Running rich and lean at the same time. Help needed.

[Tommy]

First off I'd like to say hi. Been into nitro rc for years but never really been on these forums.

I'm having some strange running issues with my savage (lrp30) but same issues on the last engine (force28)
Been running the lrp in for the past week or so and all has been going well I have 6/8 tanks left from the fresh gallon I bought to run it in and decided to lean it out to around an 80% tune to finish off the gallon. As I start leaning it out all the normal things happen. Reduced smoke, improved performance, higher rpm and so one. However... although running good on WOT lots of smoke lots of power, when I come off the throttle the rpm's don't drop properly. As if it's running very lean (and it's not) I spent a good hour yesterday and another hour today trying just about every tuning method I know and some new ones that I looked up. But no joy. It's running lean, or atleast seems to be when coming off the throttle. No issues when It's running super rich just as I start to lean it out a little. The leaner I tune it the worse it happens even though, and I stress this. It's not running lean on WOT ifs still a little rich about 80% tunes I'd say. Maybe another 180 degrees turn lean to have a close to perfect tuned hsn.

Things I've changed because of this issue. (Things it can't be)

Tank and fuel lines. Stuck new ones on yesterday thinking that would fix the issue.

Pipe. Same results with 3 differnt pipes. Stock, home made and hpi tuned.

Air leak. Searched for one last night. No luck, sealed it all anyway for good measure.

Drive trane issues. Dragging and what not. Can select neutral and free Rev the engine. Rpm's stay high once coming off the throttle. Less so but it still happens.

Servos holding the carb open. Checked this first and several time since the movement is smooth with no sticking opens full and closes all the way with and without the breaks applied.

My imagination.... Touch and go but it's defiantly running like its lean coming off WOT... I think...

Seriously any help with this issue would be appreciated. With the new engine and bits I've thrown some money at this thing the past few weeks and it's killing me that it's not running right or that I could potentially be damaging my new engine.

I'm happy to take pictures/ make videos and give any relevant information to help.

Thanks a lot, Tommy.

P.s sorry it's a long post.

 

[X]

Welcome to the site Tommy!

Sorry to hear you're having issues. Since it wasn't mentioned, can you explain how you've been tuning it so far? My first thought is that your low speed needle needs adjustment. Also, is your idle set properly? should be around 1mm-2mm gap when shut if you look down the carb neck.

Picture out of the manual for your reference (the low speed needle is called mid range needle in this picture):

 

[Tommy]

Yea I set up all the needles to stock before I started breaking it in but found them very lean so richened them up myself ego about 5 turns Out hep and lsn about 4. Lrp said 3 turns hsn 2.75 lsn. Idle is set fine at a little over a mm. At the moment the Lsn is about the same as break in, about 4 turns out. seems to lean out very quick. Pinch test tells me it's about right at the minute. Hsn is around 4 turns Out at around an 80% tune on WOT. To tune it I just did some short Wot runs and leaned out 1/12 each time going off performance and smoke there's still a few hours left in the hsn for a good tune but the over revving on lift off tells me it's running lean as. If I lean out the lsn to around 3 turns it starts to struggle with launch (lean)

When I say turn I mean a full 360 turn. Thanks for the quick reply

 

[X]

Sounds like you have a solid grasp on tuning, hard to say when first meeting someone so I like to stay pretty basic initially. You say that you have sealed the motor, what locations specifically have you done? What fuel and glow plug are you using? Do you use an inline fuel filter? Any pictures of your setup could also help us diagnose this.

 

[Tommy]

Sounds like you have a solid grasp on tuning, hard to say when first meeting someone so I like to stay pretty basic initially. You say that you have sealed the motor, what locations specifically have you done? What fuel and glow plug are you using? Do you use an inline fuel filter? Any pictures of your setup could also help us diagnose this.

Using the lrp r5 one they suggest. Temps from 200/220F. Fuel is byrons gen 2 25% last tank was a modded one with inline filter. I've gone back to stock now thinking that could have been my issue, it wasn't... The set up is just about stock now trying to track this issue. apart from the lrp but same issue on the last engine. il get up a photo shortly.

 

[Tommy]

Oh and I sealed the carb neck and green slimed the needles. But I couldn't find a leak.

 

[Tommy]

 

[Tommy]

The full set up is lrp30 engine. Less then a gallon use.
Hpi tuned pipe on stock header.
19/52 steel bell and spur with new alloy clutch.
3 speed
Just about everything else relating to engine/drive train is stock.

 

[Tommy]

The last tank that I had modded up myself to get rid of mid tank lean seemed to get infrequent bubbles of air in the feed pipe. (Lid seal was dead) That's why I was sure a new tank and lines would sort me out. Not the case. No change. And there's no air bubbles coming from the new tank.

 

[griff7373]

May I suggest turning your pipe so the spout points straight down. The deflector looks nice but I would suggest rotating the entire pipe a quarter turn to get the tip pointed down so the excess fuel in the pipe has a place to go.

 

[blown68ssrs]

Not sure if this will help. This is my experience with hard to tune engines. I have a LRP ZR3.0X and a Picco .26 P3 outlaw that I had a hard time tuning. As it turned out, the O-rings on the LSN's had some flashing. Cleaned them up, hit the carbs with carb cleaner. Problem solved.
Best of luck.

 

[Tommy]

As it turned out, the O-rings on the LSN's had some flashing. Cleaned them up, hit the carbs with carb cleaner. Problem solved.
Best of luck.

Thanks. Il try this before I take it out today.

Il also spin the pipe as I'm willing to try just about anything.