R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Nitro Off-Road

Reply
 
Thread Tools Search this Thread
Old 01-30-2009, 05:11 PM   #1
Tech Fanatic
 
Join Date: Nov 2008
Posts: 777
Trader Rating: 6 (100%+)
Default Last Question!!!!

Hi guys,

As many of you know I just got an 8ight truggy a few days ago and just got it already for break in. Tonight I ran my first tank of break in and it was a blast. If I had fun breakng it in I can only imagine how much fun full tune and racing will be!! When I was trying to start the first time I would have to put throttle on and then even with throttle it would die. So eventually I concluded that the low speed was too rich and richened about a 1/12 turn. I did this 3 times and then finnally I could goose the throttle and it would idle. When I put it down and started running it was running well, very rich but nice temps around 210 degrees. Then I realized that when I applied full break it would start to idle much higher and would start to move without me touching the throttle. My question is, is it ok that I leaned the low speed a little bit, and also what was the problem with the idle increasing? can I fiddle with the idle screw to get it to a lower idle or what??

Thanks alot!!
rgrassey@me.com is offline   Reply With Quote
Old 01-30-2009, 05:19 PM   #2
Tech Master
 
jrwoodchuck's Avatar
 
Join Date: Nov 2007
Location: Northampton, Massachusettes
Posts: 1,336
Default

a couple of things can be the problem. check if the idel screw is so the carb is open around .7 to 1.0mm. if it is then your bottom is too lean.
__________________
Doug
TLR 22/M-11

“Looks like I picked the wrong week to quit sniffing glue.”
jrwoodchuck is offline   Reply With Quote
Old 01-30-2009, 05:27 PM   #3
Tech Master
 
jrwoodchuck's Avatar
 
Join Date: Nov 2007
Location: Northampton, Massachusettes
Posts: 1,336
Default

also, i can only speek for myself. but when it comes to the idel screw i never, ever, ever, ever, ever, ever, ever, touch it after its set i don't care how the engine is running. if it's running bad. then something else is wrong.

in fact, i've never touched a idel screw at all. i run OS motors and i've always left it at factory. i have a new v-spec comming early next week and i'll bet it will be just fine also.

but like i said, thats just me.
__________________
Doug
TLR 22/M-11

“Looks like I picked the wrong week to quit sniffing glue.”
jrwoodchuck is offline   Reply With Quote
Old 01-30-2009, 05:33 PM   #4
Tech Lord
 
Jaz240's Avatar
R/C Tech Elite Subscriber
 
Join Date: Aug 2008
Location: Dwindle city
Posts: 12,492
Trader Rating: 52 (100%+)
Default

The idle usually needs to be adjusted either before, during, or after break in. You should also make sure its not the linkage thats causing the problem..remember the RTR's are built in China by people making $2 a week, and sometimes they dont always do it right. It would be wise to check that everything is how its supposed to be. I have seen screws missing, no threadlock, needles all messed up, wrong glow plugs, etc. There are allot of possible mistakes with ready to runs..Nothing that cant be fixed though. Once the engine is fully broken in, then you should be at .7-1 mm... after that its all tuning
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Old 01-30-2009, 08:02 PM   #5
Tech Elite
 
PTP Racing's Avatar
 
Join Date: May 2003
Posts: 2,699
Trader Rating: 2 (100%+)
Default

Put the low speed needle back where it was and tune the high speed needle first.

Many engines Ive had were set lean on the bottom end needle from the factory. I think they do this so the engine will fire easier and idle better during the rich break in.

I never touch the bottom end untill I have tuned the top end needle. The bottom end is a proportion of the top end so every time the top end needle is adjusted so is the bottom end.

What can happen is you lean the bottom end out with the top end still rich and then as you lean the top out the bottom end gets all out of whack because it was already too lean.

Many of my engines idle started to creep up on me after some fuel had been run through as they lose pinch. Usually at that point I reset the idle screw and then lean the bottom accordingly. I usually find they set the idle gap too large from the factory and during break in I usually leave it that way with a slightly richer bottom end needle setting. Once the idle creeps up you can lessen the idle gap and lean the bottom end and still have a good low steady idle.

You always want to start from too rich and work towards lean. When in doubt screw it OUT. Back off and start over.
__________________
Paycheck to Paycheck Racing
Jason Miller
PTP Racing is offline   Reply With Quote
Old 01-30-2009, 08:06 PM   #6
Tech Elite
 
PTP Racing's Avatar
 
Join Date: May 2003
Posts: 2,699
Trader Rating: 2 (100%+)
Default

A good tuned engine should drop right back to idle and the temp should start falling within a few seconds of returning to idle.
__________________
Paycheck to Paycheck Racing
Jason Miller
PTP Racing is offline   Reply With Quote
Old 01-30-2009, 08:13 PM   #7
Tech Master
 
jrwoodchuck's Avatar
 
Join Date: Nov 2007
Location: Northampton, Massachusettes
Posts: 1,336
Default

Quote:
Originally Posted by PTP Racing View Post
A good tuned engine should drop right back to idle and the temp should start falling within a few seconds of returning to idle.
+1
__________________
Doug
TLR 22/M-11

“Looks like I picked the wrong week to quit sniffing glue.”
jrwoodchuck is offline   Reply With Quote
Old 01-31-2009, 07:39 AM   #8
Tech Fanatic
 
Join Date: Nov 2008
Posts: 777
Trader Rating: 6 (100%+)
Default

Ok, but when I accelerate even with my bottom end leaned that little bit it is very boggy nd loads of white smoke are coming out. What I am going to do is just reset my bottom end and try to adjust the idle. Thanks for all your help!! Going to finish break in right now and I am syced!!!
rgrassey@me.com is offline   Reply With Quote
Old 01-31-2009, 08:45 AM   #9
Tech Fanatic
 
Join Date: Nov 2008
Posts: 777
Trader Rating: 6 (100%+)
Default

Now I cant even get the thing to idle for more than a few seconds, Should I raise the idle or fidle with the low speed??
rgrassey@me.com is offline   Reply With Quote
Old 01-31-2009, 08:51 AM   #10
Tech Lord
 
Jaz240's Avatar
R/C Tech Elite Subscriber
 
Join Date: Aug 2008
Location: Dwindle city
Posts: 12,492
Trader Rating: 52 (100%+)
Default

It is because your engine is started to seat..try 1/8 turn in (lean) on the high speed needle, use your radio to slightly open the carb with the trim. finish break in, then set your idle properly, and tune your engine. start the tune on the HSN, then go to the LSN. basic LSN tuning, is you want the throttle respond to be instant! The leaner you make it, the snappier it gets, unless you go to far! you will know when its perfect. it will have ripping speed, awesome response, good smoke, good idle, and temps under 250. remeber to make small adjustments on all needles when tuning, and only tune the engine after it has warmed up. never tune a cold engine!!
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Old 01-31-2009, 08:53 AM   #11
Tech Regular
 
markr04's Avatar
 
Join Date: Jan 2009
Location: TX
Posts: 421
Trader Rating: 1 (100%+)
Default

I've got the same RTR as you. The engine was more difficult to break in than others I have. Even when I thought it was broken in and ready to run as normal, it would idle erratically.

Some helpful people told me that it would behave better after a gallon was run through it. So, I ran it as best I could given the idle problem and they were right. It cleared up shortly.
__________________
Xray 808 2010 Spec - O.S. V-Spec Speed - Airtronics M11-DSSS
Losi 8ight-T 2.0 - RB Killer 9 - Airtronics M11-FHSS-2
Losi XXX-CR - Tekin RS / Novak Ballistic 13.5 - Airtronics M11-FHSS-2
markr04 is offline   Reply With Quote
Old 01-31-2009, 08:58 AM   #12
Tech Master
 
jrwoodchuck's Avatar
 
Join Date: Nov 2007
Location: Northampton, Massachusettes
Posts: 1,336
Default

fire it up and keep it running with the radio working the throttle and get the motor warmed up. if the gap is set correctly, then do the "pinch" test. pinch the fuel line at the carb and see how long it takes to go up in rpm then die. it sould be around 2 seconds before the rpm goes up. if it just dies, then its to lean, if it takes longer than 2 seconds, lean it out a little and try the test again. now this is important.... what you just did is a temperary fix to keep it running. the lsn is a slave to the hsn, so finish breaking in the motor, and once you get the hsn set for a broken in motor, then you can readjust the lsn.
__________________
Doug
TLR 22/M-11

“Looks like I picked the wrong week to quit sniffing glue.”
jrwoodchuck is offline   Reply With Quote
Old 01-31-2009, 09:46 AM   #13
Tech Fanatic
 
Join Date: Nov 2008
Posts: 777
Trader Rating: 6 (100%+)
Default

ok what I did was slightly raise the idle, and then it would idle and run smoothly. Should I still do the pinch test adnd adjust accordingly or should I leave as is. Also as long as it is running really rich (very boggy when accelerating and lots of smoke and lots of smoke when I get up to speed) but still running I should just leave it like this for all of break in and then tune right? I got 2 more tanks done today!!
rgrassey@me.com is offline   Reply With Quote
Old 01-31-2009, 09:51 AM   #14
Tech Master
 
jrwoodchuck's Avatar
 
Join Date: Nov 2007
Location: Northampton, Massachusettes
Posts: 1,336
Default

Quote:
Originally Posted by rgrassey@me.com View Post
ok what I did was slightly raise the idle, and then it would idle and run smoothly. Should I still do the pinch test adnd adjust accordingly or should I leave as is. Also as long as it is running really rich (very boggy when accelerating and lots of smoke and lots of smoke when I get up to speed) but still running I should just leave it like this for all of break in and then tune right? I got 2 more tanks done today!!
i'd leave it alone, wait until it's broke in before you do anything else. it will be a lot easer to tune once it's broke in.
__________________
Doug
TLR 22/M-11

“Looks like I picked the wrong week to quit sniffing glue.”
jrwoodchuck is offline   Reply With Quote
Old 01-31-2009, 10:14 AM   #15
Tech Lord
 
Jaz240's Avatar
R/C Tech Elite Subscriber
 
Join Date: Aug 2008
Location: Dwindle city
Posts: 12,492
Trader Rating: 52 (100%+)
Default

Quote:
Originally Posted by jrwoodchuck View Post
i'd leave it alone, wait until it's broke in before you do anything else. it will be a lot easer to tune once it's broke in.
+1 finish break in before you start messing with anything..follow the break in instructions exactly. When you are done break in, then start race tuning
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

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



All times are GMT -7. It is currently 07:01 AM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net