Hey guys,

I have been working on my 1995CBR900rr for the last couple of weeks to try and get it running. Finally Got it running but now I have a whole new set of issues to deal with. It isn't idling smoothly or dies even at a high idle. The clutch 'clunks' when released when in neutral. The throttle is extremely sticky, and it is slow to rev up and slow to rev down. She is also backfiring.

To get it running I replaced the battery and the oil. I also removed and cleaned the carburetor.

When I initially got her running she seemed to run smoothly, but as I adjusted things (Idle screw and throttle/choke cables) she began running worse, and for shorter durations.

I am not sure of the history of the bike, or even when it was last ridden, as I inherited the bike. I am also new to working on bikes.

Here are a few short videos of it being started and attempting to idle. all less that 45 seconds.


Thanks in advance for any feedback

 

Sounds like you don't have all cylinders firing at all times. One way to figure out which cylinder isn't firing is to touch the headers with a wet rag, and the one that doesn't make a sound would be the non firing cylinder (only firing cylinders create heat which makes the exhaust hot).
For my '94, I've had lots of issues with not all cylinders firing or harder starts.
I think it is because I so rarely ride it and the gas goes stale.
Gas doesn't last that long (probably not much more than a month or two).

Then, if you use the choke a lot, that can foul up your spark plugs. I don't use the choke any more than absolutely necessary.

 

Thanks for the reply!

From what you're saying my best course of action would be to clean/change the spark plugs and change the fuel?

I have been using the choke a lot, as seen in the videos, and the fuel is a month or two old. These two factors gunked up the spark plugs presumably?

Initially when I first got her running she seemed to run fine, all things considered (a bit of backfiring and throttle issues), but as I stopped and started her several times she seemed to have a harder time idling and being started. The use of the choke and having old gas in her while starting caused this issue in such a short time?

Thanks again for the reply Tony.

 

Hey I also but stabilizer in the gas, I donno if that would help, but its in there!

 

You're welcome.
Well, if the gas is old, then it's old. Only you would know how old it is.
Gas expires in bikes faster than it does in cars (from my experience).
If you were to drain the tank, you would have to take the tank off, and at that point, you could also check out the air filter and inside the air filter housing.
I have actually cleaned my air filter before and made it look new again.
It's only ten or so screws to take the top of the housing off--it's worth the 5 minutes to check it.
Stabilizer...if you mean you put that in initially, than good, but if you put it in after you had problems, it won't work retroactively.

I wouldn't say that the old fuel gunked up the spark plugs, I'm more thinking that old fuel just doesn't perform as well (sputtering, hesitation, hick-ups).

It's possible that I am pointing you off to where the problem isn't.
But I do know some things:
Old gas doesn't work as well and will make some cylinders misfire.
Fouled up plugs won't fire as well.
It isn't so hard to check on the air filter to be sure that things look normal.
Air, gas, and spark are what's needed for ignition.
And the cylinder that isn't firing in your last video, already told you how to detect that (wet rag method).
I assume you know that only 3 cylinders were firing in the last vid.

 

Its not normal to fire up so hard.

+1 for old gas !
+Check your spark plugs and make sure u are connected their cables right.1-4 and 2-3. And check ur coil cables (black and yellow on mine blade).

And you say u have been clean ur carbs ?! Did u screw/unscrew the air nut ?

But at first time try with new gas. Thats the most simple thing. If it wont crank again unmount the tank fuel and air filter box and coils then get out the spark plugs. Im sure they are wet.

U can post pics here to watch ur work.

Cheers buddy and good luck !

 

Hey man, thanks for the reply!

The fuel is no more than 2 months old, and when I put the gas in I put stabilizer in with it... so it should be fine??

I am checking the plugs right now, it seems like they are all in the right position, because the previous owner has them all marked, assuming he marked them correctly. Coil cables seen to be hooked up correctly as well, black to black and colour to colour ( I have a blue and a yellow wire).

It seems like a hassle to get the plugs out, but I'll figure it out. I have the manual so I'll read it on how to spot a bad plug and clean it, but in case I'm still in action, do you guys have any tips.

Oh and this is the state of my air filter, still ok to use? At least get it running?

 

Well filter looks not so good...

Btw...your spark plugs could looks good but its possible to work not properly. If u have a mate who can give u his spark plugs to try with them will be good.

 

thats new filter lol

 

Hey man, thanks for the info.

Quick update.

Changed all the spark plugs, drove around for 2 hours searching for them, hopefully worth it. Attached is pic of old plugs.

Only cleaned the carburetor, didn't fuss with the mixture screws. I know the mixture is a bit rich because when I had her running she was backfiring quite a bit.

Put her all back together and tried to start her, but all I got was cranking. Tried with and without choke. I'm pretty confident the gas should be good, because she was running before. She sounded like she wanted to start every know and then, but nothing.

What can I do from here?

changed;

-oil
-gas (about 2 months ago)
-sparkplugs
-cleaned carb
-fuel is obviously getting to carb cause she started before

I'm stuck!!