Black plug, black smoke

[Jere]

My bike is intermittently running rough and not starting (starter cranks.) I'm pretty sure it's flooding itself and seems to get worse after riding for awhile.

I purchased a new air cleaner but haven't installed it yet (i doubt it'll make much of a difference.)

Anyway, I installed a new plug (regular temp) and everything worked great! Then, after two separate rides of about 15 km each, it died on me again. I took the plug out and it's black, but dry. I've probably worn down the battery and flooded it by trying to start it.

Where should I look first? Clean the carb? Choke sticking? Bad battery? (my Dodge Dakota book indicates that "weak ignition" could be a cause of black spark plug.)

Thanks. Let me know if you need any other info.

[Easy Rider]

I took the plug out and it's black, but dry. I've probably worn down the battery and flooded it by trying to start it.

Where should I look first? Clean the carb? Choke sticking? Bad battery? (my Dodge Dakota book indicates that "weak ignition" could be a cause of black spark plug.)



The first thing you should do is clean the plug.
The second thing is charge the battery.
Third, you should put IN the new air cleaner (that could be the original cause and it is not always obvious when one is clogged).

If it does it again after that, then the carb. needs attention. Could be a stuck "choke" cable but I'd think that would be pretty obvious.

[Sarris]

Are you sure the petcock is not in Prime? That'll gag her for sure.

:)

[Easy Rider]

Are you sure the petcock is not in Prime? That'll gag her for sure.


WHAT??? Since when ??
I don't think so. :whistle:

[Sarris]

Although I have not personally experienced a problem, I understood from other GZ owners, that if the needle & seat is partially obstructed, that the carb could gravity flood if the petcock is left in prime. Right?

Just a suggestion.

:roll:

[Easy Rider]

Although I have not personally experienced a problem, I understood from other GZ owners, that if the needle & seat is partially obstructed, that the carb could gravity flood if the petcock is left in prime. Right?


But you didn't say all that the first time......now did you ?? :neener:

If that were the problem, or problemS, then it is likely that it would not start at all.....ever, because the cylinder would REALLY be flooded. :shocked:

:biggrin:

[Jere]

I think it's only REALLY flooded because I kept trying to start it. lol.
It's not the petcock, though I do appreciate the tip. I think i'll be taking the carb apart and cleaning it anyway as I have no idea how much maintenance the previous owners have done.

I've done it once on a lawnmower, hopefully I don't run into too much trouble. I'm not really sure how to check the clearances of the valve though. I'll read the service manual first before I ask too many annoying questions! lol.

[Water Warrior 2]

Change the air filter first. For all you know the filter could be on it's last legs. The air flow direction is from the inside to the outside so remove the filter and look inside.

[Jere]

Will do WW. I actually bought a new one anyway (air filter that is.) So I'll just change it out. Seeing as the bike is 10 years old and I don't have any service records, I figured I'll just change it so that I know it's new.

On a hunch, I went to the dealership and played with a bunch of the GZ250s there. The choke levers on those bikes were WAY easier to operate than on my bike. I would say 3 to 4 times more force is needed on mine. I bought a cable luber and am going to try that in case the choke cable is siezed or just not lubed properly.

[Easy Rider]

I bought a cable luber and am going to try that in case the choke cable is siezed or just not lubed properly.

That's not a bad idea but most people find those things messy and much harder to use than they anticipated. I'm betting that will be especially true of the choke cable since it has a "special" mechanism at the bar end.

Before you tear it all apart to get to the top end of the cable, I suggest you dump a teaspoon or so of rubbing alcohol on the choke lever and let it run down in the friction ring mechanism. Operate it a few times gently and observe where the movement in the friction rings actually happens. Blow the alcohol out with air.....or let dry for about an hour......followed by ONE drop of oil on the friction rings. Note: it is possible that the alcohol bath alone might free it up. If so, skip the oil.

If that doesn't solve the problem, THEN you can take it apart to lube the cable. Might want to inspect the carb end of the cable connection before you do that; it might be in a bind at that end too.

Good luck!

[Jere]

Ok, some good, some bad.

I took the choke cable apart and successfully lubed it with WD40 using the cable luber I got. Success! It worked well. I can actually move the lever without straining. So, this was definitely a huge part of the problem. It seems to be running good now, except..... (will get to this later.)

I also changed the air cleaner. The old one was dirty as heck and saturated in gas. I'm assuming this is because the engine was constantly flooding and gas vapours were pouring out of the vent tube that leads from the carb to the air cleaner? I took out the drain plug and almost 3/4 cup of water/gas came pouring out of the air cleaner housing. I don't think that's normal but am sure it's a symptom of the bad choke cable.

So, I've got it running fairly good except one problem. When I shut it off it backfires something fierce. Also, when I rev it then quickly let off of the throttle I can here a bit of a "put put put" as it comes down to idle speed. Also, when I got back from a ride and the engine was hot, I noticed it was idling quite a bit faster.

Stuff you should know:
- i haven't set the idle speed because I figure I have to fix whatever else is wrong first. (also, I don't have a tachometer.) I mean, I haven't set it properly. I adjusted it "by ear."
- It's still full of premium gasoline, or 1/2 full anyway. I haven't put and carb cleaner in the gas.

So, i guess the question is: "what's the next step?" The service manual doesn't mention backfiring. I'm trying to do the "easy" stuff first.
- carb clean?
- valve clearance check? (thanks burkbuilds for good advice on how to do this!)

[bonehead]

When Mine was at about 6000 mi. I noticed I had to choke it to start, and the after it warmed up the idle would be racing. After I adjusted my valves everything went back to normal. hardly have to choke to start now and the idle stays the same. Just a thought, it could be the valve adj.

[Easy Rider]

I took the choke cable apart and successfully lubed it with WD40 using the cable luber I got.

I took out the drain plug and almost 3/4 cup of water/gas came pouring out of the air cleaner housing. I don't think that's normal but am sure it's a symptom of the bad choke cable.

Also, when I got back from a ride and the engine was hot, I noticed it was idling quite a bit faster.


First, WD40 is NOT a lubricant; it leaves a sticky residue after it dries. It might be OK for the choke mechanism on the bars as it is supposed to drag......but if you put WD INTO the cable, you should follow up with some "real" oil.

What you drained out is more than "normal" but it will accumulate a few ounces over a years time. Maybe it had never been drained before.

You should set the idle speed after a ride when the engine IS hot......and then compensate for the slow speed when cold by leaving the choke on a bit longer, just enough to maintain a workable idle speed. Hopefully that will eliminate your POP on turn-off.

Now when the tank is half full is a good time to add carb. cleaner. Seafoam or Berryman's B12 Chemtool. Read the directions and put in the recommended amount for a FULL tank (3 gal. ?). Run it for about 10 minutes or 5 miles. Let it sit overnight. Fill up with regular gas. Hopefully things will improve before the whole tank is gone.

Is your bike completely stock, as far as intake and exhaust goes ? (Did I ask that already?)
At some point, you need to check for vacume leaks too; rubber boots front and back of carb. and hose going to petcock.

Sounds like you are almost "there". :2tup:

[Easy Rider]

When Mine was at about 6000 mi. I noticed I had to choke it to start, and the after it warmed up the idle would be racing. After I adjusted my valves everything went back to normal. hardly have to choke to start now and the idle stays the same. Just a thought, it could be the valve adj.

Good information. I think Alan C. had a similar experience.

[bonehead]

I'm with Easy on the WD-40. My thoughts are that if you WANT something to rust or get stuck, then use WD-40.

[Jere]

Thanks all, especially Easy. You've been very patient with a motorcycle newbie. :)

I'll check the vaccuum hoses. I might just change them all, including the fuel hoses, because the bike is 10 years old and it doesn't look like they've ever been changed. When i took the tank off, the hose ends seemed a little brittle where the clamps were.

Slowly but surely, I'll get this bike running great!

To answer your question, yes, the bike is stock and I intend on keeping it that way.

[Water Warrior 2]

Thanks all, especially Easy. You've been very patient with a motorcycle newbie. :)

I'll check the vaccuum hoses. I might just change them all, including the fuel hoses, because the bike is 10 years old and it doesn't look like they've ever been changed. When i took the tank off, the hose ends seemed a little brittle where the clamps were.

Slowly but surely, I'll get this bike running great!

To answer your question, yes, the bike is stock and I intend on keeping it that way.


Changing the hoses will be good experience and an added safety benefit for peace of mind. You also might want to add an inline fuel filter from the tank to the carb. It will probably stop smaller particles than the intank fuel filter. Cheap and easy insurance. Sounds like you are getting a handle on the bike's running issues. :rawk: :rawk:

[Jere]

Yep, things are coming together. It's been both frustrating but also rewarding. I'm starting to enjoy it.

[Easy Rider]

Thanks all, especially Easy. You've been very patient with a motorcycle newbie. :)


Glad I can help......and glad things are working out. Keep us posted! :tup:

[Jere]

He're's the latest update:
Ran some carb cleaner through the gas tank and it's running fairly decent but it's still backfiring on occasion (only when shutting it off though.) I make sure it returns to idle before shutting it off.

I've ordered the valve adjuster wrench and the feeler gauges from the dealership. I've been busy and haven't had time to play with it, but I think I'm going to take the carb off and clean it properly then try the valve adjustment. I'll report back when that's done (won't be for awhile.) :)

[Easy Rider]

Ran some carb cleaner through the gas tank and it's running fairly decent but it's still backfiring on occasion (only when shutting it off though.)

I think I'm going to take the carb off and clean it properly then try the valve adjustment. I'll report back when that's done (won't be for awhile.) :)

Is it really a back-FIRE or just a back-kick in the engine? A lot of bikes will take a half-stroke or so of BACKWARDS rotation sometimes when turning off; it makes a funny clunk-whine noise and there's really nothing you can do about that. I think the thumper does it more than most.

If you DO decide to dis-assemble the carb, I would recommend getting a "kit" for it. Gasket, o-rings, a spring or two.......WAY over-priced but invaluable if you screw something up when taking it apart.

What brand of cleaner did you use ?

[Jere]

It's definitely a backfire; doesn't happen every time though.

I asked the dealership for a carb kit last week and they said they don't sell them, only individual parts. I thought that was strange.

I used something called Slick50 Fuel System Formula at Canadian Tire. See here: Slick50 (http://www.canadiantire.ca/AST/browse/Green/EnergyConservation/FuelSavings/PRD~0380796P/Slick50%2BFuel%2BSystem%2BFormula.jsp). The selection at the dealership was pitiful. I couldn't find the two recommended on here anywhere (went to the Kawasaki and Yahama dealers too.)

[alantf]

I used something called Slick50 Fuel System Formula at Canadian Tire.

I use a similar product - Wynns fuel additive - & it certainly makes a big difference. They recommend using it every 4000 km. I reckon on 75 ml to a tankful of petrol. Only thing is - it's a lot cheaper than the slick 50 - around the equivalent of $6 or $7 for 365 ml (around 5 tankfuls) :)

[Easy Rider]

I used something called Slick50 Fuel System Formula at Canadian Tire.

I just don't have much faith in those "multi-purpose" formulas, including SeaFoam.
I'd think you could find Berryman's B12 Chemtool 'cause I believe it is a British product.
Last can I got was at WalMart. Do you have Auto Zone or NAPA ??

You have to "train" your eye to look for a "real" can and not a plastic bottle though.
It's in a white can with black and red lettering.
Original Gumout is good too; it may come in a can or plastic bottle.