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Old 06-12-2010, 08:04 AM   #1
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Default What could cause an engine to not idle when it's warmed up?

I'm pretty sure it's just shot but I want to be sure I'm not missing something. Is there something I could be doing wrong tuning wise? It runs great, plenty of power, just won't idle once it gets around 200 degrees.

Could a different plug help?
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Old 06-12-2010, 08:22 AM   #2
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Try turning up your idle speed, it's normal for the speed to drop some when the engine gets warmed up.
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Old 06-12-2010, 08:52 AM   #3
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how is the compression when engine is warm??

Normally if an engine has had plenty of use and wont idle or start once warm then its had its day. Either renew certain parts or get rid
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Old 06-12-2010, 09:13 AM   #4
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how is the compression when engine is warm??

Normally if an engine has had plenty of use and wont idle or start once warm then its had its day. Either renew certain parts or get rid
It'll start when it's warm... So does that maybe mean it's just the idle?
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Old 06-12-2010, 09:34 AM   #5
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With the engine warm, remove the glow plug and rotate the flywheel. How much pinch (resistance) does it have?
Engines have less pinch warm than cold.
When an engine loses it's pinch, the 1st thing to happen is stalling/poor idle.
A piston/sleeve set will renew your engine, if all the other internals are ok.
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Old 06-12-2010, 09:46 AM   #6
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It'll start when it's warm... So does that maybe mean it's just the idle?

Not at all, as motomatt has said, replace piston & liner. This should definately solve your issues. How many gallons has been through the engine? also what engine is it? thanks
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Old 06-12-2010, 09:52 AM   #7
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Not at all, as motomatt has said, replace piston & liner. This should definately solve your issues. How many gallons has been through the engine? also what engine is it? thanks
No idea, it's used, came with the RC8 I just picked up. It's a GB .21 something or other. Says made in italy on the back plate. I've never heard of them. The guy I bought from says it's a rebadged nova P5. I'm skeptical.
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Old 06-12-2010, 10:04 AM   #8
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No idea, it's used, came with the RC8 I just picked up. It's a GB .21 something or other. Says made in italy on the back plate. I've never heard of them. The guy I bought from says it's a rebadged nova P5. I'm skeptical.
GB .21????

pic?

low compression first guess as has already been said
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Old 06-12-2010, 10:10 AM   #9
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GB .21?


probably best you just buy a new engine mate tbh.
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Old 06-12-2010, 10:29 AM   #10
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Originally Posted by motomatt View Post
With the engine warm, remove the glow plug and rotate the flywheel. How much pinch (resistance) does it have?
Engines have less pinch warm than cold.
When an engine loses it's pinch, the 1st thing to happen is stalling/poor idle.
A piston/sleeve set will renew your engine, if all the other internals are ok.
Just because the engine hasn't got pinch don't mean it's dead.


Furadi: are you sure it doesn't say BP on the back. They make offshore racing engines, but also nitro model engines. A bud of mine was sponsored by them a few seasons back. He got 20 gallons out of his last engine from them.
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Old 06-12-2010, 05:26 PM   #11
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Default send me the piston and sleeve and I'll pinch it for $10.

Over the years I been Pinching Sleeves and machined ever pinch specific tool out there from XTM to NovaR. Anyway, I probly already have the tool machined for that motor as many of the sleeves are the same Diameter.. Anyway if your interested email me and ill send you my home address and #. unless you have a bent rod or major air leak(check the front bearing seal) it is the Piston/Sleeve.. rc12ls@yahoo.com
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Old 06-12-2010, 08:59 PM   #12
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Think I have it sorted out. Turned up the idle a bit, fattened up the bottom and leaned out the top. It will idle now for a good bit instead of dying when I let off.
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Old 06-12-2010, 09:51 PM   #13
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Quote:
Originally Posted by motomatt View Post
With the engine warm, remove the glow plug and rotate the flywheel. How much pinch (resistance) does it have?
Engines have less pinch warm than cold.
When an engine loses it's pinch, the 1st thing to happen is stalling/poor idle.
A piston/sleeve set will renew your engine, if all the other internals are ok.
Pinch hurts idle, that's why new engines are a pain in the butt. I have had new engines stall, I go to restart and find the piston locked TDC in the pinch. Replace the words "pinch" with "compression" and you will be making sense, to me at least.
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Old 06-12-2010, 10:09 PM   #14
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Quote:
Originally Posted by Furadi View Post
Think I have it sorted out. Turned up the idle a bit, fattened up the bottom and leaned out the top. It will idle now for a good bit instead of dying when I let off.
Quote:
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Think I have it sorted out. Turned up the idle a bit, fattened up the bottom and leaned out the top. It will idle now for a good bit instead of dying when I let off.
Not to throw any sticks in your spokes but you may want to read through this: http://www.rctech.net/forum/nitro-of...ing-bible.html

You could have started by leaning the low end by one hour or two, this would have naturally raised your idle and you may have been all set. Pinch Test and plug reading can help you here. Instead, you richened your low speed, this will slow the idle down because more fuel is allowed into the combustion chamber putting more of a load on the piston. If you had an idle problem before and than you richened low speed you definitely would have needed to turn up the idle screw to compensate. In my eyes, you are worse off than where you began when you first started this thread. Leaned the top end, why? Why didn't you just start by turning up the idle screw? Time to get lost in the sauce...Read the tuning bible and pay close attention to the first part of it. Let us know how it goes.
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Old 06-12-2010, 11:34 PM   #15
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Not to throw any sticks in your spokes but you may want to read through this: http://www.rctech.net/forum/nitro-of...ing-bible.html

You could have started by leaning the low end by one hour or two, this would have naturally raised your idle and you may have been all set. Pinch Test and plug reading can help you here. Instead, you richened your low speed, this will slow the idle down because more fuel is allowed into the combustion chamber putting more of a load on the piston. If you had an idle problem before and than you richened low speed you definitely would have needed to turn up the idle screw to compensate. In my eyes, you are worse off than where you began when you first started this thread. Leaned the top end, why? Why didn't you just start by turning up the idle screw? Time to get lost in the sauce...Read the tuning bible and pay close attention to the first part of it. Let us know how it goes.
This isn't my first nitro. Just needed to work the rust out of my tuning skills. + I had no idea what shape this motor was so I assumed it was dead.

If it's running good now does anything else really matter?
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