Smoking right hand pot

Hi guys, how are you?
Well the commando's on the road, unfortunately it's in the insurance assessors workshop at the mo as I clipped the back of a car and the bike went down the road on its side for a while, after dumping me on the tarmac. Hopefully they'll repair it and not write it off, just a broken footrest, both clocks and switch panel, broken lenses but a bit worried as the forks seems a bit bent, well ok, with the bars straight ahead the front tyre seems to be pointing to one side.

But the query I have is my right pot, after the bike have done a few miles, is smoking quite badly. Is there an oil feed volume adjuster for oil to the head say like on my Matchless? I don't seem to see any flow adjusters.

If there isn't one, then would you think it's my valve guides that's worn, thus leaking oil thru? Or would there be an oil seal on the valves that could be perished? It doesn't smoke on startup or for a while, but after riding for about 15 minutes then it does start smoking, and if I give it a good blast down the main road for 20 minutes or so then in traffic you can really notice the smoke. I wouldn't have thought it's the oil ring cause wouldn't it be more efficient when hot due to expansion?

Was hoping to leave it till the winter but if I do get my bike back from the workshop I may have to take the head off and have a look. Be good if I can get an idea from here where is the most likely cause of the smoking.

Cheers

Ed

Hi Ed, hurts to read the clippage event and ongoing suspense. Hope something learned by it besides Fate is The Hunter of all Pilots.
1. Tire can't point out of line with the bars unless bent stanchions or yokes.
2. Rings smoke most on cold start ups while wet sump splashing bores and still cold clearances and should clean up a lot once hot and mainly smoke on good throttling.
3. Guides would continue to smoke more and more as oil thins to drain/suck in more as things expand. Intake is the only one that sees intake sucktion so only ones to get seal in Nortons, so more smoke on let offs than nailing it, it ya can tell.
4. Expect elecrical grimlins after a take down impact.
5. If totalled likely worth buying back to restore or part out.

Commando valve guides can also come loose in the head, I had one where the timing side inlet guide became loose and smoke just poured out the back. You do need to take the head off and investigate, tough luck on the spill but at least you're ok.
sam

trident sam said:

Commando valve guides can also come loose in the head, I had one where the timing side inlet guide became loose and smoke just poured out the back. You do need to take the head off and investigate, tough luck on the spill but at least you're ok.
sam

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My coin would be on valve seal,i had exact same symtoms and replaced both seals and have had no more trouble,,,good luck.

it could also be blockage in your oil tank vent hose

I once rerouted the one on the 72. didn't quite "look righht" as it was.

wife was riding it, and 15 miles from home, started blowing smoke out of the right. I mean lots of continual smoke
so we hauled it home, and I did rings and new head gasket.

Started it up- perfect.

went for a ride, a few miles from home-0 bang- pouring white smoke.

I took off seat, looked around, thought can't be, and moved the vent hose back- smoke stopped instantly, and that was it.

so just sayin I know a blocked or kinked vent hose, cause those problems, probably not it- but the easiest to check and free.

Well trappnman, I sure hope that's it! Maybe grasping at straws to save me taking the head and piston off, but the oil vent pipe is on the right hand side too! When/if I get the bike back, they reckon about 3 weeks if all goes well, I'll check the oil breather first, sure would save me a bit of work and expense.
Though secretly I fear the valve setup, seems to have all the signs, but hey ho could be the oil vent in which case it'll be a stroke of good luck, and something else learnt new from here!!!

I thought this was a thread about some new kind of weed...

Some herb may help you slow mind enough to track everything methodically while also keeping in mind one can easily find more than one thing doing the same thing while enjoying some background rock and roll beat to keep moving with. Hope you get yours to kick the smoking habit.

OzT said:

But the query I have is my right pot, after the bike have done a few miles, is smoking quite badly.

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I have a RH4 head with 32mm ports on my workbench which has a tiny little oil path from the rhs intake port to the oil drain drilling which is awfully close to the port anyway. There is a very small but visible and tangible "irregularity" on the port wall exactly at the questionable area. My Atlas was ported to 30mm and I suspect there might be a similar issue and I was also told by the guy I mainly dealt with - Dieter "Doc Norton" Cordes - when I restored the Atlas some 15 years ago that this is something to have a look at when porting these heads.

Might be worth it to take the carbs of and have a close inspection of the rhs intake port. If there is a problem it will be at the 3 o'clock position about two, maybe three inch down the port.


Tim

Hi Tim, how are you? Thanks for that though I'm not sure I understood what you were saying. I have a Mikuni single carb with a split inlet manifold, would that apply to me too? and if so what to do about it please?
Cheers
Ed

OzT said:

...if I give it a good blast down the main road for 20 minutes or so then in traffic you can really notice the smoke. I wouldn't have thought it's the oil ring cause wouldn't it be more efficient when hot due to expansion?

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Steve/Hobot touched on the idea of guide seals, and he's correct about the intake seeing manifold vacuum causing more trouble at idle/light throttle. Exhaust seals, on the other hand, are more slave to crankcase pressure. This leads me to think that's where your problem lies, since you noted the smoke after a good blast down the road. I'd not only take a good look at your breather as eluded to by Trappnman, but go ahead and add the check valve to your breather while you're there if you haven't already. It's beautiful in its function, and will help with the exhaust guide seals (although I wouldn't say that would fix a leaky seal). 'Glad you survived the "ordeal"; don't let the insurance company get your bike! Nathan

OzT said:

I have a Mikuni single carb with a split inlet manifold, would that apply to me too?

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Yes, it would: There is a drilling (actually two which meet) from the rear rocker housing. If you remove the intake valve cover you might be able to spot it although IIRC it is relatively hidden behind all this valve gear.

This drilling - which is under an angle - from the housing meets a drilling vertically from the fireface (lower face of the cyl head to the head gasket to the cyl) very close to the rear right stud. This is the oil return for the intake valves.

This vertical drilling is very close to the right intake port, it's a matter of a few mm on std heads - which have 28.5mm ports. A 32mm port therefore already 'eats away' a little less then 2mm from these "few mm".

This might result in a little perforation or breakthrough or whatever from the intake port to the drain hole. This means the engine will suck in oil from the return path - very much like a worn intake valve guide or seal. I have one head where this definetly happend on a 32mm port but as I haven't seen it in use I don't know how bad the effect is. I also have one head which had a 30mm porting and I suspect that it might have the same problem because there is traces of slight over-oiling on the RHS cylinder.

The manifold has nothing to do with this, if this problem is there it will be in the intake port in the cylinder head - from the manifold flange to the valve seat. And from memory I'd say that it is about two inches down the port from the manifold flange. The drilling is to the right of the port seen from the rear so the port will be closest to this drilling at the three o'clock position (right hand "edge" of a circular port sounds a bit odd, doesn't it?).

On my RH4 head it is visible and tangible that there is 'something'. To be 100% sure that it is a leak I'll put it on the bench, spray some "leak finder fluid" in the port and pressurize the drilling from the intake valve housing - but this head is obviously fully disassembled.

I really don't know how common this is but I know that the problem might occur. All these old castings, especially something rather complex like this head, suffer more or less from porosities etc. and from what my experience with castings it might be that the port core could actually cause porosities in this area depending on the riser and feeder system but that is just a wild guess.

and if so what to do about it please?

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If it really is the case you need to fill that breakthrough and there is several ways to do so. My RH4 head will get a TIG spot weld there and I'll clean the port. Probably I'll also add an external drain between the ports and forget about said drilling.



Tim

A few years back i had a 650ss with smoke problems, I had fitted valve stem oil seals, but the smoke still puffed out.
Then i noticed the following: the valve on full lift,pushed through the seal, the seal edge was sitting on the valve collet taper, [gap all round] this allowed oil to enter the seal top edge. ..then when the valve started to close,it sqeezsed the
oil down the stem.
In effect "pumping " oil down ! I shortened the valve guide which lowered the seal and that cured it. are commando valves/guides and hight differant?

john robert bould said:

are commando valves/guides and hight differant?

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Yes, the old type of guides take no seal and set higher, so if a seal were put on, it would do as you say, ride up on the taper.
My new/old head (rh1) had these old type guides and I had Jim swap them out and recut the seats. Because i have the beehive springs, the taper is even further down on my valve stems so I had no real option unless I chose to reverse my intentions.

To be clear, I am not saying that this is Ozt's issue.

Thanks guys for the clues. I'm awaiting the results from the insurance people to see if I get the bike back or not, that they say will be in about 3 weeks times. fingers crosses.

If I get it back think I will take the inspection cover off to have a look, or you reckon whatever happens the head needs to come off for a proper inspection anyway? Probably I guess so.
Head gasket sets from Andover Norton I guess here in England?

You could use the copper rings and wire and up your compression 1 point. JS motorsports.

Dave
69S

Morning fellow Commando owners, how's it going?

This is an old thread and I only just saw it whilst I was googling for a plastic centre console for the Commando and saw this. Forgot I was a member and had posted this!!

Update on the bike, well they did write it off, Cat C or 3, too expensive but no structual damage. the garage quoted over £3k, included were new petrol tank, exhaust system and heapsa other stuff that weren't needed. So I brought the bike back and slowly been getting bits for it.

The bent forks just turned out to be bent handlebars. Got most things, latest bits ordered today new bezel and rubber seal for the speedo. I know it's been a few years but the bike has just been sitting in the garages, too many other things but this winter is the time to sort it out.

What I think I have left/need to do... (this list is as much for myself!!)
1) fit speedo bezel
2) fix seat locking knurl nut
3) sort mikuni carb out, slide's chrome worn but usable I think, pilot jet seems blocked
4) put new handle bar and switch gear on
5) check front after market disc brakes
6) either find a centre plastic console for ignition switch and warning lights, or make one up myself
7) take head off see if valve seals are u/s, to see if I can find the cause of the pot smoking badly after a hard run
8) get new battery and see if the bike fires up after doing the old smoking problem

and I think that is it. sure I will find other bits and pieces to do, but aim to start end of this month the restoration and get the bike MOT'ed for spring next year and on the road!

Gees that was a heapa waffle, but I think it has concentrated my mind on doing something about the bike, I had forgotten about it the last couple of years. and remind myself how lucky I am to have the bike, after all, it was my dream bike back in '76 when I was running my Matchless! (which I still have)

Must get out to that garage soon!!!