Topic: Going through my CB750 K6

[The other Derek]

There is.  It's riveted in ATM.  I've considered wrapping the header and trying to find a chrome or stainless muffler to dress it up a little.  Possibly even painting the header with a new muffler.

First thing is to get it running right and on the road safely though.

[The other Derek]

Got the carbs put back together and she is running again.  I bench sync'd the carbs using a drill bit and got the bike to start up relatively easily, but it took a little while to get the carbs balanced enough to run on the manometer.

I was able to get it pretty close, but it's not easy to get the lock nuts tightened without seeing big changes on the manometer. 

Cleaned carbs:


Getting close on the sync:
Syncronizing CB750 K6 carbs

It still wants to stall at lower RPMs.  I could hear a little vacuum leak while trying to sync the carbs.  The 1/4" tubing may be a touch large for the MIG tips that I have threaded into the vacuum ports.  I'll have to find the heat gun and see if I can get that tubing down to a tighter fit.  I'm sure I could clamp 1 and 4, but it's pretty tough to get to 2 and 3.

[The other Derek]

I finally got the new tires, sprockets and chain mounted over the weekend and managed to get out for a couple of rides this week.  I immediately noticed pulling out onto the road that it seemed to be lacking in power and especially noticed it bogging down around 5000 rpm. 

Running lean now?  My guess is that it is an air leak between the airbox and carbs.  There were/are no clamps on the air connecting tubes, but they are also pretty stiff and I'm guessing there is not a good seal between the box and the tubes- particularly on #1.  I taped that connection up this morning before heading off to work and the bogging seemed less severe.

I think I read that a xylene soak will soften up the tubes.

I'm going to try spraying WD-40 around the carbs in the AM to see if the air leak theory makes sense.  It might explain the bouncing of the fluid in my manometer when I was trying to sync the carbs.  The boots seemed like they were OK, but I'll check those as well.

Would an air leak also cause the idle speed to wander?

Looks like I'll prolly be ordering a few more parts from the local dealership. 

[bjbuchanan]

I have a K6 also, kinda cool i guess, but anyways i'm a real cheap b@stard so I resorted to the xylene soak. I'm gonna put my flame suit on now but I want to share my opinion

The xylene trick works great on the more resistant and tougher engine to carb boots but IMO the airbox boots don't take it as well. They are a little diff material so the effect isn't the same. Mine after a while shrunk and hardened again giving me occasional idle racing and sometimes a choppy idle. I sprayed brake cleaner on them and my engine stumbled bad. I replaced them with fresh boots and WOW. The airbox also went on like butter compared to the old battle with it. They are a little cheaper and will last idk maybe 20 years lol

Just my .02

[The other Derek]

After a couple of months of just enjoying the ride, I had to park the K6 in the garage after the pull throttle cable snapped on the way home from work.  Luckily I was only a couple of miles from home so I was able to turn the idle screw to adjust the speed enough to limp home on side streets.

I've since ordered a pile of parts and will have some fun going through the bike over the next couple of months to get it ready to ride again in the spring.  I was hoping to keep it running through the winter try to commute on the warm and dry days, but she's already in pieces.

Currently I'm on the fence with Benjie's 4-4 stainless exhaust.  The 4-1 currently on it functions fine, but is ugly.  Common sense tells me to make everything else right before I spend that much on a new exhaust.  It's so easy to ignore that voice sometimes though.

Plan for the winter:
   read HondaMan's book thoroughly
   finish rebuilding my vintage Delta lathe so I can use it to buff all the aluminum
   frame kit installed
   frame and swingarm painted (or powdercoated)
   check/replace swingarm bushing
   thoroughly clean engine (possibly paint too- might as well if I am pulling everything apart)
   new wiring harness
   new throttle cables
   new tach cable and seal
   soak boots in wintergreen oil
   maybe new shocks- they're very stiff solo but OK with my wife on the back

I'd also like to replace all my spokes, but that'll likely have to wait a year.  It'll depend on how productive I am.
   
 

[Really?]

I know you posted this back in September but I have been kinda away for a while.

110 main jet (changing back to 120)- staying 110 as thats what came with the kits.  Stocks are 120?

I thought the K6 carbs had 105 mains.  I think these are the K models carb numbers for 75/76 - 657B & 086A.  If it is one of those, it is a 105 main and a 40 slow.

http://www.motorcycleproject.com/motorcycle/text/specs.html

I did bump mine to a 110 because of the Mac 4-1.

[The other Derek]

Going to try to tackle pulling the wiring harness and possibly stripping the frame so I can take it to get welded and powdercoated.  I do know now that a frame will fit in the backseat of my Saturn.  It's tight, but it works.  I guess that's better than strapping it to the roof rack.

I'm not sure how far I want to take the teardown.  My garage is tiny and already packed with other stuff, but I really hate to avoid doing it now and regret it next summer.  I'm thinking that I might want to cobble together a quick shelving unit to store/organize the parts before I get too carried away.

I've peeked behind the headlight a couple of times but it still is a little upsetting to see the mess behind the bulb.  I'm anxious to get this sorted out.

[The other Derek]

Just about ready to pull the motor from the frame.  It's been a little cold for the last couple of days so I decided to try soaking the rubbers in wintergreen oil until I can get a refill for the garage heater. 

Two of the air rubbers (1 & 4) were rock hard.  I temporarily sealed the air leaks with duct tape, but I was hopeful that the wintergreen oil bath would revive them.  2 &3 were still pretty pliable, but I didn't have an idea how soft they should be so I decided to just soak them all.



The carb boots were all hard and tough to pull off the intake spigots.  They all got soaked as well.



Cheap, thrift shop crock pot:


They barely fit.  I soaked them in straight wintergreen oil on high for 1 hour.


The air boots are mush.  The rubber is way too soft now.  I kinda figured that the 2 bad ones would need to be replaced, but unfortunately the 2 good ones are ruined now too.


Carb boots fared much better.  They are pretty pliable and are relatively easy to slip on and off the spigots now.


So, I guess if you're going to try the wintergreen oil soak, exercise a little caution with the air rubbers.  I checked on their progress at the halfway point and I'd say they were ruined by then.  I just flipped them over to complete the destruction soak time.

[bjbuchanan]

The airbox boots become soft after a quick soak, not nearly as long as the manifolds. Too late to tell you now. In my experience the airbox don't stay soft, they shrink and go to hell pretty quick

IMO if you are gonna replace one of the two, do the airbox ones. cheaper and depending on how bad they were you can really notice the difference

[The other Derek]

Live and learn, I guess.  I figured 1 and 4 were trashed already so I was already prepared to replace them.   Four new air boots and clamps were ordered from Service Honda.  It'll be exciting to get the parts, but I'm guessing it'll be a couple of months until I get to install them. 

I finally drained the oil tonight and am getting ready to wrestle the engine out of the frame.   Would've been nice to warm the engine up first, but apparently I'm really into this live and learn thing.

Tearing the bike down has been a lot more interesting than I had anticipated.  There've been a few things I've noticed that really have me wondering about the bike's history.  The first of which is the cut frame- makes me wonder what work was done.   I also noticed that none of the 3 locks (ignition, seat, fork)  match.  I'm guessing the ignition switch was replaced at some point, but I assume the other 2 should have matching locks.  The condition of the wiring was also a concern.  There was enough electrical tape and wire nuts that I'm amazed that I didn't have more problems.

Hopefully on Tuesday I'll be able to fit in the Gordon frame kit and power wash all the grime off the frame- prolly in the opposite order.  Then I gotta find a welder and figure out if the frame wants paint or powdercoat.  With my budget it'll probably have to be paint - most likely from a rattle can-  but I really don't want to have to wait for warm weather to start rebuilding.  My torpedo heater makes the garage tolerable, but not warm enough to paint.  All the moisture wreaks havoc on the cast iron tools on the garage too.

[The other Derek]

Got the frame kit almost installed.  I think I need to cut one of the frame members (right front) back about 1/4" to expose a little more of the plug for the weld. 

I also spend a little time on a local woodworking forum.  They recently added a metalworking subforum and I posted in there looking for some help with the welding.  I'd love to be able to do it myself, but I'm guessing a little coaching and handholding would be helpful at first.  Practice too.  At the very least I'd like to have someone there to help me watch my garage burn down.

It was pretty cold yesterday but the heater made it pretty cozy after a couple of hours.  I think I spent more time looking for the arbor nut for my grinder than I did cutting the tubing.  I gave up trying to make the cuts with the grinder and just did them by hand, but at least the hacksaw helped keep me warm.  Here's a pic of the installed kit:

[The other Derek]

Got the frame back from the welder today.  Also got a quote back on the powdercoating- $200 + blasting.

The swingarm bushings and steering head bearings are both getting replaced this year, so I don't think my budget can handle the PCing.  Time to read up on paint I guess.

[Stev-o]

Frame kit looks good, wish I had one on my K4. 

Tapered bearings have gotten very reasonably priced...


http://www.amazon.com/All-Balls-Steering-Bearing-22-1011/dp/B000GZQ3XW/ref=au_pf_ss_1?ie=UTF8&Make=Honda%7C59&Model=CB750K%7C17058&Year=1976%7C1976&carId=003&n=15684181&s=automotive

[SOHC4 Cafe Racer Fan]

That's an outstanding deal on the All Balls steering bearing kit. 

I say save your nickels and powdercoat the frame.

[Vinhead1957]

Painting with a good quality paint costs more than powder coating. I found a guy that did my frame swing arm and many more parts for $125. Basic black but I could not have done a better job
https://www.dropbox.com/s/9lijr7edzcgb58r/DSC06401.JPG

[iron_worker]

Powder coat really depends on the area...

Around here the mining industry uses powder coat on a lot of stuff since it's very durable. This of course jacks up the cost of blasting and PC'ing. Would have cost me $750 to blast and powder coat just the black pieces (including the frame).

I paid $350 to have all of my painted parts (besides engine, gas tank, and covers) blasted.

I have no idea what it would have cost to pay someone to paint my stuff but probably similar to PC'ing here. I painted it myself and am fairly happy with the results. I will leave the tank and covers to the professionals though.

IW

[MikeKato]

Stev-O

The warning in your link is incorrect because they should fit right?

amazon warning: "This product does not fit your 1976 Honda CB750K"
 

[The other Derek]

From what I can tell, these are the right ones for my bike.

http://www.amazon.com/All-Balls-Steering-Bearing-22-1011/dp/B000GU3Y5C/ref=sr_1_1?s=automotive&ie=UTF8&qid=1357877674&sr=1-1&keywords=All%20Balls%2022-1011[/url&tag=vglnk-c1583-20

[Stev-o]

Stev-O

The warning in your link is incorrect because they should fit right?

amazon warning: "This product does not fit your 1976 Honda CB750K"
 

I believe that was for a 550 and should fit. But to avoid any confusion, link above has been changed.
Thanks for pointing it out, Mike.

[fastbroshi]

I don't think so, I thought the 750s' stems were a different diameter than the 550s?  The 550s have some oddball OD on the top bearing if I remember correctly, like 22.5mm.

[The other Derek]

Got everything that I'm having coated dropped off to the powdercoater last night.  His turn around time is going to be about a week.  I need to get moving on the engine cleanup, but it's just too cold out to be messing around in the garage for the next couple of days.  I got stuck working outside for a good chunk of the day and it was pretty chilly out.  Our weather monitor said 2° F when I rolled out of bed this morning. 

Looking forward to getting everything back and starting to get the bike back together.  I keep staring at the box of parts that's been slowly rolling in.  Soon.

[The other Derek]

It's been a bit since I've updated this.  At this point I'm still waiting on a couple of warm weekends to paint my engine.  I spent several nights scraping and degreasing in the garage trying to prep it for paint, but rolled it out into the sun last weekend only to realize that I wasn't making much progress.  It's getting closer now, but I've still got a little ways to go.  At this point it's pretty clean, but there is still quite a bit of flaking paint.  I've got some citrus stripper on it right now to try and wrap up the cleaning so I can spray bomb it when it finally gets warm.

I ordered new swingarm bushings from vintageCB750, but they were a bit loose, so my neighbor offered to make some for me at his shop.  It was pretty cool to be there while they were being made.  Also very cool to find out some history of the shop- back in the day they made parts for the GT40s to fit them to the drivers.  Apparently the head Ford at the time wanted to buy Ferarri and was denied so he became hell-bent on beating them.  Always fun to pick up a little history.

Anyway- here's a couple of pics of them getting made. 








I'm not all that happy with the durability of the powdercoating.  I've managed to chip it a couple of times already.  At the moment the frame and other PC'd parts are tucked away in the basement until I am ready to re-mount the engine and get it all back on the lift.  Hopefully I can get going on this in a few weeks.

[The other Derek]

I'm hoping to prime the engine tomorrow afternoon.  I spent the weekend knocking a few things off the honey-do list, but managed to get the engine washed and taped up.  The engine is getting painted with Duplicolor primer and ceramic paint.   

Spring has been really slow to arrive this year so I built a heat box for the motor so I can finally get it painted and keep it warm for the week necessary for the paint to dry.  I had to pick up a few 2x4s, thermostat and heat lamp, but the insulation, drywall and wiring were all scraps.  It took me a couple of hours to throw it together and it probably cost $25 for the materials I needed.  Definitely not the nicest looking ez-bake oven, but I'm hoping it'll help harden the paint a little better before I get the motor back in the frame.  I guess we'll see soon.

The box I built uses a 125W heat lamp and a water heater thermostat to keep it around 90 degrees.  It's only made it into the mid 80s so far, but I'm happy with that considering we'll likely be dipping into the 40s at night.  At this point snow is still a possibility.

Getting the engine cleaned up well enough to paint has been a long process.  I was hesitant to pull the covers off the motor so they've all gotten taped.  There were no oil leaks last year, and I've already blown the budget on this project.  I already had the blue tape, so it was an easy choice to not order gaskets.  Hopefully the cleaning process didn't damage any of the gaskets.

[The other Derek]

I put the last coat on the engine last night and rolled it back into the incubator. The thermostat has been adjusted to keep the temp between 87 and 93 degrees with the RH at about 16%.  Hopefully an ideal environment to cure that paint.  If I were to do this again, I'd likely tear the engine down and get the painted parts blasted.  Even while I was painting I found a couple of spots where I missed something.



I'm going to let the paint set up for a couple more days before I try to finish polishing the aluminum covers.  For polishing I'm using brown scotch-brite, synthetic steel wool (000 and 0000) and finally Mothers Mag Polish to shine up the aluminum.  Seems to work OK- I'm not getting a mirror finish, but I do kinda recognize the guy staring back at me.

The engine will hopefully be in the frame on Saturday- then I'll finally feel like I'm making some progress.

I wish I would have built the incubator a month ago.

[The other Derek]

Getting close.  Everything is pretty much back together.  Since my last post I've reassembled the bike, rebuilt the master cylinder, painted and wrapped the exhaust, and spent more money on parts.  I'll likely pick up the HM341's from David Silver when they become available again.

At this point I've just got to wait a few days to decal and clear the tank.  My attempts to repair the existing paint didn't go too well, so I opted to repaint everything and decided to go with silver with a K1 black stripe.  I picked up some new side covers so I can add the emblems.  I need to get that paint wrapped up in the next couple of days so I can let it cure a bit before clearing everything with the Spraymax 2k clear.

It's been a busy summer at work and I feel like I should have finished this months ago, but it's exciting to finally be getting close to done.  The busy summer has of course meant lots of overtime, so it's at least helping me pay for parts.

My wife got me ego camera for our anniversary, so I'm hoping to at least film my commute in a couple of weeks.

Oh, and I changed my screen name from Krinky.  Nothing fishy about the change- just sick of that word.  Not sure why I chose it in the first place.