GSX11ET

[bigyellowthing]

So M6 and suddenly no go.

Compression readings of 110 / 75 / 75 / 110.

top end off nothing untoward .

bas gasket weepy, carbs ok, fat spark,

filled compression chambers with oil, then petrol no leaks at all.

any ideas

[Blubber]

Cracked or bad coils?

 

They sometimes only show their faulty when hot 

[Swiss Toni]

Compression readings should ideally be within 10% of each other,  so I'd have a look into no's 2 and 3 cylinders regardless.  I'd also agree with Blubber,  the coils may be breaking down. 

[no class]

Your compresion readings indicate a poor motor ....... anything under 90 psi is dead .

[pigford]

Did you do compression readings on warm motor with carbs wide open?

[bigyellowthing]

thanks guys

2&3 don't share a coil and wouldn't it affect both pots that share the coil (1/2 - 3/4)?

Agreed compression way too low but can't see a cause ...

[bigyellowthing]

compression tested on cold motor.

I know it isn't ideal but 75 0n 2&3 is properly bad isn't it?

Head gasket?

If head gasket is the issue is this something that is a GSX 'thing'? The cam chain tunnel seemed 'dirty'?

[no class]

Could be combo of valve seats and worn piston rings..... either way that motor is tired.....70 odd psi won't even create a combustion event so all the fuel and spark you throw at it won't do sqwat . 

Edited September 27, 2017 by no class

[Swiss Toni]

4 hours ago, bigyellowthing said:

thanks guys

2&3 don't share a coil and wouldn't it affect both pots that share the coil (1/2 - 3/4)?

Agreed compression way too low but can't see a cause ...

2 and 3 do share a coil. As do 1 and 4. 

[Blubber]

In my defense....I  misinterpreted "suddenly no go" , as having a stalled motor.

 

Should have asked for more information.  Don't worry... Won't happen again.

 

 

[Sheep]

Did you make a note of the compression readings after oiling the cylinders??

[bigyellowthing]

Sorry I am an eejut could indeed be a coil...

1&4 / 2&3 of course doh!

 

[bigyellowthing]

didn't check compression with oiled bores. 

Strip down shows no damage to valves, pistons or bores.

With compression readings and age of poor old girl,  honing and new rings probably overdue...

[Sheep]

Or big bore kit

 

[bigyellowthing]

Any ideas which coils I could replace my elderly units with?

[bigyellowthing]

Sadly big bore, lumpy cams, clever ignition etc. beyond budget...

[pigford]

Do it proper & fit 3.0 ohm (green) Dyna coils!

[Swiss Toni]

'Wot e said! 

[bigyellowthing]

I should've bitten that bullet already. 

maybe I should ask advice before diving in spanner first?

 

[johnr]

did you check your valve clearances before stripping it? if the clearances were too tight then when it got warm your valves may have been partly open. seems an odd coincidence that they both had the same pressure. had you checked the valve timing was correct?

Edited September 29, 2017 by johnr

[Gsxrsam]

Leak down tester will give you answer......

 

[bigyellowthing]

I'm thinking that whatever the cause it won't do any harm to replace coils, rings and gaskets whilst doing some checking, honing and gapping. 

you guys are amazingly helpful so thanks again. I appreciate all your advice. 

 

[bigyellowthing]

And....

Which gaskets / rings?

Best

[bigyellowthing]

And which gasket sealant?

Is Yamabond the best, if so which product?

[Swiss Toni]

Yamabond/Suzibond...or Wellseal. Go with what's the cheapest/easiest to get hold of!