ORIGINAL: BJ64

Got all my bearings in and the main part of the engine re-assembled. But summat don't feel quite right.

I can feel a fain't ''lump'' when I turn the engine over by hand using the prop. Not huge, but still noticeable just the same. It's when the master cylinder goes over TDC (I think).

I also notice that one of the valves doesn't seem to move as much as all the others. Tired now, but will post a more accurate description as to which Cyl I feel the lumpiness on, and which valve doesn't look right.

I hope I haven't stuffed it up - the longer of the two valve sleeves is the Inlet valve, yah? And the longer push-rod goes with the longer sleeve?

I thought I'd labelled things up the correct way when poking the various sets of bits and pieces into my styrofoam blocks, but maybe I've made a boo-boo somewhere.

Also, I didn't pay enough attention to the cam followers (tappets) - didn't really notice they were there until the odd one started falling out on me during disassembly. So by the time I'd realised, I had no idea which tappet belonged to which set of sleeves/pushrods/rocker-arms. I have not unassembled the rocker units - the arm assemblies were taken off as a complete unit and labelled with the corresponding cylinder unit/head assemblies (cylinders/sleeves/pistons etc. were not removed).

I mentioned earlier how dry the whole front-end of the motor was - the tappets where as dry-as and some had black dust on them instead of oil. One was particularly difficult to get back in - I had to give it a bit of a rub with fine grit wet&dry paper.

As an aside, I'm quite amazed that there is no form of hardened sleeving for the tappets themselves - just a steel tappet (convex contour on the cam side, pushrod dimple on the other) running through the aluminium housing. Surely, that will wear out the clearance in no time at all?

Anyways - if someone could verify that the longer sleeve is for the inlet port, and it also uses the longer of the two pushrods, at least I'll know that I've got that part right.

The cam gear timing seemed simple enough - line up all the dots and then carefully put the nose-cone back on so that the 'double gear' finds its way into the small bearing up front.

I was hoping to have the donk all mounted up and ready to test-run in the morning, but it's been a rather loooong day with other junk so I'll give it a rest and have a look at it again with fresh eyes in the morning.

TIA for any advice...

BJ

ORIGINAL: fossmarkluni

Hi!

I purchased this engine from hobbyking two months ago. Yesterday (April 27, 2013) I started it up the first time and it ran perfectly for 8 minutes, I had the main needle 3,5 turns out and it was running rich. I was alternating between idle and full speed runs with a 21x10 APC prop.
Suddenly there was a low screeching noise increasing in intensity and I shut down immediately. I thought maybe a bearing or something similar was acting up, but when I rotated the engine by hand I could feel increased resistance when the valves where actuated, a bit more pronounced on one of the cylinders.
I dismounted the engine and opened it up to see if I could see a problem, inside the engine there were some debris, especially in front of the engine. I put some after run oil into it and turned around, the bare metal to metal feeling and noise disappeared and everything felt like it should again. For good measure I adjusted all the valve clearances to 0,05 mm, they where set to around 0,30 to 0,15 from factory (a bit sloppy imo.) The manual states 0,04 to 0,10 mm for both intake and exhaust valves. I also cleaned the crankcase internally by using light oil and pressurized air to blow everything out.

Now to the dilemma, I can´t run the engine this way as it most certainly will run the valve train dry again, I left the drain nipple open to atmosphere (as specified in the manual) but now I am wondering if i should close it up to see if it forces more oil through the valve train.

Anyone seen this before? What could cause this problem? I have seen custom back plates for sale that sucks the fuel through the crankcase before it goes to the cylinders, but I would prefer not to use 300$ more just to get this engine running as it should. The build quality seems good, although I have not inspected the valve train etc. as I would have to reset timing.

Please help!

ORIGINAL: BJ64

Hmmm...

'Screeching noise' you say?

That's *exactly* what mine did. Read back a few pages - I managed to strip 3 teeth off the cam reduction gears. I reckon it was because there was NO lubrication up the front end.

You say you saw debris inside your engine - did you have a good look at your cam gears? The teeth a pretty fine, so it may not be obvious that you could have thrown a tooth or two - on either the cam lobe gear, or the 'double gear' reduction gears. Maybe have another look?

It could just be the valve-trains have started to seize, too. That's not good either, and will bugger-up the clearances when the metal starts to wear - changing the tolerances etc.

Can you perhaps prove exactly where the debris was being shed from?

BJ

ORIGINAL: Carosel43

fossmarkluni it seems you are also suffering the lack of oil in the front end that many others are reporting. I have so far not had any issue with this myself but I am (now anyway) running with the breather closed. I get oil leaking from around the bases of the pushrod tubes but to me that shows that there is oil flow through the front end so I am happy with that. It seems to me that all new engines need to be flooded (and I mean flooded) with a 50/50 oil/methanol mix. Clearly the methanol will quickly evaporate leaving a good oil film over everything. after that initial start everything should be ok.

What I would suggest is you oil it to within an inch or its life, start it and run it for 2 minutes with a quick trip upto full power and down. Then see if any resistance remains. Also 21x10 is a bit big, I would use 20x8 and for best performance keep the rpm at 7000+. anything less than 7000 and mine just dies in the air

Can you also upload a photo of the section of the manual that tells you to leave the drain open? this has caused confusion before and I am very sure its supposed to be closed from what I have seen of the OS engines. At any rate, my engine is very happy with the plug closed so that's where I am leaving it.

Not all good news with my engine though. I flew it today and as I suspected the front bearing is spinning in its housing its ok when the engine is cold but it lets go when it warms up. I will try and rescue it without stripping the engine completely and then glue the beggar in with Loctite 693.


EDIT: The black dots will be oil with metal particles in, I got them everywhere form my front bearing housing and that's how I knew I had a problem. Also, while I don't wish to offend anyone, I personally think the additional lubrication claims created by the new induction system are overstated at best as the airflow will never get anywhere near the front of the engine unless the carb was mounted there.