Top end oiling issue

[Larry D]

It's a sad, sad story but, let's start with a couple pictures. This ladies and gentleman is the #1 intake cam lobe on my bike. Dry as a bone.....kinda greasy actually.

So is this......

My bike had been running ...funny for the last 3 or 4 rides. Last night it started ticking. At first I thought it was the tach gear making noise. The warmer the engine got the louder the ticking became. I soon realized that it was a valve making the racket. I nursed it the rest of the way home but about 200 ft from my driveway there was a loud squeal and the engine shut down........I was going about 10-15 mph in 1st gear.

I coasted in my driveway and into the garage. I said my thanks to my bike for getting me home and then began to wonder the in the world happened.

Today I removed the valve cover and discovered the dry intake lobe. The rest seemed in good condition and well oiled. I dropped the oil pan and found nothing to indicate further damage. I can turn the engine over with the 19mm ignition bolt as easy as ever.

I have a diagram of the oiling passages from the manual on Cliff's site. I guess my question is......What now ? Should I try to wash down that passageway ? Is there a top-end oiling kits for the 16 valve 750's as there is for the 1100's ?

I'm at a loss for my next move.

 

[reddirtrider]

You don't have an oil pressure problem, you have an oil delivery problem. In other words, you don't need a top end kit, you need to find out why there is no oil at all delivered to that cam.

The second issue is that the cam looks to be in no condition to be reused, and probably worse yet, the cam journals are probably worn from a lack of oil. There are no bearings associated with those journals, so my guess is you'll need a new head. I could be wrong - let's hope so.

 

[Larry D]

I just went out and turned the cam shaft over and felt the lobe.

It feels smooth to the touch. No scoring that I could feel. The picture is somewhat deceiving I think. I'm hoping it shut itself down before much, if any, damage was done.........foolish?

 

[Griffin]

I've got a spare set of cams you can have if you need them, Larry.

I agree with Steve. I'm worried about your journals too. We need to remove the cams and have a look see at what's under there.

I know Rob at Cycle Recycle has a 16 valve 750 engine int he back room. He'd probably be pretty reasonable about selling the head to me, since I'm one of his "regulars", and he's even started to let me have some little things for free.

 

[rapidray]

Larry, call me at 714-356-7845 & I will go through some things with you & see if we can get this worked out. I'll be glad to help you. Ray.

 

[Nessism]

Sorry for the problem Larry. If it were my bike I'd pull the top end and check the oil passages, you obviously have an obstruction.

 

[TheCafeKid]

Eh... Id be more worried about OTHER things than the cams or journals. You'd probably have been best served to shut that thing down when you started noticing the problem. I hope, really i do, that the cams are the only thing at fault, but, unfortunately, this is a relatively common problem on that motor, and usually, the cams are accompanied by crank bearings. The ticking may or may not have been your valves, but *I* would suggest the entire top end come apart and be inspected before you sink any real money into it. There is obviously a delivery problem, in which case a tear down to clean out whatever clogged ports would be a good idea anyway. Cant hurt to check that you havent shelled a conrod bearing or others... Just my .02 tho, someone here im sure will pipe up and tell me i dont know what im talking about...But there is a 750 motor on my bench that looks an awfull lot like that, and it IS toast. Not my doing, but i started poking just out of curiousity.

 

[67fire]

Wouldn't the biggest problem be the one that caused this?
What could have possibly obstructed the oil flow in the first place?
Ray, anyone else with experience with this dilemma?

Eric

 

[TheCafeKid]

Wouldn't the biggest problem be the one that caused this?
What could have possibly obstructed the oil flow in the first place?
Ray, anyone else with experience with this dilemma?

Eric

Dirty. Dirty oil, crap in the oiling system, whether or not it was drawn in under THIS owners possesion. The dirt builds up, like a blood clot. Sometimes it comes loose, up an oil port, gets stuck somewheres...thats all it takes on that motor. Brett, myself and others have often debated what causes this problem, alot of people, brett and myself included, believe it to be the small ports. They are pretty tiny, and it would only take a little bit of dirty crap to clog one or more up. Unlike the roller bearing bikes whith their low pressure high volume system that can survive on what seems like next to NO oil (I think Ray said the drag guys run like a half quart or something to that effect, or he's seen it happen anyway) the plain bearing bikes will GRENADE if the oil level, pressure, drops below the necessary level to keep the bearings and what not in good lube. Like I said, this is not the first, fifth or maybe even the 10th 80-82 750 motor ive seen on here and in person take its last bow. Sad but true, those motors are delicate like a daisy. This isnt to say that this is somehow Larry's fault or anything of the like. If one was to purchase one of these bikes, I would suggest pulling the sump pan straight away, cleaning it, maybe even running seafoam thru the cases, anything you can think to safely do to remove and build up that might be lurking in there. Larry may have been religious with his oil changes, and maintainence, but the PO may not have been, and, just like a blood clot....one day you're all good, the next you wake up dead...

 

[Larry D]

Thanks for the replys guys. I may take you up on the camshafts Brett. If I end up needing them. Nice talking to you Ray and congrats on the new purchase !! You're absolutely right Josh, I should've shut it down when I heard the ticking noise. I'm still mad at myself about that one......

I'm sleeping in tomorrow because it's been a long week at work punctuated by my bike breaking down. Then I'm having lunch with my daughter. So, I may get to it tomorrow evening.

I'm somewhere between removing the clutch and spinning the oil pump to see if oil is actually getting anywhere near that lobe. Or removing the top end and cleaning it all out.....Maybe I'll end up doing both. Right now, I'm tired and going to bed. What a week..........

 

[67fire]

Thanks for the intel TCK! I have one of those that I have yet to do anything with. An '82 or '83 that was given to me.

Eric

 

[GregT]

When these motors were new our local importer put out a service bulletin advising to fit 2 x 6mm spring washers under the relief valve spring.
This will of course raise the oil pressure - these first plain bearing motors certainly could use more pressure.

Greg T

 

[TheCafeKid]

Thanks for the intel TCK! I have one of those that I have yet to do anything with. An '82 or '83 that was given to me.

Eric

'83 (unless its from a 750T) is an entirely different motor. A complete redesign and ive not really read anything such as this being a problem with THOSE motors..

 

[Griffin]

'83 (unless its from a 750T) is an entirely different motor. A complete redesign and ive not really read anything such as this being a problem with THOSE motors..

Only when they're hopped up to 110 bhp at the crank by Pops Yoshimura and run at redline for thirty minutes at a time...

 

[67fire]

I'll have to check the title as for year, the steering head was badly burned and no tag. It has the front half of the tank painted red and the knee indents are white.
I think that I found the place to find out how to make it live again!

Eric

 

[headsbikesmopars]

Larry D, sorry about your situation with your bike. My son has a 1981 GS750E 16 valve motor, when he picked up used , it had 27000 on it. It also had a ticking under the valve cover. It had the same oiling issue, oil starvation at the number 1 journals, int. and exh. Both cams were trashed and so was the head. It ran but wouldn't rev above 4000. I replaced the head (used) did some port work while it was down and did a radius valve job and back cut the stock valves. The flow numbers are 75 cfm @ .350 lift. These are in the GS1100 16 valve range. Not bad for a 750. Took .010 off the head, new valve seals. We went with stock GS1100 cams , they are a drop in deal, and a give a good hp pick up with the head work. They were free I had them on the shelf. We replaced all the rod and main bearings the rods and the crank were in excellent shape. Cylinders only had .001 taper in the bore. We honed the bores, installed new rings std. bore size. (OEM). Cleaned out all the oil galleys, flushed and cleaned the cases, new oil pump, new cam chain, and a complete gasket set. With all the new parts including the cost of the used head, we have around $600.00 in this engine, doing all the work ourselves. Suzuki rated this engine @ 79 hp. With the head work along with the cams and V&H 4 into 1, I would put this one in the low 90 hp range 90-92 maybe. I know it is one of the hardest pulling 750's I have ever ridden. Larry,...we had to rebuild the engine so we just looked at it as an opportunilty to make the changes he wanted to make while it was down. You might not choose to or need to go thru the whole rebuild thing. Anyway..good luck on your bike Larry.

Terry

 

[Larry D]

Cleaned it up some.

Pulled the carbs and removed the cam chain tensioner. Moved the camshaft out of the way and had a look. Here's what I found. Again it's the #1 intake and that camshaft end. Not good.....

In the last the last pic you can see the tiny port where oil is supossed to come out below the cam lobe. I took a small wire and did some probing. It feels like the hollow rod has a slot below that hole to let the oil pass. Didn't feel obstructed.....

Seems a new camshaft is in order. Do they need to be replaced in pairs ? Also, anything I can do about the scoring on the camshaft end journal ?

It appears my riding is done for awhile....

 

[almarconi]

Hey Larry, Sorry to hear about your bike. Maybe would be a good opportunity to replace the 750 with an 1100. Probably cheaper than rebuilding the engine you have.

 

[Larry D]

This would be a good opportunity to replace the 750 with an 1100. Probably cheaper than rebuilding the one you have.

Bwringer and I discussed that last night. Just want to get down to brass tacks and see what else....if anything.... I could do.

At this point I'm at the proverbial crossroads. I have revived this particular bike and would hate to abandon it. Swapping an 1100 engine in there is an option. The other is finding another '80-'82 750 engine or at least the top end, and replace that.

It doesn't appear to me to be a repair, replacement seems the only option to ride this bike again. Don't really want to part it out and get another bike but, I suposse, that's an option as well.

 

[TheCafeKid]

Bwringer and I discussed that last night. Just want to get down to brass tacks and see what else....if anything.... I could do.

At this point I'm at the proverbial crossroads. I have revived this particular bike and would hate to abandon it. Swapping an 1100 engine in there is an option. The other is finding another '80-'82 750 engine or at least the top end, and replace that.

It doesn't appear to me to be a repair, replacement seems the only option to ride this bike again. Don't really want to part it out and get another bike but, I suposse, that's an option as well.

Larry, If you want another motor to use for parts, or it might even be good to go itself (I have not checked it out) MRiddle has a 80-82 750 motor sitting in my garage that is a spare. He may be willing to get rid of it fairly cheap. I also have a motor, but its more or less suffered the same fate, so I couldnt in good consience sell it, but if you simply WANTED it, i would toss it to you for coming to get it...