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1998 EL250 knocking after oil/spark plug change

4K views 66 replies 3 participants last post by  171985 
#1 ·
Hello all!
New to this forum, so hope I'm doing everything correctly.
I recently bought a beater Kawasaki Eliminator 250, I checked it running once I got home and the motor sounded great. The only issue was that it struggled to run. I could run it to the end of the street and back, but if I rolled off the throttle, it would stall. I could only start it on full choke (even warm) and run it on half.
After taking out the plugs, running a compression test on both cylinders, and inspecting the plugs, the fault ended up being that the spark plugs hadn't been adjusted correctly. I replaced these with new plugs anyway, as well as oil (only had 15w/40 for cars, so I put that in, read that it would be fine as a temporary alternative but clutch may slip. I replaced this with motorcycle oil the next day after running only once). After changing the oil to motorcycle oil again however, my bike has developed a loud knocking sound almost instantly. I made sure to keep anything away from the spark plugs holes while they were out, so that nothing dropped into the cylinders; almost certain I succeeded in not turning my cylinders into a temporary pinball machine for a bolt or nut.

Here's videos of the bike running:
Video 1 -
Video 2 -

I've checked the exhaust bolts, checked bolts located on the top end too. All were tight.
Noise doesn't go away when I pull in the clutch so its not the clutch housing as I'm aware that this is a common issue with these bikes. Clutch engages just fine.
Bike doesn't idle amazingly, but doesn't stall now. I've adjusted the idle screw still to no avail.
I'll check to make sure the new spark plugs are an exact replacement tomorrow as I replaced them with another brand, though I assume if the piston was hitting the spark plug, that cylinder would stop working.

Is there anything I'm forgetting to check before I assume this is a buggered top end? Just want to rule everything out before pulling the engine apart.
 
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#43 ·
Just dropping in for an update.
The new head gasket turned up, so thats in. It was odd reinstalling the camshafts. Intake was fine, but exhaust was resting on one set of rockers. I checked and this was normal. It just presses down on the valve when you tighten the bolts in a specific pattern.
For anyone who finds themselves on this page looking for answers: YES, THE OLDER GPX250/EX250 SHARES THE SAME ENGINE AS THE ELIMINATOR EL250.
It got a bit too dark tonight to finish reassembly, so I'll hopefully get it all done in the next few days.
 
#45 ·
Bike is back together, but it's not running right. No choke, it doesn't run. Full choke and it does but at a low idle and running very loud. Occasionally pops from the exhaust, so I guess that means it's running too rich. I cleaned the carb and didn't adjust anything.


Followed everything to spec when reassembling so I'm a bit confused. I'm going to get the valves adjusted at a shop because they're a complete pain. I spent about an hour trying and only got one done, the rest were close enough but theyre probably out of spec still. I'm assuming this is the issue, but does anyone else have any ideas?
 
#46 ·
As additional reference, I charged the battery, pulled and tested the spark plugs. The spark seemed weak. It was an orange spark rather than blue. When I pulled them, they were wet with fuel. Maybe the coils have gone bad? They both seem about the same though, and it seems weird that both would go slightly bad simultaneously.
 
#48 ·
If the valves aren't adjusted properly, one could be a little tight and be staying open. That could cause all kinds of popping problems. The coils, that's another issue. Read what the impedance should be and go from there (checking voltage going into coils). I'd take another shot a trying to adjust the valves. Don't be afraid to cut a feeler gauge to size if you need room. :)
 
#57 ·
Additionally, it will smell of fuel while it's running, and pop out the exhaust. Starting it without choke will get a few fires, but not enough to run.

Haven't tried starting it with full throttle actually... it seems that it's running rich, so I guess more air would make it run better. I'll try starting with half and full throttle when I get home tonight and see if there's any difference.
 
#58 ·
I could be completely wrong. but the coils are receiving a charge voltage, which should be the running voltage of the bike, so + should be to positive of the coil, and - should be to ground of the battery, for checking. I don't know how the coils are grounded on your bike. You have the service maual, that should tell you. :)
 
#59 ·
So I checked the way you said, with negative on the negative battery terminal, and got a different result. Left cylinder is 10.6v, right is 10.8v.
I checked the resistance in the coils using this guys video:

Here's what I got:
Left cylinder: Primary = 3.2/Secondary = O.L
Right cylinder: Primary = 3.5/Secondary = 190K
Manual says that O.L means 0, so judging from that guys video, I've got a bad coil. I guess the sluggishness is the bike trying to run on one cylinder?
What do you guys reckon? Order a new set of coils?
 
#60 ·
Scratch that!
I assumed that no resistance means a broken connection somewhere. So I removed the cable leading to the plug boot. The cable had broken so there was minimal contact at the boot end. I cut the cable back a bit and pushed it back in place. The bike now runs a little better, but still not well enough to run without choke. Video below (apologies about the rain noise):


The bike sounds fine while idling. Under a bit of throttle, the valves become quite noisy.
Looks like I'll have to be patient and work on the valves.
 
#62 ·
And now on to your problems. While you may have some ignition issues it is my opinion that you have carb issues. Any time a bike refuses to run without the choke, that is a symptom of the bike being starved for fuel. The "choke" or enrichener provides the extra fuel the bike needs.
 
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