Engine won't start

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loud72

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I am at my wit's end. I took my DR out last Saturday and tried to tune in High jet on Walbro 813. When I'd start going up near WOT the engine just shut off. I though it had lean seized but it turned over so I richened the High jet up a little more. Again I tried taking it from Mid throttle to WOT aand it did the same thing. This time I noticed the gas was down in the bottom of the tank so I left and came back about 45 minutes later. I filled it up with gas and I haven't been able to get it to start since then. I've tried the following yesterday and let it sit for 24 hours with the spark plug removed and it still won't turn over. I'm getting a good spark and fuel on the spark plug. I have been trying to start it with the air filter off for good air flow.


So far in the past two days I've tried the following with no luck:

  • Stock Carb
    Stock Fuel Lines
    New NGL spark splugs
    Cleaning screen of 813 carb
    tightening cylinder head bolts (2)
    Tightening carb outlet bolts
    Adjusting coil gap with business card
    tightening carb bolts
    turning upside down and starting 15-20 times to clear motor of gas
    Can't hold thumb over spark pug hole when starting suggesting good compression?
    Get a good spark
    Snappy fuel line kit


I'm beginning to think I fried my motor..


My motor is the stock HY 26cc with the DDM Modified 27.2 Zenoah cylinder head and a stuffed crank / longer throw piston kit. Walbro 813 carb plus Snappy fuel line kit.


Regards,


Loud72
 
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Tilt the front end of the car up into the air and pull the throttle three or four times to prime the engine and then try starting it. I had this problem initially with my 813 carb... just shut it off to let the engine cool down one day and next time I went to start it it wouldn't. After pulling off the air filter I noticed that there was a lot of gas soaked up in it. For whatever reason when I was pumping the throttle to prime it it was just spraying into the filter, so I tilted it up so the gas would just spray right into the intake. Hope this works for you.


It's possible that your gas cap vent is clogged, maybe that's why it was quitting at full throttle?
 
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Thanks Jeffp. I forgot to mention that I had tried that yesterday and it didn't help. The other thing I noticed is that the 813 only pumps out a small amount of fuel through the fuel accelerator pump hole. Is that normal? Fearing the worst (lean seize), I just checked my piston through the carb intake hole and saw what appeared to be scarring on the piston so I pulled the head and this is what I found....Attached Pic 3320 is front of pistonAttached Pic 3321 is rear of pistonAttached Pic 3329 is inside of front port of cylinderAttached Pic 3330 is rear exhaust exit port of cylinderHow bad does that scarring look?

IMG_3320.webp

IMG_3321.webp

IMG_3329.webp

IMG_3330.webp

/monthly_2011_03/IMG_3320.jpg.29240b26ecefaba629aca53b081f5dd8.jpg

/monthly_2011_03/IMG_3321.jpg.dba87f0986dd3c86351175ff98775511.jpg

/monthly_2011_03/IMG_3329.jpg.0c128fa91b08188ccc697431a86064b1.jpg

/monthly_2011_03/IMG_3330.jpg.a0e9c9b2e24af037cd30309c0d8d3a4f.jpg
 
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I have no idea how bad that is as I am pretty new to these gas engines. I would guess that is a lean seize.


My 813 carb is the same, it doesn't look like it spits out much gas but works great. Maybe your high speed jet was clogged and therefore ran lean when getting up to WOT. This might explain why adjusting the needle didn't help and the seize?


That sucks to see that, hope somebody else can chime in and figure out if it's still usable.
 
Debur the piston, re ring it and put her back together. The cylinder itself doesn't look bad at all :)
 
doesn't look to bad......ive never seen scarring on the front of a piston in that spot b4 tho.....if u run ur finger over the scarring is it deep or is it just at the surface......its hard to tell from the pics how bad it is. minor scarring normally will allow the motor to run but if u can feel a real high diff between the surface of the piston and the scar its probably gona need to be replaced. i would also check the gasket on the crankcase as well ive seen some of these motors blow that seal durin a minor seize
 
Underdog said:
I would also recommend you check your crank bearings. A loose bearing will cause the seal to leak, creating an air leak. I use the Nachi 6001 bearings in all my builds with excellent results. I also do an oil hole mod to the clutch side for even longer bearing life. Not sure if your cases will take a mod like this but it's worth a look.
http://www.dogpileracing.com/scripts/openExtra.asp?extra=11
Click to expand...
Will do. I'll tear the engine down next week and see what I find. I have parts on order ready to replace if necessary.


Thanks everyone for the helpful information!


Regards,


Loud72
 
Triggerman77 said:
So what was your problem????
Click to expand...
Old stock crank seals that I didn't replace when I installed a stuffed crank and new cylinder head about a month ago caused a lean seize and subsequent loss of compression. Replaced the seals, piston and ring and cleaned up the cylinder and works like a charm now....


Loud72
 
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