Kyosho GX15 engine problems

Old 02-08-2010, 10:47 AM
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Default Kyosho GX15 engine problems

Hi All, I'm new to nitro, and new to the forum. I've just bought a second hand Kyosho GP Ultima ST with a GX15 engine. It was bought really cheap, and I'm trying to get it set up. The problem I have is as follows. The engine starts straight up, no problems, and idles ok, but I'm having trouble stopping it. I've got an engine stopper, which is basically a plug to stop the exhaust, but the engine runs with the exhaust stopper in. Its also ticking over quite quickly. The main problem is also this.. When I increase the engine rpm with the throttle, it revs up ok, but a pool of what looks like oil appears under the engine. What could be causing this? The exhaust is slightly smoky at tickover, but thats ok right? Also, I can only see one adusting screw.
Any advice would be greatly appreciated.
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Old 02-10-2010, 02:32 AM
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Wow, thanks for all the help guys... Seems like such a friendly forum...
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Old 02-10-2010, 02:53 AM
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Sounds like you've got a leaky exhaust for starters, that needs to be fixed before we can tell if there are other problems. The oil under the engine and the fact that it doesn't stop when you plug the exhaust is the clue here. Either a bad gasket or loose header.
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Old 02-10-2010, 07:30 AM
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Yeah, just figured that one out last night. Got new header gaskets coming. Also think I've now got a duff glowplug... Doesn't start at all now. Tested it, and it not glow... and yes, I've checked the glowplug starter is charged.. . Off to pick up a loada spares now..

Doesn't look like there's any low end needle mixture adjustment, only high end..

I'll know more when I've got it running long enough to warm up. As soon as I hit the throttle, it cuts out at the moment. I'm a bit stymied til I've fixed the exhaust and glowplug. I'm guessing the glowplug bought it when I dropped it.. At least I haven't refitted it, and it looks as if the coil is intact, so it hasn't fallen into my cylinder..

Thanks for the reply..
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Old 02-10-2010, 07:41 AM
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When it cuts out is there any smoke from the exhaust? if so you're to rich, if there's no smoke and it dies instantaneously you're too lean.
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Old 02-10-2010, 10:20 AM
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Didn't see any smoke as such after it cut, but I had it running at idle for about 40 seconds, then the rpms started to drop off, so I opened the throttle, and it stopped. Instantly. It wasn't really warm though. I need to get it up to temperature really before fiddling with the mixture. The only thing is, I haven't been able to get it running long enough to achieve this. Once I've got the exhaust sorted, then we'll see what happens. There doesn't seem to be a low speed mixture control though, only a high speed one. Is it normal to get a lot of oil from the exhaust?? It seems to be quite oily back there...
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Old 02-11-2010, 01:14 PM
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Right, I've sorted the exhaust leak, and its much quieter now. I've fitted a new glowplug, and fully charged my glowplug starter. Engine fired on the 1st pull, started on the second, and ran at a fast, even tickover for about 30secs. It then stopped. It seems to be not drawing fuel from the tank properly. I took the fuel tank off and checked it, seems ok, but fuel lines seemed a little loose, so I replaced them. Started up ok, but stopped again quickly, then wouldn't start again, no matter what I did. I did manage to flood it, string got hard to pull, but took the glowplug out, and turned the car upside down & pulled the string, to force the fuel out. Tested & replaced glowplug again, but engine will not even fire, no matter what I do. Got fed up with it now, beginning to think its more bother than its worth.

What am I doing wrong? I've checked & rechecked glowplug & starter, all seems ok. I've purged the cylinder without the glowplug in to get rid of excess fuel, and there seems to be plenty of compression. The fuel lines aren't loose any more, and the tank is sealed. When I blow through the pipe than runs rom the exhaust to the tank, fuel flows through to the carb. But for the life of me can't get the engine running. What's wrong??
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Old 02-11-2010, 02:19 PM
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I know this might sound strange, but even if your glow plug lights out of the engine, it could be a faulty plug. One way to check if your plug is good, is when you take your ignitor off the plug is there a change in idle? If there is, most likely the glow plug is pooched.
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Old 02-11-2010, 05:12 PM
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I hear what you're saying. I was seriously thinking it is partly glowplug related. When I do get the motor running, the idle defo does drop/stop after the igniter is removed... Sometimes.. I have been tending to remove it after a few seconds, so as not to toast the glowplug. Its a brand new one, though, straight out of the packet, bought today. My old one was well toasted. Mind you, with it being a total bitch to get running, the igniter has been on for probably 10-15 secs at a time. If it doesn't start in that time, I'm careful to take the igniter off, to protect the glowplug. Mind you, what probably isn't helping is the fact that I've been outside (cos of fumes) trying to start it, & its hovering around freezing outside. The frustrating thing is, when I do get it running, it won't run long enough to warm up, even when it starts on high throttle, so fiddling with mixture settings is probably not a good idea. I'm beginning to think the engine & carb need some tlc, esp cleaning & renewing stuff. I've already renewed the fuel lines, and sorted a leaky exhaust. I think its defo a carb prob now..
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Old 02-12-2010, 08:48 AM
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Right, problem sorted. Engine starts 1st pull now, almost every time. Took the engine off the car, stripped down the only mixture needle, which is the high rev mixture, cleaned it, reassembled it, then set about tackling the exhaust gasket. The one I changed before was the circular rubber one that goes in the end of the silencer, but when I took the engine off, I could see that the exhaust flange gasket, between the head & muffler was knackered. Replaced that one, and all my starting problems were cured. Have set the mixture now, and found a sweet spot on the adjustment which gives good performance, and still blue smoke under full throttle. It runs nicely like this, but I think it is still a tiny bit rich, the running temp is about 198deg F according to my heat gun, and this was after a good 7-8 minute thrash about. I've learned a lot about these little engines, (I usually play with 6.6 litre V8s)
Anyways, thanks for the help!!

Think all that non starting has taken its toll on the pull start though, its a bit slack now. Might change it for some other means of starting.
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Old 05-25-2012, 07:26 AM
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Help,
I'm having the same problem with a similar car
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