Hi guys,

usually I got my engine program under control, but lately I had some VERY strange engine problems and I am running out of ideas.

Yesterday at a race, a buddy of mine had exactly the same problem and it's making us nuts.

Here is what happened:

1. Bought an LRP Team spec 3, Picco Evo2 based. Ran the engine at an indoor race in November and all was good. Beginning od May, when out outdoor season started, I strapped the LRP into my MTX4 and it ran problem free for about 5 tanks. All of a sudden, it started bogging out of a hairpin. It just would accelarate anymore. Sounded like it was too lean.

Checked everything, tank, pipe, fuel line. Checked the engine for leaks, nothing.
After it had cooled down, it started back like normal. Put the car on the track and ran for two laps without problems. Then when the engine came up to 85 -90 Celsius, it strated bogging in the same hairpin again. It just would take gas anymore and when you opened the throttle it flamed out.

Back to the pits, changed the tank, the pipe, the fuel line. put a Novarossi carb in it and sealed carb and backplate.

Still, after it reached temp, it bogged.Tried 3 different NR carbs, no change.

Then we thought it might not have enough compression, so we squeezed it slightly. No change. Checked the head clearance: 0.45 mm, as recommended by LRP and that's what everybody is running around here. We are at 500 meters above sea level.
Changed fuel,no change.

Timing of the LRP: crank opens at 30, closes at 65, exhaust 83, transfer 60, boost 57, then crank is modded, the sleeve is stock

2. Got a new Picco Evo. Broke it in, ran it on the track and it has exectly the same symptoms as the LRP Picco. Tried everything as above, with no luck.

crank opens at 30, closes at 65, exhaust 85, transfer 65, boost 57.

3.My buddy is running a NS 12 S5 which is brand new. It ran great for about 2.5 liters of fuel, before it started doing the same crap as my Piccos yesterday.Again, we tried evrything, but couldn't get rid of this phenomenon.

4. I bought a Plus 12-3 ST, which runs like a champ in the same car, with the same fuel, pipe and everything.


Does anybody have an idea what our problem could be, because I am about ready to start throwing engines a far as I can

Thanks guys!

Stefan, if it makes you feel better ( doubt it) I have the same problem with my LRP Spec 3.

I had mine to the point that it was 4 stroking, still ,the top of the piston is black and it does the same as yours...

I'm about to put on a Sirio carb and see what happens...it's almost like the taper in the low end needle is wrong or something..

Hi Sp Racer,

the Picco carbs can be a nightmare, but then the sucker should run with a NR carb on it and it won't. That's what's driving me nuts.

Please keep me posted on you progress.

Cheers mate.

Hey Stefan... maybe your problems is known by the dreaded three words problem : 'Picco XP Curse'.

Seriously: Disassemble the carb and inspect the fuel intake and the spraybar along the low-end needle, your problems should be there, maybe some dirt gone there and causes problems. If this doesn'ts solve the problem, swap the carb for a well known NR carb and your problems will be history (well... maybe Reto drop by and give you an answer).

Hi Alfonso,

as I said, I tried 4 different carbs, all NR, all running normal on other engines.

Reto looked at the engine last week at a race and couldn't find anything either.

Cheers,

Stefan

Could it be gearing or something binding in the car after it gets warm? I have seen this happen before.......
Paul

I have had this happen after a motor change and it was the body masking the pipe outlet under heavy cornering(hairpin)- pipe looked ok but then settled a bit forward after a while-try without the body or run the hairpin in the opposite direction.

Sounds like a front bearing leak to me .. New or not sometimes the front bearing is faulty from the manufacturer. try to move the rubber seal with your thumb nail , if it moves then you have a leak ..

What happens is once the crank case expands it relieves pressure on the outer seal.. this causes air to be sucked in through the front bearing as opposed to through the carb ...

Hoep this helps ...

Hi MassiveMods, thanks for the hint. Could this also cause the engine spraying fuel out of the carb?

Cheers.

It might be spraying from the bearing? I know this is a long shot, but are you using the right plug?

Hi Stefan,

If the engine is spraying fuel out of the carb, check if your starter box is rotating in the correct direction.

I hope this helps!

I don't think Stefan his starter box just out of the blue starts rotating the other direction.......

I have experienced the same phenomenon with my JL Red Dot. I too tried everything from compression change, pipe change, carb change and couldn't figure out what it was. My front bearing is also in great shape with no signs of any leakage at all.

I also run in Toledo where air temps and barometric pressures change dramatically and we're at 600 ft above sea level.

What Massive says makes sense about the front bearing and it's effects. The motor just doesn't seem to want to draw fuel after it warms up(two to three minutes of warm-up) Each time the motor has done it I had to richen it up about three hours on the top end. This only worked sometimes. Then I changed my clutch and bottom end tuning. I really tightened my clutch down to the point where it was slipping, and then backed it off abit so that it wasn't slipping but kept the motor up in the rpm ranges before engaging. I also richened up the bottom end about two to three hours so that it seemed fat and not where I would normally run any other engine. Running the motor that way I could lean the top end where I wanted it, and it would come into the pits and immediately idle down. It would then leave a healthy trail of smoke leaving the pits initially but would be okay on the track with some smoke and good hard acceleration. The motor has a tendency to really lean out alot after two to three minutes of hard running so a good warm-up before a qualifier is really important.

In conclusion.........running the bottom fatter then normal.........tightening down the clutch a bunch stopped my lean bogging. It sems the motor with a lean bottom and lean top starves for fuel, and the rich bottom seems to help a ton. Hope this helps.

I had very similar problems with a Nosram Speed .12. It was a totally frustrating engine and a Rossi carb made no difference,the engine's now been scrapped after weeks of frustration because it was just totally unusable for me.

Allan

Yeap, using LRP plugs.

Thx.