Start up smoke

[Sheep]

Hi guys...

Long time no speak...apologies for the lack of input in recent months but my Suzuki has been either wrapped up (other projects on the go) or performing well with no issues...

Until now...

So,I've recently had the Efe out a bit more as I've had some more time for it and I've been planning to pop along to the Efest at Cadwell.I decided to tweak the carbs a little to get rid of a hanging throttle by oiling and adjusting the cables,checking float heights etc etc...I then went away on holiday for a week,came back and gave the old girl a fresh oil change, and thought I had better check all tweaks and there's no leaks...

The ride out seemed OK although I felt it was struggling on power a little.It didnt seem as crisp as it normally is..(the hanging idle still remained)

I left the bike overnight,had a ponder and decided to give the mixture screws (RS36s) a 1/4 turn out...I started the bike and was confronted with a cloud of blue grey smoke from cylinder 1 but I had a good stable idle now lol...once the smog cleared (20 secs) I checked the oil level and to be honest I may have put a little too much in so I was thinking I may have popped a stem seal off a valve somehow (crankcase pressure??)

Next day was Cadwell (yesterday),got the bike out and again the smoke came and went within seconds...the bike ran fine all the way to Efest...then it was time to go home...fortunately I was the last to leave so that saved me the embarrassment of choking everyone.Again it chugged and cleared however this time it fouls the plug so I ended up leaving on 3 cylinders...on the way home my rear master cylinder decided to mess me about resulting it a red hot sizzler of a brake disc.It turns out this was the likely cause of the lack of power as it accelerated better even on 3 cylinders....

Anyway,the old thing got me home,I threw another plug in there and it ran on all 4 fine....

Tonight I removed the cam cover to see if I can see a dislodged stem seal but I couldn't see bugger all so I started to consider it's a head off job unless there was a way of doing in situ with the compressed air trick,not that its a massive job to be fair. Note:These seals are the Viton type i believe fitted when I went 1230 around 2000k ago.

While I was looking in the top I noticed pistons 1,2 and 4 had a little 'moisture' on their crowns,still quite shiny though yet #3 was dry, if a little sooty.

And the crowning glory ( no pun ) was the noticeable dullness on #2 and #3 exhaust lobes...

Now that I've bored you to death has anybody got an opinion on whether they think my seal has popped and would the oil level have caused it?...and more importantly, do you think my cams are goosed??..

Sorry for the long winded post but I wanted to paint a picture of events.

Any help,advice,piss taking welcome...

Thanks guys.

 

 

 

Edited July 21, 2025 by Sheep
Photo removal

[jb]

Is it possible that you’ve got fuel leaking in to the engine when the bike is standing?

[DAZ]

If you don't have an adapter for the compressed air trick , you could try feeding some para-cord into the cylinder just before tdc then gently wind the motor to tdc to squish the cord into the chamber ,did  this on a car engine once to change a damaged retainer after a rocker arm broke ..

[Gixer1460]

Can't see how crankcase pressure could pop a valve seal off - the pressure would be 'on' the seal, not under it! V seals usually fail due to age or getting mashed by the valve spring retainer. Over filled oil and parked on side stand usually / can result in smoke. If the top end is wet or 'coked' and you are fouling plugs then probably the carb tweak has gone the wrong way? Has it been dyno'd or had a wideband lambda used on it - best thing for tuning IMO!

[Sheep]

Cheers guys for replies...

The smoke has only appeared since the oil change 3 days ago and regarding the over filling,I get that on the side stand it would pool in #1 corner and weep through a worn seal at rest but surely it would still weep past the stem during normal use as opposed to just on start up..The seals are not that old really...it's an odd one.

As for fuelling,the bike has always started and ran pretty well with no fouling or misfiring but the carbs on it were second hand after I swapped them for some previously fitted 40's...jets are all recommended sizes and they are bench synched within a gnats cock of each other..the only fouling of the plug was last weekend when the weeped oil wet the electrode causing a failure to spark....on closer inspection it seems the piston crowns are not wet as such just clean were ss #3 is sooty on its own,but as you say,a dyno is the best way.I'll have to do that once I get the other issues done.

Edited July 22, 2025 by Sheep
Addition

[Sheep]

Well I think I got carried away...

What turned out to be a quick look to decide what to do ended up being a 'just one more bolt' and I'll pack up for the evening...

On a positive note I found the exhaust valves on #1 were a little oily so I can safely say i found the leaky seals (still wonder why it happened overnight as opposed to over time but hey ho).I thought about removing the seals in situ but my thoughts are if #1 seals are iffy chances are the rest are not far off..So off with the head and do it properly...

The piston crowns were actually in good clean and dry condition although #3 was a little carbonised.

On a less so positive note I found a broken cap cap bolt so that alone convinced me to whip the top off....

Just another chapter in Suzuki ownership..

 

 

[Gixer1460]

Bugger ! And down the hole as well - have to sneak up on that one . . . . . left hand drill bit I think?

[Sheep]

2 hours ago, Gixer1460 said:

Bugger ! And down the hole as well - have to sneak up on that one . . . . . left hand drill bit I think?

Haha..yeh..no idea how long it was like that!..To be honest I expected 3 more because as i was sequentially undoing them some 'cracked' but it didn't feel in a good way but fortunately it was just the one...

 

[Sheep]

It seems apt that the words of the late great Ozzy Osbourne 'Paranoia' come into play but if i didn't know better but I reckon this valve seat isn't a happy bunny...I shall bring some dye penetrative spray home tomorrow and take a more educated look

 

[clivegto]

On 7/24/2025 at 7:09 PM, Sheep said:

It seems apt that the words of the late great Ozzy Osbourne 'Paranoia' come into play but if i didn't know better but I reckon this valve seat isn't a happy bunny...I shall bring some dye penetrative spray home tomorrow and take a more educated look

 

O bugger 

[Sheep]

I think it a false alarm...

I dye penned it and it looks to be just a surface mark...I did it twice to be sure...either way I may have to take it to Grumpys to ask his opinion on possible valve to stem wear...I don't have the proper tool to measure it and the dial gauge method is a little hit and miss...

[Sheep]

Popped over to Grumpys today and received confirmation that the valve guides are toast so I left it with him to sort...

Dangerous place his workshop..so many tempting bikes on stands,parked outside and pretty much every corner...it's like an Aladdins cave of older Suzuki bikes!!,it hasn't changed a bit...good stuff.

[Sheep]

Hi guys,

Little update..recently received my rebuilt head back from Grumpys and started putting it all back together. I also sourced some nearly new RS36's as im struggling to get my existing set to run perfectly. 

Anyway, I started it up last night and was greeted by a bit of smoke which was the main reason I stripped the top end initially..Thinking it could be residual oil/petrol in the exhaust i ran it for a bit but no let up in smoke.

Tonight I had another go after 'resting' it but still the same.So, i checked the oil level which as mentioned before was probably a little too high and emptied around 500ml.I started it again and surprise, no smoke....I'm still not 100% convinced but could it really be that simple???....(the carbs sound much better and the idle is crisper with no slide rattle)...

Don't get me wrong,if it's solved then happy days but it seems too good to be true...is it?

[Gixer1460]

500ml is about 12.5% of total capacity so not a bit, it's a lot and could definitely be responsible! At or a bit low is good, over isn't.

[Suzukian]

Overfilling on my 1983 GS750ES will definitely cause some smoking exhaust.  My bike has 40K miles on it now, and it has a natural wear blue smoke that disappears after she is well warmed up.  I know it is the valve stem seals.  I hesitate to do them, as the old gal is fragile.  Two of the valve cover screws stripped.  I took off the cover and Heli Coiled all of them.  One hole that holds down the rear camshaft literally disintegrated.  As these parts are line bored, they are not available or interchangeable (well, not without some work).  I used a product called Alum-Alloy, and threaded a bolt into the hole that was there, luckily enough threads remained to get a nice straight bolt in.  Heating it up till the Alum-Alloy started to melt and bond with the aluminum, I built it up.  I then unbolted the bolt and was able to tap in a Heli COil into the thread, allowing me to torque the cover.  It makes me a bit afraid to touch her, as I have owned her since new.

 

I would just do a light valve lapping using a valve lapping compound to get a nice clean finish. 

 

Link=  https://www.alumaloy.com/

 

 

Edited October 9, 2025 by Suzukian

[Blower1]

I have about a liter of overfill in my GSX/R mix and match engine and it doesn't smoke at all. Although it has two oil pumps and two oil coolers. If the oil rings are in good condition and the upper piston rings are facing the right way, the engine shouldn't smoke even if there is a little too much oil.

 

 

 

[Suzukian]

Blower1

I took a look at some of your  projects pics.  Damn, you are so far out of my league.  Very impressive.

Edited October 9, 2025 by Suzukian

[TonyGee]

2 hours ago, Blower1 said:

I have about a liter of overfill in my GSX/R mix and match engine and it doesn't smoke at all. Although it has two oil pumps and two oil coolers. If the oil rings are in good condition and the upper piston rings are facing the right way, the engine shouldn't smoke even if there is a little too much oil.

 

 

 

yes ive seen bikes with way to much oil in them and no smoke, but as you say its probably down to how worn the rings are. 

[Suzukian]

I'd also add how old the Intake valve seals, and valve stems.  

[Sheep]

Thanks for the replies guys,

Regards to the engine, it's a 1230 with no more than 7k on the big bore kit...that's very approximate as i do not run a odometer. 

[Suzukian]

Those intake valve stem seals get hard, and will cause the bike to smoke.  Mine does, but only when it's cold.  After it warms up, it's fine (verified by other riders behind me).  I don't want to touch the engine as I purchased this bike new in 1983 and have had to do nothing but a couple of clutches, and a stator, Reg/Rect repair.  I'm not going to tear down t the engine for a little smoke, especially as the spark plugs read fine after a long ride.  That day may come, but it has 40K miles on it, and still runs as fast as it seemed too when I got it.  It's a looser motor, so it does seem to rev quicker.  When that time comes, I will put the bike back together, but keep it stock.  Besides, I have a ZZR1200 if I want to go really fast, and that has only 3700 mils on it.