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Author Topic: no compression  (Read 2311 times)

cochi

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no compression
« on: October 22, 2007, 05:27:19 PM »
sorry guys I messed up the first posting and I think I erased all I had written. Anyway, I have an 03 classic 500 that I've had since new. It has been very dependable until yesterday. I live in the city so during the riding season the Bullet lives under two  bile covers.  Yestereday, after being parked for a week  I attempted to start her. Like always, she started on the third kick.  She ran for about 30 seconds, sounded fine and then she shut down. No back fires or anything. It was as if I had switched her off. Checked the petcock it was in the "on position" and there was plenty of gas. Kill switch was OK also. I went to kick start her again, no compression! I never use the compression release but I looked at it and it was OK. I next examined the tappets , they spun easily at tdc. However, I noticed something  while checking them. I have a pancake filter and can always hear the intake hiss, this time, the hiss did not stop during the compression stroke. The pitch changed, but it continued. There was little Resistance during the compression stroke. I was wondering if there was a history of intake valves getting stuck open in these motors? I've not taken the valve covers off yet. This bike has never been over revved and it has been serviced regularly.  We have also had several days of rain here. I think the stock guides are iron, not sure if there was enough moisture to rust up the intake side .   Thanks Cochi :-\

Leonard

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Re: no compression
« Reply #1 on: October 22, 2007, 10:23:56 PM »
It is possible that a chunk of carbon broke off and got stuck so that the intake valve will not close.  It is also possible that the decompressor is gunked up and sticking open.  If it were me and I was sure the valves were adjusted properly I would pull the decompressor and clean it up before I pulled the head.  Make sure you don't pull the little cotter pin else the thing will drop into the cylinder.
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dewjantim

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Re: no compression
« Reply #2 on: October 23, 2007, 03:24:09 AM »
Mine does that when the decompressor lever gets stuck, just thumb the lever a few times and that should unstick it......Dew.
If it hurts, you're not dead yet!!!!!

Kevin Mahoney

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Re: no compression
« Reply #3 on: October 23, 2007, 08:23:49 PM »
Your guides are not iron and sticking is not a "usual" problem. It is possible to get a piece of carbon stuck under the intake or compression valve or decompresser valve. Maladjusted valves are the number one cause of this malady. If you are sure about the valves and the decompresser valve (they do stick and/or burn once in a while). if you can't figure this out a crude but effective way to get a better handle on it is to braze an airfitting on an old spark-plug that you have gutted. Bring the piton to TDC on the compression stroke and put the air to it. You do not need much pressure. You can then listen to where the air is coming from.

hoppyre

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Re: no compression
« Reply #4 on: October 25, 2007, 12:07:04 PM »
Your guides are not iron and sticking is not a "usual" problem. It is possible to get a piece of carbon stuck under the intake or compression valve or decompresser valve. Maladjusted valves are the number one cause of this malady. If you are sure about the valves and the decompresser valve (they do stick and/or burn once in a while). if you can't figure this out a crude but effective way to get a better handle on it is to braze an airfitting on an old spark-plug that you have gutted. Bring the piton to TDC on the compression stroke and put the air to it. You do not need much pressure. You can then listen to where the air is coming from.

Hey RE1, you can also do this if you have one of those compression testers with the different size hoses that screw into the spark plug hole. Just remove the air valve in the end of the hose (it's just a valve core for an inner tube) and thread the hose in the plug hole. Connect your air line to it. You can regulate the pressure if your compressor has a regulator valve on it!!  Mark

cochi

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Re: no compression
« Reply #5 on: October 25, 2007, 06:38:49 PM »
Thanks for the feed back. You guys were absolutely correct I pulled the head off and there was a small chunk of carbon stuck on the valve seat!  Didn't take much to make it leak I'm now waiting for gaskets. I couldn't believe how wonderfully easy it was to pull the head. I truly love this thing! :)

Leonard

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Re: no compression
« Reply #6 on: October 26, 2007, 10:18:11 PM »
You might want to use some of those hardned washers when you replace the head so it will be easy the next time too.

Thanks for the feed back. You guys were absolutely correct I pulled the head off and there was a small chunk of carbon stuck on the valve seat!  Didn't take much to make it leak I'm now waiting for gaskets. I couldn't believe how wonderfully easy it was to pull the head. I truly love this thing! :)
2009 Triumph Bonneville T100
2004 Royal Enfield Sixty-5 (RIP)
2001 Kawasaki W650 (going, going...gone)
http://www.romeoriders.com

cochi

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Re: no compression
« Reply #7 on: October 29, 2007, 08:32:48 PM »
Took the advice and ordered the hardened washers. I lapped the valves and cleaned the combustion chamber and piston. I ordered the stock head gasket.  I was wondering if I should use a little permatex on the head gasket. An old mechanic I once knew used to use it around the water jacket openings on old v8's. My Bullet use to ooze a little oil even after retorquing the head. Don't know if it would help. :)

Kevin Mahoney

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Re: no compression
« Reply #8 on: October 30, 2007, 03:52:33 AM »
We like the use of a good non hardening head gasket sealer on the Bullet, doesn't hurt anything and can be good insurance. One last thing measure the depth of the recess in the combustion chamber that the cylinder fits into. Then measure the height of the lip on the top of the cylinder. The lip should be some shorter so that it doesn't touch the head after the head is tightened. DO NOT take this measurement for granted with a late model Bullet.

cochi

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Re: no compression
« Reply #9 on: November 05, 2007, 07:22:19 PM »
Thanks RE1. I put the head back on using some of permatex copper  head gasket sealer. It worked like a charm . Unfortunately I read about the lip clearance today. All seems well though. I ran the motor for about 20 minutes (short ride) let it cool down and retourqed it. Will retorque in 500 miles as recommended.  The motor seems a bit stronger and quieter.  Probably just my imagination!  ;D