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New engine help needed... Or.... (The Force is not with me)

New engine help needed... Or.... (The Force is not with me)

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Old 05-02-2009, 09:54 PM
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Default New engine help needed... Or.... (The Force is not with me)

Hey guys, just put an OFNA Force .21 into my Son's buggy. I know, I know, the Force .21 is an old cheap engine, but I had it sitting here and it's new. Anyway, we set the needles to factory specs, prime the engine and heat it up to 200 degrees. Then we start start pulling on the pull starter. After a LONG time it finally attempts to fire over, but even with the carb all the way closed, when we can actually get it to fire up and run for more than a second, it it runs WAY higher than idle speed. High enough to spin the clutch fast enough to start to engage. We can't seem to bring the idle down or even get it to start on a regular basis. We've tried small needle adjustments around the factory settings with no result.

Any ideas? The glow plug is the one recommended and it's hooked to a brand new JP-2 pipe and header.
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Old 05-02-2009, 10:06 PM
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Default Seal It

Air leaks. If it's that old and has been resting a long time , you need to seal it up. Also check the o-rings on the needles. Start here and let us know if it runs or not.
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Old 05-02-2009, 10:08 PM
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richin your low end thats proberty what it is ,and make sure your idle is about 1.5 open where it doesnt turn the wheels when its started. i had nothing but problems with the force engine i coulnt tune that thing at all it would never say running. also i knoe the engine is new but check the carb bolt to see if its tight dont overtighen through . and check for leaks around the engine espially around the carb i had a leak around the carb on the force and i did put sealing around it but it still wount run worth of crap.
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Old 05-02-2009, 10:23 PM
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i would try leaning the bottom end..sounds like its dumping fuel on the bottom and making it rev...Then when its close.. the idle screw will probably be more functional and you can lower the idle as needed...

i would also go and check the o rings and seal it up for extra insurance
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Old 05-02-2009, 10:36 PM
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Its very possible that all the o-rings have hardened and cracked, that would cause major issues. You should replace the rings on the backplate, the carb, the Low and high speed needles and then seal it up good with some lucky 7
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Old 05-02-2009, 11:01 PM
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Ahhhh... I never thought about air leaks. I'll pull the engine tomorrow and check the condition of the o-rings. I'm sure that the engine has been sitting for at least 2 or 3 years anyway.
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Old 05-04-2009, 01:14 PM
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OK We pulled the engine and found that there is a BAD air leak around the inner race of the front crank bearing. We used a bit of soapy water, and you can blow into the carb and it bubbles up badly around the inner race of the front bearing. I checked several other engines and they were tight, so I'd guess that's the problem. What's the easiest way to get that bearing out without a specialized nitro bearing puller?
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Old 05-04-2009, 01:39 PM
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i brought a hyper 7 with the force .26 and barely had any run time on it and for some reason it already had a leak i might just be that engine. good luck tuning it though.
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Old 05-04-2009, 01:50 PM
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1. get a large wood dowl rod or wooden spoon and a hammer.
2. put the dowl rod in through the back of the engine (where the backplate was)
3. heat up the case around the bearing (150 to 250 dagrees should do it)
4. tap the bearing out gently by hitting the hammer on the back side of the dowl rod

ive done this a few times to front bearings, ive never tried to remove a rear bearing this way though, i use a bearing puller for that.

hope this helps
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Old 05-04-2009, 02:50 PM
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Originally Posted by CaptCrunch View Post
OK We pulled the engine and found that there is a BAD air leak around the inner race of the front crank bearing. We used a bit of soapy water, and you can blow into the carb and it bubbles up badly around the inner race of the front bearing. I checked several other engines and they were tight, so I'd guess that's the problem. What's the easiest way to get that bearing out without a specialized nitro bearing puller?
Where in Oklahoma are you at? OKC area???
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Old 05-04-2009, 06:09 PM
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Originally Posted by elcaminosslover View Post
Where in Oklahoma are you at? OKC area???

We live in Moore, just south of OKC.
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Old 05-04-2009, 07:06 PM
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Well.... we disassembled the engine and replaced the front bearing. That seemed to seal it up while cold. It ran at an idle OK until it started warming up, then went high again, so I guess we have another air leak. I inspected the o-rings while we had the egine apart, and they APPEARED to be soft and had no visible cracks or nicks. So, next I guess I'll try sealing the carb. I don't have any actual nitro engine seal, any suggestions as to what else works?
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Old 05-04-2009, 07:19 PM
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I live in Purcell and race at Action Rc in Okc. If you need some help with it just send me a PM and I will give you my phone number. You can use a very thin coat of RTV around the carb. You also need to put a small ziptie around the boot of the throttle!!
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Old 05-04-2009, 07:44 PM
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make sure its high temp RTV..oxygen sensor safe..dosnt break down at all..

seal the carb neck,back plate...as far towards the rear of the plate as possible..also seal up around the "pinch bolts" that hold the carb in...lastley if you feal like it slide the sleeve out and seal up the top edge under the flange of the sleeve with a thin bead and press the sleeve back in..that should DO IT!! as long as the carb seems fine..you can pull the needles out and lube the O-rings on the needles with some light oil

But i still have a fealing some of the issues is with in the tune

hows the STRR elacamino??
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Old 05-04-2009, 07:47 PM
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Originally Posted by elcaminosslover View Post
I live in Purcell and race at Action Rc in Okc. If you need some help with it just send me a PM and I will give you my phone number. You can use a very thin coat of RTV around the carb. You also need to put a small ziptie around the boot of the throttle!!

Is Action RC even OPEN anymore? I've stopped by there to buy parts at least a half dozen times, ant he's never open.
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