RX-1 blowing oil

[Kachess]

I pulled a bender turbo (and NOS) off our sled because it was hard to tune for elevation changes and oil consumption (quart per ride). It would lay down an oil smudge in the snow on hard acceleration. No sign of oil at idle or low speeds. I assumed the turbo was leaking it through its seals. Well, it still lays down a smudge without the turbo. It starts/idles fine, and runs at about 90% the power of our other stock one tons. Doesn't quite spool up like the others. The compression is better than our other sleds. I tried a leakdown test but can't find any obvious leaks. I've checked and re-shimmed a few valves. I looked at the piston tops/cylinders and they looked fine but looked like they were burning oil. The intakes are dark stained which I originally thought was from turbo oil but now figure it was caused by blow-by cycling oil from the breather back into the carbs. I now realize I probably should have gone and replaced rings while I had it partially apart. Could valves be a the problem? They looked tight (held solvent) when I had the head off. I'd appreciate any advice on what to do next? This sled's driving me crazy.

 

[LazyBastard]

Condition of the oil control ring is not determined by leakdown or compression tests.

How did you put the intake stuff back together? Is it all stock? Do you have the oil separator installed?

 

[Kachess]

Then it may well be the oil control rings. I was afraid of that. The intake is stock, for the most part. We don't use the oils separator, but the vent is routed into the airbox, and it's clear. One person identified excessive valve guide clearance as a possible cause. Is this likely on a low mile, turboed sled.

 

[Kachess]

I have now replaced the rings, have no oil consumption and have good compression on all cylinders, but the thing still runs exactly like it used to, like a dog. Sluggish, Slow to spool up and slow to come back to idle. Engine still only has maybe 80% power. Engine vibrates and has an odd exhaust tone. We have two other tons, and rode with 4 other tons yesterday and this feels like it has a totally different engine.

I've now checked and re-shimmed the head, leak tested the valves, replaced rings, gaged the cylinders. When I had the motor apart everything looked good and felt tight. I've swapped out coils, all elec boxes, and carburetors with a good running ton. All the plugs show good color and I know its running on all cylinders (pulled coil wires). I've had the sled overheat a few times since replacing the rings but am attributing that to the rings breaking in.

Since this thing was once turboed with nos I am now thinking it was damaged or they did something odd to retard timing. Is there any way to check or adjust timing? Could the flywheel be clocked? Could the crank be damaged and the engine still run?

I am at wits end!!

 

[dhkr123]

The engine vibrates?
Can you be more descriptive?

Have you checked all the stupid things outside of the engine? I.e. clutches and driveline bearings?

 

[Kachess]

You can feel it in the handlebars. Not real bad, and i figured maybe it was motor mounts, but all our other tons are much smoother. I've swapped out the clutch. Bearings are good and it has 3in drivers that rumble a little, but some of our other tons with 2.5 inch drivers rumble a little. I could live with the vibration if it was running right, but thought the two might be linked.

 

[dhkr123]

Typically, multiple symptoms do tend to coincide with the same problem. That being said, it does seem that you have managed to eliminate 1 problem (oil consumption), and yet two seemingly related problems remain.

I suppose that motor mounts could be responsible, it would probably explain both problems if the motor mounts were weak and the motor was shifting under load.

Are you certain that your valve timing is right on?
When you had the engine apart for doing the rings, did you notice anything that looked aftermarket?

Is speed at all a factor with the vibrations? Does it vibrate while idling or if you spin the engine up a bit with the belt off? (obviously don't spin it too fast unloaded like that...) Is it possible that your drivers are misaligned or worn? Is the track hitting anything?


If there is doubt as to whether the problem is from the engine or not, I would be inclined to put it on a dyno and see if the power levels are reasonable and whether it still vibrates while under that load as opposed to the driveline.

The thing that still gets me is that you mention the exhaust tone differing from other machines. What does it have for an exhaust system? What do the other machines have for exhaust systems? Is there anything on the exhaust system that is modified? Has a RAT or other similar vermin ever lived in that muffler?

 

[maim]

might need 8fa-16155-00-00. it is a vibration absorber it looks like in the gear reduction on the parts fiche. i would check the timing on the cams as well.

 

[Kachess]

I'm going to go back and check valve timing again. I measured distance from top of pistons to top of spark plug seat on the equal cylinders and they are right on so I'm thinking the rods are true. I've timed the valves on my other sleds and have had no problem. On his sled the exhaust cam is always a little off. I'll try going another tooth. The flywheel has a hash mark and the two hash marks that are connected. I assume the single hash mark is TDC.

It has not looked like anyone has been inside the engine. The ignition pickup is not clocked, and there wasn't a head gasket added, so I guess it's all stock.

All our sleds are running identical undertunnel exhausts. The vibration is at idle, too.

The exhaust tone is has kind of a drone to it instead of the crisp tone our other sleds have.