Topic: :( oil coming from #1 4 days old. cb750k8, poor acceleration on highway.

[turin39789]

Bringing this thread back from the dead. 

Finally admitted that I don't have the time to learn and work on this so its at a shop.  I don't really have the money either, but thankfully I know a new shop owner through some friends who is helping me out, though I may still have to postpone while I rob a bank.

I'm supposed to try to find time on saturday to go look at it with him, but so far during the phone conversation that I tried not to listen to, the little bit I retained was the oil was coming from the valve seal and that his scope camera is showing #1 is gone to hell, something, something missing rocker arm.

[turin39789]

750 rockers


750 rockers

[Jerry Rxman Griffin aka MuthaF'er]

Wow! I haven't seen rocker wear like that before. What are the possible causes? VERY poorly calibrated valve clearances? VERY poor oil circulation on that side of the head? VERY high miles on that side of the head?

[mystic_1]

Holy sh*t!

I'm thinking blocked oil orifice.

mystic_1

[turin39789]

Holy sh*t!

I'm thinking blocked oil orifice.

mystic_1

Thats where I'm leaning too, it stopped getting oil but I'm still not sure. Wanted to get the pics up here and get some ideas. 

cam lobe is gone too, iirc.  I stopped by the shop, saw it and sighed. 

got replacements to get put in, think I'm going to go stock and get a port and polish and get back on the road.

[scondon]

Damn, I can't stop staring at those pics turin. I've never seen rocker paddle wear like that before

  I don't know what your mechanic has done before those shots were taken, but from the pics I can see that the #1 bearing cap has a bolt pulling out and has been the most oil starved of the lot. Mine did this and there was some horrible screeching involved as the tower and cam were eating each other.Bike still ran, but had lost all power. I can't see how this engine could get in the state it is without some obvious warning signals, so I hope you were given full details upon purchase, or at least the "known" details and not the "ran well when parked" variety.

   One tappet adjuster is missing completely and it appears that the remaining three on that side are adjusted much further in than those on the good side, which leads me to believe that wear has been present for a long time. At least long enough for valve adjustments to be made in compensation for cam lobe and rocker paddle wear. Of course, it could just be the angle of the pics taken making it appear that way so just take this as "thinking out loud", and not any real diagnosis.

    The bit about oil pissing all over your leg makes me think that the cam tower was coming loose and all the oil pressure on that side was being directed underneath the tower and over the pucks. I would be sure to check the aluminum threads in your replacement head and helicoil where necessary.

    In my case, the good news was that pistons, bore and the rest of my engine were OK.

[turin39789]

from one of my other threads along the way -

I Bought the bike as the perfect ready to go brakes already upgraded finally gonna go faster than my 550 dream machine.  PO had ridden her a lot and was moving, says he put her up for the season and was now moving.  Seemed to run fine on my  short neighborhood test drive and then 2 days into ownership developed an oil leak between(i think) #1 and #2 about 1-2 fins down from the top, tops out at about 60-65mph.

So no, PO didn't give me a clue and I learned that I should run it by a mechanic next time, didn't have one I trusted before but finally found one or two good local ones.  I suppose my learn as you go mechanics education isn't always up to snuff.

I think he said the cam tower was loose when he got it open.  Got a full set of top end and valves(don't need them) used from a local honda guy. mech is going to go over the surfaces of everything to make sure they are in good shape, and I'm having him take the head to the shop next door to see what some headwork will run.  Can't afford to get big money into the bike, but since the engine is out and apart I figure I can at least do some headwork and keep the rest stock.

At least thats the decision I came to from this thread - http://forums.sohc4.net/index.php?topic=45442.15

[mystic_1]

Replace your cam chain tensioner gear while you're in there.

Also, clean thoroughly... all that metal went SOMEWHERE of course.  Might I suggest that it may be wise to pull open the bottom end if for no other reason than to clean everything before reassembly?

mystic_1

[Spanner 1]

Isn't the head ( valves and cam. and rockers ) ONE chamber...why would one side be starved of lubrication and not the other?? Any opinions ?

[turin39789]

Replace your cam chain tensioner gear while you're in there.

Also, clean thoroughly... all that metal went SOMEWHERE of course.  Might I suggest that it may be wise to pull open the bottom end if for no other reason than to clean everything before reassembly?

mystic_1

was hoping to avoid cracking the case

[Hush]

Dude that is one horror pic, I really feel for you as a new owner, that really sucks man!
Fix it stock, and as Mystic said, while the top is off might as well do the cam chain and tensioner, you will kick yourself if you have to dive back in and redo that and it will be one thing you wont have to worry about for a long long time.
By removing the oil sump and filter you should be able to flush out most of that excess metal fragments.
Flush, clean oil strainer, replace oil filter and oil....that's the least I would do.

[mystic_1]

Can't do the camchain without splitting cases, unfortunately, unless you go with a master link chain and that's just one more thing to worry about.

Flushing the motor may work but if it were me I'd just take the couple of days it would take to pop the cases apart and hose everything down from the inside.  There are an infinite number of places in these motors for crap to get stuck, and you KNOW there are a ton of wee steel particles floating around down there.  Steel powder + transmission roller bearing = bad.

If you clean all the crap now, you'll save a ton of wear on your crank and rod bearings, transmission, NEW cam surfaces, NEW rockers, etc.  You shouldn't have to replace much when you get inside, unless you find badness, get tempted to do upgrades, paint the cases etc.  Just pull it apart, clean, and reassemble.  You're into it this far already.

mystic_1

[TwoTired]

Isn't the head ( valves and cam. and rockers ) ONE chamber...why would one side be starved of lubrication and not the other?? Any opinions ?

Check the oiling diagram on page 26 of the 750 shop manual.  There is a right oil supply to the top end, and a left oil supply to the top end.  I believe these passages also have an oil restrictor in order to keep the mains pressure up.  For this engine in this thread, I would check that restrictor for blockage.  If it doesn't flow freely, you'll get the same damage again with the replacement parts.

Cheers,

[Old Scrambler]

Similar engine here........I bought a titled and running bike (two cylinders) for $100 for a cafe project.  The top end looked very similar with one added feature.......the cam was broken between the #2 bearing and the cam-drive.  The problem was an epoxy lump from a broken case repair. The right-side oil journal was plugged.

Yes, clean the internals and inspect the bearings....all of them.  Those rockers probably chipped as they wore down.

[WHALEMAN]

I would be shocked if the main and rod bearings were OK. If you pull the oil filter and find it relatively clean that would tell me that the PO knew something was wrong and had changed it. If it is full of steel a case could be made he did not know. I think splitting the cases is called for after seeing those photos. While I agree with the arguments about not going back to the seller for normal wear or a hidden problem I don't feel that this fits the normal wear or problem situation. This look to me like fraud. dan

[turin39789]

I would be shocked if the main and rod bearings were OK. If you pull the oil filter and find it relatively clean that would tell me that the PO knew something was wrong and had changed it. If it is full of steel a case could be made he did not know. I think splitting the cases is called for after seeing those photos. While I agree with the arguments about not going back to the seller for normal wear or a hidden problem I don't feel that this fits the normal wear or problem situation. This look to me like fraud. dan

It might have been, but that ship has sailed.  Bought the bike almost a year ago, went through denial for a bit and then wanted to learn on it myself, finally admitted that I don't have the time and found a nice shop.

[Jerry Rxman Griffin aka MuthaF'er]

At the VERY least pull the oil pan.

[turboguzzi]

dont feel too bad, got a friend that had an ebay CB750 cafe job shipped across the ocean and when it arrived, it run for exactly 50 miles before a serious top end oil starvation problem showed up. Engine out, all the top end had to be re-done

And yet, he couldn't test ride the bike and took a risk, but it begs to be asked, did you have a spin on the bike before shelling out the money?

A destroyed rocker as yours should make some very serious clatter even at idle.

With the amount of metal powder you had sloshing about there for a while, I would seriously consider an engine swap.
If any got into the oil pump, most chances are that big ends got starved/slashed too at which point I would leave that engine alone.

Sorry that you had such a nasty introduction into bikes.....

TG