Blowing smoke but compression good and plug not oily

[Giles C]

Hi everyone,
I recently replaced my 500's head gasket and unfortunately one side has started to smoke.
I've done a plug chop and a compression test and found that the compression is the same both sides, and the plug isn't wet. Do you think the attached video shows oil or fuel coming out the exhaust? Also do you think I can continue to ride the bike this summer or do I need to look at the valve guide and or seal or ring now?
I've also attached a pic of the plugs, before and after a new set.
Everything is stock carb wise, there's a fresh air filter and it's running Sachse electronic ignition.
Thanks for any help.
View attachment 20230422_183016.mp4

 

[Giles C]

Sorry I'm having issues with the loading of the right files!
I'll try again

 

[The Sock]

Check/change the exhaust pipe sealing ring on the affected side.

Leaking oil from exaust?

Hello, This is my first post on here so correct me if I do anything wrong... I went to the Laverda meeting in Breganze 3 weeks ago (I was probably the youngest rider around) and my exaust started leaking oil right where it leaves the engine. I went to visit Ricardo Oro (probably many about who...

www.laverdaforum.com

 

[iis_iis]

Check/change the exhaust pipe sealing ring on the affected side.

Leaking oil from exaust?

Hello, This is my first post on here so correct me if I do anything wrong... I went to the Laverda meeting in Breganze 3 weeks ago (I was probably the youngest rider around) and my exaust started leaking oil right where it leaves the engine. I went to visit Ricardo Oro (probably many about who...

www.laverdaforum.com

Giles C. You dont know how pertinent and huge time saving efforts this simple advise is. Pulled a motor out of frame and tore it to bits, to only keep smoking on re-assembly and installed in frame. Clever Mr Sock.... he has no shoes i do believe... sorry, cannot help myself. j

 

[Cccg]

Suggest doing a leak down test.

 

[Giles C]

Thanks so much for the replies and help, fantastic forum.
I'll get another gasket and try that with loctite blue.
Can anyone point me in the right direction for the best copper gasket?

 

[Paul Marx]

Copper gaskets are common to 350/500, 750 and 1000.


Exhaust : OEM size (source: parts book): 38.2mm (ID) x 43.7mm (OD) x 2mm.



1. Imperial (aircraft) alternative

AN900-24 = MS35769-39



1½” x 1¾” x 3/32” = 38.1mm x 44.4mm x 3.4mm.



These work.



2. Honda alternatives

Part number: 18291-MM5-860

(37.4mm x 44.8mm x 4.1mm)



Part number: 18291-MN4-920

(35mm x 43mm x 4mm)

Honda CB250 (Super)Dream; CB 450S, VT 600C; XL 600V '87-'99; NTV 650 Rev. '88-97; XRV 650; CBR 900 RR '92-99 etc etc

 

[Giles C]

Brilliant thanks very much. I'll update the thread when I get them in.
Fyi the nuts were far too loose which surprised me as it's not done many miles since I did them up. I tightened them and went for a ride, I think there's less smoke which bodes well.

 

[Beucars]

Copper gaskets are common to 350/500, 750 and 1000.


Exhaust : OEM size (source: parts book): 38.2mm (ID) x 43.7mm (OD) x 2mm.



1. Imperial (aircraft) alternative

AN900-24 = MS35769-39



1½” x 1¾” x 3/32” = 38.1mm x 44.4mm x 3.4mm.



These work.



2. Honda alternatives

Part number: 18291-MM5-860

(37.4mm x 44.8mm x 4.1mm)



Part number: 18291-MN4-920

(35mm x 43mm x 4mm)

Honda CB250 (Super)Dream; CB 450S, VT 600C; XL 600V '87-'99; NTV 650 Rev. '88-97; XRV 650; CBR 900 RR '92-99 etc etc

Flying doctors?

 

[Paul Marx]

Flying doctors?

Lying doctors?

 

[Rob]

the nuts were far too loose which surprised me as it's not done many miles since I did them up

The copper gaskets do compress under initial tightening but as you have found, the compressed gasket is affected by heat and will need retightening a couple of times. Don't overtighten the exhaust clamp rings - they will bend and crack if you overdo things. Blue loctite is no good for this application - it's rated to 150 deg C. Original brass nuts and decent spring washers are essential... or copper plated nuts used on BMW exhaust manifolds.