OT - JD ZTR need help

souNdguy

Well-known Member
stepdad has a JD ZTr.. maybee 10-12ys old... Not sure of what model it is. 2 cyl He mowed with it 2 days ago. wouldn't start yesterday.

When i got there he had put new inner/outter air filters in it and changed spark plugs.

it turns over good.

I pulled both lines to the plugs and held them back and it has snappy spark.

while turning over it will occasionally fire thru the exhaust like a gunshot report.

It did it twice thru the intake as well, blowing the breather cap off the filter canister, the canister latch door off, blew both filters out, and caught the plastic canister on FIRE!.. same gunshot report.

i pulled the 4 10mm bolts holding the valve covers on thinking it might have a bent pushrod, or otherwise valves hanging open.. but nada, valves and pushrods all seem to be moving well.

Checked the fuel pump, turning over it is producing great flow.

You can make the plugs get wet trying to start repeatedly or using choke, so it is for sure getting fuel.


At this point, i'm wondering if it has a keyed flywheel like a pushmower, and maybee it is sheared or partially sheared throwing timing off.

Ideas?

Thanks
 
QUOTE:

"At this point, i'm wondering if it has a keyed flywheel like a pushmower, and maybee it is sheared or partially sheared throwing timing off."

This would be my first guess!
 
Yup.. that's what I'm down too.

I checked the obvious stuff. spark, fuel, valves moving... can't think of much else it could be but timing.. and that's the main timing issue that comes to mind.
 
I think I would try a confirmed good ignition coil before I would break it into to check the key???

If the key is not sheared then when the cylinder is at top dead center compression stroke the magnets that fire the coil should be in line with the coil

Or if it only has a pickup coil in a distributor the magnetic pickup should be in line with the rotor???

Did you Google it????

Zane
 
didn't google it, was kind of unsure exactly what I would google, can't find a model id number on the thing..

I'm really not thinking it is a spark issue... it has GREAT spark.. thus chasing a spark issue seems to be a waste of time.

the spark will jump a 1/4" + air gap with no problem as long as you hold the key turning it over, both cyls.

witht he engine installed int he frame, and the cover on, you can't get to where the spark plug wires dive under the cover. to take the cover off, there will be some major disassembly.. if i'm going that far, I think I would be looking at a timing issue for the keyway... it's going to be a PITA type job i can already tell.
 
My dads john deere riding mower never got to the point of NOT starting, but it was going thru a very odd and seemingly random series where it would be VERY hard to start, and sometimes start with a loud bang out the exhaust.

for us a new coil fixed it.

just some food for thought
 
You have spark and can see the valves, so maybe you could see how the spark coordinates with the valves - ? Maybe there are other timing marks? Just trying to think of ways to check timing before digging too deep... Some of the small engines are throwing sparks at various times to help manage emissions (complete combustion) so it gets messy. Any reason to believe the flywheel would have sheared the key? Have the wires gotten crossed to the cylinders during troubleshooting? Good luck. Let us know what it is!
 
not sur eif this one uses waste spark or anything like that.

plug wires are arranged on opposite sides of the engine, so no way to swap them. I'm down to taking it apart...
 
it's got spark in spades. it's got more spark than any old ford out there with or without an ei.

it's NOT the coil...

if the spark was weak, intermittant, etc.. I might look at the coil setup.. but with lightning storm quality spark.. I got to rule it out..
 
(quoted from post at 15:16:34 07/07/15) it's got spark in spades. it's got more spark than any old ford out there with or without an ei.

it's NOT the coil...

if the spark was weak, intermittant, etc.. I might look at the coil setup.. but with lightning storm quality spark.. I got to rule it out..
aybe the lightening storm knocked out your coil.....have you checked for spark? :twisted: :twisted: :lol:
 
You said you were not sure of the model, but do you know the
make of the engine? Kawasaki maybe. JD used a lot of them.
The make might at least point in the right direction?
 
Rain came today so I had to oversees my pasture before rain, so never made it back over, maybee tomorrow
 

Its not the flywheel key or the valves unless the valve seat came out of the left side do to overheating from grass in the cooling fins, its the spark plugs...they might be making a good spark but that doesn't mean nothing in a Kaw.
 
I'm closing this thread now..

i've stated it 20 times now.. it is not a spark problem!

it has enough spark to run 3 mowers.

the plugs are sparking good.

I have 3 sets of plugs in front of me. the perfect ones that my stepdad took out of it, the new set he put in it, and another new set. they ALL spark fine.
 
(quoted from post at 10:10:18 07/09/15) I'm closing this thread now..

i've stated it 20 times now.. it is not a spark problem!

it has enough spark to run 3 mowers.

the plugs are sparking good.

I have 3 sets of plugs in front of me. the perfect ones that my stepdad took out of it, the new set he put in it, and another new set. they ALL spark fine.

threads not closed I can still post.

why not come back and tell us what the problem actually is instead of closing the thread
 
i pulled the 4 10mm bolts holding the valve covers on thinking it might have a bent pushrod, or otherwise valves hanging open.. but nada, valves and pushrods all seem to be moving well.

That just means if it has a valve related issue you can not see it... Its what you can not see that you have to eliminate.

I would see if I could get it to run on one cylinder at a time Remove one are the other plugs and see if it will run and not back fire with the other removed..

Cross yer fingers and hope it will run on one cylinder are the other with a spark plug removed... If it has a valve, seat are guide/spring issue compression on that cylinder will fight you because it only has 2 cylinders... Removing a plug will help the compression fight...
 
Its rained here every day after work, so yesterday I got his craftsman 24hp rider serviced so he can mow his foot tall grass while I work on the ztr. I'm goin to trailer it to my shop so I can actually work on it, under cover, and with access to more tools, a lift , jacks and air tools..

I did some research and some of those engines have plastic cam gears.

Yep, the valve cover look see was more just to see if any valves were stuck down, or bent pushrods.
 

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