Geezatec

P-0 are torquey engine. When they came out some 11 years ago installed in a Xray NT18. Better engine than the .07 they had.

fyrstormer

iTrader: (1)

I think the XRAY NT18 uses a Toki .05 engine, and yes, the P-0 .08 is way better than that. More torque and way higher redline. 35,000 rpm sounds so sweet.

My Turnigy Nitro Buggy came with an SH .07 engine, which ran great and I would've been happy to keep using it, but there was a critical defect in the pullstart design that could never be fixed. The P-0 .08 is more finicky to tune than the SH .07 engine, and the parts are way more expensive, but because of the pullstart issue the SH .07 just wasn't reliable enough, which really sucks because it was otherwise a very good engine.

+ YouTube Video

Geezatec

You running strictly Asphalt, dirt or speed runs?

fyrstormer

iTrader: (1)

With this little vehicle, pretty much just asphalt. It doesn't have the ground clearance for rough dirt or grass, and there aren't any groomed tracks anywhere near me.

Geezatec

winds out redline. See if larger spur and pinion available for it. Then you will have max speed with the little bugger!

fyrstormer

iTrader: (1)

There isn't a larger pinion available; there's only one clutch bell in the whole world that will fit this little buggy properly. There's a two-speed gearbox, but I can't get the shift-point tuned high enough to keep the engine in its powerband after it shifts, and anyway, this vehicle is a foot long -- when I used the two-speed gearbox, it went so fast it was impossible to control. Also, the engine bogs at low RPM, and a year later I'm still finessing the clutch to get it to engage just at the bottom edge of the engine's powerband, instead of way below or way above.

blis

can you lighten the shifting mechanism (the throws) so it shifts later?

Geezatec

Is there a exploded view of the 2sp tranny?

fyrstormer

iTrader: (1)

The shift pawl is tiny, and not made of the hardest metal in the world in the first place. I'm not sure I could lighten it without making it weak enough that it would break. The real problem is the retaining spring is way too soft. I suppose I could try cutting the spring shorter (it's a coil spring) and filling the extra space with something non-compressible, so the remaining coils will flex more for the same amount of travel, thus effectively making the spring stiffer. However, the one time I tried driving the vehicle with the two-speed transmission installed, it went so fast I couldn't stop it before smashing it into a curb. I had to rebuild the entire vehicle. That left kind of a bad taste in my mouth. It's a small-enough vehicle that it's really best-suited for parking-lot racing, and the parking lots where I am have short-enough straightaways that a single-speed transmission is fine.

If I ever want to go really fast on-road, I'll just buy a Nitro 4-Tec or something similar.

None that I know of, but I'll try to describe it. The first gear is mounted on a one-way bearing that allows it to turn the output shaft. Also attached to the output shaft is the shifting mechanism, consisting of an engagement pawl and an adjustable retaining spring. When the output shaft spins fast enough, the engagement pawl pivots out and engages against the inner surface of the second gear, locking the second gear onto the output shaft. When the second gear is locked onto the output shaft and starts transferring power, the output shaft starts spinning faster than the first gear is spinning, and the one-way bearing allows the first gear to continue spinning slower than the output shaft.

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On a different note, as the engine is aging, it's having more trouble maintaining a stable idle, though it revs-up just fine. What is the most likely cause of a fluctuating idle on an engine that does have rubber seals on the crank bearings, carb fitting, and backplate?

Geezatec

Noticed the idle speed on video. Its a bit high. Tell me your air gap. For it hunting at idle speed your LSN could be alittle lean. Larger engine guys like to drop idle speed wlthin 5 sec. Actually I adjust it to immediate. Puff of smoke when accelerating a 1/4 sec. Your clutch maybe engaging to late, I like it early for a small engine. Let me know the air gap of the slide.

mtpocketsracing

iTrader: (2)

https://www.youtube.com/watch?v=IwzcTPUx8Tk

fyrstormer

iTrader: (1)

I have the clutch engaging late on purpose; I've actually been trying to get it to engage even later, without having to make the huge jump to stiffer springs. This tiny engine, combined with this pipe (there is no other option), produces no power at low RPM, and if the clutch engages early it will lag for several seconds before reaching its powerband. The LSN may be a bit lean, but every time I enrich the LSN even a little bit, it starts lagging like crazy.

Also, keep in mind that while the idle may sound high, it's a .08-cubic-inch engine with a redline of 35,000 rpm, and it has a tiny little 25mm flywheel -- it's gonna idle high, because it has to.

fyrstormer

iTrader: (1)

In other news, I rebuilt the engine a while back and replaced the crankcase because I couldn't get the bearings out of the old crankcase, and ever since then there's been rather a lot of oil on the side of the engine after each run. For whatever reason, I only just now examined the engine carefully enough to notice there's a casting defect on the underside of the exhaust mount. So I rebuilt the engine *again*, using another crankcase that I know has no casting defects. Maybe that will fix the idle-fluctuation problem; if nothing else it will at least keep the inside of the vehicle cleaner.

While I was in there, I modified the clutch shoes again; I shaved the middle of the clutch shoes flat, to reduce contact area, so they engage more like a 3-shoe clutch. Here's what it looks like now:

Geezatec

Havent answered my question. What is the air gap of slide? Show a photo. Again mine is installed in a Xray NT18 which has aluminum clutch shoes. More aggressive engagement.

fyrstormer

iTrader: (1)

The air gap is approximately 1mm.