Author Topic: Well, it seems my bike is being a little bit of a drama queen, shifting, oil, sm  (Read 331 times)

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Offline LadyTano

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So I've been checking oil like clockwork since I bought my bike. I've put 1700 miles on her since I did new oil change right after buying. Odometer is 25,000.


So I checked oil last night. Thin, but no gas smell. Darker than I'd like, but I figure it's just old oil crap from previous owner.



Today, headed to work, she's not wanting to shift into first. Second is fine. Kinda weird, but ok.

At red light, it won't shift at all, oil light flashes. I push her to side. Give things a poke. And seems fine. Shifts great, etc.


Jump on freeway, I get.. half mile? Power just disappears, oil flashes once, engine sputters and stops.

So now I'm on side of road waiting on fam to lend a hand.

I pulled the oil dipstick. Smoking a bit (not a ton, but still.....).

Oil level -seems- fine. I'm hoping I'm just misreading the oil.


But anyone care to venture a guess?
Any/all info or input is very welcome.


Thanks!

*Crossed fingers I didn't cook the motor*

Offline bear

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I'm no expert on autos but at a guess the clutch plates may have failed and the friction material from the plates could  have blocked the oil pump.
Good luck with it.
« Last Edit: June 04, 2020, 04:16:44 pm by bear »
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Offline RAF122S

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Gas tank could be vapor locking due to cap not venting. Any number of issues. Going to have to be more descriptive in what it is doing now.
David- back in the desert SW!

Offline LadyTano

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Well, after a long day of wrenching and testing....


Engine seems to be seized. Starter just kinda whines, and I can't manually turn over the engine.

So.... Started tear down. Pipes removed, gastank pulled, spark plugs and such all pulled. Top cover removed (I thought those screws we're gonna break) but damn. All out.

As soon as I figure out parts needed, I'll order. And hit the other stuff she needs. New front pads (was gonna be this weekend's project), new sprockets/chain, rear fender, etc.

So, I'm thinking shipping times and such. She'll be down for a bit. But I'm luckily able to focus on her after work and weekends, so hopefully I'll have her running asap.


I keep seeing hondaman's book as recommended. Good buy I assume? Like I have the original service manual. But more info> less info.


Thanks yall! Pic added cause... Well. It's purdy (photographically speaking-its edited, not nearly that brown in real life).



Offline 754

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Does one end of head appear less oiled than the other ? If so it could be topend.
Maker of the WELDLESS 750 Frame Kit
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Kelowna B.C.       Canada

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Offline LadyTano

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754- sadly no.....


So I spent a good chunk of today with my Dad pulling apart, carefully organizing parts, etc.

It seems the #3 cylinder (2nd from right -riders right) the piston arm bearing in the crankshaft is seized.

The cylinder at a (non gauged) look look damn good. Polished, no burrs or weird spots. The #3 has a little staining?  But smooth, and clean. Surprisingly so. Pistons seem decent. Hell, rings too.

It was apparent the #3 was burning oil. The valves had scaly looking oily deposits on them.


So next I gotta pull the upper part of the clamshell (if that's the right word....) Of the motor/transmission to check for other damage.



So far, other than the seals all being shot (of course), and the one bearing. Things are surprisingly good condition.



I guess my question is. Having never done engine work, but being incredibly handy. I know I need a full seal kit. I know I should find someone to spec the pistons, the crankshaft, the cam shaft (I think that's the term, I'm bad with words -the upper shaft), and replace the pistol arm bearings, and main bearings.


Is there anything I should hit/get checked by a pro that I'm missing?

Or any suggestions for where to get the items spec-ed? I'd prefer reasonably local (detroit-ish) but I'll drive a couple hours of the person is good and fast.

Pics as soon as I can modify to fit.....

I'm good with a wrench and mechanically inclined. But I know there's a few things I should get a pro for help so I keep her running as long as possible.

🖤

Offline bear

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Have you had a chance to check if there is any contamination or blockage affecting either the oil pickup screen or the oil filter?

Cheers,
Brian
The older I get the faster I was.

Offline 754

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If the rod is seized , it usually is not to do with piston, it's lack of oil..
 Used cranks and rods are cheap, but you will usually have to fit new shell bearings.
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline LadyTano

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Bear- the filter looked pretty decent I think. Nothing seemed to be clogged in or around it. Other than the filter looking kinda beat- especially for being only 1,700 miles on it (I did K&N). I didn't see anything in the oil pickup screen. Or anything clogging.


754- So I did get everything pull down to the lowest level of the engine. I could see the pistons, rings, and the beginning of the crankshaft (the last seal is being a pain....) So not open all the way yet.
The #3 piston is very, very tight when moving/rocking  forward to back.  The others, move pretty freely. (Front to back of course).



So when I purchased, she had the tiniest of tick. Hardly noticeable, but on my list of to do's. It got noticably quieter the more I rode, and after I did oil, etc. I think it was a bearing going. Judging by the oil color when I did the first change, and the literally disintegrated filter.... I'm guessing the damage was already done. And any oil I did after buying was a bandaid at best.


I'm a little lost on bearing size to crankshaft wear. I read there's colors, but some advice said just do yellow... *Shrug*


I'm taking the camshaft, piston heads, cylinder block into a local place (my cousin recommended,-Detroit Iron) so get everything checked for the tolerances (I understand theory of this, but I'd rather a professional get the info so I don't mess it up). I'll be bringing the crankshaft in as soon as I have it pulled.


So is there a place y'all would recommend to get the seals, and parts in a quick (ish) manor? I want to replace every seal. I don't want to do this any time soon, and the seals have to be 43 years. I was do all fresh seals, and new bearings, piston rings if needed. I want to do this right, to have her last as long as possible.


Thank you all! I do very much appreciate everything you've tossed out. It's an amazing learning experience. If anyone happens to be Detroit (well surrounding area) and would be willing to help, I'll happily bribe with beer and bad jokes (and Irish music.... Radio, I can't play yet).

-Cassie
🖤

Offline LadyTano

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I had a friend and local a machinist check the bored, pistons, etc.

Here's what we got:

Bore expected: 61.01 mm
Bore actual: 61.0616 mm (2.404")

Piston expected: 60.965mm

"What can I get away with?"


Piston 1 actual: 60.9727mm
Piston 2 actual: 60.9649mm
Piston 3 actual: 60.92mm
Piston 4 actual: 60.92mm


He thinks new pistons at 61mm would be best if I wish to keep the bike and keep working well (and I do, so ...)


I found some new-aftermsrket pistons on eBay for $120 (ish) shipped, with rings. Good reviews, etc.



My only question at the moment is:


Will this work? It's for a K, but... I know a lot of the parts are the same.

https://www.ebay.com/itm/174138579061


Thanks!

Offline MauiK3

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#1. Hondaman’s book will answer most of your questions as well as steer you clear of expensive mistakes.
#2. Look at the oil pump screen, it may tell you something.
#3. Since you are this far in, don’t cut corners.
#4. Most machine shops that do car work cannot properly help with these motors, use one of the experts here on the forum. I used Mark Paris ( Hondaman) for my head and cylinders. Perfect work.
1973 CB 750 K3
2009 Ruckus!

Offline LadyTano

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1) that's the plan :)
2) as soon as I can see it I'll check. I'm wondering if it's blocked as well. It'd fit the old "sat a long time" kinda thing

3) imma trying. I found pistons that are right. I just don't want to wait for shipping from Japan.... During covid junk. But, if it's what's I gotta do ...

4)  so he's actually a machinist by trade. Motors are a side thing he enjoys. He knows a lot, but.... Not bikes so much. A lot of similar stuff between the two, but he did say to make sure I have solid info. He'd help, but it's beyond his area of expertise. .

I did just order a whole Athena seal kit, and am now ordering the book. :)
I thought I already ordered book, but I guess I didn't hit the pay part ...

Offline LadyTano

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-jist- a quick poke, but the book info doesn't mention the auto series.

I know a lot is applicable, but is it still worth it? I know he pistons are different, crankshaft, etc. *shrug*

Offline MauiK3

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The book will help you with the motor in general, things like the head and cylinders.
Well worth it.
1973 CB 750 K3
2009 Ruckus!

Offline 754

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 And the rest of the bikes, brakes, sprockets,  wheels, forks, electrics, carbs  , those sort of things.
   I think  the Clymer manuals that go to 1978 have auto info in them..
« Last Edit: June 10, 2020, 01:50:51 pm by 754 »
Maker of the WELDLESS 750 Frame Kit
dodogas99@gmail.com
Kelowna B.C.       Canada

My next bike will be a ..ANFOB.....

It's All part of the ADVENTURE...

73 836cc.. Green, had it for 3 decades!!
Lost quite a few CB 750's along the way

Offline Don R

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 I'm not big on shipping, but if you wanted to do a road trip I'd donate an A crankcase, trans and rotating assembly. Unknown condition but the price is right.  I removed the top end (head and Cylinders) for parts for another bike. I'm in Galesburg Illinois.
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