Spurious non starting for no apparent reason

[Bananas]

So...putting the kickstarter issue to one side (and as I cannae do bugger all fault finding til it's resolved I might as well throw this out there)...

the damn thing decides of it's own free will to not to fire up, despite a couple of months ago having no problems what so ever.

There's fuel there...and it's getting to the carb.

There's a healthy spark when I kicked it over.

There is sufficient resistance to my right foot when trying to start it to indicate there is compression (not got the gauge on it yet - but nothing to suggest there is a problem in that department).

Hmmm...

Perhaps I should point this out tho, as I think herein may lie the crux of the problem.
Since I bought it at the beginning of the year, I like the previous owner before me, have been running it pre-mix. Not a problem for me, but I was getting peed off by having to carry a pot of 2T around just incase I had to fill up with fuel whilst out on it. No idea if the carbs been re-jetted for pre-mix or not, but seemed to run fine regardless.
So, thought "bugger it, I'll start using the oil pump as intended, that way I only have to top the oil tank up each time I go out and can leave the castrol ttx on the shelf in the lockup".
Being a crafty old Hector (ie. knowing the foibles of 2 strokes and having been caught out like this before) I had an understandable distrust of things on a 22 year old bike that hadn't been used for a while working properly, so filled up as normal with fuel and slightly reduced the premix as well as filling up the oil tank - just in case the pump didn't work properly and left me running sans oil with the disasterous consequences that comes with that. My thoughts being "I can handle the engine running a tankfull overoiled rather than running dry, that way I can check the pump works properly without any risk of seizures!" If it meant 100 odd miles of having to clean the plug occassionally and it being a tad smokey, then so be it. At least I'm erring on the side of caution.

I did obviously check the setting of the oil pump before running it I should add...

Anyhoo, ran fine the first couple of times I tried the bike, yes a bit smokey but all seemed fine.

Didn't ride it for a fortnight or so (having another daily bike at my disposal means the CRM does spend most of its time in the dry and warm), but when I go back to it inspection of the oil indicator pipe on the frame seems to show that a quantity of oil has mysteriously disappeared since I last looked - certainly more than I would have expected to us. Again fired it up and it ran as normal but was very smokey whilst warming up. Still, couple of laps around the field it seemed fine, nothing to worry me.

So there's me considering the implications of the missing oil. Searching this forum and it looked like the probably the oil seal between the pump and engine case had probably gone south, and hence dribbling 2T into the sump. A nusance, but not the end of the world as I would just drain it completely of oil and refill, and keep running it premix. Problem solved!

So, we come to a few weeks later, and the 2T appears to have drained completely out of the oil tank when I go to use it. It is at this point that the bladdy thing decides resolutely not to start (and the eventual destruction of the kickstart occurs). Ok, I think, probably all the 2T is now in the sump and causing a lot of pressure down there, possibly working against the engine. I drain it out - at a guess around 750ml off grey/black oil comes out, maybe a little more than would be expected from the sump normally, but not as much as I would have expected from there if the best part of a litre of 2T had ended up swilling around down below as well.

The plot thickens...

Refill the engine oil with nice fresh and expensive stuff (I don't scrimp when it comes to stuff like oil) and try firing it up again. Still it won't run...bugger!!!!

So here in lie the questions I need answering...

1. any idea where the 2T has gone? I'm starting to think the internal seal on the oil pump has perished from not being used and has dribbled through by a combination of gravity/suction/capilary action via the carb into the crank case. Anybody else been victim of this scenario or am I barking up the wrong tree? If so, how did you get it back out again without splitting the crank cases (I sooo don't want to have to do that unless it really is needed!)

2. if a litre of 2T sitting in the crankcase isn't the reason for it running (I'm thinking big resistance to the crank turning and oil hitting the plug killing the spark perhaps - I checked the plug initially and it was both wet and very black) then what on earth has happened since I last ran the thing and now to stop it firing up.

A long winded post I'm sure you will agree, but I thought I'd give you all the facts to save the "have you got petrol in it/cleaned the plug etc...." questions, and to give you CRM gurus the facts to base your assessment on.

I suppose I should say that I'm not a novice at such things as spanner weilding on 2 strokes (I have many years experience of knuckle bashing and cursing at various bikes), although the 3 other currently non running machines gathering dust in my lock-up I suppose should be taken into consideration!

Cheers!

[knackeredMk1]

It is bad practice to put oil in the premix and use the pump. This could explain the black wet plug because the engine is being way overdosed with oil. If there is a lot of oil in the crankcase you will need to drain it out. This could cause the engine to run very rich or not run at all depending on the level.

If you want to use the oil pump you would probably be best to replace the whole thing with a known working one.

This is very partial answer to your questions but I think you need to do more exploring ........

[Bananas]

[quote="knackeredMk1"]It is bad practice to put oil in the premix and use the pump. This could explain the black wet plug because the engine is being way overdosed with oil. If there is a lot of oil in the crankcase you will need to drain it out. This could cause the engine to run very rich or not run at all depending on the level.

If you want to use the oil pump you would probably be best to replace the whole thing with a known working one.

This is very partial answer to your questions but I think you need to do more exploring ........[/quote]
Agreed, running both premix and oil pump is not good practice, but considering the unknown state of said oil pump it is sensible practice for less than 1 tank of fuel to determine whether the pump is functioning correctly. Judging by the result of said test, I'd say it was a good job I did as running just the oil pump probably would have starved the engine of lubrication and potentially done a considerable amount of damage.

The plug had been cleaned, and the deposit on it when I rechecked was not indicative of an engine which had been running at 150% approximate over oiled for less than a miles worth of running, but considerably more therefore making me think that possibly there was unburnt 2T lurking in the crankcases.

Drain the crackcase if there's oil in it you say? Errr...yeah...NSS...how without splitting the engine was what I was asking! lol

As I said, running it on premix is no great shakes, it would just be more convienient to use the pump. As it is looking probably knackered (unless someone can suggest that there is some other reason for the oil level dropping excessively) then I may invest in one should I really feel inclined.

Yes, you've hit the nail on the head there...a bit more exploring is required...

[knackeredMk1]

Take the plug out. Turn the bike upside down and stand on handle bars and seat to drain over a few days. Empty tank first .

Way to test if oil pump is working is to fill oil tank and bleed system. Then put output pipe into some bottle or sort. Then run on premix whilst checking for pump output. Also check pump cable alignment as detailed in FAQ section.

[voodookid37]

stand on the bars for a few days...........he'll be "knackered" and nod off for sure......

sorry couldn't resist.. hahaccc