Honda cbf 125 leaking gasket

[Tuckermoto]

Hi all

Update on my little Honda cbf 125 engine rebuild ...

Barrel/ rings / piston replaced the engine is all back together and started on the button straight away ..after leaving the bike on tick over for 15 minutes to run the new piston rings and barrel in I’ve noticed that the rocker cover had a slight oil leak all the way round the gasket ...I’ve retorqued the cover down and it’s still weeping oil ..the gasket is new I’ve retook of the cover and redone up the cover bolts but still the same weep of oil ..I’m used to working on car engines and normally the rubber gaskets hold good on them ..is it advisable to add some instant gasket ( high temperature resistant) to back the rubber gasket up and ideas

[Guest Richzx6r]

Yea I'd give it a sparing tickle with some gasket sealant

[Tuckermoto]

Thank you for responding I’ve got some clear instant gasket that I use for when I replace water pumps on cars

RTV silicone rubber sealant it goes up to temperature 250 Celsius do you think that’s ok to use

[Guest Richzx6r]

Thank you for responding I’ve got some clear instant gasket that I use for when I replace water pumps on cars

RTV silicone rubber sealant it goes up to temperature 250 Celsius do you think that’s ok to use

 

Yea I'm sure it is fine, just go sparingly with it

[Westbeef]

Did you clean the old gasket off the faces?

[Tuckermoto]

Yes I did with gunk

[fastbob]

I'd have another look at both surfaces because reusable rocker box gaskets don't usually leak . There shouldn't be any oil under pressure behind them so I'm puzzled as to what's causing seepage .

[Guest Richzx6r]

I'd have another look at both surfaces because reusable rocker box gaskets don't usually leak . There shouldn't be any oil under pressure behind them so I'm puzzled as to what's causing seepage .

 

Could be a breather pipe blocked or something?

[Tuckermoto]

I’ve taken cover back of and going to check for blocked breather pipes and then put instant gasket on and put rubber gasket back on and try ..there’s no pressure it’s just weeping ...I’ve looked on you tube and it seems many people fitting cam gaskets ( my one is rubber ) also back up the gasket with instant gasket it seems Honda gaskets instant gasket is used

[Fozzie]

I've rebuilt one of these engines, the gasket was an absolute pain to get on right as it sort of slots into the cover, but it twists and moves around and kept slipping out of place as I tried to refit it. Took about half an hour of fiddling about to get it on perfect.

Put up some pictures of it so I can have a look. Hopefully all you need is a smear of instant gasket to get it to seal fully, but I didn't need it which is why I'm probing a bit further.

[fastbob]

What you do is " Glue " the gasket to the cover with silicone sealant, put the cover on a flat surface with a weight on top somewhere warm to set . When it's dry , just bolt on the cover . Easy . No need to over do the silicone , just use enough to stick the gasket .

[fastbob]

I've rebuilt one of these engines, the gasket was an absolute pain to get on right as it sort of slots into the cover, but it twists and moves around and kept slipping out of place as I tried to refit it. Took about half an hour of fiddling about to get it on perfect.

Put up some pictures of it so I can have a look. Hopefully all you need is a smear of instant gasket to get it to seal fully, but I didn't need it which is why I'm probing a bit further.

 

It was hard to re fit because this type of gasket tends to swell slightly upon exposure to chemicals . One way to shrink it is to put it in a moderately hot oven for a little while but don't blame me it you bugger it up . This also works with brake caliper dust seals that won't go back in .