Backfiring and uneven idle

[patrick_777]

You don't have to blow in them or anything, just make sure the fittings are tight and there are no really visible cracks or other imperfections.

Also, get an inline fuel filter on that thing quick. They are CHEAP and EASY to install so there's really no excuse for not doing it.

[roncg41677]

Originally Posted by patrick_777

Also, get an inline fuel filter on that thing quick. They are CHEAP and EASY to install so there's really no excuse for not doing it.

Any recommendations?

[patrick_777]

http://www.gz250bike.com/viewtopic.php?t=1377

[Easy Rider]

Originally Posted by roncg41677

About the idle...

Is this nothing to worry about? Playing with the idle adjuster could fix something like that?

It's probably not a serious problem but it IS a problem. If the idle speed is WAY too low, it can stumble a bit.
After it is thoroughly warmed up, tweek the throttle open just a TINY bit, until you can just BARELY notice an increase in idle speed. If it also seems to run smoother when speeded up slightly, then your idle adjustment is probably too low. Adjust it up a bit with the knob beside the carb.

Originally Posted by roncg41677

As far as checking vacuum hoses, can I just look at them, or do I need to try to blow through them or something?

First, visually check for cracks or other obvious damage.......including checking for holes/modifications to the air cleaner or the box. Then look to be sure there is a plug in the end of the air box drain hose.
If that doesn't yield anything, get a can of spray carb cleaner (Gumout). Spray a little around the OUTSIDE of the vacume hose going to the petcock; also the boot going into the engine; also the outside of the air box and the drain hose in the bottom.......if the engine speed changes, you are spraying it on a spot where there is a vacume leak.

If the idle speed is not the problem and you don't find any vacume or exhaust leaks, remove the air filter, start the engine and spray the Gumout directly (as possible) into the carb intake, slowly at first and then fast enough to kill the engine. Turn off the ignition and replace the air cleaner and covers. Let it sit for about 15 minutes then go for a ride.

PLEASE print this message out (and maybe my earlier one too). Refer to it (them) until you have checked out all the things I mentioned. If none of that helps, then you need to ride it for 100 miles or so to see if the cleaner does the trick. If not, you need to SERIOUSLY consider taking it to a shop.

Based on your questions and answers, I do NOT think YOU should be taking the carb. apart.
Sorry but I just don't.

[roncg41677]

Originally Posted by Easy Rider

PLEASE print this message out (and maybe my earlier one too). Refer to it (them) until you have checked out all the things I mentioned. If none of that helps, then you need to ride it for 100 miles or so to see if the cleaner does the trick. If not, you need to SERIOUSLY consider taking it to a shop.

Based on your questions and answers, I do NOT think YOU should be taking the carb. apart.
Sorry but I just don't.

No problem. I'm not interested in doing work I don't need to do . I wouldn't tackle the job myself. I have friends with much more experience than me who were going to help me with it, none of them with GZ's, mind you (hence my putting the issue before you fine people ). I didn't think it would hurt since the bike sat for so long. I will check the vacuum hoses when I get to the spark plug.

Patrick, thanks for the link!

I'll be sure to update when I get further.

[roncg41677]

Well, I put in the new spark plug. Checked the hoses and everything looked okay.

Once the new plug was in I fired it up and it's back to running like complete garbage again. I can peg the throttle and it revs a tiny bit then starts sputtering and backfiring with the occasional ultra-cool flame out the exhaust :pissed: . No way I can take it out on the road.

New plug - check. Clean fuel tank - check. vacuum hoses - check. Clean air filter - check. Carb cleaned - sort-of-check.

I can attack the carb a bit more on my own I guess. I haven't gone through a gallon of fuel with the Berryman's in the tank yet. I bought a can of spray carb cleaner. Someone on another forum suggested removing the air filter and spraying carb cleaner into the carb while the bike was running until the bike stalled, leave it, then start it up again.

Someone else suggested it may be a problem with the gas cap not allowing atmospheric pressure into the tank O_o . I'm only mentioning these things to see if they are plausible. One more thing; when my friends helped me check the carb they checked by sticking a small wire into the jets to check for obstructions. I'm told this could have caused real damage?

I'm clueless and broke.

[mr. softie]

I had similar problem when I first got my gz. It had been sitting. Would not run without pumping throttle. Backfiring like crazy. Tried stuff in gas. I "sort of" cleaned the carb three times. Finally I *!completely!* disassembled carb and soaked all the jets etc. including the body (after removing all the rubber parts) in straight carb cleaner (gumout) overnight. Pay attention to the idle mixture air screw. There is an "O" ring down in that tiny hole. You must remove it and all other plastic and rubber parts or the carb cleaner will ruin them. There are tiny passages in the body that get clogged up. Soaking is the only way to clear them.

This worked. I blew out all the passages with compressed air. Checked float level. Reassembled carb. Installed and really tightened hose clamps holding the carb. Like new bike now.

[patrick_777]

Softie, I imagine that would make ANY bike run like a new bike.

:bow:

[Easy Rider]

Originally Posted by roncg41677

I bought a can of spray carb cleaner. Someone on another forum suggested removing the air filter and spraying carb cleaner into the carb while the bike was running until the bike stalled, leave it, then start it up again.

Someone else suggested it may be a problem with the gas cap not allowing atmospheric pressure into the tank O_o .

Yes, the first proceedure is a good thing to do.

A blocked vent in the gas cap will cause it to stumble and die after running for a couple of minutes. Up to that time, it should run fine. From your description, I don't think that is your problem.

You DO need to run it a bit to get the cleaner through the carb. If you can't run it up and down a side street, letting it idle for 10 minutes every couple of hours might work. (Don't idle it too long or it might overheat.)

I'm thinking you need to save up your $$$ for a trip to the shop for a "real" carb cleaning. Ask first but should be about $100-150, and get a fuel filter installed.
Yes, poking wires into jets is not a good thing to do.......for an amateur.

[roncg41677]

Originally Posted by mr. softie

I had similar problem when I first got my gz. It had been sitting. Would not run without pumping throttle. Backfiring like crazy. Tried stuff in gas. I "sort of" cleaned the carb three times. Finally I *!completely!* disassembled carb and soaked all the jets etc. including the body (after removing all the rubber parts) in straight carb cleaner (gumout) overnight. Pay attention to the idle mixture air screw. There is an "O" ring down in that tiny hole. You must remove it and all other plastic and rubber parts or the carb cleaner will ruin them. There are tiny passages in the body that get clogged up. Soaking is the only way to clear them.

This worked. I blew out all the passages with compressed air. Checked float level. Reassembled carb. Installed and really tightened hose clamps holding the carb. Like new bike now.

That's encouraging . Did you have to buy a rebuild kit? Or were you able to replace all of the rubber parts?

Originally Posted by Easy Rider

Yes, poking wires into jets is not a good thing to do.......for an amateur.

Uuuuh, :oops: . I didn't actually do it. A friend of mine did. Hope it didn't mess anything up :puke: .