Daves motors 29cc upgrade for DBXL

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Pull the spark plug out or use a known good plug and with the coil wire attached to the plug touch the ground electrode to something metal on the engine (the head or the engine case) and give the pull start a few tugs. If the ignition is working you should see a spark bridging the gap between the center electrode (copper center) and the ground electrode (the L on the bottom of the plug). The DBXL manual may have a trouble shooting guide to help somewhat.
 
k5krazy said:
Pull the spark plug out or use a known good plug and with the coil wire attached to the plug touch the ground electrode to something metal on the engine (the head or the engine case) and give the pull start a few tugs. If the ignition is working you should see a spark bridging the gap between the center electrode (copper center) and the ground electrode (the L on the bottom of the plug). The DBXL manual may have a trouble shooting guide to help somewhat.
Click to expand...

Spark plug showing spark.
 
I put the same head kit on mine. Using the stock 668 carb. I had to open the idle screw about a full turn clockwise to get the motor to start the first time. Also it is easy to flood these engines. Remove plug and inspect. Check for a wet, fuel soaked tip.
 
+1

Another couple quick checks are make sure the fuel lines are on right (the filtered line goes on the bottom) and double check the carb gaskets are installed (D'oh!). If these are good try to richen the needles a quarter turn if the engine wasn't flooded.
 
+1

Another couple quick checks are make sure the fuel lines are on right (the filtered line goes on the bottom) and double check the carb gaskets are installed (D'oh!). If these are good try to richen the needles a quarter turn if the engine wasn't flooded.
 
I just realized I cracked the screw hole of the intake manifold by over tightening it. Think that could be the problem? I spoke with Dave's motors who said I should check the piston for scuff marks and the piston might be bad. Will probably start with the manifold then trouble shoot. Don't want to take the engine apart again. Didn't think the piston was that sensitive.
 
Oh bummer!! The reason it won't start is that crack is letting air past the carb not picking up fuel causing a lean condition. I think these pistons are just cast aluminium which is fairly sensitive. If it has deep gouges it is probably done but if it has light scratches you may be able to knock then off with a very fine file. It sucks I know but if you need a head anyway if the piston is marked up you may as well get them both. If it makes you feel better somehow I cracked the head on my 5ive so I'm in the same boat! A 100 buck eff up!
 
I took everything apart (AGAIN) replaced all gaskets inspected piston and head upgraded the carb set the proper distance to get proper spark and NOTHING! Wishing I would have never bought this upgrade!!!!! Haven't been able to use this in months. Need help!!!!! I have a $1,000+ paper weight.
 
Man that is a tough nut to crack! Where are you located? I know it is a big PIA but have you tried to reinstall the stock head and piston to see if it runs? An engine needs air, fuel and spark to run. I wish I could lay my hands on it. The spark is run off.the flywheel by a key, so as long as the coil is gapped right and you have spark timing shouldn't be an issue. What carb did you install and does it have a choke? You could try to pull the spark plug out, put a few drops of fuel in the cylinder, reinstall the plug and see if the engine sputters. I know it gets frustrating but you will be a pro when you get done!
 
k5krazy said:
Man that is a tough nut to crack! Where are you located? I know it is a big PIA but have you tried to reinstall the stock head and piston to see if it runs? An engine needs air, fuel and spark to run. I wish I could lay my hands on it. The spark is run off.the flywheel by a key, so as long as the coil is gapped right and you have spark timing shouldn't be an issue. What carb did you install and does it have a choke? You could try to pull the spark plug out, put a few drops of fuel in the cylinder, reinstall the plug and see if the engine sputters. I know it gets frustrating but you will be a pro when you get done!
Click to expand...

I readjusted the coil and made sure it was gapped correctly. I checked and saw that I was getting a good spark. I'll try the drops of fuel. How many drops of fuel and should I use an eye dropper to add the fuel? Not going to reinstall to old head I think I'll flip out if I have to take it apart again. I have just installed the wt-813 carb. I had the stock carb and the engine did not start.
 
I don't think you need an eye dropper, just try to carefully drop in 3 to maybe 6 drops of fuel. It should try to kick over. If you think it needs a little more fuel give it a little more. Maybe you will get lucky and it will fire and stay running. I'm just running through ideas in my head but have you tried with the air filter off to eliminate an air restriction?
 
I tried the gass thing but didn't work. I also tried with the airfilter off. I will attempt again today. Going nuts over here!!!!!
 
Are you sure you have compression? If you remove the plug and put your finger over the hole you should feel air coming out. If you have a compression tester that will give you a number to reference. I wouldn't think a few drops of fuel would flood the motor completely. This is a long shot but your muffler isn't somehow plugged is it? I'm running out of ideas if we have air, fuel and spark.
 
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