Brand new engine wont stay running

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Indy420

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May 15, 2016
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I was wondering if anyone else has had this problem.
Just built my 2nd motorized bike yesterday and when I went to start it, it wasn't easy. Had to keep trying for a few minutes, which is normal, then when it started it felt like it was falling on it's face. I took it around the block and it was sputtering the whole time, like it wasn't getting fuel or it had intermediate spark. I took it ONE WHOLE BLOCK and it died when I pulled up to my house. I tried for the next hour to start it again and it wouldn't start back up. I took the bike inside and checked it for spark. I have spark at the plug. I took my carburetor apart to check for dirt in the floats, I didn't see anything so I put it back together. I took it back outside and tried to start it again. This time it started for about 15 seconds and then died. I gave up for the night. Today I took my carburetor apart again and disassembled it completely. I cleaned it up and put it back together. I took the bike outside and tried again. This time it started up, just like the very first time, and I rode it around the block, sputtering the whole way, never reaching 20mph. As I came around the block and pulled up to my house, it died again. I tried to restart it and it will not start again.

Do I have a bad carburetor? Is my magneto bad? Is my CDI bad?

My kill switch is not plugged in.
I have an inline fuel filter.
My petcock seems to be functioning correctly.
I am using premium gas with the correct oil/gas mixture.
I do not have the tools or the know-how to use an ohm meter. All I know is it does have spark. It did run 2 times for about 120 seconds each time.

I ordered a racing carburetor today. I am hoping this fixes my problem.
Should I order a new CDI and magneto too?

I have $432.00 in this bike already. A new CDI and magneto will put me at $450.00.
 
MEASURE TWICE

MEASURE TWICE

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http://motorbicycling.com/showthread.php?t=35090 Maybe you already looked at the top thread of this section on troubleshooting. Note if near a Harbor Freight Store like mentioned for the cheapest, but probably OK for a lot of stuff to test with it, there are coupons all the time and some are for this cheap meter for free with any other purchase.

I don't have really any experience with the kit engines for bike and I never had a magneto on my Briggs engine go bad. I have had a China made Generator that the Coleman made and its magneto was very intermittent. I replaced it and had a spark always after that. See info on making better connections at the magneto.... I've read some where that helps sometimes. Some will mention that a spark at ambient pressure is not always mean that it sparks under compression. There are some spark testers sold, but that is a special piece of test equipment not usually found used. The meter info is something that post mentions what a lot of work went into I can tell, see if it helps. Someone else will probably post a reply soon. See what you can find out. And welcome!
 
crassius

crassius

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first, I'd stay with standard carb until it is sorted out - any kind of 'performance' carb is hard to work with & one wants a good running motor before trying to get one of those carbs working right

one thing that comes to mind is a bad gas cap vent - fuel flow can be checked by opening drain plug on bowl & turning on petcock to watch flow

is plug wet when you check for spark? if not try to put a few drops of fuel in hole, then see if it fires a bit

clean outside of motor really well and after it fires for a block again, look for any oil seapage at a bad gasket
 
Greg58

Greg58

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I have had bad connections on the black/ground wire at the magneto coil, take the screw out and sand the magneto and wire end where they meet. Make sure you have a good connection between the cdi wires and the mag wires, the push together connectors are not that great. As was said above check the gas cap, a good way is to have about a 1/4 of a tank of fuel and loosen the cap but leave it on the tank. Then start it and ride it to see if that cures the problem.
 
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Indy420

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Fort Wayne IN
I took the wire connectors off and wired the wires directly when I installed the CDI.
I tried running it w/o the gas cap on it the other day when I was trying to start it.
I have spark. It will run for approximately 120 seconds. Each time I get it running, it is AFTER I have just taken the carburetor completely apart and reinstalled it.
I'm thinking it's running out of fuel after those 120 seconds. For some reason the fuel isn't flowing on it's own. I seem to be missing the filter that attaches to my petcock, but I have an in-line fuel filter on it and it isn't plugged. I will check petcock again and make sure I have good gas flow. I don't see how a brand new tank would have dirt in it to restrict my fuel flow, but I guess anythings possible.
 
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Indy420

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The manufacturer is sending me a new carburetor. Be here in 1 week.
I also bought a racing carburetor. Be here in 1 week.
I also bought a new CDI and magneto. Be here in 1 week.
I have a spare plug I can try from my other motorized bike. It is slightly used but it works. I took it out because my old bike didn't run as good with it. (NGK B-4L)
I am taking the petcock out of my tank and replacing it with a nipple fitting tomorrow. (I don't need it, my racing carburetor has a built-in petcock)

I think I have everything covered. If it don't run after all this, I am going to melt it down and make patio furniture out of it.

After I buy a nipple fitting to replace my petcock, I'll be at about $455.00 on this build. ($155 more than I planned on spending)
But it has a lot of upgrades.
 
Greg58

Greg58

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Be sure to replace one part at a time then try to run it, I'd start with the carb then cdi, magneto last. By trying each separate you will know which part is or isn't bad.
 
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MEASURE TWICE

MEASURE TWICE

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Greg58 said:
I have had bad connections on the black/ground wire at the magneto coil, take the screw out and sand the magneto and wire end where they meet. Make sure you have a good connection between the cdi wires and the mag wires, the push together connectors are not that great. As was said above check the gas cap, a good way is to have about a 1/4 of a tank of fuel and loosen the cap but leave it on the tank. Then start it and ride it to see if that cures the problem.
Click to expand...
As GREG58 said 1 part at a time changed and then tested is best. Sometimes intermittent problems still will possibly have you thinking you fixed something while you just replace 1 part and it was not even at fault. Still one part at a time is still necessary if you want to be better sure you have not gone off track.

Also as prior Quoted above about sanding the metal and wire connction for a good ground, I also have on my Briggs engine used external star tooth lock washer between sanded metal ground on magneto where I have a wire with ring terminal attached.

It was years back I had an non-OEM air-conditioner installed in my car. After about 5 years I had a cloud starting to come from the floor right side where the blower motor and vent were. A tip from the seller mentioned to me if I did not want to bring it in for repair I could check one thing myself. He said numerous installs had been done with out sanding enough paint off to get a good ground for the motor electrical connection.

I also added a external star tooth washer to get a better contact electrically. The fog at that time almost filled up to my shoulder height before I pulled over. More than that and I would not had had any vision to see where I was going.

I actually did once lost sight out the windshield driving but I had just started out and was not going too fast and used the window washer without any antifreeze... duh California still can freeze your windshield over at sea level. I pulled over and let it thaw. No more of that again.
 
Chaz

Chaz

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Jun 3, 2012
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Brand new gas tanks are notorious for having crap in them. Without that little filter on the tank petcock I suspect that crap has plugged up the tank petcock and restricting the flow. It's possible that your engine is only running on the fuel contained in the fuel line, filter, and carb bowl. Once that is used up then she dies.
 
crassius

crassius

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if your fuel filter was gotten from an auto parts store, it may not flow properly - I've seen several that won't gravity feed since they were designed for a high pressure fuel line - just take it off for a test or do that fuel flow test with drain plug out

are you sure that float level is set right? with carb upside down and float on prongs, one should just barely see a bit of brass main jet peeking up thru center of float
 
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Indy420

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May 15, 2016
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Fort Wayne IN
crassius said:
if your fuel filter was gotten from an auto parts store, it may not flow properly - I've seen several that won't gravity feed since they were designed for a high pressure fuel line - just take it off for a test or do that fuel flow test with drain plug out

are you sure that float level is set right? with carb upside down and float on prongs, one should just barely see a bit of brass main jet peeking up thru center of float
Click to expand...
I wasn't aware you could set the level.
 
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Indy420

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May 15, 2016
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Fort Wayne IN
Chaz said:
Brand new gas tanks are notorious for having crap in them. Without that little filter on the tank petcock I suspect that crap has plugged up the tank petcock and restricting the flow. It's possible that your engine is only running on the fuel contained in the fuel line, filter, and carb bowl. Once that is used up then she dies.
Click to expand...
That's what it seems like to me. I'm going to remove the petcock and install a brass fitting.
 
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Indy420

New Member
May 15, 2016
67
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Fort Wayne IN
crassius said:
if your fuel filter was gotten from an auto parts store, it may not flow properly - I've seen several that won't gravity feed since they were designed for a high pressure fuel line - just take it off for a test or do that fuel flow test with drain plug out

are you sure that float level is set right? with carb upside down and float on prongs, one should just barely see a bit of brass main jet peeking up thru center of float
Click to expand...
I'm using the inline fuel filter that came with the kit.
 
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