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Very odd low compression issue

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mr-inteligent
Nitrous Nuisance



Joined: 04 Nov 2008
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PostPosted: 16:55 - 27 Aug 2010    Post subject: Very odd low compression issue Reply with quote
My bandit 400 was running sweet as a nut and then the starter motor stopped working.

Since changing this small part the bike has run like shit and will not idle. So either its a very odd coincidence that the bike now runs like shit or its something I have done when I replaced the starter motor.

its important to stress the bike literally went from running very well to running like shit in the space of 1 hours time while I put on the new starer motor.

The mechanic has just told me the bike has bad compression on 3 cylinders. He wants to start looking inside the engine for possible causes but before I give the go ahead I want to ask here if there is anything I could of missed?

To replace the SM I removed the carbs and also the cam chain adjustment, could this of caused the issue?
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mr-inteligent
Nitrous Nuisance



Joined: 04 Nov 2008
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PostPosted: 17:09 - 27 Aug 2010    Post subject: Reply with quote
I agree mate but I have checked and re checked everything.

Why would the bike suddenly lose compression just from me changing the SM?

Should I of put some sort of sealant around the cam chain adjustment part when replacing?
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chris-red
Have you considered a TDM?



Joined: 21 Sep 2005
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PostPosted: 17:09 - 27 Aug 2010    Post subject: Reply with quote
rob yarrr wrote:
maybe the cam chain needs adjusting properly

i wouldn't take it to the mechanics,they will charge you a bomb for just looking at it,never mind fixing it


A poorly adjusted chain chain wouldn't make it run shit it would just be noisy. It may have skipped a tooth but I doubt it, also that wouldn't cause low compression on 3 cylinders. Hows does the mechanic know it has LC on 3 cyclinders?

People pay mechanics because usually they know what they are talking about.
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mr-inteligent
Nitrous Nuisance



Joined: 04 Nov 2008
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PostPosted: 17:24 - 27 Aug 2010    Post subject: Reply with quote
chris-red wrote:
Hows does the mechanic know it has LC on 3 cyclinders?


He has checked the valves and says they are ok, he has done a compression check and says they are low on 3.

lowest being 75 but this is a 20year old bike.

When I say "running shit" I mean not idling and slowly comeing down from 4k revs making a whirling noise.
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loply
World Chat Champion



Joined: 24 Mar 2004
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PostPosted: 20:08 - 27 Aug 2010    Post subject: Reply with quote
The starter motor isn't somehow staying 'connected' is it?

So the engine is spinning the starter motor over?

Might be completely impossible as I only know how the starter engager works on a Mille, no idea how it is on other bikes.
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mr-inteligent
Nitrous Nuisance



Joined: 04 Nov 2008
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PostPosted: 20:35 - 27 Aug 2010    Post subject: Reply with quote
loply wrote:
The starter motor isn't somehow staying 'connected' is it?


I havent thought of that.. and its worth checking tomorrow when I get the bike back.. I cant let the mechanic go into the engine as it will cost more than the bike.
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Old Thread Alert!

The last post was made 16 years, 53 days ago. Instead of replying here, would creating a new thread be more useful?
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