Mikuni BS34 carburetor throttle shaft seal replacement. Police Bike.

[@Pete-from-Tn]

Lost one BB and spring. But I always open carbs up on a big tray with 2" lips around it. So all parts were found, but sure was surprised when those baby's fell out.

[@MotoRestoFL]

Good idea.

[@johnrowley4993]

Excellent video, thanks for sharing 👍

[@lundyracing]

Mine fell out not when I hit the bowl and top side with the impact driver on all 8 bolts, but it fell out in the ultrasonic cleaner 😂

[@Pete-from-Tn]

I open mine up inside a plastic tote. That way no parts can get away. If not for that, those BB's would have been gone. Thanks for watching.

[@karlvanboxel561]

Nice job good tip on staking the throttle screws

[@marcusscott9800]

Outstanding video, thanks for the great info. I have a set of Mikuni Mk 1 BS34 carburetors off of a 1980 Yamaha XS850 and the butterflies are seized closed. Can you recommend any tips to free them up and I would like to separate them but they have no clip on the end only what looks like a large washer and the shaft is larger on that end. Thanks for your help and keep up the great work:)

[@MotoRestoFL]

Thanks. I'd have to see what you are saying, I cannot find a good picture of a MK1 rack of carbs to give an answer. I don't quite understand your description. Email me a pic, [e-mail].

[@bennyblanko3]

Thanks for making this video. Excellent! I have had to get carbs rebushed that were really worn. I don't know what material they used for the bushings (bronze?), but, worked great after.

[@MotoRestoFL]

If these were significantly worn, which they’re not, I’d have set up a reasonably repeatable fixture and drilled and reamed out the bushes. Then turned some bearing grade bronze (not oil-lite but stuff from McMaster Carr which I’ve used before; turned to a 1-1/2 thou crush and reamed the ID small, and final ream after pressing them in. I’d have had to order a bunch of reamers and maybe some non-standard drill bit increments, but could have done it in the mill. It would have a taken awhile. Glad I didn’t have to.

[@bennyblanko3]

@@MotoRestoFL You are a great mechanic! Keep up the good work and videos!

[@gregbright7882]

Did this solve your hanging idle? I am thinking about doing the same thing. Where did you get the seals, and fuel connectors? Thanks for your help

[@MotoRestoFL]

No. Jetting did. Larger slow jets. I'll have to look up the size it ultimately needed. The jetting on the bike these carbs were off, really threw me for a loop because of many factors, you'd have to watch those videos.

[@henryhawk978]

Nice job, tedious work working on carbs. Very good information Tom . Enjoyed the video and RIDE SAFE OUT THERE! Watching again and I have a question. Did you check the shape of the o rings in the choke plungers and mechanism?

[@MotoRestoFL]

Yes. They aren’t new but aren’t petrified. Id have replaced them but they are wicked expensive. Another viewer commented he successfully made new ones out of Viton rubber and using both a 7mm and 1.5mm punch. I ordered some rubber but it’s coming out of the UK. Ordered punched too. I plan on trying it.

[@lundyracing]

@@MotoRestoFLI think Zed over at KZrider makes them that way too

[@itacud2]

What was the running symptom that lead you to the throttle shaft seal? I would assume a vacuum leak/poor idle? Great video!

[@MotoRestoFL]

Throttle shaft seals were a guess. Running like an intake vacuum leak and hanging idle, if you look at the police bike videos it’s in one of those. I have to do a better job organizing playlists. I tried everything, replaced everything and it still ran like crap. Which is why I’m doing the entire top end including these carb operations to rule them out. I’ll eventually get to even testing flow through the exhaust to make sure nothing is blocked. The valves were smoked.

[@lundyracing]

@@MotoRestoFLgot it running right now?

[@MotoRestoFL]

@@lundyracing yes. The final video has all that. It’s long gone.

[@kenwattleworth9409]

Great informative videos! Where do I get a rebuild kit for a 1983 GPZ750 Mikuni Carb Rack? - thank you.

[@MotoRestoFL]

Just about anywhere. I’d recommend the K and L kits. The Chinese kits are junk. Do a Google search and if they’re available you’ll find them.

[@MotoRestoFL]

www.z1enterprises.com/carburetor-kit-zx750-kz750-1982-85.html?fits-motorcycle=Kawasaki/ZX750/ZX750-A1/1983

[@kenwattleworth9409]

@@MotoRestoFL yeah I got the junk China one with regret. Hoping to find a OEM kit. Can’t tell online which is legit.

[@MotoRestoFL]

@@kenwattleworth9409 OEM parts in my experience can only be grouped by the purchaser one part at a time off the parts fiche from whichever supplier you choose. The Z1 Enterprise kits aren’t bad. I linked to one above.

[@qivarebil2149]

"Bearing balls", not "Ball bearings"...😬Other than that, nice video! Thanks! 🤩

[@wdhewson]

My goal in life is to work all day without dropped something. An unrealized goal at 73 y old !!

[@TalonGames]

hello, does somebody knows the measurments for those throttle shaft seal, need it for a different bike, it should fit but I am not 100% sure

[@MotoRestoFL]

Not sure. If you go to eBay and search for BS34 throttle shaft seals you’ll see the listing for them and perhaps the seller can tell you. I did not measure the shaft or the counterbore in the carb body, but if I had to guess I’d say 8mm OD and 5.5mm shaft diameter. But again that’s a guess.

[@DavidElleker]

hi nice job i think you should have pulled the choke plungers out and renewed the rubber at the tip if they are hard they will leak fuel all the time

[@MotoRestoFL]

I did pull each one and checked the tips. The rubber feels pliable. Not like new, but I suspect they’ll seal ok. The plungers are wicked expensive. Thanks.

[@DavidElleker]

thanks yes they are shocking i did mine i brought some 2 mm nitrole rubber and 2 hole punch 7 mm and 1.5 mm applied some heat dug them out and pushed in the new rubber its a bit of a fiddle but it works i did my z1r carbs they were hard as rock @@MotoRestoFL

[@DavidElleker]

sorry i ment vitron rubber

[@MotoRestoFL]

@@DavidElleker I might try that. It’ll be a snap to pull the rack apart again and snatch out the plungers. Thanks.

[@DavidElleker]

the smaller punch was 1.8 mm on the vm carb some of these dont have the spike at the end as you know

[@stevecaton1595]

Couldn't you just lock tite the new flap screws , with removable serviceable thread lock

[@MotoRestoFL]

Probably. But peening them over and Loctite I think is better for such a fastener that can never, ever be allowed to come out.

[@lundyracing]

Remove the choke shaft first 😉

[@lundyracing]

Finished the video, good call 😎

[@RichardDash-dq8gv]

Repeat repeat repeat sorry I’m deaf what did you say ?

[@MotoRestoFL]

Go take your Adderall and watch again, then it'll make sense to you.