Tuning Puzzler

Old 02-13-2013, 04:51 PM
  #1  
Tech Rookie
Thread Starter
 
Join Date: Feb 2013
Posts: 10
Questions?? Tuning Puzzler

Okay guys, got a tuning issue for which I can not find an answer. I have a Losi 8ight 2.0 rtr with 350 nitro engine. Ran everything stock with 20% for about one gallon. Ran perfect. Tuned perfect. Decided to upgrade to turbo head conversion and go to 30% nitro. Tune is way out of wack now. Car cranks only if warm. It idles very high. Haven't touched idle screw. Idle screw is set at about the width of a dime. Since idle was high, I set lsn about a quarter turn richer. Idle came down. I can pull throttle a couple of times no problem. Then about the third time of pulling throttle it bogs down a little and then when I let of the throttle it idles high again. Leaning lsn only increase idle speed. Did a pinch test on the fuel line. When I restricted the fuel line about an inch from the carb, the engine raced out of control. Conflicting information, idle suggests go richer, restricing fuel line says go leaner. Any suggestions?
DrewB is offline  
Old 02-13-2013, 07:10 PM
  #2  
Tech Regular
iTrader: (5)
 
Join Date: Aug 2012
Location: Forney, Texas.
Posts: 267
Trader Rating: 5 (100%+)
Default

Originally Posted by DrewB View Post
Okay guys, got a tuning issue for which I can not find an answer. I have a Losi 8ight 2.0 rtr with 350 nitro engine. Ran everything stock with 20% for about one gallon. Ran perfect. Tuned perfect. Decided to upgrade to turbo head conversion and go to 30% nitro. Tune is way out of wack now. Car cranks only if warm. It idles very high. Haven't touched idle screw. Idle screw is set at about the width of a dime. Since idle was high, I set lsn about a quarter turn richer. Idle came down. I can pull throttle a couple of times no problem. Then about the third time of pulling throttle it bogs down a little and then when I let of the throttle it idles high again. Leaning lsn only increase idle speed. Did a pinch test on the fuel line. When I restricted the fuel line about an inch from the carb, the engine raced out of control. Conflicting information, idle suggests go richer, restricing fuel line says go leaner. Any suggestions?
You idle gap is way to big. You should only be around .5 to 1mm gap. If your pinch test the engine idles up a lot your rich on the lsn. I would set my idle gap and start over with your hsn and lsn settings.
Gsnow39 is offline  
Old 02-13-2013, 07:15 PM
  #3  
Tech Master
iTrader: (15)
 
sschultz's Avatar
 
Join Date: Mar 2012
Location: SW Minnesota
Posts: 1,351
Trader Rating: 15 (100%+)
Default

Originally Posted by DrewB View Post
Okay guys, got a tuning issue for which I can not find an answer. I have a Losi 8ight 2.0 rtr with 350 nitro engine. Ran everything stock with 20% for about one gallon. Ran perfect. Tuned perfect. Decided to upgrade to turbo head conversion and go to 30% nitro. Tune is way out of wack now. Car cranks only if warm. It idles very high. Haven't touched idle screw. Idle screw is set at about the width of a dime. Since idle was high, I set lsn about a quarter turn richer. Idle came down. I can pull throttle a couple of times no problem. Then about the third time of pulling throttle it bogs down a little and then when I let of the throttle it idles high again. Leaning lsn only increase idle speed. Did a pinch test on the fuel line. When I restricted the fuel line about an inch from the carb, the engine raced out of control. Conflicting information, idle suggests go richer, restricing fuel line says go leaner. Any suggestions?
It's hard to help from a keyboard, but, I'm guessing your idle gap is way to big. Pull you air filter off and set your idle gap to .5 to .7mm. That's about half the thickness of a credit card. Set your needles to factory or flush( not sure what kind of engine you have). Once that idle gap is set, adjust your idle with the low speed needle adjustment ONLY! That will get you in the ballpark with your lsn. Adjust your hsn as needed. If you start with flush or factory settings, You'll have to lean it to find your sweet tune....Hope this helps...
sschultz is offline  
Old 02-13-2013, 08:24 PM
  #4  
Tech Regular
iTrader: (23)
 
jhold87's Avatar
 
Join Date: Oct 2010
Location: Toney Alabama
Posts: 460
Trader Rating: 23 (96%+)
Default ......

Once you get your idle set ,and back to factory settings remeber to set your hsn before you ever touch the lsn.
jhold87 is offline  
Old 02-13-2013, 09:34 PM
  #5  
Tech Prophet
iTrader: (96)
 
houston's Avatar
 
Join Date: Sep 2004
Location: Sherwood,OR
Posts: 15,837
Trader Rating: 96 (100%+)
Default

Shimming
houston is offline  
Old 02-13-2013, 09:58 PM
  #6  
Tech Master
iTrader: (15)
 
sschultz's Avatar
 
Join Date: Mar 2012
Location: SW Minnesota
Posts: 1,351
Trader Rating: 15 (100%+)
Default

Originally Posted by houston View Post
Shimming
Yep, that's probably a lot of it. I'm not familiar with engines that are shimmed for anything but 30%. I don't wanna step on toes but was my advice good? I can take it if I'm wrong cause if I am, I'll keep my mouth shut, or my keyboard. I don't wanna give bad advice. I know what works for me.
sschultz is offline  
Old 02-13-2013, 11:03 PM
  #7  
Tech Rookie
Thread Starter
 
Join Date: Feb 2013
Posts: 10
Default

Thanks for all the feedback. The engine is a Losi 350. Still not ready to upgrade to new motor so just trying some mods to use will I continue to learn and train. Pulled engine and did a leak check. Has some leakage around carb. Have it sealed now. I will try again tomorrow. I will follow advice and set everything back to factory stock and try from there with idle set at about .5mm. As far as shims go, the turbo conversion came with three shims. Two that are .2mm and one that is .1mm. Instructions said to use both the .2's (which I did) and only add the .1 if I live in a high humidity area, which I don't. I'm going to leave shims as set and try again tomorrow with smaller idle gap. Still not sure why idle setting was fine before and now isn't. Does going from 20% to 30% make that much difference? When changing to 30% what carb adjustments usually have to be made?
DrewB is offline  
Old 02-13-2013, 11:57 PM
  #8  
Tech Elite
iTrader: (3)
 
merdith6's Avatar
 
Join Date: Oct 2009
Location: Brazoria, TX
Posts: 2,350
Trader Rating: 3 (100%+)
Default well

If it worked great before why not just go back to what worked. If it aint broke, don't fix it.
merdith6 is offline  
Old 02-14-2013, 01:15 AM
  #9  
Tech Master
iTrader: (15)
 
sschultz's Avatar
 
Join Date: Mar 2012
Location: SW Minnesota
Posts: 1,351
Trader Rating: 15 (100%+)
Default

Originally Posted by merdith6 View Post
If it worked great before why not just go back to what worked. If it aint broke, don't fix it.
Are you really asking this?

The guy is looking for performance!

Obviously
sschultz is offline  
Old 02-14-2013, 06:35 AM
  #10  
Tech Fanatic
iTrader: (95)
 
Join Date: May 2006
Location: cincinnati ohio
Posts: 886
Trader Rating: 95 (100%+)
Default Turbo

I have a 350 and the turbo head will for sure wake it up alot.I think your problems are first the idle gap and second is that when you went from 20% to 30 % you need to richen it quit a bit. If you use the same shimms that were on the standard head it will be fine. Hope this helps.
latemodel13 is offline  
Old 02-14-2013, 07:29 AM
  #11  
Tech Prophet
iTrader: (96)
 
houston's Avatar
 
Join Date: Sep 2004
Location: Sherwood,OR
Posts: 15,837
Trader Rating: 96 (100%+)
Default

Sounds like you may have the shimming correct but should triple check just to be certain
houston is offline  
Old 02-15-2013, 06:13 AM
  #12  
Tech Rookie
Thread Starter
 
Join Date: Feb 2013
Posts: 10
Default Problem Solved

First of all, thanks for the feedback everyone. It is forums like this that help all of us learn. I had an air leak at the carb and back plate. Sealed both. Also backed off the idle. Engine idles great now. I will have to do some fine tuning when weather warms up, but what a difference the turbo conversion makes on this Losi 350. Going to make this 8ight 2.0 a great car to continue to learn on before I make the big investment into a better engine.
DrewB is offline  
Old 02-15-2013, 08:23 AM
  #13  
Tech Prophet
iTrader: (96)
 
houston's Avatar
 
Join Date: Sep 2004
Location: Sherwood,OR
Posts: 15,837
Trader Rating: 96 (100%+)
Default

Originally Posted by DrewB View Post
First of all, thanks for the feedback everyone. It is forums like this that help all of us learn. I had an air leak at the carb and back plate. Sealed both. Also backed off the idle. Engine idles great now. I will have to do some fine tuning when weather warms up, but what a difference the turbo conversion makes on this Losi 350. Going to make this 8ight 2.0 a great car to continue to learn on before I make the big investment into a better engine.
Good deal Drew

The odd thing is you must have had this issue before right?
houston is offline  

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.