Bike dies when throttle engaged

[justincan423]

So I recently bought a 2000 GZ and I'm not very knowledgeable in the motorcycle field. Since I bought it I've gotten the carb "cleaned out", new spark plug, new battery, drained the tank and filled with gas and a system cleaner. So the issue that I'm having is no matter how much fine tuning of the choke, throttle, mixture screw and everything I cannot get it to go. It starts up and idles decent but when I give it throttle it just dies out. Again I'm kind of new to motorcycles so I'm not fully knowledgeable with them I mainly work on cars so any information will be helpful. Thanks in advanced, and if you need any more info from me about the bike please let me know! https://uploads.tapatalk-cdn.com/20170520/578fce045bcde2f4ab9a98fe9e90880e.jpg

[blaine]

Almost sounds like a vacuum leak.....Have you checked around boots & petcock hose for leaks?.........Other thing that comes is a torn or not seated in grove diaphram.

[justincan423]

Almost sounds like a vacuum leak.....Have you checked around boots & petcock hose for leaks?.........Other thing that comes is a torn or not seated in grove diaphram.



No leaks in petcock hose or anything and by grove diaphragm do you mean where the carb goes into the block? Both sides are good no tips or anything in air box boot either. Is there a way to do a vacuum leak test like you can on a car?

[spldart]

I'm starting to get the same problem with my 2000. As if I needed more problems.
My start regime is this:
full choke and crank.
modulate the choke for the first 10 to 30 seconds then settle it into an idle.
If I simply get on the throttle it will just die.
if I rev rev rev rev the throttle really fast to build revs I can get underway.
warming it up is best done by short shifting to prevent overrev but keep the throttle pinned.
after 1 or 2 miles I can keep it running fairly easy.
Less than that and if I don't do everything perfect it just dies over and over.

Found a Mikuni carb expert website.
It says Pilot circuit problems or vaccum leak.

Thing about a vacumm leak is once you get it started and idling if you hose
it with starter fluid *auto parts store* it should react big time.
Be johnny on the spot with the ignition kill and a fire extinguisher though.

I plan on trying this on mine.
Don't spray the carb intake. It's prolly not your problem. Spray the boot between the engine
and carb and the carb itself. Assuming you have a vacumm leak.
The intake of the carb will react even if the carb is perfect.

Don't overspray. If you have a vacumm leak it should react dramatically.

[blaine]

No leaks in petcock hose or anything and by grove diaphragm do you mean where the carb goes into the block? Both sides are good no tips or anything in air box boot either. Is there a way to do a vacuum leak test like you can on a car?
Sorry...I mean the slide diaphram when you take the top cover off.

[justincan423]

I'm starting to get the same problem with my 2000. As if I needed more problems.
My start regime is this:
full choke and crank.
modulate the choke for the first 10 to 30 seconds then settle it into an idle.
If I simply get on the throttle it will just die.
if I rev rev rev rev the throttle really fast to build revs I can get underway.
warming it up is best done by short shifting to prevent overrev but keep the throttle pinned.
after 1 or 2 miles I can keep it running fairly easy.
Less than that and if I don't do everything perfect it just dies over and over.

Found a Mikuni carb expert website.
It says Pilot circuit problems or vaccum leak.

Thing about a vacumm leak is once you get it started and idling if you hose
it with starter fluid *auto parts store* it should react big time.
Be johnny on the spot with the ignition kill and a fire extinguisher though.

I plan on trying this on mine.
Don't spray the carb intake. It's prolly not your problem. Spray the boot between the engine
and carb and the carb itself. Assuming you have a vacumm leak.
The intake of the carb will react even if the carb is perfect.

Don't overspray. If you have a vacumm leak it should react dramatically.



Awesome thank you for the information. I'll try that out possibly tomorrow and let you know how I make out

[justincan423]

Sorry...I mean the slide diaphram when you take the top cover off.



I will double check that tomorrow. Thank you! I just want to get to riding so bad this thing has been such a headache. It'll all be worth it in the end though (hopefully) [emoji1360]

[derbydave]

I would put money on the pilot circuit. Mine ran like crap until I cleaned the pilot jet and replaced the tiny o-ring.

[blaine]

I would put money on the pilot circuit. Mine ran like crap until I cleaned the pilot jet and replaced the tiny o-ring.
Yep you could have a vacuum leak there if the o-ring is bad.

[justincan423]

Yep you could have a vacuum leak there if the o-ring is bad.



Sorry to be annoying but being that I'm new to the carb game, which o-ring are you taking about? When I took the carb apart to clean it the only o-ring I saw was the one on what I believe is the main jet, the pilot jet did not have one on it. Is it supposed to? Because that could be my issue right there. The carb refresh kit I bought came with a few little o-rings that I'm not sure where they go. Thanks again for the advice!

[blaine]

Yep pilot screw should have spring,washer, & small o-ring.....There should be one in the kit...... :)

[derbydave]

You may need to drill out the plug to get to the pilot jet if it hasn't been serviced before. I had to drill mine.

[justincan423]

Yep pilot screw should have spring,washer, & small o-ring.....There should be one in the kit...... :)



Awesome! Will definitely check that out I didn't know about that .. thank you!

[nn329]

Did you manage to fix the bike?

[Director59]

I'm starting to get the same problem with my 2000. As if I needed more problems.
My start regime is this:
full choke and crank.
modulate the choke for the first 10 to 30 seconds then settle it into an idle.
If I simply get on the throttle it will just die.
if I rev rev rev rev the throttle really fast to build revs I can get underway.
warming it up is best done by short shifting to prevent overrev but keep the throttle pinned.
after 1 or 2 miles I can keep it running fairly easy.
Less than that and if I don't do everything perfect it just dies over and over.

Found a Mikuni carb expert website.
It says Pilot circuit problems or vaccum leak.

Thing about a vacumm leak is once you get it started and idling if you hose
it with starter fluid *auto parts store* it should react big time.
Be johnny on the spot with the ignition kill and a fire extinguisher though.

I plan on trying this on mine.
Don't spray the carb intake. It's prolly not your problem. Spray the boot between the engine
and carb and the carb itself. Assuming you have a vacumm leak.
The intake of the carb will react even if the carb is perfect.

Don't overspray. If you have a vacumm leak it should react dramatically.
What is the address for the Mikuni expert site? I can't find it!