R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 07-10-2009, 03:33 PM   #16
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

Sounds like a cracked case maybe..only problematic once the case is heated enough to expand the crack
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Old 07-10-2009, 03:42 PM   #17
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

case? so not sleeve and piston? so i need a new motor? i had a problem with my radio, and had 2 run aways that ran WOT for maybe 15 seconds.

i still have compression, and i don't have any air leaks in the engine. thanks for your input Jaz. still trying to figure out whats going on with this 24.7
builtb16a is offline   Reply With Quote
Old 07-10-2009, 03:43 PM   #18
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

you think it would make sense to try and see whats going on with the motor by taking off the plastic pull start and maybe put it in the oven.. get 220 and then check for leaks. (gloves of course)
builtb16a is offline   Reply With Quote
Old 07-10-2009, 04:30 PM   #19
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 builtb16a View Post
case? so not sleeve and piston? so i need a new motor? i had a problem with my radio, and had 2 run aways that ran WOT for maybe 15 seconds.

i still have compression, and i don't have any air leaks in the engine. thanks for your input Jaz. still trying to figure out whats going on with this 24.7
Compression has nothing to do with a cracked case, and no you do not need a new engine if the case is cracked you will only need a new case. It could be a hairline split by the mounting tabs, or on the bottom where you cant see it. It wont hurt to check. Eliminate one more possibility. My Vspec case was cracked and the only way it could be found was with a flux test. ( I sent it out to be done)..New case, No more problems
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Old 07-10-2009, 05:17 PM   #20
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

this sucks. 50 bucks for a case. 50 bucks for a sleeve and piston.

its 100 for a new complete motor. do the math.

hrm. might look into aftermarket. that was for a stock replacement 24.7 XTM.
builtb16a is offline   Reply With Quote
Old 07-10-2009, 05:24 PM   #21
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

Cracked case is just a theory bud..Theres no way to be sure unless you check. Run your engine, and then as soon as it losses power..take it out and look for signs of fuel/oil on the chassis
__________________
nothing to see here................................
Jaz240 is offline   Reply With Quote
Old 07-10-2009, 08:10 PM   #22
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

oh.. i KNOW the engine is dry. i ran it in a really DUSTY field this afternoon, and it was DRY.

so if the case had a crack, we would have oil/fuel all over the place. well thats good news.

so.. maybe im asking too much for these nitro engines... theoretically, can you run tank after tank without letting it cool down?

i can get maybe a 3/4 a tank that rips.. after that my LSN goes down hill.. so maybe its my tune.

but i know for sure im not leaking oil or fuel onto the chassis, or block.

so thats good news right?
builtb16a is offline   Reply With Quote
Old 07-10-2009, 08:29 PM   #23
Tech Champion
 
air8's Avatar
 
Join Date: Apr 2007
Location: Hutch, KS
Posts: 5,748
Trader Rating: 7 (100%+)
Default

A cracked case doesn't mean it WILL leak fuel onto the chassis.

To answer your runtime question, most people here are racers I think. We go to large race events that have 30 minute to hour long mains depending on the level and size of the event. So the engines must run consistently for that long. When tuned properly these engines will perform and run great for several gallons of fuel. Of course that depends on quality of the manufacturer. Could be as low as 2-3 gallons and upwards of 12-14 gallons. Also the way you drive the vehicle and maintain it plays a HUGE role in engine longevity. Keep er clean, keep er spinning bind free, and keep er tuned.

The only problem is determining when and how to do all this. LOL. Enjoy the hobby.
__________________
--Driver...you are cleared into the track.....Smoke On.

--"U Ain't Fast!!"
Chris Pearce
air8 is offline   Reply With Quote
Old 07-10-2009, 08:36 PM   #24
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

well, the truggy is relatively new. im relatively new to off road.

im not running after run oil.. im still running the truck atleast every other day.. i always run very clean air filters. and i never leave fuel in the tank over night. so i think my upkeep is pretty decent.

my onroad i never had issues like this. i could run tank after tank, all day and night.

so im kinda wondering what the hell is going on with this LSN. i know its teh LSN, because when i get going, it starts to take off, with plenty of smoke and screams! my HSN seams fine.

tomorrow im headed to the track, and hopefully someone can help me with my tune.

its weird, usually i can't get the engine to fire unless im 2 1/2 turns out of the LSN. then after i get it running i can lean the LSN down to 1 3/4 - 2turns.

im running a med OS plug and i think i broke the engine in properly. anywyas.. i'll post updates soon.
builtb16a is offline   Reply With Quote
Old 07-10-2009, 10:20 PM   #25
Tech Master
 
SkarTisu's Avatar
 
Join Date: Sep 2001
Location: Minnesota
Posts: 1,669
Trader Rating: 8 (100%+)
Send a message via AIM to SkarTisu Send a message via Yahoo to SkarTisu
Default

Quote:
Originally Posted by builtb16a View Post
its weird, usually i can't get the engine to fire unless im 2 1/2 turns out of the LSN. then after i get it running i can lean the LSN down to 1 3/4 - 2turns.
In my experience, I've never had to play with the LSN just to get the engine running, then tune it afterwards to optimize performance. The LSN setting it starts on should be fine for driving afterwards.

Have you tried richening up the LSN yet? I don't think you have a cracked fuel tank or engine block, either.
__________________
Marshall Skare
Team Associated - Reedy Powered - JConcepts - LiveRC.com
SkarTisu is offline   Reply With Quote
Old 07-11-2009, 04:24 AM   #26
Tech Champion
 
air8's Avatar
 
Join Date: Apr 2007
Location: Hutch, KS
Posts: 5,748
Trader Rating: 7 (100%+)
Default

Hopefully your clutch bell clearance is ok. If the bells warms up and starts binding that could cause some low end drag and tuning problems. Are you using soft clutch setup? Sometimes slightly stiffer clutch springs, or fresh clutch springs, help with low end bog issues. Are you using 30% nitro or 25% even? Some engines like a hot plug when using the higher nitro content.
__________________
--Driver...you are cleared into the track.....Smoke On.

--"U Ain't Fast!!"
Chris Pearce
air8 is offline   Reply With Quote
Old 07-11-2009, 07:48 AM   #27
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

20% and ive blown both inner and outer clutch bell bearings.

this is the weird part. 1st time i blew the bearing was because the button head bolt broke. so i changed the outter bearing. it fell apart. about a week later, the internal bearing came apart. (found out later its best to change them as a pair)

the internals are completly stock.

im headed to the track here in a few mins. im going to try and get with a old timer there and see if i can't get any pointers on why my LSN is tripping.
builtb16a is offline   Reply With Quote
Old 07-11-2009, 02:07 PM   #28
Tech Champion
 
Jason Pelletier's Avatar
 
Join Date: Jul 2007
Location: New York
Posts: 8,820
Trader Rating: 33 (100%+)
Default

Prolly worn out piston and sleeve.



Lean is mean !!!!!!
__________________
Island Raceway & Hobby
Jason Pelletier is offline   Reply With Quote
Old 07-11-2009, 08:45 PM   #29
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

with the 2 run aways.. i think my piston and sleeve might be done.

i can get it running. but only really lean. like 1 - 1 1/2 turns out. and still doesn't get over 220. i took the truck to the hobby shop, and the old tymer there felt the flywheel and said it was done.. but i had compression still, and it runs, so i didn't take it that serious.

but i have a new piston and sleeve, so i might put it in, and see if my tuning issues go away.

sucks, cuz i took my time, ran 2 tanks through it at idle. putted 2 tanks around at 180-190.. then a tank more at 200.. and then TRIED.. to get the tune on it.. and had some bad luck, and a couple run aways.. and its been downhill from there.
builtb16a is offline   Reply With Quote
Old 07-11-2009, 11:22 PM   #30
Tech Regular
 
builtb16a's Avatar
 
Join Date: Jun 2009
Location: Redlands, CA
Posts: 295
Trader Rating: 1 (100%+)
Default

ok. went ahead and changed the piston and sleeve. im sure glad i took my time, i almost ruined the wrist pin retainer.

i had no troubles starting the new build, so thats a good thing. it was a bit tight. i had to loosen up the plug on the bump box. (might be my batteries)

but i let it run for maybe 2 or 3 mins.. its 11pm.. so i'll start the break in tomorrow.

here's some pics of the old junk.. dunno if it shows any damage.
Attached Thumbnails
i loose low end power after warm up..-0711092312.jpg   i loose low end power after warm up..-0711092314.jpg  
builtb16a is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Houstons Engine Service H.E.S. houston Offroad Nitro Engine Forum 8821 06-17-2017 12:29 PM
"the tuning bible" houston Onroad Nitro Engine Zone 311 04-24-2017 11:18 PM
Please Help Muah! Speedjunkyz Nitro On-Road 36 09-05-2008 07:13 AM
Engine Tuning 101 (General Tuning) Kemorc Onroad Nitro Engine Zone 41 11-19-2007 06:04 PM



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 07:15 AM.


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