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Losi 3.4 engine rebuild help

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codfish said:
This is what I thought. I have already marked the flywheel so I am good to go there. It is supposed to be 50 tomorrow but the street is still snow packed so I think it might be sitting a while. We will see.

Thanks,
Codfish
Click to expand...
Keep us posted and don't be afraid to ask questions- come back and ask as many as you want :)
 
Ok. Last question. "After cycling the engine in this manner for about 20-25 total minutes" Is this including the 15 minutes of 2-3 minutes or in addition...so a total time of 35-40 minutes? If finally as above 55 after work tonight.

Thanks,
Codfish
 
Yeah, roughly 40 minutes of run time with about as much (if not more) cool down time as it takes time to let it cool back down. I usually don't let it get below 70F at the head before I fire it back up again.

The engine will kind of let you know how it's doing as you get through the cycles. I did a similar break-in recently with my OS21TM and I babied it quite a bit for probably 10-12 tanks after. Still keeping it a bit on the rich side, but not doing any long WOT runs with it or running it more than a few tanks at a time before shutting it down and letting it cool.

It's near a gallon of fuel through it now and it just started to really calm down with tuning and is really coming to life. I had similar experiences with my LRP28's. Nearly a gallon of fuel through them before the tune started to stabilize, idle became predictable and head temps became stable without fussing over the tune constantly. One of my LRP's probably has 6 gallons through it. The later 4 of those were not easy gallons. It's still a screamer in my revo.

Once an engine is fully broken in and has some run time, I drive them pretty hard, but I still do my best to keep the temps in check and make sure I get proper smoke trails. I also don't run them even after they are broken in if the ambient temps are below 45F. I keep my really old and worn engines for winter bashing, but really, this year I didn't bother setting up my revo like I had planned with my old 3.3. Just never had the time to run it.
 
I broke in a couple of 2.5 and a 3.3 traxxas engine using their method without issue and ran every drop of 4 gallons through each of them without issues.

Now back to this mess....stinking ROSS system failed....let the smoke out of the ROSS motor. bummer. Ended my day.

Going to work on my old starter box and see I can get it going...don't have any good 7.2v batteries so I'm gonna break out my 12v deep cycle and see if I can make it work.
 
The most I got through an engine to date was about 10 gallons and it started flaming out really badly. I had it repinched and put another 3 or so through it. Was an old OS21RG that I had a bb maxx then later in a savage. I wish I had kept better track of how much fuel I put through each of my LRP's. I'm guessing I should break 10 gallons pretty easily.
 
That's a lot of fuel. Starter box works...good thing...if I get out of work tomorrow early enough I will be able to keep breaking it is....but first its time to remove the ROSS.

Thanks for your help
 
You think? I think the only way I could do that is to put a new bearing in it. So far the new engine has been great...until I launched it off of the sidewalk and did a lawn dart into the lawn of all things....and off came the air filter. Great. I shut it down immediately and I will be pulling it apart before I run it again to make sure it didn't get anything in side oh and redo the zip tie holding the filter on.

See what happens.
 
I contemplated getting one of those for the revo when I put the trx 3.3 in, but just decided for ease of install, I just went with the 3.3. Looks like a very similar engine though. Guessing there are internal differences. I know the carb's venturi is a bit larger as I have one of the 3.4 carbs to try on my 3.3 at some point. Others even suggested putting that carb on my OS21TM... might try that too.
 
Thanks for the tip. The revo isn't known for it's carb slide alignment... I hate the throttle setup on that thing. Very little room for error or the ability to change it.

All the posts at the traxxas forum about the 3.4 carb vs stock seem favorable though. If it has issues, then it was a $35 mistake.
 
If it seems that some posts are not in order it's because several were removed due to an unauthorized poster.
Now that I've removed the babbling BS of this "Mystery Wizard", feel free to continue this thread in our normal courteous manner. :)
 
Last edited:
olds97_lss said:
Booooooooo. I was having a nice time with mister wizard.
Click to expand...
He's graced our humble forum before. I'm surprised you didn't recognize his style.
======================================================

EDIT:
I need to re-word that. I should have said, "He's DISgraced our humble forum before."
 
Well, the guy that was retired was on point about the 3.4 carb... ran pretty good for 500 cc's of fuel, then started hanging up and binding bad for no reason. Also about the same time, tune was like chasing a schizophrenic rabbit. Blubbery or not running or sounding lean as all get out. Not worth the headache at $34 a pop to get an hour of bash time. I blew my first plug in many years today chasing the tune! I've had one just not work right here or there and swap out a new one, but this one actually had a deformed coil.
 

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