LRP Z.28R Back from the dead report and questions

[gutshot]

I have a used 4.6 X that came with an LRP Z.28R that hasn't ran in about 8 yrs or so. Two weeks ago I started a methodical assessment of this rig and found that the engine wouldn't pull over. Since I bought the rig used and only ran it for a short time I was thinking a tear down of the engine and the rig in general was the way to go. I flooded the intake with Kroil and after a few hours was able to turn it over by hand. It seems to have decent pinch so I dove in on the carburetor first. The slide seemed to drag horribly and it wasn't just due to sludge build up. I cleaned it well and still it dragged. I polished the slide piston with 0000 wool and was finally able to get it to move freely.

Questions:

* Was using the wool to get the slide to move a good idea?
* O-rings on the needles look good, should I replace them or just go with it?
* More to the point, Should I go ahead and tear the engine down the rest of the way, clean and lightly polish the piston and crank, replace the one way bearing and seal it back up?

Thanks , this is purposely a work in progress

 

[Nadboo]

I am still new at nitro but I learnt a few lessons the hard way. I had the same issue with the slider sticking on my first savage 25. Long story short, I replaced the motor with LRP (my motor was caked with muck and the bearings were leaking and then I damaged it). The new motors carb didn't feel too smooth once installed, until I removed the throttle return spring. It seems to pull the slider to the side slightly. I moved the spring to the throttle linkage and it seemed to solve the issue. If you can replace the seals, do it for piece of mind. They aren't too costly.
If you decide to open up the engine, be very careful you don't damage the piston, or sleeve, or crank case. I bent the sleeve and gouged the case. That's the main reason I had to replace it. Lesson learnt. Good luck,

 

[olds97_lss]

If it's been sitting for 8 years, odds are the o-rings are all dried out and shrunken. With fresh o-rings, they bind on the needle hole and help keep the needles where you set them. With old dried out o-rings, the needles tend to turn on their own once there is vibration of a running engine. I've had that happen a few times with old engines that sat for 1+ years.

 

[gutshot]

Thanks olds97_lss . I'll call LRP and see if I can get a set from them.

 

[olds97_lss]

Also, if it was nearly seized up, odds are, the bearings are full of old oil residue/varnish and the pin hole in the connecting rod may be plugged. Surely the one way bearing can't be faring too well either.

I'd definitely do a full tear down, soak everything in DA and run a pin through the con-rod pinhole to make sure it's clean. Try and blow compressed air in the crank bearings after it soaks a while to loosen up any gunk. After soaking the OWB, twist up a piece of paper towel, soak it with DA, then run it through the bearing and spin the bearing both ways on it quite a few times to work the gunk out of it. Then wet everything down well with some ARO and use new o-rings if you can.