Topic: CB750 K6 086A Carb Rack Shaft Sticks

[newday777]

The Carb Rack shaft is very stiff to move the throttle lifts.
I've soaked it multiple times with brake cleaner, Carb cleaner and PB Blaster to no avail to free it up. Anyone run into this and found a good solution to fix it?? This is one of the few racks that has the right side idle screw mounts for the K5/K6 left side petcock so you can get to the idle adjustment screw.
I have other racks from earlier carbs that are very easy to move so I know there must be rust/corrosion in the rack boss that the throttle shaft goes through on this 086A rack.

[PeWe]

Try WD40

[BenelliSEI]

Stu….. did it com to you in pieces? Could the shaft be slightly bent?

[newday777]

Stu….. did it com to you in pieces? Could the shaft be slightly bent?

No John, they were together. 086A carbs set.
 I'll put a straight edge on the rack later to check for bend.

[bryanj]

You can strip the shaft right out BUT be carefull to remove any keys or pegs in the shaft before drifting out

[newday777]

You can strip the shaft right out BUT be carefull to remove any keys or pegs in the shaft before drifting out

I've tried on another unsuccessfully.....unless you know of the technique

[CycleRanger]

Try a little white grease.
Yes, taking the carb rack apart is not fun. It's very difficult to remove the roll pins.

[newday777]

Try a little white grease.
Yes, taking the carb rack apart is not fun. It's very difficult to remove the roll pins.

Where is the roll pins? There?
And how?

[denward17]

Try a little white grease.
Yes, taking the carb rack apart is not fun. It's very difficult to remove the roll pins.

Where is the roll pins? There?
And how?

I think I read somewhere they have to be drilled out, then tapped for a small bolt to go back together.

[MauiK3]

Not sure how the later racks were assembled but I had to strip mine down to free it up and remove corrosion. A little fiddly but I got it to work fine.

[newday777]

Not sure how the later racks were assembled but I had to strip mine down to free it up and remove corrosion. A little fiddly but I got it to work fine.

I think the earlier racks are similar, they only had just the left side screw hole where as the K5/K6, F0/F1 have 2 screw holes, one for left or right side idle screw.

[newday777]

Not sure how the later racks were assembled but I had to strip mine down to free it up and remove corrosion. A little fiddly but I got it to work fine.

So how did you get the shaft out?

[BenelliSEI]

Drill the pin and make sure it is all out or it will break the bronze bushing when you knock the shaft out. Been there, done that….

[CycleRanger]

Try a little white grease.
Yes, taking the carb rack apart is not fun. It's very difficult to remove the roll pins.

Where is the roll pins? There?
And how?

Sorry, you're right that's a solid pin.
I took apart a rack many years ago to replace a broken fork but I honestly don't remember now what method I used to remove that pin.

[Oly]

Stu...Reference the following Hackaweek episode "73 Honda CB750 Custom Build Part 28 - Carburetor Install". 
It shows how Dino replaced the pin that holds the rod in position.

[newday777]

I will thanks Oly

[CycleRanger]

Ok, because I couldn't remember I went and found my box of stay plate parts.
It appears that at some point they changed the stay plate design.
The one that I repaired secured the rod with a set screw covered by a staked-in aluminum cap.
That's how I was able to dismantle and repair my stay plate.
(Here's a couple of pix.)
I also have one just like yours with the pressed-in pin, it's got 086 carbs on it so I assume it's from a K6.
The stay plate with the pressed-in pin were clearly designed without disassembly in mind..
Sorry, I know that's not any help.

[newday777]

Yes Oly and CR the videos and pictures helped to figure it out. I went through the carbs that I have and found the different caps to the pin of the K5/K6 iteration.
I haven't had time to drill it out yet as I was scheduled for some use of a friend's vapor Blaster, plus it's bike night. I'll get back to it in a couple days. Thanks much for all you do.

[HondaMan]

Ok, because I couldn't remember I went and found my box of stay plate parts.
It appears that at some point they changed the stay plate design.
The one that I repaired secured the rod with a set screw covered by a staked-in aluminum cap.
That's how I was able to dismantle and repair my stay plate.
(Here's a couple of pix.)
I also have one just like yours with the pressed-in pin, it's got 086 carbs on it so I assume it's from a K6.
The stay plate with the pressed-in pin were clearly designed without disassembly in mind..
Sorry, I know that's not any help.

I've done at least 2 of the K5/6 era racks with this little cover plate over a screw, underneath it. The cover plate was glued on and the screw's tip had collected quite a lot of grit, making the rod drag. The screw easily unscrewed, though, and I glued the little cover back onto it afterward with little damage. I used a small , sharp pick to get it off.

I've also seen them filled in with metal like Cerrobend instead of the cover. This melts out like low-temperature solder with either a soldering iron or propane torch, and I used ordinary solder to fill it in afterward.

The early racks (K1) sometimes just have pins in there, harder to remove those. Had to drill some of those, and then installed a roll pin afterward - with solder on top.

[newday777]

Ok, because I couldn't remember I went and found my box of stay plate parts.
It appears that at some point they changed the stay plate design.
The one that I repaired secured the rod with a set screw covered by a staked-in aluminum cap.
That's how I was able to dismantle and repair my stay plate.
(Here's a couple of pix.)
I also have one just like yours with the pressed-in pin, it's got 086 carbs on it so I assume it's from a K6.
The stay plate with the pressed-in pin were clearly designed without disassembly in mind..
Sorry, I know that's not any help.

I've done at least 2 of the K5/6 era racks with this little cover plate over a screw, underneath it. The cover plate was glued on and the screw's tip had collected quite a lot of grit, making the rod drag. The screw easily unscrewed, though, and I glued the little cover back onto it afterward with little damage. I used a small , sharp pick to get it off.

I've also seen them filled in with metal like Cerrobend instead of the cover. This melts out like low-temperature solder with either a soldering iron or propane torch, and I used ordinary solder to fill it in afterward.

The early racks (K1) sometimes just have pins in there, harder to remove those. Had to drill some of those, and then installed a roll pin afterward - with solder on top.

Mark
The K6 086A, my 76 F0 064A, along with the late 7A(K5??) racks that I have ave all have the pressed in pins( and have double idle screw locations). The three 657B racks I have also have pressed in pins.
The early 7A K1 racks(2) and the 657A K2 rack that I have, have the staked caps and I figure they have the locator screw in them.

[Oly]

Thanks for posing the question Stu,  CycleRanger for the pictures that sent me back to look at my carb stack project one more time and Hondaman's input related to the types of rod retaining devises used thru the years.
CycleRanger's picture of the retainer looked familiar and sure enough my 8/70 manuf'd K1 looked like it had the cap with a screw configuration.
Cap came off easily, unscrewed retainer, disassembled parts, replaced broken parts I received from John and it all went back no problems.
Thanks to all....
Sorry for hijacking your thread a little Stu!

[newday777]

Well I set up my 1/16" drill bit in the drill press, did a center punch mark in the center of the locator pin and slowly drill it, and watched it walk on me on an angle away from the pin center....Arg. Chucked in a 7/32" bit(smaller than 3mm pin size), put a wedge under the rack to try to get it to center, nope...it went at an angle also....ophhh. I'm thinking, now what??? We'll it didn't clear out the pin, but it did free up the action a bit. So I squirted in some LPS-1 greaseless lubricant(Mark's fix for corrosion in electrical connectors!) in the hole hoping that it would get in the groove and help. Yes it did! So I squirted more into the bearing surfaces on either side of the rack rod boss and worked it back and forth a bunch. I'm going to find a small set screw to fit in there to strengthen the remaining section of the pin, cap it and call it a win!
So thanks for all the replies and suggestions to get it freed up. Thankfully, I didn't have to try and remove the throttle rod to go further with it.

[newday777]

Thanks for posing the question Stu,  CycleRanger for the pictures that sent me back to look at my carb stack project one more time and Hondaman's input related to the types of rod retaining devises used thru the years.
CycleRanger's picture of the retainer looked familiar and sure enough my 8/70 manuf'd K1 looked like it had the cap with a screw configuration.
Cap came off easily, unscrewed retainer, disassembled parts, replaced broken parts I received from John and it all went back no problems.
Thanks to all....
Sorry for hijacking your thread a little Stu!

Oly that isn't a hyjack, as your information will probably help someone later that comes across it doing a search on finding an answer for their problem. I have some of the K1 and K2 racks of carbs that have the same cap and screw so hopefully they will continue to be good but now I know what to do if needed to take them apart.

[CycleRanger]

I knew my K5 had some K1 parts on it, like the side covers, but I didn't realize the stay plate had been changed since the carbs were 657B's.
I guess I lucked out when I got a replacement for parts because it had the set screw as well.

[newday777]

I knew my K5 had some K1 parts on it, like the side covers, but I didn't realize the stay plate had been changed since the carbs were 657B's.
I guess I lucked out when I got a replacement for parts because it had the set screw as well.

Which side is your idle screw on?