Author Topic: Splitting the cases on my CB750...first of many ?'s (Read 86800 times)

HondaMan · « **Reply #250 on:** March 07, 2010, 10:25:10 PM »

Quote from: twostrokecrazy on March 07, 2010, 07:36:11 PM

Quote from: HondaMan on March 07, 2010, 07:19:35 PM
Quote from: MCRider on March 07, 2010, 10:17:29 AM
HM. Interesting take on the 4th gear problem. He has a 76K, but still may have been shifting down to 4th a lot.

This is me...

Hmm, I took it as if you meant to lump the f's and the k's together. My bike did come standard with an 18t and was sort of doggish until I installed that 17t. Regardless, the po probably shifted it alot around fourth. It's got 41,000 miles on it, really clean and still has the yellow on the bolts. I'm guessing it's all highway miles.

The K5 and K6 suffered the most from the overgearing that appeared on the K2 first, because the K5 and K6 were so low on HP compared to the earlier bikes (typically only about 46-50 HP). At approximately 60 MPH, you could roll on the throttle and literally NOTHING would happen on those bikes if you were pushing a Vetter fairing. So, you had to drop a gear, pour it to it, then pick it up again in high at 80 MPH or so.

The "F" models had later cam openings, and this problem was even worse. They had the 630 chain with gearing almost as tall as the late "K" bikes, losing almost 3 HP in the final drive. We frequently swapped them to the 530 chains and sprockets with the 17T front and 48T rear to solve it.

There's lots of things that will improve the later K bikes: that's what that book is all about.

ron.cieri.313 · « **Reply #251 on:** March 08, 2010, 06:48:40 AM »

Yeah Matthew!

...I still have a leak and an electric gremblin (unrelated to splitting the cases)...the leak I believe is coming from behind the drive sprocket which probably means the countershaft oil seal which I understand I can attempt a fix without splitting again...which I may do cuz I might want to ride for awhile eventhough she slips.

BTW...I haven't been working on the 750 cuz i bought a '79 Honda XL250S for the trails in northern michigan....I'm defintely getting better at picking out good old ones...$650, all stock, very good shape...I'll post a pic...just put on new tires, new sprockets, valve adj....etc....trails riding is hoot.

...but!...mission not accomplished until the 750 rides totally like a champ again.

8 Track · « **Reply #252 on:** March 08, 2010, 02:31:59 PM »

Quote from: HondaMan on March 07, 2010, 10:25:10 PM

There's lots of things that will improve the later K bikes: that's what that book is all about.

Are you referring to the book you're writing here on soch, one tech tip at a time? Because I've been paying attention.

mystic_1 · « **Reply #253 on:** March 08, 2010, 02:41:54 PM »

Quote from: twostrokecrazy on March 08, 2010, 02:31:59 PM

Quote from: HondaMan on March 07, 2010, 10:25:10 PM

There's lots of things that will improve the later K bikes: that's what that book is all about.

Are you referring to the book you're writing here on soch, one tech tip at a time? Because I've been paying attention.

Nope, he's referring to his recently published "My CB750 Book" that you can get here:

http://forums.sohc4.net/index.php?topic=65293.msg716274#msg716274

mystic_1

8 Track · « **Reply #254 on:** March 08, 2010, 03:07:21 PM »

Ooooh, thank you!

nobody · « **Reply #255 on:** March 18, 2010, 08:05:02 PM »

OH YEAH! We're making progress!

Though, I am a bit concerned about one thing. Honda, while very wise in most areas, must have overlooked an obvious error with making three wires on one harness all the same color. I can't say for certain that I've got these wires connected to the wires that they were originally connected to. According to my diagram, they run from the AC generator (alternator?) to the rectifier. I'll be honest, I have no idea what the rectifier does. What possible repercussions could this have? How can I know for sure if they're connected correctly?

Excuse the lack of focus, camera died and I had to use my phone.

mystic_1 · « **Reply #256 on:** March 18, 2010, 09:07:14 PM »

Your alternator's stator coil has three sets of coils in it. Those coils are connected to the three yellow wires. It does not matter which yellow wire gets plugged into which yellow wire, it all comes out the same in the end.

The alternator produces alternating current (AC) like in your house. The rectifier turns this into direct current (DC) that your bike can use. The regulator than makes sure that the voltage stays at the proper level to run the bike and/or charge the battery.

mystic_1

nobody · « **Reply #257 on:** March 19, 2010, 07:22:38 AM »

I knew what the alternator did but not about the rectifier, good to know what function that bit serves. I thought from loooking at the diagram that maybe it didn't matter, they all seemed to intertwine, so it's good to know that I won't blow anything up when I try to start it. Thanks Mystic.

Now I just need to look over the bike and figure out what I need to get for it. Clutch, lower brake hose, 105 jets (going to switch back to the airbox, no more pods) are a few things I know of for sure. Hopefully she'll see some asphalt soon.

nobody · « **Reply #258 on:** May 07, 2010, 09:01:11 PM »

So I just finished my test run and I've got to say, I had forgotten how amazingly fun this bike was to ride! Overall, the ride went well... with one small snag. The bike shifts smoothly and runs great. I blasted around the neighborhood for a good five minutes, having tons of fun and being slightly reckless. On the final stretch I go wide open, smash it into second and hear this *KERPLUNK click click* then it just revs through the roof. At this point I'm thinking "oh bloody hell, you've got to be kidding me!". After about twenty seconds of fiddling I realise that something is missing... I threw my chain! The cases are fine save a couple small scratches, the chain was about a block behind me. I ended up pushing the bike the remaining two blocks home. HA!

I tell you though, I'm on cloud nine right now, I just need to get a new master link tomorrow. Oh, and I don't miss my pods at all, no flat spot = AWESOME!

nobody · « **Reply #259 on:** May 13, 2010, 08:50:50 AM »

So occasionally, when releasing the clutch from a dead stop, it makes this sort of creaking noise. It sounds like a door that needs to be oiled. It functions properly and the creak doesn't accompany any sort of noticeable malfunction, it's just a weird noise that I hear every here and there. Any ideas what that might be?

Other than that just about everything is good. I've got a K&N filter coming in, I'm hoping that will correct my slightly rich mixture. I also need a new battery, the one I have is noticeably fatigued when the temperature drops.

ron.cieri.313 · « **Reply #260 on:** May 13, 2010, 10:27:39 AM »

that creaking sound...that is my heart breaking

nobody · « **Reply #261 on:** May 13, 2010, 10:34:09 AM »

BAHAHAHAHAAHAHA... awwwwwwwwww, poor Ron, need a hug?

ron.cieri.313 · « **Reply #262 on:** May 13, 2010, 10:39:54 AM »

yes, always...but no offense, only u got a nice looking gf

steamnjn23 · « **Reply #263 on:** May 13, 2010, 12:47:51 PM »

clutch lever need lube?

mystic_1 · « **Reply #264 on:** May 13, 2010, 12:49:24 PM »

Quote from: steamnjn23 on May 13, 2010, 12:47:51 PM

clutch lever need lube?

I was just about to say that.

mystic_1

nobody · « **Reply #265 on:** May 13, 2010, 01:15:24 PM »

I don't believe so, the creaking sound comes from underneath me, somewhere in or on the engine.

mystic_1 · « **Reply #266 on:** May 13, 2010, 01:46:34 PM »

I'd pop the chrome cover off the clutch cover and work the clutch to see if you can determine where the creak is coming from. It may be the pivot where the lower end of the clutch cable meets the clutch lifter lever. Everything upstream of that in the clutch runs in an oil bath so shouldn't be creaking unless something is cracked or damaged somewhere.

mystic_1

ron.cieri.313 · « **Reply #267 on:** June 14, 2010, 06:18:49 AM »

Fyi...I'm at it again...starting stripping the bike to get to the engine. After looking over these notes I decided to follow some helpful advice in one of the earliest posts...."start from the top and work you way down"...it feels like 5 times easier to do this again....of course, most of the angst and fear of taking soooooooo many parts off is absent this time. Plus, I cleaned all bolts/nuts, etc during the first time which makes things way easier this time. The exhaust was still a pain but that's been really it...still have a bit work ahead of me (lower left side, then crash bars, then lift prep) and then need to enlist some help to pull her out.

I can't believe I'm doing this again but can't wait to see what i find this time...ttyl...ron.

nobody · « **Reply #268 on:** June 14, 2010, 08:56:09 AM »

Hey, nothing beats hands on experience right? Haha. I hope it's something easy to diagnose and repair. Good luck, Ron.

ron.cieri.313 · « **Reply #269 on:** June 14, 2010, 10:30:55 AM »

Thx Matt...I'm going to re-seal with velcro so its will be even easier the third time

nobody · « **Reply #270 on:** June 14, 2010, 01:26:47 PM »

Hahaha, you may encounter some difficulty with that idea but i wish you the best of luck.

HondaMan · « **Reply #271 on:** June 15, 2010, 07:11:33 PM »

Quote from: matthew gabrielse on May 13, 2010, 01:15:24 PM

I don't believe so, the creaking sound comes from underneath me, somewhere in or on the engine.

This might sound strange, but...runit a little while, like 500 miles or so, then change to synthetic oil like Mobil 1 (15w50 or 20w50 weight).

The squeak (I call it a "sqwak") often goes after the bike has been sitting for long periods of time. It's a sympathtic vibration between the clutch plates, primary chains, and a little bit of wear in the needle bearings inside the clutch hub, on the mainshaft. I've seen it (heard it?) many times on bikes going through "startup" after years of sitting. If the clutch hub has one loose rivet (fairly rare occurrence), it will tend to stay with the bike until a new hub is installed. Changing any one of the components can make it disappear, sometimes for good, sometimes for a while. I've also found that synthetic oils make it go away in about 100 miles or so.

It seems like a crust of old, burned oil may break loose (I'm guessing, here, at the cause) if the bike was sitting a long time, then it gets caught in those needle bearings. Then one or more of them does not turn with the others, and the vibration starts on the mainshaft, which is what you hear. The loads are greatest when pulling away in 1st or 2nd gear, while slipping the clutch, making it vibrate until the rollers all spin together.

You have a leftover clutch hub in that other "K" engine there: if it doesn't go away, you'll at least have another part on hand!

There is a different scenario that should not be confused with the "sqwak", and that's the "crack" sound. Gammaflat has this in his, and it happens on every shift. I think it might be a broken rivet(s) on the hub: he's about to dig into it and find out.

ron.cieri.313 · « **Reply #272 on:** June 15, 2010, 07:56:25 PM »

Well, bike is stripped for the second time and ready to push the engine out....might have to wait till next week till my help is available.

ron.cieri.313 · « **Reply #273 on:** June 25, 2010, 02:21:57 PM »

Okay, engine is now out for the second time...hope to have her split this weekend and see what's inside.

steamnjn23 · « **Reply #274 on:** June 25, 2010, 06:46:59 PM »

may you work with enlightenment and quickly discover the problem ...the open road is calling should i tell them to hold on?

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Author Topic: Splitting the cases on my CB750...first of many ?'s (Read 86800 times)