New GZ Project - Lesson Learned - Stumble Off the Line

[SusKatCas]

Howdy, new to the forum and this bike. Long time farm kid, engineer, played with lot of engine driven equipment throughout the years.

I bought a GZ250 with low miles, 2130, and not running this spring. Sorted out a bad crank position coil and then dove into the carb. It was one of those "carb should be in good shape, my buddy went over it last summer" kinda deals. Whoo hoo! Jet need spring and holder were missing, the small diaphragm was wrinkled and mis-located. Usual varnish crud from sitting since 2014 inside.

Over night carb dip and $40 in small parts got the ole girl running. It started nicely but stumbled badly off the line. Once moving it was fine, but tended to cough or stutter in wide open throttle condition. I could somewhat counteract the first problem with the choke. I pulled the carb a couple times messing with jet needle shim mods and making extra certain that I had cleaned all the passages.

Eventually traced the problem to: Me. The plunger in the float valve is very soft, when I turn the carb upside down to set float height I was setting it with plunger fully depressed. So, I laid it on the side with a small angle to allow contact, but not depression of the plunger. I have not noticed a fuel height guideline for the bowl? Anyway, after tweaking that setting the bike runs great. Currently 2.5 turns open and the pilot jet and the small washer moved to the bottom side of the e-clip on the jet needle.

A few closing thoughts:
1) This forum is great, you guys saved me hours of time. Thank you.
2) Thank you for posting the .pdf of the service manual.
3) Both old and new plunger springs were very soft and would fully depress when the carb was upside down. Is this normal?
4) Sorting out the terminals for that coil was a hoot. I ended up getting terminals from cycleterminal.com and soldering in addition to my hand crimp. Just couldn't stand to buy a new set of crimpers for one job.
5) Front brake is flushed and bled.

Seems like a fun machine.

Cheers, Alan

[wacio]

Yes that is normal. You have to adjust sideways or will end up with level way too low and running lean.

Refer to great tech video (general motorcycle carb but still helpful):

[Water Warrior 2]

Welcome, we've been waiting for you. Sounds like you are having fun riding a GZ. RIDE SAFE.

[blaine]

Welcome to the family!!

[Vegas Street Rider]

Welcome to the forum. It sounds like you will be bringing a lot of mechanical knowledge to the group. Some of us are just backyard mechanics, and some of us are very keen in specific areas such as electrical, structural, long time riding experience backgrounds. I fall in the former category and have really learned from this forum. Regardless, have fun with it and be safe. Send pics of your ride. We love to see any mods you may make as we share what we do with our rides. The GZ holds a special place in our motorcycle world.