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Used ofna hyper .21 too rich? Help please!

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Used ofna hyper .21 too rich? Help please!

Old 10-07-2008, 05:37 PM
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dacaur
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Default Used ofna hyper .21 too rich? Help please!

I edited this post to reflect the current situation.....

OK, so I recently got a great deal on a Used T-maxx... In the max is an engine, that on the pullstart says "hyper .21 turbo" and it says hyper .21 on the case.. so i guess its an Ofna hyper 21....

First time I tried it: First thing I did was replace all the fuel lines, then set it to the factory "post break in" settings recommended in the manual.... It actualy fired right up, but as soon as I gave it ANY throttle, it would die instantly.... I quickly determined that it was flooding (based on the large amount of fuel that came out when I changed the glow plug)
So I ended up turning in the low speed needle 2 turns and the high speed needle about 1.5-2 turns to even get it so I could apply throttle and get the clutch to engage... There is still a LOT of fuel at idle and a healthy amount of smoke and even more fuel when its revving comming out of the pipe, and it still didnt get up to more than about 5mph.... It seems I need to lean it more.

Second try: HSN 4.5 turns out the truck will run, but bogs on throttle application, and will barely move 5mph.. HSN 3.5 turns out, the truck moves now, but still not full speed... HSN 3 turns out it seems to run ok, but the tune keeps changing.... I noticed bubbles in the fuel line, so replaced the fuel filter... no more bubbles, but it still wont run good at any more than 2.5-3 turns out, and still spits a lot of fuel out the exhaust at idle....

Today I took off the carb, the original owner had not installed the bolt to hold the carb on, and instead had rigged a piece of stiff wire to keep the carb from spinning.... also the O-ring was in sorry shape.. I replaced it and installed a bolt but I cant help but wonder..... Wouldn'T an air leak cause a lean condition? This engine seems to have a problem being too rich... I'm confused... Going to try it tomorrow to see if the new o-ring helped....

One more thing... In the pinch test, even when the engine seems to be running ok, it will run for about 12 seconds when I pinch it close to the carb... this is with the HSN at 3 turns out....
Old 10-07-2008, 05:52 PM
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JB COMP
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Default RE: Used ofna hyper .21 too rich? Help please!

I think I went 4 turns out from closed on the LSN on my Hyper 21, or flush. (which every is more turns out.) and I think about 4 turns out on the HSN.

I think it was flush on the LSN, because it seemed like it was way out. (like 8 turns or something like that)

Lean the HSN first then tune the LSN.

My Hyper 21 didn't have very much Low end at all, it was kind of weak on the low end, but it would rev out. The timing on my Hyper 21 was very high. So I'm not sure how well its going to do in a maxx.
Old 10-07-2008, 08:53 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

I agree with JBCOMP you set your HSN first then start to tune your LSN. I don't know what the factory settings are for that engine, but when you make needle adjustments, make small 1/12 turns until you get desired performance. You can not rush a nitro engine tune. Especially on a used engine.
Old 10-11-2008, 03:41 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

Ok, So it looks like the pipe in the truck is this one http://www3.towerhobbies.com/cgi-bin...&FVSEARCH=4942 which i think is made for the .15 engine.. could that be the trouble? my friend who sold it to me says the pipe is too small so makes too much pressure in the fuel tank, which makes it run rich... I have no idea if thats even possible.... (I havent even tried starting it again yet....)
Old 11-09-2008, 04:11 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

Another update...

I seem to have arrived at this engines "ideal" tune....

Here is the really weird part. HSN is 1 3/4 out, and its still a little rich!!!!
Good smoke trail on acceleration.
Still lots of fuel being spit out at idle, especially when i blip the throttle... even at the end of a high speed pass, when I bring it back I can blip the throttle and fuel will spit out.
Pinch test runs about 5 seconds before rpms drop.
Temp is good, spit test takes about 3-5 seconds to boil away.

I dont understand this at all.... This engine should be way too lean at 1 3/4 turns out shouldn't it? But if I richen it, the truck bogs and wont accelerate.....

Should I just run it like this? Is there something I can check that could cause it?
Old 11-09-2008, 04:24 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

What fuel and what plug are you using? Also there are several Hyper.21's, which one do you have?
Old 11-09-2008, 05:44 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

Im pretty sure its just a normal hyper 21... not the 8 port or race one...

Fuel is O'donnell 20% racing fuel.
Plug im not sure of, it was one that came with the t-maxx, it was open but unused when i put it in.... could that make a big difference?
Old 11-09-2008, 09:14 PM
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Default RE: Used ofna hyper .21 too rich? Help please!


ORIGINAL: dacaur

Im pretty sure its just a normal hyper 21... not the 8 port or race one...

Fuel is O'donnell 20% racing fuel.
Plug im not sure of, it was one that came with the t-maxx, it was open but unused when i put it in.... could that make a big difference?
The plug makes a huge difference! All the Hypers I have seen regardless of what model they are seem to run the best when running 20% with an MC8 unless it is below 40 degrees outside then maybe go the MC59. The MC8 is a medium range plug, the MC59 is a hot plug, MC9 is a cold plug. When I run 30% I use the MC9 unless its below 40 degrees outside then I go with the MC8.
Old 11-10-2008, 07:08 AM
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Default RE: Used ofna hyper .21 too rich? Help please!


ORIGINAL: cltcrns

The plug makes a huge difference!
Well the thing is, the engine runs fine, the problem is that it only runs fine with the HSN out 1 3/4 turns. It wont even start with the HSN set at the recommended 4 turns out, it floods and locks up.... I cant see the plug causing that? But I do have a mccoy #8. Ill try it....
Old 11-11-2008, 11:21 PM
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cltcrns
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Default RE: Used ofna hyper .21 too rich? Help please!

Do you have the 3 needle carb? A MSN, LSN and a MID range needle?
http://www.ofna.com/forum/viewtopic.php?t=4339
The above is the carb I am talking about with a 3 needle set up.
Old 11-12-2008, 09:28 PM
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Default RE: Used ofna hyper .21 too rich? Help please!

Yes, 3 needle.
Old 11-12-2008, 10:51 PM
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cltcrns
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Default RE: Used ofna hyper .21 too rich? Help please!

Check out the link I gave you, it describes the 3 needle set up perfectly and how to make sure your mid needle is set properly. I have a friend on that site that turned me onto it and it was a God sent to me when I messed with that needle for the first time. Also you have to remember that the "factory" needle settings are just a baseline setup and no 2 engines tune the same, so I would say set the HSN and LSN so it will fire up after you have checked the propper setting for the mid needle then tune from there. Real quick in case the link doesn't work, remove the HSN housing and look in the hole, with the mid needle flush to the carb body or very close to it your mid needle hole should line up with the HSN hole. Going that way with the mid needle, you should never really have to tune it again unless you get very good at tuning and notice the small change it will make for you in performance. Something else to consider is marking the carb body and needle so you can tell if it ever walks on you. Hope some of it helped.

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