1981 CB750K - Repair/Tune-up

[TOOLS1]

You turn the screws in untill the RPM drops. Then back them out until the RPM goes up to it's fastest point. That is where, you set them. If the idle is too high, then back off the main idle adjuster. The same with syncing the carbs. After they are synced, adjust the main idle adjuster again if needed.
TOOLS

[cdaiscool]

TOOLS, that's exactly what I needed.

Man, at this point, I should just fly you out here to work all the kinks out of my bike. I seriously appreciate everything you've done for me.

I know I keep saying this, but I can't really express how much you've helped. Make sure you don't give me your number. Your costs would go up exponentially.

[TOOLS1]

you-can-doit
TOOLS

[shinyribs]

No need to post that number. It'll be a waste of his time.

[TOOLS1]

I heard they had really good tec support there.
TOOLS

[shinyribs]

Yeah,but no one listensI can always forward him to Kansas City Motorcycle Emporium!

[cdaiscool]

Awww, you gone and did it....


BRB, phone's still in garage.

[cdaiscool]

ROFL.

I have the original phone number from e-mail. Google tells me the original 540 number is Roanoke, VA. No wonder why Shiny freaked out.




Calling the OTHER number. Storing the first one.

[shinyribs]

Naw,not freaked out. Feel free to call anytime...I'd be glad to lead you astray.

[cdaiscool]

Excellent!


I just need to figure out this sudden high idle. While I was doing the vacuum sync, it suddenly started to idle HIGH. I'm thinking it's due to issues with #2 cylinder. As TOOLS told me on the phone, that cylinder seems to have issues. Which sucks, since all other cylinders are adjusted to that one.

The motor got way too hot. Even 20 minutes later, she's still sizzling any water put on 'er.

[shinyribs]

Dang.That is hot. Keep your fan on her and mist it lightly with your hose.

[cdaiscool]

I ain't got a fan. :/

I think a big issue was the fact the pilot screws are so far in. I'm done trying to adjust 'em. I'm just going to put 'em all to 1.5 - 1.75 from tight, and keep the idle around 1100. Then I'll do another vacuum sync, get 'em close, and just go with it.

Sprocket cover is done, just need to adjust the rear brake and that entire thing will be done. Then it'll just be finishing up putting everything on and go for a ride.

Oh, and show 'er running once more. With the surprise on it.

[cdaiscool]

Here. Something shiny to keep you occupied.

[cdaiscool]

Arghh. It WAS running so smooth n nice! Now... not so much.

AND, AND, I broke the vacuum gauge thingamabobber. I tried taking out the tube when it was warm still apparently. The bottom screwed out from the top. So I took vice grips to get it out, since I couldn't grab it. But now the threads are shot. :/

Need to know where to get either the brass tube, or the nipple that goes between it and the motor.

Current plan of action: readjust all pilot screws to 1.75 turns from hard in. Start engine. Adjust idle to 1100 - 1200 rpm since that's its sweet spot. Shut off. Put in 3 vacuum tubes. Start engine. See if any are way off. Test throttle. If not, then adjust the 4th one so it revs nicely. Once it revs nicely, STOP.

Put all stuff away. Cut hose. Put in fuel filter. Put on tank. Put on surprise. Put on seat. Start it, test some more. Check oil. Take video of bike. Take off center stand. Ride off into the sunset.

Find hot chick. Throw her on back of bike. Ride to nearest motel. Make babies, without the creation part. Ride home. Wonder how the hell I'm going to pack everything by tomorrow.

[cdaiscool]

Okay. So, I think I got it.

A lot of people said their pilot jets do best around 1.75. Stock starting says 1.5 for starting 'em. Since I've had nothing but issues, I said SCREW IT and did it my way. I did 1.5 + a tweak for roughly 1.63. Roughly.

I then fired 'er up, and started tuning the throttle adjustments by ear. I got 'em all pretty close, then messed with the idle adjuster, got her up a bit, dropped idle down by adjustments, checked my rev. If it still bogged, then I raised idle again, got my throttle adjustments set so it was around 1k for all, and then checked again.

Watch my video for more explanation. Once it's uploaded, that is. I'll make another post as to how she is.

Now it's time to start buttoning 'er up. First up: finding what I did with my fuel filter.

[cdaiscool]

Arghh. I can't find the fuel filter I bought, and can't get another one because my dad was supposed to be  here 45 minutes ago... he needs some help quick.

Screw it, I'm getting one. In the meantime...

[TOOLS1]

Glad, you got it going. However, you better send me those vice grips, and any crescent wrenches, you have, so I can dispose of them properly. You can get replacement fittings from Z1 Enterprises.
TOOLS

[shinyribs]

"twenty minutes later I was still sizzling water from rain coming down...and spit..." You should be in public speaking! HAAAHAHA! I cracked up over that one. I dig your videos,but agree with Tools.Relinquish your adjustable wrenches at once

[cdaiscool]

How else was I to get the nipple out? I told my dad what happened, he agreed. I'm keeping my vice grips.

Meanwhile, just got back from a 55-mile ride. Dude. The bike... it's SO much better.

9k rpm? Check. Enough power to lift the front wheel? I think so. NOT trying that one. 70 mph in THIRD? Easy. Outgunning my dad's '87 Gold Wing though cylinder 2's got issues? Difficult, and he was reeling me in, but he was doing 90 when he passed me and I'd already shut it down several seconds earlier...

Did I mention it's a new bike now? In other news, she bogs down at lower speeds, especially lower RPMs. I suspect this is due to the new gearing being a bit harder, AND the nonexistent carb tuning in the pilot jets... I think I am going to find a professional to do it for me. Maybe see if someone from SOHC can recommend a shop in Ann Arbor for me to take the bike to...

[TOOLS1]

"How else was I to get the nipple out?"
Wait, for it cool off, the screw it out with your finger. I leave the hoses on mine, and screw them out with the hoses.
TOOLS