Bike oil light came on - shut down

[1983lux]

just when I thought I'd finally get to enjoy riding this thing!

some background in case it's related:

So I had noticed a leak around the valve cover after about a 6 hour ride. stupidly tried tightening the valve cover bolts to make sure it wasn't loose and snapped one. took it apart to try using an extractor to get it out but couldn't really get my drill to go straight. I loosened off my cam carrier bolts thinking I could get some more room, but it seemed like it was under tension from the valves and wouldn't come off easy so I just tightened them back on. put valve cover back on with a wedge between the crash bar and broken bolt to keep it tight to the valve cover.

started bike up and could see no major leaks. thought I should test ride to make sure valve cover wasn't leaking too bad so I could take it to a shop that might be able to get the broken bolt out. Bike started and ran fine, sounded normal. after going a couple miles, the oil light came on for a few seconds, I downshifted to pull over and the bike just kinda lurched and stalled. coasted to a stop and pulled over. after this point if I hit the starter button, it would just make a noise like it's trying to start but wouldn't turn over. oil was about halfway up the sight glass with bike level at this point.

battery is a week old and seems to have lots of juice.

Anyway, hoping to get some suggestions for diagnostics to figure out whether this is fixable and if my engine is totally screwed or not. I've already swapped the engine in this thing once!

Thanks for any help! sorry if writing is poor as I'm a bit flustered about the whole thing, haha

[flyin900]

Loosening off the cam carrier bolts may have allowed some movement in there that has caused an issue. The cam would be under tension from the belt and possibly hasn't seated with proper clearance in the carrier.

See what others suggest. It may be worth pulling the cam and carrier and belt assy on that side to see what is happening in there.

[Track T 2411]

Loosening off the cam carrier bolts may have allowed some movement in there that has caused an issue. The cam would be under tension from the belt and possibly hasn't seated with proper clearance in the carrier.

See what others suggest. It may be worth pulling the cam and carrier and belt assy on that side to see what is happening in there.

+1 If it were me, I would remove the valve cover and timing belt and give everything a very thorough inspection, looking carefully for any cracks along the cam carrier. Then loosen all of the rocker adjusting screws on that side so there is/will be no valve opening, and you should be able to turn the cam by hand. You can also turn over the engine by hand at this point. From there it would be removing and inspecting the cam carrier and cam, inspection, then reassemble if appropriate...

[1983lux]

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Yep, I guess loosening your cam carrier while it's under tension is a bad idea. i forgot they cant be removed without taking out the bolt behind the cam pulley. once I took off the timing belt to the head in question (left side), the engine would spin freely by hand. it was locked up tight before that. I got the camshaft off after having to go get a gear puller for the pulley which was on tight. the front journal for the camshaft is gnarled up a bit, with some wear on the camshaft itself and the carrier in the same spot. not sure if reassembling properly will allow this shaft to operate still or if a full head replacement is required. At least I can get at that broken cover bolt better now, haha. photos are upside down.

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7

[flyin900]

I would replace the head and cam and carrier with one complete head assembly. They are pretty reasonable parts wise to find and not too expensive and a member on here may have one for sale. That journal and cam surface is chewed up and it’s not worth messing with IMO to try and get it serviceable again.

[pidjones]

I would replace the head and cam and carrier with one complete head assembly. They are pretty reasonable parts wise to find and not too expensive and a member on here may have one for sale. That journal and cam surface is chewed up and it’s not worth messing with IMO to try and get it serviceable again.

I agree. I'd offer a spare '79 head if it is of any help. I'm afraid the cam is a bit rusty, but the bearing journals were protected by oil. You would need another '75 cam to match the other side, anyway.

[1983lux]

Thanks for the help, guys. No worries Pidjones, I've still got a head from the original 1975 motor that should be good. I swapped its cam to the 79 motor when I rebuilt and installed my 75 carbs rather than swap the whole head to save the head gasket. while my 75 cam is now discolored, it seems to be smooth still, it seems to be of harder material than the head and carrier and I wonder if it might still be okay. I'll try to find a new one regardless just in case.

In the meantime, I had to put the bike back together as the only shop I have access to is the one at work and I can't leave it in pieces there through the week. motor turns freely by hand now. I tried starting it up to see what will happen (dumb idea?), but the starter just clicks. Battery load tester says 12.6v at battery and 10.9 under test load. I wonder if trying to start the bike a few times while the cam was seized up might have burnt out the starter. will hopefully get my hands on a volt meter tomorrow. can a burnt out starter still be fixed by the take apart and clean it up method or would it just be toast?

[pidjones]

To eliminate a large chunk of electrical connections and parts, try connecting (carefully) an automotive jumper cable to you positive battery post and tapping the starter motor connector with it. Make sure it is out of gear, wear safety glasses, be expecting sparks and the starter running, don't do it in an area with flamables. If the starter turns the engine over, start pulling apart and cleaning connections (starter solenoid contacts fail over time). If it doesn't, you need to check the battery and starter. Also check your 30 amp fuse although it is not inline for the starter.

[1983lux]

Starter is definitely getting full power, but will not turn. Either needs rebuild or replacement I guess, might've been the stress of trying to start the stuck motor. Got the bike going by rolling down a hill and popping the clutch. I wanted to see if I could figure out how bad the damage is despite the risk of making it worse. Really sounds awful, maybe the cam binding up at highway speed was enough to damage more than the head/valves? It sounds an awful lot like my last engine did when I blew a conrod bearing, although that engine still ran fine despite the noise. I can barely keep this one running despite the choke being pulled out, and it backfires pretty often. I'd be very happy if its only bent valves and a matter of replacing that head, but I suppose if pistons hit valves while my cam was stuck I've probably ruined the pistons too? See what you think and have a listen. Sorry for the bad selfie video, was desperate to capture the noise before it stalled. The noise does seem to be coming from the left head. https://m.youtube.com/watch?feature=you ... B0QaSMc2rA

At this point I've obviously got to swap out that left head, cam and valves, but I'm wondering how I can figure out whether the whole engine block needs to be replaced/rebuilt. This is turning out to be a very costly mistake! Maybe I should get out of the DIY bike repair business haha.

[flyin900]

Pull that head and see what is going on with the piston faces and valves on that side. If there is more damage to the pistons too then maybe a used motor is in your future. They are cheap enough up this way, yet maybe not as plentiful and cheap down there where your located.

[1983lux]

Hmmm I'm a bit confused. Before disassembling any further I double checked my timing belts. definitely lined up correctly. I removed the head but am not seeing any major damage as far as I can tell. How can I tell if the valves are bent at all? No idea what could cause it to sound and run like it did.

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[1983lux]

Upon further investigation, I rotated the camshaft on the left head which I removed. The intake valves should totally seat and form a seal at some point in the rotation, right? Carefully observing the head, they never seem to fully close at any point, although the exhaust valves do. There seems to be a point in the rotation where all the valves lay pretty much flat, but here's how the intake valves look at their lowest point:

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[Track T 2411]

That would be the problem... A very close inspection of the piston top and valve face might show signs of a 'kiss' but if it happened at a low RPM there might not be much to see. If you remove the valves and roll the stems on a flat piece of glass, or chuck them in a drill for a spin, you'll know pretty easily...

[1983lux]

Yeah, the intake valves are bent for sure. There are a couple of little marks on the pistons and little scrapes on the valves that could be signs of contact, but it must've been relatively light contact as its barely visible. I took another close look at the timing belt on that side and noted that a few of the teeth on the belt look a bit chewed. The full story is probably that the left cam seized on the road due to being slightly misaligned or improperly tightened down, the crank continued to turn a bit and skip some belt teeth before the bike shut down or I pulled the clutch, allowing the pistons to hit the intake valves and bend them.

The main question is, judging by the pictures above, is it very likely that my pistons/engine block are still good? It'd be a shame to put a bunch of time, another head, new starter, and a bunch of new gaskets on a bad engine. Judging by the appearance though I assume that the pistons are probably okay? Is there any way to test it without splitting the cases?

I drained the oil and it was clean, no sign of shavings.

My plan is to get the original '75 head/carrier from back home and swap these rockers and hopefully still usable '75 camshaft into it. Not ideal, but I don't think I'm going to have any luck finding a used head anywhere close to me, and shipping something that heavy will be a fortune. Maybe I can get a machine shop to look at the cam and see if its usable. Not much cash left in the bike fund unfortunately.

[robin1731]

Yeah, the intake valves are bent for sure. There are a couple of little marks on the pistons and little scrapes on the valves that could be signs of contact, but it must've been relatively light contact as its barely visible. I took another close look at the timing belt on that side and noted that a few of the teeth on the belt look a bit chewed. The full story is probably that the left cam seized on the road due to being slightly misaligned or improperly tightened down, the crank continued to turn a bit and skip some belt teeth before the bike shut down or I pulled the clutch, allowing the pistons to hit the intake valves and bend them.

The main question is, judging by the pictures above, is it very likely that my pistons/engine block are still good? It'd be a shame to put a bunch of time, another head, new starter, and a bunch of new gaskets on a bad engine. Judging by the appearance though I assume that the pistons are probably okay? Is there any way to test it without splitting the cases? Looking at the pics you should be fine.

I drained the oil and it was clean, no sign of shavings.

My plan is to get the original '75 head/carrier from back home and swap these rockers and hopefully still usable '75 camshaft into it. Not ideal, but I don't think I'm going to have any luck finding a used head anywhere close to me, and shipping something that heavy will be a fortune. Maybe I can get a machine shop to look at the cam and see if its usable. Not much cash left in the bike fund unfortunately.