Hi, After a run, I have a petrol/oil leak seaping from the lowest part of the exhaust on my MK2 project, the top end has a slight knock, i'm guessing that maybe all the fuel is not being burnt due to worn piston/rings. I'm planning on rebuilding the top end now i have got the MOT today. Apart from the small hole I must have on the exhaust weld, is there anything else I should check ?????? PS. She also like a smoke when giving it some !!.
Any helpfull advice will be appreciated. Thanks John

definitly not a 2 stroke guru but I would say for certain your rings that have gone mate
- don't ride it many more until you get it sorted - and you might save yourself some money on a rebore.
check that the only knocking sound is definitly coming from the barrel and not lower down on the engine (gear box). As after I did my top end I realised the knocking was still there and it turned out to be one of the main
bearings that caused one side of the ring(s) to wear and cause the initial seizure.

Have a look here - it will give you some usefull info on things to inspect when you take the barrel off.
http://www.offwidth.co.uk/bike/crm_rebuild

the reason why it is probably smoking lots - is probably because you are losing alot of petrol
through the rings which may be in effect leaning out your petrol/oil mix since the oil has more vicosity.

Go down to the dreaded Halfords or similar, buy a compression tester ,its money well spent.
Check the compression before tearing the engine down ,any thing of about 135 + psi should be o/k, check it on a cold engine , ignition off, fuel turned on.
Is it using gear box oil , pay close attention to oil level, it may be pulling oil through the crank seal on the gearbox side, this would give the excess smoking, but so would to rich fuel mix ,check the autolube pump is not sticking partially open , again this would make it smoke.
Is the air filter clean? often overlooked ,yet a critical component in the 2 strokes mixture sequence.Does the exhaust system need a de coke? re-pack the silencer i expect that s shot to pieces .
In short eliminate all the easy factors before pulling the motor apart, its things that should be checked in any case and may save you bundles of money and time .
good luck
mike

fallenmikethebike wrote:Go down to the dreaded Halfords or similar, buy a compression tester ,its money well spent.
Check the compression before tearing the engine down ,any thing of about 135 + psi should be o/k, check it on a cold engine , ignition off, fuel turned on.
Is it using gear box oil , pay close attention to oil level, it may be pulling oil through the crank seal on the gearbox side, this would give the excess smoking, but so would to rich fuel mix ,check the autolube pump is not sticking partially open , again this would make it smoke.
Is the air filter clean? often overlooked ,yet a critical component in the 2 strokes mixture sequence.Does the exhaust system need a de coke? re-pack the silencer i expect that s shot to pieces .
In short eliminate all the easy factors before pulling the motor apart, its things that should be checked in any case and may save you bundles of money and time .
good luck
mike

Thanks for all the useful ideas. I took it out again today, not smoking quite so bad but definitely lots of oil mix coming back from the silencer and dripping everywhere. I re packed the silencer when I first got it running, it was "soaked " in oil, so previous owner must have had same problem. Strange thing is it goes really well, this is my forth CRM, it pulls like a train, even with a standard front pipe, so I think a compression test first, followed by gearbox oil level check and oil pump settings should help me diagnose the problem. thanks again. j

Have you checked the oil pupm settings?
Maybe just pumping too much oil in!

Hi John, how does the plug look?

kernow krusty wrote:Hi John, how does the plug look?

Mines a bit black Tony.

tut tut....less water, more 'Matey'

fallenmikethebike wrote:

kernow krusty wrote:Hi John, how does the plug look?

Mines a bit black Tony.

'Butt' mike, where has it been????

<<<<< iv only just seen that, it don,t take all day to do a days work you know.

kernow krusty wrote:Hi John, how does the plug look?

I fitted a new plug when I first got it going, its had two good runs since then, so will check at w/end, i'm travelling all week. Thanks

John crm wrote:

kernow krusty wrote:Hi John, how does the plug look?

I fitted a new plug when I first got it going, its had two good runs since then, so will check at w/end, i'm travelling all week. Thanks

John you need to do a plug chop test, this has been posted on the forum before, quite recently.

fallenmikethebike wrote:

John crm wrote:

kernow krusty wrote:Hi John, how does the plug look?

I fitted a new plug when I first got it going, its had two good runs since then, so will check at w/end, i'm travelling all week. Thanks

John you need to do a plug chop test, this has been posted on the forum before, quite recently.

Just back from the dreaded T5, and back again tomorrow, for more !! Not much time, but had a look at the gearbox oil level, as crank seals sounds expensive. Oils a good colour and correct level . I will try the plug test at the wekend. Noticed the 2 stroke level has dropped a bit, maybe to much ? So maybe its something as simple as the pump setting ? Thanks for your feedback . John

John crm wrote:Hi, After a run, I have a petrol/oil leak seaping from the lowest part of the exhaust on my MK2 project, the top end has a slight knock, i'm guessing that maybe all the fuel is not being burnt due to worn piston/rings. I'm planning on rebuilding the top end now i have got the MOT today. Apart from the small hole I must have on the exhaust weld, is there anything else I should check ?????? PS. She also like a smoke when giving it some !!.
Any helpfull advice will be appreciated. Thanks John

Ok, Done the plug test today, All OK plug a nice brown colour. Checked the oil pump setting, thats also correct to the manual. On start up, clouds of smoke, but when warm runs fine with minimal smoke. Unfortunatly found a slight weep from the petrol tank, that explains the petrol oil mix that was dripping from the exhaust, I'll have to fix this next .

I think when the bike is left for a week, the oil thats collected in the silencer is dripping back down into the front pipe, on start up this is then causing excessive smoke.

Thinking of taking off the front pipe for some investigation work, Any ideas ??????????????????????????????????????