Commando smoker

Hi Ian,

Can you help by giving a few more details:-

What Commando is it ?

Do you have standard carbs / exhaust.

Does it appear to start and run OK ?

Is the tickover OK or very lumpy ?

Does it smoke as soon as you start it, when it gets warm, straight from tickover, when you give it a handfull of throttle or what ?

If you give it a handfull of throttle, does it smoke a lot worse with the throttle closed as the revs come down ?

What colour are the plugs ? and are they both the same ?

Do you know if it used to be OK and has suddenly started to smoke or has it done it for a while.

Is it a gentle cloud or can you not see the bike after a few seconds ?

Is it by any chance the left hand side and the bike was sitting on the side stand ?

What is the oil level in the tank ?

That should be enough to get started.

Regards

Tony

Hi Ian,

Working from memory, white smoke is much more likely to be oil. If the bike is running really rich it would tend to be blue / black.

Can anyone else confirm / deny ?

Have a look at :-

http://www.nortonownersclub.org/support/technical-support-common/smoking-engine/?searchterm=smoke

It may help.

Tony

All of that is valid but IME the most popular cause will be either a loose guide or a hardened/detached inlet valve seal. The seal gets my vote and since the head will have to come off........of course there is a chance the oil drain adjacent the rh inlet spring seat is blocked but the seals should cope with that condition.

Your problem is not likely to be the carbs unless the RH side has run too weak and you have seized the piston and messed the rings up. A compression check using the kickstart will give a clue here.

My money is going on a worn pressure release valve spring. On a cold start up, this allows the release valve to flood the timing cover with oil. On early engines with camshaft breathers, a good dollop then used to head outthat out way and end up on the drive. The rest managing to squeeze past the RH pistonto smoke out the neighbours.

Bet number two would be a worn oil pump failing to help clear problem one.

Strongodds also in favour of worn inlet guides and/or the seals that sit on their ends.

Previously wrote:

All of that is valid but IME the most popular cause will be either a loose guide or a hardened/detached inlet valve seal. The seal gets my vote and since the head will have to come off........of course there is a chance the oil drain adjacent the rh inlet spring seat is blocked but the seals should cope with that condition.

I agree it could well be the seal or guide, although when I had this trouble it was blue smoke not white. The wet spark plug on that side is a strong indicator as well.

It isn't neccessary to remove the head to change the seal. I have an article in .pdf format on how it is done (too big to attach here). Carried out the procedure myself recently with complete success. I found the seal had hardened and was floating on the valve stem. If anyone would like a copy, email me.

David

hi ian, you have to take off the exhaust downpipe and run the bike . if a guide is passing oil you will see it weeping oil and splash out through the exaust port. no experience of a worn oil ring but plenty of experience with u/s plugs, coils , leads,worn carb or wrong settings causing same white puffy smoke your experiencing

Had the same problem on my MKIII many years ago, valve stem oil seals replaced - job done. The oils consumption was high as well, I just thought it was normal. Tony George highlighted that I had a problem after following me to Birmingham as he wore most of the oil that was being spat out the pipes.

Previously wrote:

It isn't neccessary to remove the head to change the seal. I have an article in .pdf format on how it is done (too big to attach here). Carried out the procedure myself recently with complete success. I found the seal had hardened and was floating on the valve stem. If anyone would like a copy, email me.

David

Could you please send me a copy of the article? I tried to email youvia this website, but I couldn't get it to work.

Allan.

Previously wrote:

Previously wrote:

It isn't neccessary to remove the head to change the seal. I have an article in .pdf format on how it is done (too big to attach here). Carried out the procedure myself recently with complete success. I found the seal had hardened and was floating on the valve stem. If anyone would like a copy, email me.

David

Could you please send me a copy of the article? I tried to email youvia this website, but I couldn't get it to work.

Allan.

Hi Allan, I can't email you either as the site says your email address is invalid?!? Drop me a line to pd.lord@btopenworld.com and I'll send over the article.

David

Previously david_lord wrote:

Previously wrote:

Previously wrote:

It isn't neccessary to remove the head to change the seal. I have an article in .pdf format on how it is done (too big to attach here). Carried out the procedure myself recently with complete success. I found the seal had hardened and was floating on the valve stem. If anyone would like a copy, email me.

David

Could you please send me a copy of the article? I tried to email youvia this website, but I couldn't get it to work.

Allan.

Hi Allan, I can't email you either as the site says your email address is invalid?!? Drop me a line to pd.lord@btopenworld.com and I'll send over the article.

David

David,

Iâve just sent you an email asking for a copy of the .pdf

thanks

Dave

Hi ..

just read that there is a way to change valve seals without removing the head, could you please email me the method, Iâm trying to eliminate a slightly smoking engine, I have a 750 commando.

Thanks in advance

Russ

russberry@msn.com

Previously russell_berry wrote:

Hi ..

just read that there is a way to change valve seals without removing the head, could you please email me the method, Iâm trying to eliminate a slightly smoking engine, I have a 750 commando.

Thanks in advance

Russ

russberry@msn.com

Hello Russ,

the article you need is on page 5 of the commando technical forum on this site. Just go to the bottom of this page and select item 5.

I tried to copy and paste the article here in this reply but for some reason it won't allow me to.

Previously gordon_robertson wrote:

Previously russell_berry wrote:

Hi ..

just read that there is a way to change valve seals without removing the head, could you please email me the method, Iâm trying to eliminate a slightly smoking engine, I have a 750 commando.

Thanks in advance

Russ

russberry@msn.com

Hello Russ,

the article you need is on page 5 of the commando technical forum on this site. Just go to the bottom of this page and select item 5.

I tried to copy and paste the article here in this reply but for some reason it won't allow me to.