LSN ? bog? Rev?

[Mn Monster]

i have been working on my t maxx 2.5, new body, new tires and rims, i was running hot with my new suburban body (325*) cut out the front and rear windows, got the temp down to 256*. it still bogs out of the hole, shifts greats, runs great high end speeds. my questions is? is the bog caused by my Lsn setting?.

second question:
when i let off the throttle at high speed, it seems like my motor rev's very high before coming back down to a lower (slower) idle. is this normal?

Tmaxx 2.5
resinator pipe
6.3 tires
venom temp/failsafe gauge .
after market cooing head.


i set the Hsn first, good high end good trail of smoke,
i think i have the Lsn close to where it should be, but ii can't get rid of the bog???

idle is fine you could walk away and it would idle all day


any help appreciated!!!!!!!!

 

[MotoGod]

Sounds like your high speed needle is too lean, and your low speed needle is too rich to me. Is it a bog off the line...or a stutter? If it's stuttering then it's a lean bog for sure. If it's kind of gurgling a bit with a huge puff of smoke it's too rich.

You want your HSN tuned to get a nice high speed pass with the engine revving up enough, but still leaving a good smoke trail....and you want your LSN lean enough to give you a quick launch, without stuttering or bogging. Temps don't really matter much in the end. My Revo liked it's tune where it ran 290+. Any richer and it was blubbering all over the RPM Range. Each engine is different ;-)

Good luck with it though!

 

[Mn Monster]

it's a bog, followed by a puff of smoke, than it takes off! no stutter!

 

[BamaFan]

it's a bog, followed by a puff of smoke, than it takes off! no stutter

 

[MotoGod]

If the LSN was too lean it would take off like a rocketship from a stand still (or stutter). The bog is indicative of the low end being too rich. What I have seen (more often than not) is a HSN that is way too lean, and an LSN that is way too rich to compensate. The engine runs, but gets hot.

Now this is just from experience. Which means I've done it too often personally. hehe What I would do Mn.....is go back to factory settings and then zero in on your tune from there. When tuning, you always want to tune from rich to lean....and not lean to rich whenever possible. At least for your base tune....once you get a decent base tune on it...then you can add and subtract 1/2 hour to 1 hour at a time from there as needed.

It is difficult to offer tuning advice without hearing it run and such, so take everything people tell you on a forum with a grain of salt. If it doesn't make sense to you, ask questions until it does. Don't just take my advice (or anyone else's) blindly.

On that note, how is the engine when it's idling? Does it idle well? Will it stay idling for 20-30 seconds or longer without any throttle input? How about after a full throttle pull? If you have it on a stand and pull it wide open for 3-5 seconds and let go of the throttle...what does the engine do? Does it settle right back to idle? Does it go back to idle and then rev up? The more details you can give us...the better the advice we can give you.

Here is a video of my buggy idling on the box after a tuning session with a modded engine. I was filming it to let the modder watch and listen since I was having issues. My LSN ended up being a tad too lean when driving, but on the box it was fine.

[ame="http://www.youtube.com/watch?v=mlwA2_On_kU"]Ptm f850 at idle - YouTube[/ame]

Here is another filmed the same day of me trying to tune out a hesitation off the line. My LSN ended up to lean in the end, so fattening that up @ 1.5 hours was the answer.

[ame="http://www.youtube.com/watch?v=BinsyJACdFI&feature=related"]007 - YouTube[/ame]

...by the way I am NOT a pro tuner by any means. I'm a weekend racer that still asks for help here and there ;-)

 

[Mn Monster]

On that note, how is the engine when it's idling? Does it idle well? Will it stay idling for 20-30 seconds or longer without any throttle input? How about after a full throttle pull? If you have it on a stand and pull it wide open for 3-5 seconds and let go of the throttle...what does the engine do? Does it settle right back to idle? Does it go back to idle and then rev up? The more details you can give us...the better the advice we can give you.



it idles fine pretty much all the time, when i hit the gas it comes right back down to normal idle, same on a high speed pass( minus the high rev) than it drops right back where it should be.

 

[MotoGod]

I would fatten up both needles a few hours and see where that gets you. worst case it will be way rich and you can slowly lean from there and see what happens....or go back to factory and re-tune from there.