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| < Engine Clinic - Mini Off Road Buggy ~ Carb back fire |
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I have been working on a 2003 Dazon Raider 150R for a friend. Spark plug stripped out beyond salvage so I replaced the head with new. Also put in new valves and valve seals since it did swallow some metal from the spark plug threads. Problem is that the machine starts just fine and will sit and idle with no problem and is even drivable up to around half throttle where it starts popping and spitting fuel out of the carb with an occasional backfire out the exhaust. Checked valve clearance and is good. Checked valve timing, also good. Spark advance is working properly. Carb was disassembled and cleaned thoroughly. Spark plug is very black, not wet but black and sooty from only a short time running. What could I be missing?? Possible weak valve springs? I did lap the new valves into the head so they are sealing. Another possible symptom is getting oil blowing out the breather pipe, don't think it is blow by on the rings as compression is good.
Any help is appreciated.
Thanks,
Rich
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Sponsor
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Are you sure the jets were tight? idles fine-1/2 throttle,compression good,timing ok.alot of gas out the carb.black sooty plug.maybe head gasket from cylinder to timing chain could be why you are getting oil out your breather. hmmmm
_________________
Blade DX 150*
* on the juice
Sunl 150
440 Yamadog
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Thanks for the reply,
Jets are definately tight, new head gasket was installed with cylinder head. Currently running with no air cleaner in place, don't believe that to be an issue but just a little more info..
Rich
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Sponsor
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id say you need a air filter now with out it it is running either to rich are to lean not to sure cause i dont know about jetting but some one will help you out
btw welcome to the site
_________________
06 joyner 250 sand viper,red metallic..blue clutch spring 17 gram sliders
polaris ranger
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Still seems to me that the valves are not adjusted right,
mainly the intake valve, it seems to be staying open
longer than it should, I think there's not enough clearance
in your valves, thats whats causing that popping and sputtering through your carb, the intake valve isn't closing all the way. Just my opinion.
_________________
05 Blade SX-550 Suzuki
07 Sand Viper 250 ( SOLD )
89 Honda Pilot
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