XR400 lost compression after rain

noodnurd · L Plate Warrior Joined: 19 Jun 2013 Karma :

Hello. I have a 2001 model XR400 which is (was) in very good condition; never flogged, well maintained, premium fuel, etc.

I recently left the bike out in the rain for 2 nights in a row. Not normal behavior however circumstances couldn't prevent it. After this, I can no longer start the bike.

The strange thing about this is that I seem to have lost almost all compression. A couple of days ago it was perfect; nice and stiff and easy to start. Now I can kick through freely as if there's no plug installed... The bike had been sitting all afternoon before the rain began and wasn't hot at all, so nothing should have cracked.

It's possible there's still some water in it although I can't see how that could affect the compression.

Any advice or tips very welcome!
https://s24.postimg.org/79c8so3o1/20130619_123950_Medium.jpg

https://s24.postimg.org/pmcu38e4x/20130619_124030_Medium.jpg

https://s24.postimg.org/olcle3x5d/20130619_124042_Medium.jpg

Ariel Badger · Super Spammer Joined: 02 Dec 2006 Karma :

Could it be that you have compression but water has got into the clutch causing it to slip?
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robstat · L Plate Warrior Joined: 12 Jun 2013 Karma :

It's nothing to do with the clutch it would still kick over properly, if you took the clutch out you would just get no drive also I doubt it's anything to do with the rain, it could be a few things assuming the plug is still there it's probably a valve stuck open.

P. · Red Rocket Joined: 14 Feb 2008 Karma :

doggone · World Chat Champion Joined: 20 May 2004 Karma :

Will there be a decompression thing on these to help it start turning?
How does it engage/disengage

noodnurd · L Plate Warrior Joined: 19 Jun 2013 Karma :

A small lever above the clutch controls compression in the XR400. If I pull this in I get even less resistance so there is *some* compression but nothing like a couple of days ago.

Note that the bike has not been tampered with as it's been with me, just unused.

noodnurd · L Plate Warrior Joined: 19 Jun 2013 Karma :

I don't think it's the clutch. I rolled it down a hill and released the clutch in 2nd. The engine turned over a good 15 or so times but no sign of ignition at all. Clutch didn't slip - it's only a week old!

I'm guessing it's electrical but hell, a bit of rain shouldn't bother that.. Why is it that I can ride through creeks and do 4 hours enduro in the Cambodian monsoons without issue, but if I park the bloody thing in the rain it can't handle it?!

robstat · L Plate Warrior Joined: 12 Jun 2013 Karma :

noodnurd · L Plate Warrior Joined: 19 Jun 2013 Karma :

Note this photo:
https://postimg.org/image/sini87ubx/

The cable going into the alternator/dynamo was wet upon inspection. The sheath also contained some water. It's possible that water seeped in here and got the dynamo wet, preventing it from functioning. But now I'm just stabbing in the dark.

Update: If I kick it over and hold in the horn button I get sound from the horn, so there's definitely power going through it.

P. · Red Rocket Joined: 14 Feb 2008 Karma :

I hate to say it... but if you can feel the engine turning over in gear whilst rolling on a hill, I reckon it is safe to say that something has failed and the engine needs to be looked at. I couldn't bump my big single in 5th, it just locked the wheel

noodnurd · L Plate Warrior Joined: 19 Jun 2013 Karma :

The other side to the issue is that I live in Cambodia and all the mechanics in my area look like this:
https://s14.postimg.org/5g1y6vnwd/5960585_Cambodian_mechanic_and_gas_station_0.jpg

I do most of the work myself for obvious reasons. A visit to a 'real' mechanic would be very time-consuming...

Any more advice on what I could do to diagnose further?

iooi · Super Spammer Joined: 14 Jan 2007 Karma :

Spark plug out.
Place Something in the hole. So that hits the top of the piston and SLOWLY push the kickstart down and see what happens.
Or place finger over hole.

Cam cover off and check valves are moving as they should.
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..... · Quote Me Happy Joined: 15 Jan 2005 Karma :

I'd be focusing on the auto decompression system. Have you checked it's working and the cable is adjusted OK?

Fizzer Thou · World Chat Champion Joined: 06 Aug 2011 Karma :

I would go with what Joe has said.If you disconnect the decompression cable that connects to the handlebar lever,you should get full compression back.

It sounds as though the cable has seized up,causing the right hand exhaust valve to stick open slightly.Hopefully it has not bent that valve if it was held open too far.
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kartl · Derestricted Danger Joined: 14 May 2013 Karma :

Compression test would be the best thing to do to check your engine compression. Im guessing that the may be really out due to internal damage. Or it could be a head/block leak.