Blue Smoke on decel and accel

Information relating to the Matchless G85 500cc Heavyweight, AJS 7R, Matchless G45 and Matchless G50
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Re: Blue Smoke on decel and accel

Postby SPRIDDLER » Wed Jan 17, 2018 2:23 pm

Matchymarty wrote:My previous piston was a Wellworthy, and currently using a JP Piston (Aust) rings. Top two rings do not have an up or down, ie. no rebates or chisel shape to ring. Oil ring is 'solid' as in 1 piece ring, with slots cut in it, and also does not have an up direction to my knowledge. In anycase, my engineer gaps the rings and installs them on the piston for me, as he know's the rings and pistons well, and that way I don't stuff up which way they go on. Current 'new piston' is a JP +0.060" and has been ceramic coated.

Well that seems o.k. then.

As for the oil coming from the spark plug hole, the oil seems to seep past the plug during running. Now, the first 18-20 miles, this did not seem to happen. Only on returning after 30 miles had been done, and the bike stopped and wouldn't restart, did I notice the oil on top of the head and surrounding the plug.

Too much oil getting into the combustion chamber (as we are already well aware) combined with a (not unusual) poor seal at the plug washer.

As for the crank case breather, it always seemed to push oil out of the long hose I had finishing near front of back wheel. Always made a mess. Does this mean too much oil in the sump?

I would think that the long hose was fitted either by the previous owner or yourself, especially in an attempt to cure this topic's chronic and ongoing oil/smoke problem when it first arose, Is the 'long hose' still fitted? Since the breather points downwards a hose would normally have be routed upwards to its open/ discharge end. This means that instead of a fine oil mist constantly drifting down onto the road via the standard approx 3" long breather tube a dollop of coagulated oil will collect in the lower run/loop of the hose causing back pressure and inhibiting the free movement of the breather disc. In addition, if the oil puddle/dollop in the long hose is causing back pressure or even blocking the hose the crankcase pressure will increase forcing oil up the bore to get burned, make smoke etc.
Perhaps you haven't re- fitted the long hose so I won't waffle on about the possible effects of it any more :roll:

The main issue seems to be one of a smoky zorst and the plug oiling up, whether that's from oil coming down into the combustion chamber from above, or being forced up from the c/case. However, the consensus seems to be that it's oil being forced up from the c/case and also out of the c/case breather. Since these symptoms don't occur in the first 10 miles or so after start up it's unlikely to be a case of wet sumping. Therefore I suggest that you a) drain the crankcase and then go out for a run until the smoking starts (take a spare plug with you!), return home and drain the c/case to measure how much oil has collected. Then just for the sake of eliminating the wet sumping possibility replace the drain plug and leave the bike a minimum of 24hrs and drain the c/case again.
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Re: Blue Smoke on decel and accel

Postby Matchymarty » Wed Jan 17, 2018 6:12 pm

Sprid,

I actually suspected something to do with the Long CC breather pipe. Not quite as smart an idea as yours mind, but thought something could be up none the less. I hacked it off before my first start up with new piston in it so it pointed down below the engine around 3" coincidently.

For clarification, my '30 odd miles' is the total of mileage broken up into 3 separate rides after installation of new piston, rings, rebore and head decoke and valve lap. For further clarification, the head had previously been checked and had one guide sleaved and one was 'within tolerance'. Certainly, was disassembled and blown out and cleaned before putting back on with new piston etc.

Thanks for the tips on CC pressure and wet sumping. Didn't get home till late last night so, didn't get to run it and check things. Will do today, as I asked the boss for the day off to investigate my old bike woes! ahahaha.

More checking to do! :) cheers.
Marty


SPRIDDLER wrote:
Matchymarty wrote:My previous piston was a Wellworthy, and currently using a JP Piston (Aust) rings. Top two rings do not have an up or down, ie. no rebates or chisel shape to ring. Oil ring is 'solid' as in 1 piece ring, with slots cut in it, and also does not have an up direction to my knowledge. In anycase, my engineer gaps the rings and installs them on the piston for me, as he know's the rings and pistons well, and that way I don't stuff up which way they go on. Current 'new piston' is a JP +0.060" and has been ceramic coated.

Well that seems o.k. then.

As for the oil coming from the spark plug hole, the oil seems to seep past the plug during running. Now, the first 18-20 miles, this did not seem to happen. Only on returning after 30 miles had been done, and the bike stopped and wouldn't restart, did I notice the oil on top of the head and surrounding the plug.

Too much oil getting into the combustion chamber (as we are already well aware) combined with a (not unusual) poor seal at the plug washer.

As for the crank case breather, it always seemed to push oil out of the long hose I had finishing near front of back wheel. Always made a mess. Does this mean too much oil in the sump?

I would think that the long hose was fitted either by the previous owner or yourself, especially in an attempt to cure this topic's chronic and ongoing oil/smoke problem when it first arose, Is the 'long hose' still fitted? Since the breather points downwards a hose would normally have be routed upwards to its open/ discharge end. This means that instead of a fine oil mist constantly drifting down onto the road via the standard approx 3" long breather tube a dollop of coagulated oil will collect in the lower run/loop of the hose causing back pressure and inhibiting the free movement of the breather disc. In addition, if the oil puddle/dollop in the long hose is causing back pressure or even blocking the hose the crankcase pressure will increase forcing oil up the bore to get burned, make smoke etc.
Perhaps you haven't re- fitted the long hose so I won't waffle on about the possible effects of it any more :roll:

The main issue seems to be one of a smoky zorst and the plug oiling up, whether that's from oil coming down into the combustion chamber from above, or being forced up from the c/case. However, the consensus seems to be that it's oil being forced up from the c/case and also out of the c/case breather. Since these symptoms don't occur in the first 10 miles or so after start up it's unlikely to be a case of wet sumping. Therefore I suggest that you a) drain the crankcase and then go out for a run until the smoking starts (take a spare plug with you!), return home and drain the c/case to measure how much oil has collected. Then just for the sake of eliminating the wet sumping possibility replace the drain plug and leave the bike a minimum of 24hrs and drain the c/case again.

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Re: Blue Smoke on decel and accel

Postby SPRIDDLER » Wed Jan 17, 2018 11:27 pm

Hmm, well, at this distance and short of going back and running through all the previous checks you've made I'm running out of ideas.
Really widdling in the wind now but is the inlet valve oil regulating screw the correct one; is it pointed, or has someone just stuck a blunt ended standard bolt in there?
Is the primary chaincase becoming overfilled with oil (i.e. from th'engine?)

I think you still have to check that the end plate on the oil pump isn't leaking and sucking in air. Do you get a good oil return at the tank? At low'ish engine revs it'll probably be returning in spurts or pulses rather than a solid continuous flow since the oil pump is the oscillating plunger type rather than a rotating vane type of pump.
However, there still remains the issue of the bore quickly becoming scored and signs on the piston of seizing. It isn't completely unusual or a total disaster if an engine nips up slightly when being run in but obviously it isn't desirable and it does throw doubt on the true cause of the smoky zorst and plug oiling.
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Re: Blue Smoke on decel and accel

Postby Matchymarty » Thu Jan 18, 2018 4:29 am

Sprid,

To answer your last set of queries. I've now wound inlet oil feed screw all the way in. Tick. Brand new feed regulating screw and it's pointy. :)
Drained sump this morning with a 'Matchless whisperer' as my witness. (get to that in a minute) And he was absolutely ok with the amount of oil in the sump, and it has been standing since Tuesday morning, now Thursday morning when I drained it.

Chaincase does not appear to be gaining any oil. CC relief breather seems to be working great, and Oil return is also as it should be according to the MW (Matchless Whisperer).

Right. To get on with today's events. Through deperation, I rang a guy who knows a guy who knows about a guy who is a guy who knows Matchless'. I rang, and turns out he's the most helpful man, and seems to be quite the Matchless encyclopedia. It's not what you know... it's who you know who knows other people who knows the right people.

So, teed it up, took the day off work, and took my bike to him this morning. I hadn't touched the bike so, that he could see what we were dealing with.

He looked at the oil fouled plug. He peered in the plug hole and said the bore still looks fine. I started it with a new plug. he played with it, revved it a couple of times, diddled with the advance retard, and listened. He says'... "that's mostly black smoke... bottom end richness." We pulled the carb, he looked at it, measured the choke size and consulted his books.

I was running a 260 main. He believed it should be more like a 380-400 for the 389 monobloc it has with a 1 1/8" choke size. All I had with me was a 400 and he had a 350. We tried both. He didn't like the plug after a bit of a run around the streets and a chop. Still a bit lean he said. Popped in the 400 (I run a pancake filter too) and he was happy with that plug chop, I was happy with the throttle response and, he said... "that my friend is why you cooked the last 2 pistons!".

See, the bike had that jet in it when I bought it, and, as far as I could find out in the books, it seemed about right, and the slide, NJ etc all checked out too. Also, I have NO idea what these bikes are supposed to perform like, so can only go from what other old guys say when I ask them.

Funny, I've always said to my partner's father whom has had Matchy's all his life, "Why doesn't my 500 go up the hills any better than your 350?" He replies with" oooh theres' never been that much difference mate... your's goes fine don't worry about it!". Then... I see photos online of G80CS's in scrambles with dirt roost flinging from the rear tyre, and know for a FACT mine will NOT do that! So, I've always wondered....

Sorry... getting side tracked.

So. It seems according to M.W., that predominately, my problem is lack of fuel. HOW? Well he believes, it's labouring, preignighting, and running hot, causing the oiling issues and, most likely the excess oil is coming from the head, and, as such, the combustion is not burning fully due to lack of fuel, and round and round it goes. Additional heat, preignition, extra load on rings, seals, etc etc etc all due to inefficient burn and power.

Even longer story short, I had three test rides with him, with different jets, and with the inlet valve oil feed screwed in. The oil burn cleaned up nearly completely straight away, and he said I was pussy footing the engine too much. It shouldn't need that now that fueling is correct.

Here's to fingers crossed!

Thank you all for your help, it is invaluable. I'm an novice backyard mechanic, 40y/o and only with around 2 years of experience of owning old bikes and working on them. I'm certainly learning lots and I'm certainly not afraid to try! Thank you again. Knowledge is dying here in Australia, and access to such knowledge here, is quite limited, and only certain numbers are willing to even talk to me. It's a hard process, but I love it!

Will post an update soon after a few more test rides. Fingers Crossed!

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Re: Blue Smoke on decel and accel

Postby SPRIDDLER » Thu Jan 18, 2018 9:04 am

Yep, there may be some logic in that; a weak mixture (undersized main jet) could cause overheating although I'm still not convinced that an undersized main jet/overheating would cause excess smoke, but it isn't something of which I have any first-hand experience. Sadly the colour of the smoke wasn't visible from here. (Could've asked I suppose but your topic title did say 'Blue smoke on decel and accel' ;) )
But it wouldn't be fun if it was easy!
Keep us posted.
:beer:

P.S. Whilst on the subject of overheating/sluggish performance (and in view of the P.O. possibly having fitted the wrong main jet) it may be worth mentioning that this can also be the result of over-retarded ignition (but we won't go there).
Last edited by SPRIDDLER on Thu Jan 18, 2018 10:54 am, edited 1 time in total.
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Re: Blue Smoke on decel and accel

Postby SPRIDDLER » Thu Jan 18, 2018 10:45 am

Have just had a look at carb spec'ns in the original Owners Manuals in Christians Archive here: http://archives.jampot.dk/book/Owners_manuals/.


A smaller main jet is used when a filter is fitted. The '54 data ('old type' 89 carb, with and without filter) is:
54 CS carb data (640x199).jpg


The '55 data (389 Monobloc carb- presumably without filter - see NOTE re early '55 models up to engine number 27000):
55 CS carb data (640x276).jpg



Interestingly the nearest data I can find to your 400 main jet (389 Monobloc carb) is for a '56 short stroke CS (open pipe) CS. This data is from the Competition Models Supplementary List here: http://archives.jampot.dk/book/Owners_m ... ctions.pdf


56 CS carb data (640x257).jpg


Enjoy!!!
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Last edited by SPRIDDLER on Thu Jan 18, 2018 4:33 pm, edited 1 time in total.
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Re: Blue Smoke on decel and accel

Postby Mick D » Thu Jan 18, 2018 11:05 am

Hi

Good luck and I hope you've made progress but there are some significant anomalies with the MW's diagnosis:

If you have a 389/1 fitted, (which incidentally should have a 1 5/32" bore, (have you mis-measured?), the main jet should be a 260, pilot 30, needle jet .106, needle position 3 and a 3 1/2 slide.

A weak mixture does not produce black smoke - this is normally indicative of a rich mixture.

You say the smoking has almost stopped - and that you've screwed in the inlet valve oil feed all the way - there may be a link here.

As I say - good luck but I can't help feeling you're further away from a result than before.

Regards Mick

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Re: Blue Smoke on decel and accel

Postby Matchymarty » Fri Jan 19, 2018 1:10 am

SPRIDDLER wrote:Yep, there may be some logic in that; a weak mixture (undersized main jet) could cause overheating although I'm still not convinced that an undersized main jet/overheating would cause excess smoke, but it isn't something of which I have any first-hand experience. Sadly the colour of the smoke wasn't visible from here. (Could've asked I suppose but your topic title did say 'Blue smoke on decel and accel' ;) )
But it wouldn't be fun if it was easy!
Keep us posted.
:beer:

P.S. Whilst on the subject of overheating/sluggish performance (and in view of the P.O. possibly having fitted the wrong main jet) it may be worth mentioning that this can also be the result of over-retarded ignition (but we won't go there).


You are absolutely correct SPRIDDLER. Seems that undersized main jet, did cause mild seizures of previous piston installations. The smoke I saw after my 30 run in miles this time around, in the light of day, (and under the watchfull eye of my new found best friend and Matchless Whisperer) was indeed actually, black smoke (he called it rich bottom end smoke) and a puff of blue, which, we rectified by screwing in the inlet valve oil feed screw to seat. At the end of our testing yesterday, there was no more blue, and black had cleaned up due to turning the throttle a little more. Again, fingers crossed for more run in miles.

Also, you are right on with your comment about overly retarded ignition. I, yes, [insert heckling here] do not know how to time correctly via the use of a timing disc. I use the ye ol' stick in tha plug 'ole trick and measure 1/2". I do get kick back, so have always thought timing was pretty good. Next on my list is to learn how to do it properly for more precise timing. Matchless Whisperer seemed ok with my timing as it stood, but did not check it.

Time for some more fun run in miles. :)

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Re: Blue Smoke on decel and accel

Postby Matchymarty » Fri Jan 19, 2018 1:19 am

Hmmm, and yes. You're '55 data is exactly what I'd been using to date. It says a 260 main etc. Which is pretty much what my bike was set up with when I got it. My new friends extensive data says otherwise, and incorporates cam usage etc also. His documentation immediately asked for a 389 with a 1 3/16", #3 1/2 slide, D 106 needle, 30 pilot and 400 main. Both my '55 and '56 have SH cams.

The 400 main, actually came out of my '56 G80CS with a 389/12 monobloc.

You can now imagine my suprise when he told me and showed me the documents he has, showing the much larger main than what I had found in the very information you have provided here SPRIDDLER! :)

Seems, there is a whole lot of information out there that is not available readilly. I'll be doing my best to get a copy of such and will pass it on when I can obtain it. :)


SPRIDDLER wrote:Have just had a look at carb spec'ns in the original Owners Manuals in Christians Archive here: http://archives.jampot.dk/book/Owners_manuals/.


A smaller main jet is used when a filter is fitted. The '54 data ('old type' 89 carb, with and without filter) is:
54 CS carb data (640x199).jpg


The '55 data (389 Monobloc carb- presumably without filter - see NOTE re early '55 models up to engine number 27000):
55 CS carb data (640x276).jpg



Interestingly the nearest data I can find to your 400 main jet (389 Monobloc carb) is for a '56 short stroke CS (open pipe) CS. This data is from the Competition Models Supplementary List here: http://archives.jampot.dk/book/Owners_m ... ctions.pdf


56 CS carb data (640x257).jpg


Enjoy!!!

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Re: Blue Smoke on decel and accel

Postby SPRIDDLER » Fri Jan 19, 2018 11:27 am

Well you do seem to be making progress. Personally (other opinions are available) I wouldn't get too hung up on relatively minor main jet or slide variations vs various bits of documentation as these can be tweaked for best performance once you are satisfied vis-à-vis the smoke and overheating issues. It's worth bearing in mind that up to about 1/3rd throttle opening th'engine is being supplied mostly by the Pilot jet, then Pilot jet and slide/needle up to half throttle, then slide/needle and main jet up to full throttle. Much of the time most of us are running around locally at half throttle or less therefore the Pilot jet setting is important.
You may find this carb tuning guide useful/interesting:

http://www.hitchcocksmotorcycles.com/mo ... to-tune-up

As far as ignition timing goes I have only ever used the 'stick in the hole' approach which I find entirely satisfactory and far more straightforward than faffing about with a timing disc and which isn't as easy to set up on our h/weight singles. On a minor point, with modern fuels and on touring engines I time to 7/16" BTDC at full advance (set points gap first) but to be quite honest if you time to 1/2" BTDC you can fiddle a tad with the A/R lever and experiment whilst out on a ride. My ignition is on full advance when the cable is tight (i.e. pulled) so when I set the timing on an unfamiliar bike I leave a bit of movement (1/4" of cable) available at the handlebar lever so that I have a bit of adjustment to play with whilst out on the road. On some magnetos the ignition will be fully advanced when the cable is slack. There is frequently confusion with new owners as to which way to move the lever for advance and retard. I assume you must have this clear in your mind........?
Not wishing to bore you but when setting the timing it's best to loosen the lower mag chain sprocket to make adjustments rather than the upper sprocket on the mag shaft since it's easier to prevent the lower sprocket from moving when you tighten the sprocket nut.

High tech wire coat hanger timing probe:

CIMG4398_zps5b2c3873 (240x180) (240x180) (240x180) (240x180).jpg


CIMG4402 (480x360).jpg
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