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#96543
Using the oil tank as its own catch-can makes a whole load of sense. You could still experiment with a non-return valve in the pipe from the crankcase to the filler neck to see if there's any further improvement, but a longer run - give it a good blast - will be a better test for what you have now. Looking forward to reports of the back of the bike staying clean.

A.
#96544
As Adrian wrote earlier, if you wire up that plug via a second coil you could double the power - one bang sends the piston down and a second bang in the oil tank sends it back up again!

Then again, that might just make your oil loss problem more than a bit worse.... ;)

I seem to remember that an Italian bike manufacturer (either Ducati or Moto Guzzi) fitted some bikes with an oil separator, which was a plastic case with interior baffles. Oil and vapour would enter the case, the baffles would collect liquid oil drops and the vapour would vent to atmosphere. Any liquid would drain back into the oil tank/sump. Essentially the same as the catch can on the Bullets, but more effective, probably because the pipes were larger in diameter. The Hitchcock's kit looks as if it does the same job where the adapter sits higher than the oil reservoir and raises the height of the breather tube.
#96545
I converted my tuned up Reliant 850 for my Liege trials car to an improved breather setup. The engine was designed for a camshaft driven fuel pump. I used an electric fuel pump and fitted a 1/2" breather from the crankcase where the original pump sat up to the side of the rocker cover. The idea was that could then equalise the pressure between the crankcase and the top end. The engine then breathed through an improved vented rocker cover filler cap, rather than to the inlet of the carburettor (the latter is not good for engine output).
#96730
Well after a bit of jiggery pokery all seems to be working well, AVL engine is now breathing via our hosts oil tank tower extension, I can feel it through the rubber pipes pulsing in and out and rear chain is getting a very slight oil mist, much tider and all old gubbins removed, also oil tank level is now at middle of the dipstick and it appears to be staying in the oil tank, so happy days!

One problem I did have was a bad oil leak via the gasket on the tappet cover (right mess) , tried two separate new gaskets with grease and then Wellseal but just really leaking. Measured the gasket thickness and was around 1.6mm, recovered the old black one that was on it (poss OEM) and it is 2.5mm, put it back on dry and no oil leak! I think the stud that holds the cover has too short a threaded length so the gasket is pushed too tight against the shoulder, i could see a very pronounced hexagon shape pushed into the gasket meaning I am just crushing the gasket in the centre and leaving the edges loose, think he shaft needs the shoulder turning down a bit to allow the nut to pull it up fully and tighten as the gasket crushes and not before, of course works fine with the thicker gasket as the centre sand edge crush points are equal.

However, I seem to have lost compression :cry:
#96743
Yes, my first thoughts too but first thing I did was slacken them off and then removed them to see if one had bent but all ok, I can hear a hiss on compression stroke and i could stand on the kickstart before but now it drops much easier so something is amiss!

Have the top end off for inspection, I did know the bore was on the upper limit and it made the piston ring gaps also at upper limit of 0.8mm from when it was honed/new piston after the piston slap incident so didn't expect it would last for ever but not sure why it would suddenly go after only a few 100 miles! I did have the rings all the correct way round etc

I have a new valve spring compressor on order to check valves seats etc as may be something in the head leaking, I didn't touch the head before so possible!

The top of the piston was black and slightly oily so something is clearly wrong, maybe a rebore was really needed when I had it honed, we shall see...............
#96744
Adrian wrote:
Thu May 13, 2021 8:39 pm
Sudden or gradual compression loss?

A.
Not instant but quite quickly, running fine (very well in fact) but stalled when slowing down (on main road of course!!) and was then hard to start followed by a in loss of power and limp short distance home. Could later hear the hiss (engine cold) and did start but not easily. Still have CV carb fitted and if it had not been for the hiss it manifested like a carb problem, cold start with full choke was not high revving as it had been but revs increased as it warmed up but no easier to start when warm. And Kickstarter is really easy to use where I could stand in it before.

Sticky inlet valve?

Need to helicoil the little stud by the tappet door anyway as it really didn't feel right when tightening so just pulled the barrel off anyway for a look in case it was a broken ring etc but looks ok (if on top limit). I just can't imagine a barrel suddenly gives up with no sign of damage, only done 250 miles since assembling it.

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