Could it be spark plug?

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RampageHopUps said:
I would get a new carb and try that before you get a new engine. Most likely your carb is dirty or your needles are screwed up.
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I agree with you Rob, but note that at the time I try starting my engine with the known good needle setting. I was force to go to default setting in attemp to start my engine. My bro in law insist its my needle but can't help me because he is 115 miles away and our schedule don't match. He said in two weeks he will be here to help. Two week is too long for me :( It could be carb too.... but I don't want to replace and spend money unless I know for sure.... I just want the engine to start so I can re-tune it :(
 
and you are using a new plug right?

I would start lean on the low needle, listen how she sounds every two pulls. Keeping bumping it up an 1/8th of a turn out if she doesn't start after two pulls at each setting. IF you get all the way to the recommended starting point and no luck, i'd see your local hobby shop help if you have one that sells 1/5 scales.

You have no gasket leaks, air, fuel, compression. good spark. Seems like only needle settings or the internal failure of the carb diaphragm could explain it dieing out after long runs (coming off WOT), or it not running since it died. The stock carb is crap, might as well upgrade early ;) .
 
ImminentFailure said:
and you are using a new plug right?I would start lean on the low needle, listen how she sounds every two pulls. Keeping bumping it up an 1/8th of a turn out if she doesn't start after two pulls at each setting. IF you get all the way to the recommended starting point and no luck, i'd see your local hobby shop help if you have one that sells 1/5 scales.

You have no gasket leaks, air, fuel, compression. good spark. Seems like only needle settings or the internal failure of the carb diaphragm could explain it dieing out after long runs (coming off WOT), or it not running since it died. The stock carb is crap, might as well upgrade early ;) .
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Yes tested on stock and new plug. Was thinking that if my bro in law's XB is here I can truly test both my new plug and stock plug with his XB. I do agree with you regarding carb upgrade. Can you point me to DDM site to all the necessary parts and gasket and screws for my carb upgrade? I want to do it right and once only :D
 
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ImminentFailure said:
That is something I actually haven't had to do on mine. So i'm not the best in that area. I'd personally go Walbro 990. http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.7550/.fThere are different types of gaskets, not sure on the 'best.' Hear about blue ones, and copper ones ect ect. There are a couple threads in the forum on carb upgrades. I'd probably end up using stock, and get this kit to have backups of the other ones. http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.4154/.f
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Yea... probably use stock gasket but then copper gasket would be nice. Is that carb one of the best out there for our 1/5? I think once I take out the carb, I should replace every gasket?
 
Go with a 668, if you're used to using a choke. If you don't mind giving a few extra pulls to get the engine started, go with the 990. You might also want to upgrade the intake, while you're at it. The stock intake is plastic and can crack or warp. I use the ADA intake, and I like the added security against air leaks with the Teflon gaskets. Plus, the gaskets are reusable.

Walbro WT-668 Carb - RC use

ADA Billet RC / CY Intake Manifold
 
I've read most of this thread and believe a new walbro carb with help heaps as it will give a better starting point to tune. And would check the exhaust bolts too as a leak from the gasket there will not help start up or hold the tune that you need.
 
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