I had my ride put away this winter, but was starting it every couple of weeks to keep the battery charged.  Once in December, it started, but died right away, so I tried again, and it backfired and wouldn't start.  I pulled the battery because it went dead while trying, and kept it in the garage the rest of the winter, keeping it charged.  Well, it's been a few days since our last snow, so I decided to get it out.  I put the battery in, and turned on the ignition, waited for the fuel pump to run and shut off, but it won't start.

I have checked all of the fuses, and they're all good.  I figured before I spent a ton of time chasing all over, I'd see if anyone else had had a similar issue, and had suggestions of things for me to check or try.  Let me know if you have any ideas.

Thanks.

[2015 Z Force 800 53/Trail EPS]

I would check that there is in fact the proper fuel pressure to the injectors and that the plugs are getting spark. And...are you sure its turning over and not just slipping on the one-way clutch. I would also pull both plugs and make sure they are not wet. It's also possible the gas has gone bad. It's not unheard of that after only 3 or 4 months gas won't even burn anymore under compression.

Something most don't realize is that it takes around 15 minutes of running at 3500 RPM to fully put back into the battery that the starter motor takes out...even if it starts on one or two revolutions. So running less would actually help pull the battery down. The tender or smart charger is the way to go. 

Sure sounds like a "low voltage/amperage" condition prevented it from running before the battery was taken out.

I'll assume that the battery is at least 3 years old (2017), and that it's never been tendered. If that's the case, my first suspicion would be the battery. I would have it load tested.

It has spark, but I replaced the plugs anyway. It appears to have compression, but I can't tell how much, since my compression gauge doesn't have a small enough adapter to fit these small plug holes. The fuel doesn't appear to have any water in it, and doesn't smell very bad. I did pull one injector, to see if it had any fuel pressure, and it definitely does. The fuel that came out doesn't look or smell too bad, and burns really well. I took the air cleaner off, and had a friend hold the throttle body open while cranking, and I squirted some starting fluid up it, and it didn't fire at all. While turning over, it sounds like it's pushing air out the intake, which makes me believe that the intake valves are open during the compression stroke, so I'm guessing jumped timing, or intake valves stuck open.

Does anyone know if these are an interference engine?

We've seen a few jumped chains in this forum, and one case where the casting that supports the rocker pivot  was broken.

A compression test is a good next step, but also to remove the valve covers for a visual inspection.

What's odd though, is that it is a two cylinder, and  I would expect at least one to pop. I still wonder if there is a low voltage condition involved messing up the ECU (we've seen this before too), but you have to ensure the mechanical check out first.

Yeah, it seems strange that it's not popping and backfiring, at least a little, unless the valves are hung open.

When you say low voltage condition, do you mean one that damaged the ECU, or lower voltage than needed by the ECU?

You will find posts of people who had batteries strong enough to turn the engine over, but the engine would not run until a new battery was installed. It seems that these systems are temperamental to marginal voltage and the lifetime of these batteries is limited, especially if they are not maintained. Your description seems to fit that scenario (but it's just one possibility).

That's why you will see lots of recommendations to check cable, ground, and fuse holder connections.

Clark would likely know more about it than me.

The battery voltage was dropping to 11.7 while cranking, so I got a new battery for it. Unfortunately, it does the exact same thing.

I need to try to get my hands on a compression gauge that will fit these tiny holes.

The only compression tester I could get my hands on today with a 12mm connection was a Harbor Freight, so I don't know how accurate it is, but the cylinder towards the front doesn't have enough compression to move the needle, and the rear one shows about 20psi.  The one towards the front sounds like it chuffs air out the intake while cranking, so I'm guessing the intake valves are open during the compression stroke on that cylinder.

Fun stuff.

[2015 Z Force 800 53/Trail EPS]

The only compression tester I could get my hands on today with a 12mm connection was a Harbor Freight, so I don't know how accurate it is, but the cylinder towards the front doesn't have enough compression to move the needle, and the rear one shows about 20psi.  The one towards the front sounds like it chuffs air out the intake while cranking, so I'm guessing the intake valves are open during the compression stroke on that cylinder.

Fun stuff.

Well...check the lash...then check the valve timing. Take a close look ate the rockers and the rollers that ride on the cam. I had a seized one when new so I know they can have issues. But with both down I'll bet there is something chain-related going on.

Can you easily get to the front valve cover from behind the seats if you remove the plastics?  The guy that owned this before me was trying to control dust, and spray foamed and taped every seam and gap in there. 

[2015 Z Force 800 53/Trail EPS]

Can you easily get to the front valve cover from behind the seats if you remove the plastics?  The guy that owned this before me was trying to control dust, and spray foamed and taped every seam and gap in there. 

Yes...well you have to pull the center plastics but its right there. There is one hose that runs over it that is a little problem but not too bad. How did you get to the spark plug without pulling the plastics? You must be way more agile them I am...lol

Actually, I'm not very agile at all, but after years of working on cars, I usually figure things out.  I pulled the center cover of the bed, stood on a block, and reached down from there.  I've had back surgery, so crouching and bending is pretty painful.  That's why I think if my dealer actually reopens tomorrow, it may need to go to them.

Thanks for your help.

[2015 Z Force 800 53/Trail EPS]

Actually, I'm not very agile at all, but after years of working on cars, I usually figure things out.  I pulled the center cover of the bed, stood on a block, and reached down from there.  I've had back surgery, so crouching and bending is pretty painful.  That's why I think if my dealer actually reopens tomorrow, it may need to go to them.

Thanks for your help.

Might not be a bad idea.

11.7 volts under load is OK and expected. CLoser to 10V would be a problem.

but the cylinder towards the front doesn't have enough compression to move the needle, and the rear one shows about 20psi

I'm curious as hell to understand what would make both cylinders fail like that at the same time.