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2003 kawi 636 runs but very low on power

SpeedyCorky

SpeedyCorky

rides minibikes;U should2
Joined
Mar 9, 2003
Location
East Bay Area
Moto(s)
are clearly addicting; so you see - it's really not my fault...
Name
key-tay
bike ran great when i bought it with a hair under 14k miles.
16k miles currently
full system w/ PC3 and generic map installed by the previous owner, K&N air filter, otherwise stock motor

a few rides ago i started to notice it would pop on the deceleration, when in high rpms. especially around 8k rpm.
problem didnt happen all the time, but sometimes. i figured it might be a less than perfect fuel map.
then it got worse, started happening more. then last ride it started happening at 9k and 10k rpm sometimes, more times.
on todays berryessa ride, it started at ALL rpms. had to truck the bike home.

it seems/feels/rides like a spark plug was loose, or a spark plug wire/boot was loose, and maybe was vibrating at 8k rpm and not sparking, then maybe vibrated more loose, and eventually loose enough that it didnt make contact. but opening up the bike the spark plug coil/boots were pretty darn tight on there, and all the spark plugs were fairly tight. a couple a bit loose, buuut

of the 2 plugs that were *a hair* loose (cylinder 2 and maybe a bit cylinder 3), i didnt think them loose enough to cause this kinda issue.

i pulled all the plugs. all looked normal (cylinder 2 pictured on the right), except cylinder 1 (left) which was oily and nasty looking. sooty looking. wet looking. all other cylinders were dry and a bit of white on the tips and looked like cylinder 2 (right), yeah a bit of black soot, but not THAT bad i thinks. but cylinder 1 was the only one that was wet/oily looking.






when you idle the bike from cold, cylinder 3 doesnt seems to heat up as fast as the other cylinders. making me want to blame cylinder 3. but again, cylinder 1 has the nasty spark plug. cylinder 1 plug was in tight enough, as was cylinder 3. cylinder 2 plug was *a hair* loose, but again, it warms up normally.

AND

cylinder 1 has this red powder kinda stuff on the spark plug coil/boot.
cylinder 1 pictured on left, cylinder 2 on right. remember cylinder 2 has a normal looking plug and spark plug boot/coil, so it is suspected to be normal.



so cylinder 3 is suspect b/c it doesnt warm up as fast; and cylinder 1 is suspect because of the nasty plug and weird red powder

i think plan now is to get 4 new spark plugs. put 'em in there nice and snug. put the boots on nice and snug, and see if that solves the problem. if not..... suggestions?!?!!? suggestions anyway!??!!

i'm really hoping that cylinder 1 rings arnt toast..... but knowing my luck..... :cry
 
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Popping is not uncommon on that bike on decel. It's unburned fuel combusting in the exhaust.

However, if this occurred with the loss of power, that's indicative of a spark issue. Start with the obvious: check coil resistances and then swap them around and see if the same header heats more slowly.

Typically, white on plugs means you're running lean; oil means ring blow-by. (I'm no expert though)

If you're ambitious, you could also pull off the throttle bodies and switch up the injectors themselves to see if the headers heat differently.
 
+1 for doing a full compression check while you got it apart anyway. No sense in buying a new plug for a motor that has low compression. If it's oil getting past the rings you will just ruin a new plug.
 
^^^^ except for cylinder 1, which was wet. hard to tell if it was oil or fuel wet tho

i sure hope it was the fuel pump. but with a bad fuel pump, you'd think the bike would start to run like shit in higher rpm (more fuel demand) but run OK and low rpm. not the case. it runs crappy at all RPM

today i'm gonna do a compression check, clean the spark plugs, and swap the coils, reassemble and report back to u guys
 
If the compression is good, and it runs well with new plugs, I would get it mapped on a dyno. Those plugs look lousy rich. It may be that bad fueling just fouled out the plugs.
 
^^^^^^^ here's to hoping!

i KNOW/KNEW it is running rich, as cuz of the popping it does on the deceleration at high RPM.... getting a custom dyno fuel map was next on the list for this bike - lets hope that is still the highest priority!
 
did a compression test; odd results

from left to right (clutch side to throttle side), here are the results

160 ; 120 ; 155 ; 180psi

i've been calling the "160" cylinder 1. hence 180 is cylinder 4. i hope thats right(!)

AFAIK, sportbikes should be around 150 to 165psi. so looks like cylinder 1 and 3 are normal for compression, cylinder 2 is low, and cylinder 4 is quite high.

odd that cylinder 2 warmed up super fast (yet it has the lowest compression), and that cylinder 3 warmed up the slowest (by far), yet it has normal compression.

should that 120psi for cylinder 2 cause the bike to run OBVIOUSLY wrong? i wouldnt think so (?)


what to do now? would it be worth the time to clean the plugs (wire wheel), reinstall 'em, see what happens? or does cleaning them not do very much and should i just wait until tuesday when i can get some new plugs?


<---------- very confused. was expecting low compression on cylinder 1 and/or 3, got opposite results. remember cylinder 1 had the nasty wet spark plug, and cylinder 3 heats up slower than the rest
 
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The compression for the cylinders should be within ~10PSI or so. There may be more than one issue here, could have a bad coil or wires and the plugs might have been bad.

I would check all plugs/coils for spark first, and if there are no issues then it might be something in the fuel system. Make sure the plugs all put out a nice strong spark, sometimes a weaker spark will not fully ignite the mixture. This may be what is happening on cylinder 3.

good luck man
 
SpeedyCorky said:
did a compression test; odd results

from left to right (clutch side to throttle side), here are the results

160 ; 120 ; 155 ; 180psi

i've been calling the "160" cylinder 1. hence 180 is cylinder 4. i hope thats right(!)

AFAIK, sportbikes should be around 150 to 165psi. so looks like cylinder 1 and 3 are normal for compression, cylinder 2 is low, and cylinder 4 is quite high.

odd that cylinder 2 warmed up super fast (yet it has the lowest compression), and that cylinder 3 warmed up the slowest (by far), yet it has normal compression.

should that 120psi for cylinder 2 cause the bike to run OBVIOUSLY wrong? i wouldnt think so (?)


what to do now? would it be worth the time to clean the plugs (wire wheel), reinstall 'em, see what happens? or does cleaning them not do very much and should i just wait until tuesday when i can get some new plugs?


<---------- very confused. was expecting low compression on cylinder 1 and/or 3, got opposite results. remember cylinder 1 had the nasty wet spark plug, and cylinder 3 heats up slower than the rest
Click to expand...



I wouldn't bother cleaning the plugs. Call your local Pep Boys, Autozone, etc. and see if they stock those NGK plugs. The numbers are on the plugs. Cleaning with a wire brush can put streaks of metal on the insulators, causing fouling. If you clean them, use media blasting, but better to just replace them and be sure. Have you checked your air filter for dirt? As for the compression, I think I would check to be sure all valves have at least minimum clearance. The high one could be carbon buildup. I would put in a set of plugs, and take it out and blast it a while, then mabye re-check the compression.
 
the valves are due to be adjusted, so that could be the cause of the uneven compression

the cylinder 1 spark plug is wet, as said, i just sniffed it. smells like fuel - which is a good thing
 
Looks like you found out why the PO recently replaced the plugs.

I'd clean up the plugs and see if the blow-by and/or fuel mixture disparity is fouling them. Just blast it with some carb cleaner. That should be enough to diagnose. If it runs okay, then you've got your answer.

If not, then you have more diagnosing to do.

I can't imagine valves could be so far off to make that much difference in compression.
 
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so look like consensus at this point is buy new plugs, install, reassemble, test ride

will happen tuesday
 
SpeedyCorky said:
did a compression test; odd results

from left to right (clutch side to throttle side), here are the results

160 ; 120 ; 155 ; 180psi

i've been calling the "160" cylinder 1. hence 180 is cylinder 4. i hope thats right(!)

AFAIK, sportbikes should be around 150 to 165psi. so looks like cylinder 1 and 3 are normal for compression, cylinder 2 is low, and cylinder 4 is quite high.

odd that cylinder 2 warmed up super fast (yet it has the lowest compression), and that cylinder 3 warmed up the slowest (by far), yet it has normal compression.

should that 120psi for cylinder 2 cause the bike to run OBVIOUSLY wrong? i wouldnt think so (?)


what to do now? would it be worth the time to clean the plugs (wire wheel), reinstall 'em, see what happens? or does cleaning them not do very much and should i just wait until tuesday when i can get some new plugs?


<---------- very confused. was expecting low compression on cylinder 1 and/or 3, got opposite results. remember cylinder 1 had the nasty wet spark plug, and cylinder 3 heats up slower than the rest
Click to expand...

254A93C2-3595-425A-986C-54FEBA40402D-350-000000E5B38294CF_zps4cdc895d.jpg


Ever use one of these? The differential compression test gives you a lot more info than just a simple compression test. You'll be able to tell rather easily if where you compression loss is, if you have any that's excessive. They can be had for about $80.
 
remembered that cyclegear is open sundays, went down there got 4 plugs, $7each~

put 'em in, reassembled.
test run was beautiful. runs great!
cant believe i lost a berryessa ride over a shitty fuel map (thanx previous owner), and as a result - fouled plugs.

still doesnt explain the compression difference tho. but it makes plenty of power, so imma just run that shit! ....... or given said shitty 120psi number, now that the bike runs ok, would I be smart to just sell it and buy something else?


and if not, anyone wanna gimmie some kinda deal on a custom dyno created fuel map? bike has a PCIII USB. last shop i called wanted $300, which was more than i'm willing to pay. i could swing like $200...
 
You could pull the valve cover off and check your clearances to see if any are getting tight/hanging open on that #2 that might be causing your compression woes.
 
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