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valve spring replacement

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Hi, I have a '04 crf450 with about 30 hours on it. No valve problems but, after one season, I want to replace the stock valve springs with a Kibblewhite set I've got. I've allways done all the work on my 2 strokes (except rear shock service) so was thinking about getting the proper tools to service the 4 stroke. Should I get the Honda spring compressor and attachment ($92) or do some of the others like Lisle ($29) or Motion Pro's ($95) work well? I thought I saw somone here say they compressed the springs by hand (40lbs intake 75lbs exhaust seat pressure), but that doesn't really sound doable. My clearances are fine but I'm worried about the stock springs sacking out. Should I just take the head to a local shop?

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I used a c-clamp, a couple of red shop rags to protect the combustion chamber side, and a open end 14mm wrench between the clamp pad and upper valve spring seat to provide a straight push. Reach in with a small magnetic screwdriver to grab the keepers...a dab of grease on the stem when reinstalling...

It does not take much pressure at all with any kind of clamp....doing it by hand, you better have strong thumbs, especially with new springs.

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I have the Motion pro compressor and it works perfect. Yeah it's more expensive than the sears unit, but you don't need to rig anthing special to make the MP work.

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You guys crack me up. I knew you'd be lurking out there but that was in record time. One follow up, does the Motion Pro type tool really let you do the work without removing the head? I guess you'd have the piston at TDC to stop the valve from completely falling in on removal but you'd have to hold it up with a zip tie or somthing when reassembling and then cut the tie off when done.

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One follow up, does the Motion Pro type tool really let you do the work without removing the head?
I've been contemplating spring changes without removing the head, but haven't come up with anything yet. If you find something, please post as I suspect that regular spring replacement may open the door to longer OEM valve life...

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I would think leaving the head on while changing springs is sooner or later going to invite bent valve stems. Sure, I guess you could do the old thread the soft rope into the spark plug hole trick and then move the piston up as far as it will go, using the rope as a cushion for the valves so you can press down and remove the keeprs...but jeesh, it's cramped in there with the head on the bike :cry:

It's only another 6 bolts or so to remove the head. Takes a couple minutes to get it off....ok, well, you still gotta remove the back mounts but hey, it really don't take long...

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I guess you could do the old thread the soft rope into the spark plug hole trick and then move the piston up as far as it will go, using the rope as a cushion for the valves so you can press down and remove the keeprs...but jeesh, it's cramped in there with the head on the bike :cry:

It's only another 6 bolts or so to remove the head. Takes a couple minutes to get it off....ok, well, you still gotta remove the back mounts but hey, it really don't take long...

You do have a point, but I suppose you have to also drain coolant, install a new head gasket (clean both surfaces), refill coolant, etc.??? No one thing is particularly time consuming, but taken together, they all add up for "routine" maintenance. Faster would definitely fit into my schedule better if I do it every 15 - 30 hours or so as I'd like. My friend worked it out on his race car and cut his routine spring replacement time (every 10 passes down the drag strip) down by something like 2 hours - of course, that's a V-8.... but still...... There's just gotta be a good, convenient way.......

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all you have to do is put the engine on tdc and use air pressure through the spark plug hole it will hold the valves up.never tried it on a bike but it works great on car engines :cry:

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all you have to do is put the engine on tdc and use air pressure through the spark plug hole it will hold the valves up.never tried it on a bike but it works great on car engines :cry:

Holding up the valves is pretty straight forward, I'm more concerned with working out a way to controllably compress the springs, not lose digits, have access to remove/install locks/keepers, avoid having parts fall in bad places, etc., etc.

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Well that's what I was inquiring about. A method of removing/installing valve springs without removal of the head. There's a motion pro tool that you just press onto the spring. One setting removes the keepers, the other installs them. There are others on the web. I checked google searching for valve spring compressor. They run around $95. I guess I'm going to do it the old fashion way though.

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