[bad egg]

I've had an on-going issue where I get un-burnt oil from the left side exhaust. Given there's no smoke and the oil looks fine, I assume it's not entering the combustion chamber and is running down the exhaust valve. However, I just can't seem to find new guides and valves and am considering buying a whole CB cylinder head (as I'm in the UK and postage from the US is crazy) and using that instead.

I know that the cams are different, and I'd still use the SL one, but does anyone know a good reason why using a CB cylinder head would be a stupid idea and save me a few hundred pounds*

Thanks!



*FYI, since the stupid decision to leave Europe, a few hundred pounds £ is about three dollars

 

[Boomer343]

Short answer is that there is no difference in the CB and SL heads so they will interchange.

Long answer is it isn't your valves and guides causing the problem unless there is a burnt valve causing no cmpression. Fuel doesn't bypass the combustion chamber.

Before doing anything else you need to do a proper compression test. Then if it shows acceptable results it is either an ignition problem or carburetor.

If it is left side check to see if it runs properly with the points cover off. The points wiring often shorts out on the cover.

 

[bad egg]

Hi Boomer,

sorry - my fault, I'd accidentally written 'fuel' instead of 'oil'... now edited on my original post. I'm getting un-burnt oil through the left exhaust... I'm confident oil isn't coming via the pistons as I've just had a rebore with new 1st oversize pistons and rings.

Thanks!
Chris.

 

[Boomer343]

Good to have clarity!

It could still be fuel if you are getting poor combustion/missing in that cylinder.

Every head I have taken apart has needed intake valves as they get dished on the seating surface. Valve springs are usually out of spec especially the inner springs. Guides are usually serviceable. I doubt you will find a used head without issues so you may be best to rebuild your own.

Sirius here in Canada has the valves, valve guides are available on ebay either OE or aftermarket. Springs can found on ebay as well. Time and money.

I would still suggest doing the compression test and maybe pulling a tappet cover off after a 20 minute run to see what the oil level is in the area around the left valve. If you are parking it on the sidestand, do SL's only have a sidestand? .... then oil may be puddling there.

 

[Boomer343]

https://www.siriusconinc.com/pro-detail.php?pid=&product_id=223

 

[1wheeldrive]

https://www.davidsilverspares.co.uk/SL350K1-MOTOSPORT-1970-1971-USA/part_108613/

https://www.davidsilverspares.co.uk/SL350K1-MOTOSPORT-1970-1971-USA/part_108618/

https://www.davidsilverspares.co.uk/SL350K1-MOTOSPORT-1970-1971-USA/part_108619/

 

[bad egg]

Sorry for the late reply - Yesterday I had to go to a meeting at the Triumph factory and meet their chief designer, which was pretty awesome!

Anyway, these links are great... and subject to releasing funds from the 'joint account'... I'll get going

1 Wheeldrive - also thanks, though I'd checked with DS first, but the valves are out of stock..

 

[TexasMark]

Short answer is that there is no difference in the CB and SL heads so they will interchange.

Long answer is it isn't your valves and guides causing the problem unless there is a burnt valve causing no cmpression. Fuel doesn't bypass the combustion chamber.

Before doing anything else you need to do a proper compression test. Then if it shows acceptable results it is either an ignition problem or carburetor.

If it is left side check to see if it runs properly with the points cover off. The points wiring often shorts out on the cover.

I thought the SL350K1/K2 had smaller intake bores and only the SL350K0 was the same as the CB350. Good to know that they are all interchangeable. Thanks

 

[Skyliner]

According to the part numbers the head from a SL350-K2 only fits the K2 and K3. The intake ports are smaller.