85 GPz 750 Cafe Project

I thought this Q&A might possibly hold a clue for your problem. If not, its still interesting. This is a great project that you are doing. It's inspiring and you are very creative and talented. You will fix this, I'm quite sure.

Here's the link: www.motorcycleclassics.com/tech-corner/h...roblems-zb0z1203zbea

New set of carbs, 42.5 pilots, 125 mains, runs fantastic all the way to 9K. ( I stopped there) I pulled a plug and I know with certainty it isn't rich. They look just like they looked before. Since the white powder of lean was on them when I started with this set of carbs, I suspect I won't be able to read these unless the AFR is extreme one way or the other. Tomorrow I'll color tune the idle circuits and vacuum sync the carbs. Over joyed may describe my state of mind well. Between the tank BS and the carbs, I lost about 6 months of my life. I think that just means I'm slow.

Nice, that's good to hear. I'm slow too so I can't say anything.

Are they a different type of carb, or can you see any difference between the good carbs and bad carbs?

Not to my eye. Both are BS34s. Slightly different vintage. The 83 -85 have plastic caps, prior to that they have metal caps. I ultrasonically cleaned them twice, flushed with hot water, then compressed air. Next carb and choke cleaner to verify all passages are open and chased that with air. I did put the plastic caps on the carbs that had metal caps. Some have suggested that can be a problem. The bottoms look identical to me, but I'm going to swap them and see what I get.

That is strange. It sure would be nice to know what the difference was.

There are usually air jets up in the diaphragm chambers, When I put pods on a 400 with CV carbs, the air jets were drilled already drilled out, along with some of the other jets. I wonder if they might be different on your two sets of carbs (assuming everything else is the same).

Long day and I don't think there is a difference between the caps. I put the metal caps on the trot led carbs making certain the rubber on the sliders was properly seated. I color tuned them, vacuum sync'd them. Same thing, totally falls on it's face at 5K. Move the two cable pulley over to the 82 GPz BS34's, put 132.5 mains in it since the 125s seemed to be lean. Color tune, vacuum sync'd, runs fantastic. I drove out to a country road, went through the gears shifting around 8k to 9K rpms. It screams. That run took to 110 mph and I shut it down. The owner and I are going for a ride tomorrow.

Owner and builder went for a ride today. 100 miles through the Rocky Mountains. Bike performed great. Michael (owner ) said it exceeded all his expectations. Good thing after 21 months. Thank you to all who offered help and their insights. I'll paint the tank for the third time next week and deliver it to him. Pics below of the bike he bought Dec 2015 and the finished product Sept 2017.

Good job, it looks great.

Matt

Michael is a proud owner of a very cool unique bike .
I wish him a million road miles of luck with his unique designed bike.
You have done a good job ajsfirehawk

I gotta say, that is a cool bike, or maybe, it's a hot one. Having have ridden my old 1978 kz 650 and now my gpz 750 they are a different breed. To see them comingled is great. You and owner have both shown a level of patience that is admirable.

What's the next project?

Thank you for the kind words. The next one is an 82 KZ1000 CSR. The owner has a ZRX from end and swingarm along with the brakes for both, He wants to integrate them into the CSR, different tank, he likes the round 70's KZ1000 tanks, Wiseco overbore, cams, LED lights all around. A ducktail is a possibility. All his thoughts aren't fully formed as yet. The CSR is a nice starting point, 13,500 miles. Head gasket is blown but that doesn't matter as this will all be rebuilt from the engine case up. He needs to come up with a rendering before I get too deep into it. Lots of tear down and clean up to do. I'l get a thread rolling once I get eyeball deep in it.