IAME Leopard: Excessive Oil and Smoke From Exhaust

Careful, it’s the opposite of this. In NGK, lower numbers represent hotter plugs. 8 is a hotter plug compared to 9 (The 8 retains more heat) for colder conditions. That said, 8 is a little too hot for my personal taste, emphasis personal.

My mistake. I would expect you would only use a hotter plug in very cold weather. In Texas, I only ever ran the 9 before being told I had to run the Spec X30 plug.

I used NGK BR10EG but I have too BR9EG. Jetting H 1T.O . L 1&1/4 T.O Photo after engine brake in.


That’s a decent amount of oil alright. Sorry to see that the engine is damaged. Can you post some pictures of the piston, cylinder head. It can be hard to diagnose these things over the internet, but we can hopefully give some pointers.

At this moment engine is after rebild :slight_smile: I put new piston and clean cylinder. I buy, and using Jetting App for Leopard , and tomorrow I try engine run in.



Add more pictures please. Top of piston and the combustion chamber. Do you know what the piston to cylinder wall clearance was? Did you allow the engine temp to get to operating temp before pushing it hard?

My first guess here is the piston ring stuck during the breakin process. This caused poor compression and incomplete burn (all the oil/fuel not burning and passing through the exhaust). Looks like a cold seize after that. Piston to cylinder wall clearance may have been too tight to start with.

Piston to cylinder wall clearance 0.10mm. After run in must be 0.11/0.12mm. Yes, first I warm up engine. Its my fault, I wrong carb adjusting. The grinding of the cylinder and the fitting of the piston were performed by a very good engineer from Poland. After rebuild, exhaust have the same oil leaks. Before engine stuck, he runing 2.3mth

My opinion is that 0.10mm (.0039") is too tight. I’d say 0.14mm (.0055") minimum would be better.
I know this is more than suggested in the owners manual.
Again, this is my opinion and others may vary.
@Christian_Fox @Rapid1

Yes, .10 is way too tight. You want a minimum of at least .13mm

How about those oil leaks? Has anyone from the forum had a Leopard, or has anyone seen what it looks like in kart other people?
It leaks on stand to, and makes a lot of smoke.
I set carb with jetting app. This foto is after engine run in procedure.
@wsalisbury3 @tjkoyen @KartingIsLife @GregF ???
I am asking about it, maybe I have some other fault? Although everything is after the service, there should be no problems. On Youtube, I see movies with this engine, no one is smoking that much. Nobody has such oil leaks, even when the kart is in the stand.

Honestly the amount of oil is not unusual for an a Leopard or similar (racing) two stroke that’s being operated below it’s correct RPM for a long time, or not being driven very hard. Smoke on the stand is not unusual either. Since you’ve confirmed your popoff is holding it’s probably not getting a bunch of fuel.

I’d be more worried if there was no smoke. At lower RPM a lot more of the fuel and oil escapes out the exhaust and leaves oil deposits. Also, if they engine is not being used hard and has longer times off full throttle, the oil accumulates in the crankcase and is then expelled when power is added again.

To seal it, usually wrapping the flex part between the header/manifold and the pipe will reduce the leaking at that point. Securing the exhaust wrap with safety wire can help it stay in place.
Come to think of it, it might be worth checking the flex for cracks.

0.10mm is going to take a long time to break in I think, pretty tight for an iron bore. Is the builder familiar with the leopard in particular? If they are, then they should understand the difference between the dot colors on IAME pistons. This chart is worth reviewing…

While we’re here, here’s the Leopard Owners Manual
MY09-Assembly-Manual.pdf (3.4 MB)

Agree with James, it’s a lot of oil, but impossible to say if it’s too much since you’re never getting the engine up to racing speed and RPM. Lots of 2-stroke engines will load up and be really rich on the bottom end if they never get a chance to rev and clear out.

I have Tag engine. Not RL, but carb jetting is similar. This is manual for my engine. leopardmanual2003.pdf (3.2 MB)

Both models are TaG (Touch and Go, ie electric start), you have what’s sometimes called the pre-09 leopard. They are very very similar.

One thing to note, and you may already be aware… but jetting recommendations are based on a specific oil ratio (and popff). The manual recommends 6% oil and you mentioned you’re on on 5%. Something to keep in mind as you begin to tune the engine for performance as currently it will run rich on the fuel side for a respective jet position.

My '09 Leopard spits a lot of oil also if I run it on the stand too long and then smokes on the grid waiting to go out. Generally I only try to warm it up a little on the stand until water temp comes up to 95 F or 100 F then take it easy on my out lap until water temp hits at least 105 F. If you have cooler weather, you can cover the radiator with rows of tape and peel them off as needed to regulate temps.

Like James said, you may need more break in time.

Are you suggesting me make a 6% fuel mix? I have a pop off of 10.5psi.
I don’t think I fully understand you.

10.5psi is good.

I would recommend going with 6% to isolate that variable. The downside is that all of this is based on the kart being run in a racing situation.

Also depends on what oil you are using. Full Synthetic can probably take 5% but especially during break in, error on the side of caution. Remember as thing heat up, they expand at different rates. The Iron Cylinder will expand slower then the piston and you risk Seizure with smaller tolerances. By going to 6% oil ratio you are adding protection. After my last Top End rebuild, I took it slow, building a lot of heat in the cylinder by taping the radiator, gradually building up RPM and letting it cool between sessions. It is possible you did not allow enough time before pushing the engine for everything to seat properly. Do not worry about the oil spitting from the pipe during this time. After a thorough break in, the oil spitting should get better. Best done on track, where toward the end you can fully open throttle.

I mentioned the oil previously Mike, even just to discount that variable I’d run it with spec oil (one that contains castor oil as per IAME recommendation)

The stuff you’re using Motul Kart GP doesn’t contain castor oil.

This is just my thoughts by the way, I’m not familiar with the Leopard but I am an engineer - airplanes, we don’t do anything technically that isn’t by the book and that translates into pretty much everything I do in life :rofl: , others will chime in I’m sure if that oil is fine to use