Author Topic: Squeal on start up 78 750F2 -SOLVED (Read 3487 times)

MotoMartin · « **on:** May 24, 2009, 12:25:55 AM »

I have recently reassembled the top end after replacing an exhaust valve. Today is the second time the bike has made a high pitched squeal or squeaking sound on start up. Sounds like metal on metal, every other revolution of the motor, I'm not sure where the sound is coming from. Last week when it made the noise, I squirted engine oil through all the valve adjustment openings. The sound went away after kicking the bike over awhile with the ignition off. Then I rode it for about 5 miles and it seemed okay. I took a valve adjustment cap off while the bike was running and oil went everywhere, so it does not seem like an oil supply problem. I had not run the bike for a week and today it made the same squealing sound, again I squirted oil in to the cam, and kicked it over several times. I rode the bike for about 12 miles with out hearing the noise. Any ideas? Cam lubrication problem?Starter clutch? Clutch?Oil pump?

750goes · « **Reply #1 on:** May 24, 2009, 03:36:51 AM »

Just because oil is showing in one tappet cover does not mean it is circulating the whole area. I would think you possibly have an oil jet clogged....I hope not - because squealing is not good....

bwaller · « **Reply #2 on:** May 24, 2009, 03:43:17 AM »

Remove caps from both #1 & #4 and check for oil. Also try the long screwdriver trick (or a stethoscope) Place the blade of the screwdriver against different parts of the valve cover, etc. with your ear on the handle end to try to pinpoint where the squeal originates.

Was the top end well lubed on reasssemby? The oil restrictors were clear?

wrenchmuch · « **Reply #3 on:** May 24, 2009, 09:25:36 AM »

After a hard run I stopped at a light and the squealing started . Engine stalled as the squeal got louder but started after a couple minutes rest and got me home . I pulled the covers and looked for oil and saw oil in all 4 oil caps . I didn't trust what I was seeing though and started pulling apart my engine . Something had happened to starve oil from the #1+2 cam holder . The cam had heated up the bearings and almost closed the oil hole by wiping molten aluminum around the bearing as it spun . The damage was the worst next to the camchain but the outer bearing was damaged as well . Cam lobes and rockers were also bad indicating that the holder was probably not where the problem started . I'm betting the oil jet in the head was the problem but I used a different head when I rebuilt and the jet in my 71 head doesn't seem to come out . One day I will back flush it to see what it was . I hope this is not what is happening to you . If it is the longer you run it the worst the damage will be . I ended up doing a complete rebuild to make sure a the old 38 year old crap was out of the engine and oil tank and now after $4000.00 it runs sooo good

Still a little paranoid of oil starvation though .

MotoMartin · « **Reply #4 on:** May 24, 2009, 02:42:57 PM »

I pulled the valve covers, lots of oil #4 exhaust valve, none splashing out of #1.
I guess I'll have to take the motor out and check it out.

MotoMartin · « **Reply #5 on:** May 24, 2009, 07:55:23 PM »

Quote from: heffay on May 24, 2009, 06:40:23 PM

you pulled the valve cover or the valve tappet covers?

pull the valve cover and look at where the cam rides in its circular grooves on the outside ends... if you recently did the top end... that is first suspect.

I just took off the tappet covers, I have to take the motor out of the frame to get the valve cover off. That's got to be one of the biggest design flaws of all time. I have to get myself mentally prepared before taking the motor out again.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #6 on:** May 24, 2009, 09:57:13 PM »

Get one of Gordon's (Ilbikes) frame kits and install. Then you can leave the engine in to repair your top end.

MotoMartin · « **Reply #7 on:** May 25, 2009, 05:30:39 PM »

Quote from: 750goes on May 24, 2009, 03:36:51 AM

Just because oil is showing in one tappet cover does not mean it is circulating the whole area. I would think you possibly have an oil jet clogged....I hope not - because squealing is not good....

Oil jet / oil restrictors is that the same as oil control orifice (#6) in this link?
http://motorcitypowersports.com/fiche_section_detail.asp?section=125271&category=Motorcycles&make=Honda&year=1978&fveh=2986

Jerry Rxman Griffin aka MuthaF'er · « **Reply #8 on:** May 25, 2009, 06:04:10 PM »

MotoMartin · « **Reply #9 on:** May 26, 2009, 01:35:50 AM »

I took the motor out of the frame tonight. Much faster second time around, partly because the motor is cleaner and none of the bolts are seized. (What is annoying is not only do you have to take the motor out for a simple valve cover removal, but also the frame lug in the way makes removal way harder than it needs to be). As people have suggested the left side oil jet was blocked. A piece of metal from where the timing chain had rubbed away part of the valve cover was inside the jet orifice. The damage to the cam and cam caps is not too bad - light scoring on the cam caps discoloration on the cam. I am going to polish all of the surfaces, put it back together and see how it runs (it ran okay after I squirted oil into the valves previously). I'm not sure how or when the valve cover wear happened, I think at one point I had the bike idling with the chain tensioner slacked off to see if that was the source of the squeal. The timing chain area now has another opening into the breather cover, I'm thinking this may get too much oil into it which could be a problem, I wonder if a "metal putty" type product would be okay to fill the hole with?

martino1972 · « **Reply #10 on:** May 26, 2009, 01:49:12 AM »

how can the chain wear into the valve cover i wonder....you didn't by mistake install the cam sprocket on backwards..

? if you would have pictures of your top end etc. would be a great help......

fuzzybutt · « **Reply #11 on:** May 26, 2009, 02:02:54 AM »

Quote from: Jerry Griffin aka Rxman on May 24, 2009, 09:57:13 PM

Get one of Gordon's (Ilbikes) frame kits and install. Then you can leave the engine in to repair your top end.

+1,000,000!

i just finished pulling the top end of my motor off for the 3rd time in a month. thank goodness for the frame kit! before i had it i had to get the idiot son-in-law to help me pull the motor OR pull it myself and walk bent over for the next week or so. and an added plus, Ilbikes is a hell of a nice guy (even if you dont like kitties Gordon)

MotoMartin · « **Reply #12 on:** May 26, 2009, 02:15:36 PM »

Quote from: martino1972 on May 26, 2009, 01:49:12 AM

how can the chain wear into the valve cover i wonder....you didn't by mistake install the cam sprocket on backwards..? if you would have pictures of your top end etc. would be a great help......

After looking at the valve cover again today (that was about 1.30 am last night when I looked at it before). It has not been worn by the cam chain. The metal is really thin at that place and pushed through. I'm not sure what kind of pressure is at that point. I'll post pictures later.

MotoMartin · « **Reply #13 on:** May 27, 2009, 03:56:58 PM »

I've polished all the cam lobes and cam caps that got scuffed by the oil starvation, and removed the stray metal part from the oil jet. Used a epoxy metal stick to fix the hole inside the valve cover. Hopefully it'll be okay, looks alright, will soon find out.......
First I've got to get the motor back in and the damn air box back on.

Jerry Rxman Griffin aka MuthaF'er · « **Reply #14 on:** May 27, 2009, 05:32:04 PM »

Do you have the retainer washer/thrust washer on the end of the cam?

I believe I'd find a new valve cover rather than risk getting another piece of metal stuck in an oil orifice again.

MotoMartin · « **Reply #15 on:** May 27, 2009, 07:25:48 PM »

Quote from: Jerry Griffin aka Rxman on May 27, 2009, 05:32:04 PM

Do you have the retainer washer/thrust washer on the end of the cam?

I believe I'd find a new valve cover rather than risk getting another piece of metal stuck in an oil orifice again.

Yes I have the thick washer at the end of the cam, it wasn't that the cam chain hit the cover, just that the cover was really thin at that point and just disintegrated.

You could be right, if the epoxy metal fix comes unglued and falls back through the hole it'll make a big mess. However I do want to see what it runs like....

MotoMartin · « **Reply #16 on:** May 30, 2009, 11:56:05 AM »

Well, I put the motor back in the frame, started it up, still no oil at tappet cover #1, plenty of oil at #4. Obviously, I did not clear the oil jet. I figured that when I removed the metal fragment my job was done. What is the proper procedure (or quicky fix

) for cleaning out the oil jet? Hopefully it does not involve removing the head (new head gasket).

MotoMartin · « **Reply #17 on:** May 30, 2009, 03:53:09 PM »

Quote from: heffay on May 30, 2009, 02:09:36 PM

if its a brand new head gasket... you can probably reuse it... and yes, you'll probably have to remove the head as well... i'd go all the way down, because who knows where all the orifices are clogged?

The oil jet located in about a 3/16 diameter hole, I could not actually see it, is this something that you can run a guitar string through, or spray carb cleaner into?
It would suck to have to get a new head gasket, it has about 20 miles on this one.

martino1972 · « **Reply #18 on:** May 30, 2009, 03:55:11 PM »

with just 20 miles on the head gasket you can re-use your head gasket......but yes,you will have to remove the head to take that oiler out....not sure about yours but mine (cb650) has them between the cylinders and lower block....

MotoMartin · « **Reply #19 on:** May 30, 2009, 06:56:19 PM »

Quote from: martino1972 on May 30, 2009, 03:55:11 PM

with just 20 miles on the head gasket you can re-use your head gasket......

It seems like if the gasket gets up to operating temperature it sticks to the metal surfaces and peels apart once you pull the head from the cylinder. If it were a metal gasket it'd be okay but with the felt type who knows?

fuzzybutt · « **Reply #20 on:** May 30, 2009, 08:04:02 PM »

i had to replace my head and base gaskets after the motor running just a few minutes on the lift, enough to sizzle skin on the header but no warmer.

MotoMartin · « **Reply #21 on:** May 30, 2009, 10:41:17 PM »

Quote from: fuzzybutt on May 30, 2009, 08:04:02 PM

i had to replace my head and base gaskets after the motor running just a few minutes on the lift, enough to sizzle skin on the header but no warmer.

That's what I'm worried about, I want to just try and clean the jet out from the top.
(I have the motor out again, it took 2 1/2 hours on my own, whilst watching basketball play-offs and road racing, would have been under 2 hours but got the motor wedged sideways.)
I've pushed wire and guitar string through the orifice, I'll also spray a bit of carb cleaner down there and see if that fixes the problem......

CB750F2 · « **Reply #22 on:** May 31, 2009, 01:51:00 AM »

Moto, the orifice is in a removable holder so it is important to remove the holder so that it can be cleaned out properly. There may be foreign matter in behind that blocks the orifice as soon as the oil pressure builds up. While you have the holder out pour some clean oil down the hole, remove the oil passage plug on the RH side of the bike just above the points cover and see if oil runs out there. You should try and prove that the oil passage to the orifice is clear before re-assembly. Pat

MotoMartin · « **Reply #23 on:** May 31, 2009, 03:02:13 AM »

Thanks for the heads up, I was cleaning out the wrong passageways. I searched other threads and found a photo. I removed the aluminum jets and cleaned them out, the left side jet appeared to be blocked. Those are pretty small openings, clean oil for these bikes seems really important. Hopefully that was the problem. I'll start putting it back together tomorrow.
Thanks again for the info.

MotoMartin · « **Reply #24 on:** May 31, 2009, 09:31:07 PM »

I shoved the motor back in the frame today, started it up, pulled off the #1 tappet cover and ....oil, quite a lot of lovely, lovely, oil jumping out of the cover onto the floor. Hopefully any damage done to the cam/valve lifters was minimal, like I said I polished out the scuffing, we'll see....

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Author Topic: Squeal on start up 78 750F2 -SOLVED (Read 3487 times)

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