Tuning questions and symptoms

[VinnieMacIDG]

What's up everyone,

I have a 1/8 buggy with a xtm 247 powering it. I just rebuilt the motor with a new sleeve and piston. All internals were good. The reason for the rebuild was the piston clip that holds conrod and piston popped out on one side and scratched everything all up.
Any how, now that I got most of the info on my motor, I broke it in and buggy feels good but...

1. I just recently got a temp reader and I was at the track yesterday and was running about 230-240f. Is that good or you think I an lean it out a little more? I got a nice trail of smoke when gunning it through the straights. But I think I an get a little leaner but not too sure if I will hurt it.

2. I got a pull starter and was wondering if there is a way to check if I got an air leak from the back plate? And does it make any difference for compression sake? And is there a good solutions to seal it? The gasket ring is a little worn down and I can't find another to buy unless I buy the whole back plate.

3. Does anyone or know of anyone with this motor (xtm 247) having problems with the one way bearing getting stuck and greased over? Can that be because it's running too rich?

Thanks in advance for your help!


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[sv250]

Tune the HSN 1st. Make full blasts leaning after you make the pass when you lean too far you will notice the engine cutting out at top rpm. Richen it until performance is at peak. It will run just before cutting out, but that wont be the sweet spot. Generally its about 2hrs richer on the hsn than its leanest running point. Dont tune with the temp gun no matter what synnyztr says.

You can seal the backplate with any Oxygen sensor safe rtv. 3 bond is the best, but not absolutly necc. Permatex black will suffice.

I've seen people spraying Carb cleaner around the seams while the enging is running to see if the engine bogs. I've never tried this. I just seal it from jump and dont worry about air leaks.

Oneway gumming? Thats an internal oneway. Prolly has more to do with your fuel than tune. Traxxas for instance has a very high oil content 12% so it can wreck oneways. Not sure what your running.

 

[BillyC74]

Ditto on all that.

 

[VinnieMacIDG]

Yeah, I've been running it without temp gun and going off expierance with real race cars. I just got the temp gun just to make sure since everyone is saying so. Lol
I'm running o'donalds, switched from bryons. Actually noticed a little more performance gain but maybe that was because I put a new sleeve and piston?

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[BillyC74]

I think temp guns are handy when breaking in a engine. Other than that let the performance do the talkin. I run Byrons myself and have been really happy with it. I've never tried odonnels.

 

[olds97_lss]

Canned air can be used too to find air leaks. Less caustic than carb cleaner.

I used odonnels once and it made all of my internal OWB's slip. I threw away half the gallon as it was just a pain to use that fuel.

I run byrons 25% race now and all my rigs really run well on it. Also, no OWB's gumming up on me.

 

[sur3fir3]

when i ran nitro found VP pro nitro fuel... great stuff.

 

[VinnieMacIDG]

Thanks for the info guys! Yeah I'm thinking about going back to byrons.. I was at the track today and the odonnels was running good but had a ton of oil residue while warming up in the pits and the temp wad aground 230f. Other than that I'll look into look into carb cleaner or aircan.. how would I use those anyhow?



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[olds97_lss]

The carb cleaner/air can is used to find air leaks. Get the engine running and spray compressed air near all the seals as close as you can. If the engine pitch changes, you found your leak.

The air being forced in will pretty instantly change the tune and possibly stall it depending on how bad the leak is, which will cause the rpm's to change.

 

[davidac49]

what are the symptoms of an engine having an air leak? how necessary is it to seal the entire engine from air leaks? how much of a performance drop can an air leak cause?

 

[sv250]

Air leaks make tuning esp LSN difficult to impossible. RPS climb, idle is erattic. It happens but isnt as common as people think.

Sealing is a precaution. I tear down every engine that I buy even if its brand new. I have found metal shavings and missing screws in the past. Now I tear down, clean, inspect, and seal every engine before I run it.

 

[davidac49]

rps = rotations per second?i guesss these nitro engines are measured in rps and not rpms?

 

[hamz9561]

I think it was a typo. I'm pretty sure he meant RPMs.

 

[sv250]

Yes typo i ment RPMs. Forgot the m

 

[synnyzter]

For the record I've never told anyone to tune to temps. Inexperienced people I tell to keep an eye on them and not go over the limit. Just because "you" are good at tuning doesn't mean a major mistake can't be made by someone new to it. I actually care that people not damage them, I've seen it happen many times. I did it to my first...

But anyhow good advice here. Also note the sticky threads that go into detail for tuning. They are useful.

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[sv250]

Hmm... lokks that way, but oh well

For the record I've never told anyone to tune to temps.

10-220 is way too cool....you want around 260 or your losing a ton of performance.... if your running 210 your engine is crazy rich

 

[synnyzter]

Don't post text from other threads that are specific to a particular discussion, all that does is confuse people and its pointless. That was for a different engine and specific to it. This is just counter productive for him and others. I doubt he cares about that specific thread that doesn't apply to this one anyhow.

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[sv250]

So now your trying to save face by saying you only give bad advice for one engine.

Those are direct quotes from you and represents your credibility. I'm glad you realize just how stupid you sound.

That crap you post is just bad advice no matter what thread its in.

 

[Rolex]

Enough.
Take this to PMs or preferably drop it completely. It does NOTHING to help the member with the advise he needs.
Both of you read this, agree to drop it, then I'll remove those useless posts for the good of the forum.

 

[Alexander_0_1]

You made Mr. Hat yell at you, sorry Rolex.