Starter won't turn the engine over

Hey all. Apologies if this has been covered, didn't find anything in a search.

Reviving the XJ650 Seca after a long slumber. I've installed a new head, corrected by incorrect ignition wiring, and it was running! Rough, but running. But no longer..



This is what I'm running into. I'd installed the new head following all the steps to align timing, there are no oil leaks, and I turned it over quite a few times with no ignition (unintended, but that should lubricate the cylinders). The bike was starting up pretty quickly until I suddenly ran into the issue in the video. I know I've run into this in the past, but it didn't persist as it is now.

I have fears, but I thought I'd just put this out there to see if there's a simple issue and resolution here. Thanks!

 

Can you turn the engine over by removing the cover on the left hand end of the crankshaft and rotating it anticlockwise?

 

Ah, good call. Just checked. No, not able to turn it over at the crankshaft anticlockwise.

 

You should be able too. Remove the valve cover to check the valves. Sounded to me like the engine was locked, hope valves and pistons are not in contact. They should not have been if the engine ran freely. Don't try and turn the engine on the starter motor or with a spanner on the crankshaft again. Do you have any photographs on how you set up the engine timing?

 

No pictures of timing settings. I'll remove the valve covers and check the timing marks on the camshafts and report back. Assuming the timing marks will not be where I need them to confirm, is there any harm in rotating clockwise to line them up? At this point, I want to avoid pushing against any resistance.

Thanks much!

 

Have a look at the cams first you can turn the engine clockwise slowly, slightest resistance stop. Before you do that can you remove the spark plugs to see if the pistons are all roughly midway in the bores. Use a timber dowel or a large thin screwdriver or in the dark use a torch shone down the spark plug hole to see where the pistons are. I am hoping that the pistons are not touching any valves which would only occur if the cam timing was wrong or the engine dropped a valve. I have never heard of an XJ dropping a valve though.

 

Thanks. Interference was my concern as well, but having experienced this before and 'knowing' the timing is good, I wasn't too concerned. But that'll be the first think I look for, and will be careful doing so.

 

https://photos.app.goo.gl/G77GDkgirQoQSXRr5

Hope that link works. Camshaft markings look aligned. However the crankshaft marker appears quite.. off.. though I don't believe those spin 1:1? I should add I replaced the crankshaft sensor parts since (I imagine) a wrench displaced one of the magneto contacts.

 

Crank moves 180 degrees and camshafts move 90 degrees. Did you line up the T mark on the crankshaft rotor with the line on the small plate held by the screw above the bottom pick up?

 

I did line up the T mark when reinstalling the camshafts. I have a Haynes manual, and while having done this before, I followed the steps.

That said, this is all to my best memory and knowledge. I'm not above making mistakes, so if something is obvious, it may be true contrary to my statements..

 

What is your battery voltage? As you had the engine running cam timing should be fine. Just trying to figure out why crankshaft won't turn.

 

https://photos.app.goo.gl/v6fBJYuX8dgMnaDX8

Voltage on the battery is fine. It's a ~1 year old battery for my other bike, normally plugged into a trickle charger when not in use (very not in use this year).

 

Load test it.

 

Fuel leak into the cylinders is the first possibility.

OP, check the crankcase for gas.

 

I was just thinking that hope you are right.

 

yup a cylinder full of fuel will just not let starter spin motor. had this happen.
started bike checked a few things when running. shut it down a few minutes later went to start locked up solid. pulled plugs out hit starter fuel sprayed all over the wall.
if you do pump out the fuel when cranking disconnect spark plugs and tci do it out side or with a lot of rags over spark plug hole
what a mess it can make let alone fire hazzard.

 

No rags. Those add to the fire hazard.

 

This xj750k did in a big way

 

Had that ones with a suzuki gs450. After a crash the petcock leaked and the bowlneedles were slightly off. 12L of fuel all down in the cylinders and below.
Same story as xj550H was telling.

 

Yes good picture showing the damage it did. I read in Motorcycle Mechanics magazine about a GPz 900 dropping a valve at Santa Pod years ago.

 

Wow.. that's pretty intens.

 

Looking for updates on how the engine is coming along. If you did all the checks from the above posts you should have some news for us.

 

Thanks all. Lots to catch up on, but have been tackling other projects today. I'll review and act based on comments, and report back on progress this week.

 

Sorry, just read comments. So we're assuming possibly fuel leaked into a cylinder, and perhaps into the crankcase, one of those preventing turnover? Drain the oil and check for separation, pull the plugs and look for pooled liquid in the cylinders?

 

If you take the plugs out disconnect your battery first and turn the engine over with a spanner on the end of the crankshaft slowly preferably outside your garage in case a cylinder is full of fuel.

 

Gotcha, thanks. I worked on a LeMons team for a few years, and we did set an engine bay on fire placing the plug against the block to check for spark without disconnecting the injector. We had a fire extinguisher and all was fine, but I've been sure to have one on hand since. Appreciate the guidance on next steps, I'll check it out and report back.

 

Removed the plugs and drained the oil. Snapshot of oil: https://photos.app.goo.gl/QguC7xiHAT1w3ovB8 I see a hue of blue, not sure if that's a concern. Looking into the cylinders, no evidence of pooling fuel. Unable to rotate the crank with slight pressure on the crank.

 

back in post #8, is that on the crank marks? because the cam looks about one tooth off

 

Is it safe to rotate the crankshaft backwards/clockwise? If not, I don't think I can confirm. I believe I'll need to remove the head, check the valves, and realign/reposition everything.

 

With the oil out of the engine and no fuel in the cylinders it's got to be cam timing. If you turn the crank try and get all the pistons away from the cylinder head to be clear of the valves. Turn clockwise as it was locking when turned anticlockwise. Yes you need to check the head, valves etc.

 

Yes it is definitely out.

 

Does the oil smell of Petrol? If not petcock should be working properly.

 

Looking at the position of the T mark on your rotor piston two or three could be hitting one of the valves.

 

Cylinder 2 looks like it may be the cylinder of interest, though I can't tell too much peering through the spark plug hole and cam/piston positions. Winter has come in Chicago, so it'll be slow going for a while, but I'll remove the head and check the valves/pistons. While I'm in there, I'll do a thorough cleaning of the head and change the valve stem seals as well, something I should have done initially with this transplant.

 

Yes inlet valve no 2 is depressing the valve in the photograph. If you can turn the engine clockwise and get the T mark on the line on the plate held by the single screw that's 1 and 4 TDC mark. I think the dot on the camshaft will be nearer the head instead of near the triangular timing mark on the alloy caps when the T mark is at TDC.

 

Engine runs anticlockwise so the piston has come up and hit inlet valve No 2 by the looks of it.

 

Update: Took the head off and removed the valve assemblies for inspection. Didn't notice any damage, didn't even notice signs of impact (though I agree that is likely the cause of the problem). Reassembled, and noticed that while installing the chain sprockets on the camshafts and rotating a full cycle, the intake would fall a chain link or so behind the exhaust camshaft, even though they were lined up initially and the chain pretty tight. I'm guessing the chain was not taught enough, and I probably assumed the difference was 'close enough'. Didn't allow myself that clearance this time. Had to advance the intake camshaft a few degrees, to the point that they misaligned inversely (the intake camshaft was ahead of the exhaust camshaft). However after a full rotation, they aligned perfectly.

Bottled everything up, and it ran again, sounding much better than before. The carbs are clearly out of tune, but that's a better problem to have.. I'll be tackling that next. I also found a colortune, so I'll search for some guides, but would appreciate any links to good posts/articles/videos.

 

Are you going to rebuild the carburettors? Here is a how to bench sync them although a full rebuild would be better.

https://xjbikes.com/forums/threads/how-to-bench-synch-your-carbs.6366/

 

Thanks for the link. I'd recently rebuild the carbs (mileage-wise) and bench sync'd them, but I've bought supplies to liquid/vacuum tune them as well.

 

I'd like to close this thread. I've turned the engine over many, many times. A previous rattle sound has long subsided (since adjusting the cams to match the timing marks), and that alignment hasn't shifted. I think it's clear my cam alignment was off, and valve(s) were tapping on cylinders. I assume the engine stopped at a position where the starter couldn't turn the engine over due to the interference. For what it's worth, I disassembled and inspected all the valves, and saw no damage (nor on the pistons). I've reassembled, assured the timing aligned after many revolutions, and the engine is running much healthier. Not as healthy as I like, but I believe that's another issue, and I'll search/create another thread that fits the current situation. Thanks all!