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klx450r who has high miles

By kingdomdad,
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ben williams

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But when they are zeroed out they don't bang against the valve seat. The valve is held open. Once adjusted in spec they should seal fine unless they go too long without proper adjustment.?

They zero out because of the "ditch" beat into the seats. Think about why they zero out, if the cam wore, there would be more clearance.

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klx450junkie

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They zero out because of the "ditch" beat into the seats. Think about why they zero out, if the cam wore, there would be more clearance.

Nobody said the cam is wearing. I'm simply saying you should not have to do a valve job just because they have zeroed out. If that that be the case the manufactures would not make shims for them to be adjusted.?

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klx450junkie

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Same problem with the CRF450X...the valves get beat to death and look beat to death when they are zero'd. I'll post pics of my old 450X later tonight. I had to swap them out for SS because of this. This is common with Ti valves, especially Honda's, but I knew it'd be a problem with this bike too.

With the RPM and addition of titanium valves it's no wonder they get beat, but as long as the valve is sealing it's doing it's job. The biggest problem I for see is valve steam stretching to point of failure. If the valves are left to long zeroed out it will burn the valves and valve seats. At that point it would be necessary to do a valve job. I will check mine again at the end of the desert season to see how much stretch I'm getting. Thank god they didn't use titanium on the exhaust side.?

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klx450junkie

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I have been doing valve jobs in the marine and auto industry for 15 years, have never seen a stem stretch.

In your high revving high performance motors it is not uncommon for the valve to stretch. At the base of the valve were the stem is attached is were it stretches. The titanium valves are the worse.The reason it stretches is the valve is slamming shut at the high RPMs. So hence the term stretching the stem.?

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jefeinlb

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3750 Miles on my '08. I've done oil changes about every 200 miles and I clean the air filter every trip. Adjusted the valves at 200 miles and they didn't need adjustment for another 3500 miles. The motor is stock except for an AIS kit, a JD jet kit, and a stock '08 KX450 exhaust. The bike has been super reliable with mostly desert miles on it and some D37 Enduros.

Started getting hard to start last trip (when cold) so I checked the valves this weekend and found the right intake zeroed out. Left intake at about

.001" below minimum spec.

Local shop says, based on their experience, if it's zeroed out it's probably done and I should do a valve job. They said I can adjust the valves, but it won't last long. And while I'm there I might as well do the piston.

Looking for others experience (and opinions)

Quick update - I went ahead and did the top end and found the intake valves in pretty bad shape, especially the right one, pretty deep grooves. The piston and bore looked really good, but I decided to put in a new piston while I was there. It's was a fair bit of work to get it torn down that far and not that much more for a new piston, rings, and pin. Runs and starts great again.

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GreenHornet450

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Quick update - I went ahead and did the top end and found the intake valves in pretty bad shape, especially the right one, pretty deep grooves. The piston and bore looked really good, but I decided to put in a new piston while I was there. It's was a fair bit of work to get it torn down that far and not that much more for a new piston, rings, and pin. Runs and starts great again.

What was the cost of the total rebuild?

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Apprentice

white line

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i have 4700mi on my bike with no valve adjustment . i ride mostly trails, dirt roads, in the western states. i have checked my valves 3 times , and basically nothing has moved . one exhaust is on the low end but hasn't moved. i am going on a extended trip this summer and want to feel comfortable making a change if needed. i have read the service manual about the procedure, and have some questions . #1 is taking the change tensioner out and replacing a big deal? what is a holding plate that you use on it to replace. #2 how do ya'll hang the chain once the cams are out. is there a chance the chain will come off lower sprocket? #3 what about sanding down shims,grit, setup. what diameter is the shim,approx.

i know i will be doing a new piston and valves one day, but if it's not broke i don't want to mess with it. it starts great ,runs strong. i am a old fart and don't high rev it, but i am no grammaw either. great machine, love to explore those mountains and desert, within my ability, B-

i'll be in new mexico in june, july, aug if anyone wants to meet up. i have a toy hauler, boondocker , rider,hiker ,mild mountain bike , porta-boater.

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ben williams

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The exhaust do not seem to move. If it is still within spec I personally would just run it. If you do, under no circumstance should you try and sand/grind/file the shim. You must put in the proper size. Well at least that is my $.02 worth. I have over 7000 miles on mine. Have had to do replace the intakes twice, the exhaust I shimmed once, just cause I had it a part.

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Apprentice

white line

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thanks for the replies. i won't be grinding the shims . the shop here said nix on the grind too,they will trade them out. looks to be quiet a few dealers in new mexico if i need them.

Ben, did you go back with TI intake valves both times and why not SS. have you put a new piston in yet? thanks, keith

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ben williams

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Yes, like a dumb ass (donkey) I put ti back in both times. Thinking they lasted a long time. Didn't realize how many miles I am putting on it:ride: Hindsight being what it is I wish I would have switched to stainless. I was talking with a guy who owns a Husky dealership locally and he believes the ti valves go bad because of the super fine dust that gets sucked up the carb vent lines. Where I do most of my riding it is very dusty/silty. After seeing how many miles some other guys are getting, he just might be correct. He even sells a nifty little filter that hooks them all together. I am going to look into that.

I did change my piston at the 7000 mile rebuild, it had worn through the coating on the skirt, but the bore was fine.

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Apprentice

white line

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when i need to do the valves and piston i will go to SS from what i get from my shop. these guys were great and i didn't buy the bike there, trades shims and gave a lot of enough. the TI coating is very thin a few thou, and will go quick in racing. they stressed of course, clean filter and oil,and for the riding i do , it can last and last. the filter cover doesn't do a good job on sealing. they told me you can get a rebuilt head with new SS springs and valve ready to go, $600 plus piston and labor.

i did my valve adjustment, that was a learning experience, next time will be a lot easier. digital caliper w/ both scales rules. thanks for the replies. kk

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