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Xr400r 2003 Manual Compression Removal

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It will not hurt anything to remove it. My advice is to leave it on there, it is very useful for easy engine starting, especially if you drop the bike and the engine floods.

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It is also an assist in cold starting. With choke on, kill switch pressed, no throttle, pull compression release and make several priming kicks. Then, release kill switch and compression release, find TDC and kick away.

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I've taken mine off after the first year I had it. Never used it, dropped or other wise. Leave the little spring on the lever thingy on the head.

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I've had 4 XR400s and never used it. I take them off.

i've got two 400's now, i've taken off the levers and cables a years ago, never looked back (and i race too)

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I only use mine to prime when cold starting. Otherwise it's not like a 650 with too much compression. The lever has come in handy on the trail more than once when I have crashed and broke the clutch lever. I do carry extra levers, gearshift, etc..., but after loaning all my extra levers out I needed one. Off came the decomp lever and onto the clutch. That day was full of bike carnage. No one got hurt though.

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Don't any of you 400 guys ride technical downhills? The decom lever is a life saver when you stall going downhill (steep loose), pull in the clutch and the decom, let out the clutch and then the decom and boom your running again.

Nothing worse than kick starting on the side of a hill or getting to the bottom and haveing a steep hill you need momentum for and haveing a dead motor.

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Don't any of you 400 guys ride technical downhills? The decom lever is a life saver when you stall going downhill (steep loose), pull in the clutch and the decom, let out the clutch and then the decom and boom your running again.

Nothing worse than kick starting on the side of a hill or getting to the bottom and haveing a steep hill you need momentum for and haveing a dead motor.

Mine does same without using the decom.

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It sounds like some of you guys so realize that the compression release isn't just used to start a bike. Don't remove it!!!

Pulling in the compression release while manuevering on a very steep,rocky downhill will allow you to pick your way very slowly down in first or second gear through big rock fields without locking up the rear wheel.

On the other hand, if you instead use a higher gear with the clutch out to avoid locking up the rear wheel or pull in the clutch for such steep descents this results in both wearing out and fading your brakes from over use and taking the chance that the bike will run away from you. Pulling in the compression release will supply just enough gentle compression braking to keep the bike under complete control without any chance of locking up the wheel (just as long as your bike is still in forward motion.)

I have had bikes with compression releases for over forty years and I have used them numerous times on each and every one.

Once you learn how to use the compression lease when the bike is moving, , you will consider it the godsend that it is.

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Pulling in the compression release will supply just enough gentle compression braking to keep the bike under complete control without any chance of locking up the wheel (just as long as your bike is still in forward motion.)

Once you learn how to use the compression lease when the bike is moving, , you will consider it the godsend that it is.

I have ridden with guys that use this practice with no problems. Maybe it was anomolous, but I have witnessed two cases with XR600 engines ( I disassembled them) where the tab on the RH exhaust rocker arm that the comp release linkage pushes against has actually broken off as result of this practice. In the first instance, only minor damage resulted, but in the second, major transmission damage was done. You be the judge.

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I ride lots of single track, up and down hills. Proper gear selection and judicial use of the throttle is the way you're supposed to do it.

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When your buddy bails in front of you on a steep loose downhill it's always nice to ride over his bike and do the decomp bumb start after you stalled it and then wait at the bottom.

I have used the decomp bumb start for years and have never had a problem on my XR250R 96 and it has about 12,000 miles of really abusive riding.

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I'm in the group that uses it only for clearing an engine and bump starting. I've never liked the idea of using it consistantly for engine breaking for reason stated by Creeky. Brake work is a lot easier and cheaper than engine work.

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Using a compression release for steep downhills will never cause harm just as long as the valves are already correctly adjusted. When damage does result it is usually the result of valves that were simply too tight to begin with. I go all the way back to the British big single dirt bikes of the 1960s so I can tell you outright that I have never ever seen any damage caused by the use a properly adjusted compression release used for going downhill.

If you are wondering what most often causes improperly adjusted valves on XRs, it is probably the result of the failure to completely understand how the apparently very simple automatic compression release works and how it effects valve clearances. Don't think this is a novice error. I know of motorcyclists with virtually thousands of hours of mechancial (and race) experience on other bikes who had to have master mechanics explains the archane tricks required to get these valves adjusted. If you think adjusting valves on an XR is an absolute breeze, you are probably doing it wrong.

When the process was first explained to me, I couldn't believe all the extra steps that were required.

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Using a compression release for steep downhills will never cause harm.

If you are wondering what most often causes improperly adjusted valves on XRs, it is probably the result of the failure to completely understand how the apparently very simple automatic compression release works and how it effects valve clearances. If you think adjusting valves on an XR is an absolute breeze, you are probably doing it wrong.

When the process was first explained to me, I couldn't believe all the extra steps that were required.

Ummm don't you just have to turn the engine over backwards so the auto decomp doesn't engage and line up the timing mark (on compression) :thumbsup:

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I leave mine on so I can do the "just dumped my hot XR400" drill and clean it out.

Pull the comp release, kick it through 4-6 times.

Release, kick it over once or twice.

Every time I try to take a shortcut, I end up kicking it 20 times.

Good tip for adjusting the valves without pulling the spark plug.

Another tip is if you kill the engine with comp release, it will be at TDC.

Puts the piston in the right place for kick starting at a dead engine start.

Closes the valves for long term storage.

(from Ty Davis as I remember)

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