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Old 08-12-2012, 01:21 PM   #1
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Default First Nitro, first run - Losi LST XXL

Just thought I'd share my experience with my first nitro. Took it apart to check screws, add differential oil, and put on the RPM arms. Went to start it for the first time and nearly sh!t my pants after hearing it roar, then promptly forgot all I read about tuning. Let it idle for 2 tanks then pulled the trigger only to have it stall immediately. Yanked on the pull-start a few times and what a mother' to pull, then broke the spring and yanked out the string. Don't have a battery for the roto-start so called Losi and they sent me 2 new pull-starts! Went to start it then stalled again. Several starts later and it snaps again. Onto the 3rd pull start, then the piston gets stuck on the upper position and being impatient kept yanking on the rope. Of course the rope pops from the handle and I go ahead and take it apart, wind the spring while almost gauging my eye, and it works! But the rope somehow ends up longer so is now limp after retracting inside, banging on the chassis. O well, but it still works and finally get it tuned decently and let it rip a little.

Hearing it scream was so much more exciting and scary than the first time running the Savage Flux. Imagining a clutch engaging with a real working engine with exhaust killing brain cells and shifting into 2nd is a whole new feeling. Going about 25-30mph at a turn I misjudged the distance and hit smack onto the curb, with an old guy right next to it staring at it. Sh!t!! but I remembered reading how tough it is, and pulled the trigger again. Rev'ed a bit but stayed still. It's ok, maybe the linkage popped out. Walked to it and nope, the carb isn't moving =/ The guy was still staring the whole time without a word, and I walked back to the car.

Don't know how the carb got stuck all a sudden. Needed a wrench to nudge it out, then took it apart and looked fine inside. No visbile warpage or scratches, so I just kept sliding it back and forth to loosen it. The servo can move it now, but the return spring won't pull it all the way anymore. Is this something to worry about?

Also noticed the side frame cracked and the whole front bulkhead was twisted 1 or 2 degrees. Pretty much all the aluminum supports were twisted a bit - can see it a bit on the 3rd photo. Luckily, found a full frame on ebay for $16 total, and bent back a few parts. Even the plastic receiver case got all cracked on the 4th photo. Don't know why Losi would design the bumpers to be nearly rigid without give like most other vehicles. You can see the force pretty much goes straight to the body in the 2nd photo and that aluminum brace is the first to bend. Guess it's still my fault for smacking head on with concrete.

Noticed a missing ball bearing on the thruster bearing for the slipper. Is this something to worry about? Doesn't seem like a high load area with just the spring tightened on it. Hoping to tune it some more later.
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First Nitro, first run - Losi LST XXL-0363.jpg   First Nitro, first run - Losi LST XXL-0365.jpg   First Nitro, first run - Losi LST XXL-0366.jpg   First Nitro, first run - Losi LST XXL-0367.jpg   First Nitro, first run - Losi LST XXL-0368.jpg  

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Old 08-15-2012, 09:48 AM   #2
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Went for a 2nd run going full throttle a few times and overheated once at 290 F for a few seconds. The fuel went backwards from the pressure (there's a term for it but forgot) and the glow plug seemed to go bad. Replaced with a new cold plug and ran fine again at 220 F but the pull start spring unbent at the joint, so rather than bending it back and weakening it anyway, will wait for a new one from Ebay :/

Will a few seconds of overheating damage the engine? I think it mostly happened after I slowed to a stop and the idle increased until I pinched the fuel line, and stopped almost instantly. There was a little smoke and smelled burnt a bit, but there's no noticeable loss of power when I ran it and the pull start didn't feel looser.
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Old 08-15-2012, 10:43 AM   #3
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"the engine break in bible"

"the engine tuning bible"


A few helpful links for you

When you start your engine for first few times you need to preheat the engine with a hair dryer or heat gun. Try to get the temps about 180 degrees and it will be easier to pull start and you won't keep breaking those pull starts.
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Old 08-15-2012, 11:22 AM   #4
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Default Why?

No one cares.
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Old 08-16-2012, 05:17 AM   #5
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Quote:
Originally Posted by Maxxed-out View Post

A few helpful links for you

When you start your engine for first few times you need to preheat the engine with a hair dryer or heat gun. Try to get the temps about 180 degrees and it will be easier to pull start and you won't keep breaking those pull starts.
Thanks for the links. I read through the bible and read of both the "idling through 2 tanks" and heat cycle restarts, and did a mix of both I guess. Idled through one tank then cycled a few times before going full throttle. I bring the truck out to a parking lot 15 min away so I can't preheat it unless I buy a portable hairdryer or something - probably will be the cost of 1 or 2 pull starts.
But the pullstart is much easier to pull now. Before the last one gave out.

@Sosumi - Like anyone would say - apparently you cared enough to post. Thanks for stopping by.
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