Starter · #1 ·
Hey y’all I got an 06 trx450er that I need some advice on. It’s my dads old four wheeler I bought from him it never cranked up from the starter we use to always have to bump start it. A while back I took it on a ride and it ran like a top didn’t give me any issues but then while I let it idle it died. It wouldn’t bump start anymore and i let a buddy take a look and he suspected that the pistons went out. I also took it to a shop and they said it needed a top end. But I figured they did a compression test which is not possible from what I’ve heard because of the decompression spring. I was just wandering if I needed to look into the decompression spring? If so what do I look for? I’m getting a leak down tester to tell the tale on the cylinder and rings but I was wandering if there’s something y’all have up your sleeve to check. I’ve been looking but I can’t find nothing on my situation. Thank you for your time
 

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You need to quit listening to some people and just because it's on the internet it's not a fact and your 'buddy' is as ignorant about motors as you are. Pistons do not 'went out' and the engine only has one piston - rings on the other hand wear out, but it's gradual and does not usually cause a sudden problem.

Now from what you have disclosed in the short synopsis presented here, my first question is why did you just let it idle and how long did it idle? When the engine idles, things heat up (even if it's liquid cooled some parts may over heat when left idling).

Here's what the service manual has to say about compression:
4813


Now compression is normally checked with the engine cold and the throttle wide open - normal compression is usually higher than indicated on a cold engine and with the ER, you have to check the compression using the electric starter.

Since you were bump starting it previously and let it sit and idle, I suspect the valves have tightened up to the point they are dropping compression to a point low enough it will not start and/or there is a problem with the cam, valves or rings (piston possibly) all due to the idling session.

Now not starting with the starter, but starting by bump starting it is the first indication that the valves are tight and you just exaggerated the problem by ignoring the symptom and instead of having it serviced, just worked around the problem to where you are today.

I suggest you take it to a competent mechanic (yeah, they are kinda scarce because everything is maintenance free nowadays), but adjusting the valves is regular routine maintenance and the camshaft has to be removed to do it - it's part of what makes a performance engine perform.

Don't leave this thread hanging - let us know what is determined and how you make out solving the issue.
 

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Discussion Starter · #3 ·
You need to quit listening to some people and just because it's on the internet it's not a fact and your 'buddy' is as ignorant about motors as you are. Pistons do not 'went out' and the engine only has one piston - rings on the other hand wear out, but it's gradual and does not usually cause a sudden problem.

Now from what you have disclosed in the short synopsis presented here, my first question is why did you just let it idle and how long did it idle? When the engine idles, things heat up (even if it's liquid cooled some parts may over heat when left idling).

Here's what the service manual has to say about compression:
View attachment 4813

Now compression is normally checked with the engine cold and the throttle wide open - normal compression is usually higher than indicated on a cold engine and with the ER, you have to check the compression using the electric starter.

Since you were bump starting it previously and let it sit and idle, I suspect the valves have tightened up to the point they are dropping compression to a point low enough it will not start and/or there is a problem with the cam, valves or rings (piston possibly) all due to the idling session.

Now not starting with the starter, but starting by bump starting it is the first indication that the valves are tight and you just exaggerated the problem by ignoring the symptom and instead of having it serviced, just worked around the problem to where you are today.

I suggest you take it to a competent mechanic (yeah, they are kinda scarce because everything is maintenance free nowadays), but adjusting the valves is regular routine maintenance and the camshaft has to be removed to do it - it's part of what makes a performance engine perform.

Don't leave this thread hanging - let us know what is determined and how you make out solving the issue.
Got it I’ll try to run it through a mechanic soon. I don’t just go off anything I just try to take note of anything that makes sense. I’m young so I don’t know much so this is all a learning process. Hopefully it’ll just be valves and nothing serious like the piston and or the cylinder. I let it idle for probably 5-10 minutes while talking to a friend on another four wheeler. I would’ve cut it off but I didn’t want to have to go through the trouble of bump starting it again. Another thing to add was my dad when he use to bump start it he had to mess with the carb I think he had to play with the choke when it first cranked up. Don’t know if that plays a role in anything since Honda motors are just cold blooded. Another question though, and this is just something I’ve heard you can approve or deny it true but I had a man tell me that if the piston rings did go out and lost compression, if I were to put new rings and rehoned the cylinder and it had better compression that it’d wear out that bottom end. Do you think that’s true or was he just trying to pee on my foot and tell me it’s raining?
 

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He was referring to a plain bearing motor and the TXR (as well as most motorcycle and ATV engine even the Chinese ones) have roller bearing rods and crankshafts. Now for the real truth...................

I've been a mechanic for about 50 years and I race a Honda CRF250 - your TRX is based on the CRF motor, but the CRF requires rebuilding every 30 hours - my 04 CRF got a new piston and rings twice a year and the lower end has never been touched. Original crank, clutch and water pump - also original cam, but the valves had to be replaced. So he was right for a high mileage plain bearing motor.

And another thing, the cylinder is plated and should not be honed even when installing new piston and rings.

If you have any questions, I'll be glad to answer them.
 

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Discussion Starter · #5 ·
I’m glad to hear that about the bottom end cause I’m sure that alone is a nightmare. Now for something I just realized but completely forgot about. I dumped the oil out a while back just to see what it looked like and this is what I found. Any suggestions?
4816
 

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Photos are not very revealing and what I see is either oil emulsified with water, oil mixed with aluminum (the aluminum can come from many different parts including the clutch, piston, oil pump and cam chain well) oil mixed with very fine steel particles that comes from the cam chain, transmission, clutch, cam and lifters, clutch and oil pump. It may be indicative of a non JASO rated oil being used, infrequent oil changes, condensation, high pressure washes or alcohol contamination from use of ethanol blended fuel. It would require oil analysis by a laboratory to determine the contaminants in the oil causing the appearance you observed.
 
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