GRP Engine Problems

[davebeef1]

My .21 Tuned engine was running just fine all day Friday until 10 mins from when i was due to leave.

Suddenly the engine would loose power as you open the throttle over 50%.

I have tried all i can to find air leaks but am now totally confused. I now have all new fuel lines, new fuel tank and now changed the glow plug, but no joy.

I can start the car but still when throttle opens it just dies. Carb settings are fine and no fiddling around with the needles has made any difference.

Anybody got any ideas???

Cheers

Dave

[Mac]

I had a similar problem this past weekend. I was about two minutes into my quali and my GRP went so fat I could hardly make it around the track to my pit guy. He looked at everything and then just stoped it and we called it quits.

Back at the pit I looked at the Fuel lines, the plug, the clutch, the tank etc, etc,

Well it turns out what I did wrong was warm it up on the box too much before the qual, when I came in my temps were way high and so my pit guy leaned out the high speed. As it ran it cooled so much that the the temp fell off and so did the engine.

If this is not the case one other problem I had a couple months ago was that my engine kept going fat and slowly I figured out the problem was that the o-rings around the high speed and the idle. They were turning out as I drove and cousing it to go way fat and then the engine would fall on its face!

Hope one of these two help as they were both simple fixes once I figured out the problem.

[Full Montee]

check your clutch bearings.
I find that if I go to far between changing the bearings that one of the two will come apart and isn't apparent until inspection.
The engine will idle fine and work properly on the box but the moment I try to drive it, it'll just choke.

[Mac]

I second that!

[davebeef1]

Still no joy I'm afraid. Tried retuning etc etc. No obvious marks on engine piston / liner. The crank pull in and out slightly - is that normal.

No obvious leaking on front bearing, could the rear bearing be an issue?

[jrlosi]

the crank movement is due to the engine bearings, which may need to be replaced. how loose are the needles?
Check to see if you have the idle screw turned in too much which would throw off your tuning, especially the bottom end tuning.

[Briguy]

The crank will pull in and out a bit when the flywheel is off .