R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 12-14-2008, 10:48 AM   #1
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default HPI .25 Nitro motor HELPPP???

Hey guys,

I got a weird one. Yesterday i raced my Losi 8T with a HPI .25 motor in it. Its the motor that comes from the Savage RTR. I was desperite and needed a motor and it was all i had. It was new, had been broken in, and ready to race, i thought?? I had a .28 in the truck before so i adjusted the clutch to come in a little sooner (softer springs) cuz i knew the motor would have less power and i didnt want the clutch to slip. I tried running the original clutch set up, but it slipped way to much. So i got the clutch tying up about right, but then, i noticed that the motor just would not REV!!!! It would just go flat. No snap, no top end, just really tame, like having half throttle or something. Put on couple different pipes, one was a JP-2, same results. Try to lean it up, to get it to scream, and it would lean bog up top, never got hot, just wasnt running????? Had 2-3 different guys asking the same questions, we all took a stab at tuning it up, but just could not get it to rip. Any ideas????? Its a new motor, should be decent for now until i can get a new race motor, but why wont this thing rev??????

Thanks in advance!

Last edited by motoclay; 12-14-2008 at 12:22 PM.
motoclay is offline   Reply With Quote
Old 12-14-2008, 12:28 PM   #2
Tech Fanatic
 
Join Date: Jul 2008
Posts: 855
Default

Either the clutch is engaging way to soon, air in the fuel line, plugged fuel filter or something in the carb plugging it. Check air filter
pdmustgt is offline   Reply With Quote
Old 12-14-2008, 12:45 PM   #3
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

bumpity bump bump
motoclay is offline   Reply With Quote
Old 12-14-2008, 01:04 PM   #4
Tech Adept
 
kevinmajor's Avatar
 
Join Date: May 2007
Posts: 192
Trader Rating: 3 (100%+)
Default

It sounds like an airleak. It will make the engine starve for fuel and lean bog like you described. Check the fuel line, gas tank, fuel filter, the neck of the carb, engine backplate, etc.
kevinmajor is offline   Reply With Quote
Old 12-14-2008, 02:37 PM   #5
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

another thing, the motor will bench tune fairly well. It idles like a dream, has great throttle response on the stand, but once you put it down, is where you notice the problem. If it was an air leak, wouldnt it got LEAN sitting there, and idle irratic??
motoclay is offline   Reply With Quote
Old 12-14-2008, 03:44 PM   #6
Tech Fanatic
 
Join Date: Jul 2008
Posts: 855
Default

Check your clutch then
pdmustgt is offline   Reply With Quote
Old 12-14-2008, 05:06 PM   #7
Tech Champion
 
JAMMINKRAZY's Avatar
 
Join Date: Jun 2007
Location: Pittsburgh PA
Posts: 6,575
Trader Rating: 17 (100%+)
Default

Quote:
Originally Posted by pdmustgt View Post
Check your clutch then
+1 this is probably the problem.
__________________
-Koby Kubrin-
Thanks to my Sponsors:
Serpent America | Team Novarossi | Desoto Racing | Race AKA | Ridgeway Bodies
JAMMINKRAZY is offline   Reply With Quote
Old 12-14-2008, 05:58 PM   #8
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

what am i looking for in the clutch?? I was thinking that maybe the motor just cant pull the gearing. 13/48 (stock Losi gearing). I know the springs are right now, because before it would just slip and never tie up. Now it ties up and hooks, but it just wont rip. I figured it would work, but if i put stiffer springs in, it revs, but still not to what i feel it should or is capable of, and its slipping the shoes, which i dont want??
motoclay is offline   Reply With Quote
Old 12-14-2008, 08:22 PM   #9
Tech Fanatic
 
Join Date: Jul 2008
Posts: 855
Default

Is the car trying to move at idle?
pdmustgt is offline   Reply With Quote
Old 12-14-2008, 10:05 PM   #10
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

nope, the clutch is not hung up. i rebuilt the clutch for the motor, i have green and gold springs on it. with aluminum shoes, all Team Losi hardware. 13/48 gearing. all stock gearing in diffs and drives.
motoclay is offline   Reply With Quote
Old 12-15-2008, 01:18 AM   #11
Tech Champion
 
JAMMINKRAZY's Avatar
 
Join Date: Jun 2007
Location: Pittsburgh PA
Posts: 6,575
Trader Rating: 17 (100%+)
Default

Hmmm interesting. if it revs in the air but not on the ground it seems like the clutch, but if you just rebuilt it then idk. Mabey it is your gearing. Mabey try a 14 or 15 tooth bell.
__________________
-Koby Kubrin-
Thanks to my Sponsors:
Serpent America | Team Novarossi | Desoto Racing | Race AKA | Ridgeway Bodies
JAMMINKRAZY is offline   Reply With Quote
Old 12-15-2008, 10:07 AM   #12
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

i was thinking that too, maybe just cant swing the gear?? i dunno, .21s can i dunno why this .25 wont go. Are HPIs horrible engines??? 150 bux if i was to buy it out right, i just happen to have a new savage that i got in a trade, so i thought, wth, ill run that motor, should do fine, but nope??
motoclay is offline   Reply With Quote
Old 12-15-2008, 11:53 AM   #13
Tech Fanatic
 
Join Date: Jul 2008
Posts: 855
Default

It's not a bad engine it's better than the hpi .21 that came on my savage. It's not a high end engine but it should do fine. Going to have more low end torque.

The only reason why we are saying it's the clutch. Because you say it revs fine on the bench. But on the ground it won't go
pdmustgt is offline   Reply With Quote
Old 12-15-2008, 02:02 PM   #14
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

it will move, and run a decent speed, but it just seems to be flat? Ya know, you can nail it and it dont just leap into action, its real tame like a slipping clutch, but it ties up good and loads the motor about right, but then it just doesnt SCREAM on top, like i know it should!!
motoclay is offline   Reply With Quote
Old 12-15-2008, 09:26 PM   #15
Tech Addict
 
Join Date: Sep 2008
Location: Marble Falls, Texas
Posts: 515
Trader Rating: 3 (100%+)
Default

still lookin for other suggestions?????? I really want to make this motor work, cuz i know its capable, ne one ever run this motor before?
motoclay 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 08:36 AM.


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