Cen CTR 5.0 - Help

[Makaveli 160]

Hi,

 

New to the forum and after some advice please.

 

I have a Cen CTR 5.0 I believe this has a Rev-Line .30 Corsa Engine bought many years ago, haven't used in a while and having some issues. I'll try to keep it as brief but informative as possible.

 

From my experience and many hours trolling the internet and youtube I think it may be an air leak issue (bearings or carb) and/ or piston and sleeve??

 

First strange symptom I need to know if its normal (which comparing to the exact same model my friend has, he doesn't experience) is that I can hear a very distinct 'hissing' / 'air puff' noise when pulling the pullstart gently when the engine turns over? This seems to be coupled with fuel leaking from behind the flywheel (much less so, once I found the flywheel was loose and dismantled to tighten). Which makes me wonder if the front bearing is faulty? Although the sound seems to come from the air filter / carb, less noise when removing filter and covering the venturi opening with my finger.

 

Another symptom is it will start literally first pull (when cold) and idle for a while, but then usually dies after around 15-30s. But doesn't want to start well at all when warm or once ran. Could this be a possible piston and sleeve issue, although the compression is good? But again once started does leave a line underneath the flywheel of light spray, not sure if this is because its a little too rich or an issue?

 

All settings have been returned to factory settings and is running a little rich. Although it seems to give symptoms of running lean. After running a little while it also borderline floods and I can turn on the side and fuel dribbles out the exhaust.

 

Currently running on Optifuel Optimix RTR 20%.

 

Before taking to an rc shop just wanted to see if anyone had any ideas as I have racked my brains and tried everything so far. 

 

From googling people say the front bearing isn't really an air seal as such, but is sealed via the fuel and oil creating a barrier to seal it? Is it worth dismantling again and using the soapy water method to see how much the bearing bubbles?

 

I have had it running a few good times idling, but again it will run and drive, but if i open the throttle up quickly (rather than smoothly) it will konk out and not start again.

 

Any ideas appreciated.

 

Thanks in advanced.

 

(Possibly failed keeping it 'brief'...)

[Nitroholic]

'compression' is not the same for these engines as with a full sized motor with piston rings. The piston is in a liner that tapers slightly as you go towards the glowplug. The piston is also slightly tapered. The 'compression' comes from the piston squeezing into the liner. This is why breaking in an engine is so important for decent life. It does sound as though whatever is wrong with your motor gets worse when it warms up...and I would suspect the piston/liner is worn or scored. You can still have a feeel of 'pinch' there but it clearly doesn;t like running when warm.

 

If it's not that.... then it's going to be an airleak issue.

 

This can come from the backplate ( behind the pullstart ), froim around the carb neck where it goes into teh crankcase...or from the front bearing. If thats badly worn, you would also see some slop in the crankshaft. There should be a front and back bearing. Normally...air leaks happen from the carb or backplate. Both can easily be sealed with some silicon type instant gasket ( not bath sealer....it wont handle the heat)

 

Have you taken the cooling head off to have a look at the state of piston and liner?

 

If that's goosed, then you are really going to be looking for a new engine. The cost of a piston, liner and rod..assuming you can actually find one for an old engine like this... would be high enough to be not worth doing in all likelihood.