Me again....engine runs....just won't stay running,any help?

dgsoles · Post by **dgsoles** » Mon Oct 20, 2008 9:18 pm

Ok, so I installed the new piston rings and the engine fired right up. Good, I thought my troubles were gone. Nope. Now, once it runs for a little bit, I can't keep it going. Starts and idles fine, you can even gun it a little bit (not too much, of course, still breaking in the new rings). But, when you let it run for a little bit, it won't stay running. It'll idle for a while, but the minute you try to give it any throttle, it bogs down and wants to die. The only way to stop it is to let off the throttle and let it idle. I even took it for a half-block ride (got it up to 15 mph!! woo-hoo) before it quit on me. I've cleaned the carb twice (yes, even the emulsion tube). I've de-carbonized the exhaust....twice. Plenty of air making it through there. New spark plug (even though I might replace it again, you never know). Nice white/blue spark. Brand new, lightly oiled air filter. Fuel flow out of the petcock is good, I even tested it cranking the engine. I'm wondering if maybe it's running too rich? I might also mention that when you let it sit for a while (10 minutes or so), it starts and runs for a couple of minutes, again. When I plug-chop it, it comes out wet, with gas. And, final note, when I went to start it this morning, the fuel line from the petcock to the carb was empty (I have transparent tubes). Leaking float (needle) valve maybe? Any help would be appreciated, as I feel that I'm in the home stretch of getting this bike running right! Thanks.

BTW, this site has been BEYOND invaluable to help get the bike running, you guys are doing a tremendous service to the rest of us!

dgsoles · Post by **dgsoles** » Mon Oct 20, 2008 9:41 pm

Oh, I forgot to add that, thinking it may be flooding the engine, after it wouldn't run anymore (right after no amount of throttle feathering could keep it alive), I quickly unscrewed the drain plug on the carb and let out a fair amount of gasoline, then screwed it back in. The bike fired right up and ran as if it had been sitting for a few minutes.

Kenny_McCormic · Post by **Kenny_McCormic** » Mon Oct 20, 2008 9:53 pm

clogged vent vapor locking carb?

dgsoles · Post by **dgsoles** » Mon Oct 20, 2008 10:47 pm

Thanks for the suggestion, but, sadly, I also tried to run it with the gas cap off, thinking that it might be vapor lock. No luck. BTW, with the idle jet, whenever I run a small wooden rod (kind of like a little toothpick) into it, it hits something hard. I can't seem to get it out with carb cleaner/compressed air. Any suggestions?

Kenny_McCormic · Post by **Kenny_McCormic** » Mon Oct 20, 2008 11:04 pm

Th idle jet is only suposed to pass a pinprick of light, need a dark room and small flashlight to see it.

rekonize · Post by **rekonize** » Sat Nov 01, 2008 4:40 am

i had this same problem, and just fixed it today, im not sure why it worked, but it did.. i tightened up both screws on the side of the carb, ALLLL THE WAY SHUT ( i belive its an air screw and a something else screw) it idles nice and has LOTS of power now.. try it out see what happens.

chevyguyjay · Post by **chevyguyjay** » Sat Nov 01, 2008 10:38 am

Kenny_McCormic · Post by **Kenny_McCormic** » Sat Nov 01, 2008 10:44 am

Check the bystarter!!!

dgsoles · Post by **dgsoles** » Sun Nov 02, 2008 4:16 pm

Ok, update for everyone. I installed a brand, spankin' new float-valve in the carb. I also checked the bystarter (works fine, by the way). I was in doubt as to my piston-ring installation job (first time I've done it), so I took the engine apart, checked them, and honed the cylinder (I didn't do it when I installed the new rings). The reason I checked all of that is because, according to the compression tester I'm using (which is a tube style, I don't have access to one without a rubber extension), my compression is an appalling 60 PSI. I wonder how it runs at all.....
Anyways, after doing all of the above.....it still does the same thing.

Start it up.
Runs fine for about a minute.
Putters out and dies (happens quicker when you give it some throttle).
Won't restart until either it sits for a minute, or you drain a little bit of gas from the carb (even after that, it won't run for very long).
Also, it blows out a lot of white smoke....well, a fair amount.
And yes, my idle mixture screw is 1 1/2 turns out from seated.
I also have a brand new air-filter installed.

I am using a Champion equivalent spark plug, as my local auto store doesn't sell NGK, could this be a potential issue?

Bear45-70 · Post by **Bear45-70** » Sun Nov 02, 2008 6:08 pm

The reason it runs OK on start up and runs for a minute or so is the by starter is enriching the mixture. When the bystarter closes and the engine leans out it quites running. Pull carb and recheck everything looking at the idle circuit. The idle jet, passages and fuel passage to the idle jet.

dgsoles · Post by **dgsoles** » Sun Nov 02, 2008 9:15 pm

I don't know why I didn't think of it, but Bear, you got it right. Just as a test, I pulled the plug to the bystarter (to test the theory that my bystarter enrichment circuit was substituting my idle circuit) and fired it up. I let it idle for about 5 minutes....which is longer than it ever has before. After that, I decided to pull it out of the garage for a test drive. Well, the thing ran great. So, Bear, you got it right. My idle jet must still be clogged. I'll tear the carb down again, and this time, I have some nasty carb dip to try out (I'll just have to make sure it doesn't react with aluminum). As everyone says: Clean, clean, clean your carb (apparently 4 times isn't enough).

As to why I'm only getting from 50-60 PSI compression, I'm guessing my tester is bad.....because the bike runs fine.

devenex · Post by **devenex** » Sun Nov 02, 2008 9:44 pm

A good way to check that the idle jet is clear is to shoot carb cleaner in the hole that the fuel screw threads into. Make sure to get the straw in as far as you can.

If it sprays out both directions it is atleast partially clear. If in doubt just keep shooting the cleaner in there until you feel confidant, or dip it some more.

Hope this helps for diagnosing.

dgsoles · Post by **dgsoles** » Mon Nov 03, 2008 3:14 pm

Hmm...I've tried that several times....something good must be stuck up there......I'll gonna soak it and blow it again....and again....and again until the dang thing clears out. On a positive note, the bike runs rather nicely using the bystarter enrichment circuit in place of the idle jet (I know, it's a naughty thing to do, my first priority is to get the idle circuit clear).

dgsoles · Post by **dgsoles** » Tue Nov 04, 2008 3:36 am

Alright, I believe I've solved the problem. After checking the labels on my carb dip (which it claimed aluminum and other alloys were perfectly safe to put in it), I disassembled the carb, and dipped the carb body, main jet, emulsion tube, the mixture screw, and the idle screw. After about 20 minutes of carefully watching for a reaction, I took the stuff out. I hosed it off with some water, per the instructions, and started blowing through everything with my can carb-cleaner and compressed air. Sure enough, my idle jet is not clogged anymore. For the first time since I bought this thing, I can see carb cleaner coming out of the idle jet. So, I cleaned the carb up real nicely, and dipped it again. I let it sit for about...6 hours, and came back to it. I don't think that my carb can get much cleaner now, in all honesty. Can't wait until tomorrow when I put everything back together! You guys have been a great help.