KX Riders
Maintenance & Technical => KX500 Original => Topic started by: kelcrist on April 17, 2011, 03:42:03 PM
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howdy folks.
heres the situation im facing. i have a 92 that i have done a top end job on. i had the cylinder re-plated and used a wiseco piston. since then the bike just doesnt seem to run right. at first it had unstoppable low end power but no top end rev. i discovered that i had the power valves timed wrong so that cured that issue. it will now rev and still has decent low end but it actually sounds like it misses at low rpm. i have a 94 that runs completely different. i would consider it "normal" since my brothers 95 and my friends 97 all seem to run about the same. the timing is set at stock on all the bikes mentioned and the jetting is all similiar, within a size or 2. pipes differ a little, one stock, one fmf desert and one fmf woods. all in all none the bikes are mostly stock so im wondering what can make such a difference? any thoughts at all??
oh and i have not done any leak down or any tests like that.
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when i was setting mine up i put some vids on youtube. i got a good response from the guys on here. i vid can describe things better than words imo
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howdy folks.
heres the situation im facing. i have a 92 that i have done a top end job on. i had the cylinder re-plated and used a wiseco piston. since then the bike just doesnt seem to run right. at first it had unstoppable low end power but no top end rev. i discovered that i had the power valves timed wrong so that cured that issue. it will now rev and still has decent low end but it actually sounds like it misses at low rpm. i have a 94 that runs completely different. i would consider it "normal" since my brothers 95 and my friends 97 all seem to run about the same. the timing is set at stock on all the bikes mentioned and the jetting is all similiar, within a size or 2. pipes differ a little, one stock, one fmf desert and one fmf woods. all in all none the bikes are mostly stock so im wondering what can make such a difference? any thoughts at all??
oh and i have not done any leak down or any tests like that.
Do a compression check first, you should be up around 150 psi . You also might have the KIPS gears incorrectly timed. I did this myself, and made my KX500 feel like a mellow 250 for mid top end power.
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i didnt do compression cuz as i said the rings are new and the cylinder is new. it will try and break your foot off if you dont have boots on when you start it. i do believe it is still in the kips valve. i was just wanting some fresh ideas before i buy another top end gasket kit.
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Keep an eye on your kips actuator arm is still connected to the kips rod, mine has jumped off a couple of times, im still trying to work out if its over rev when missed gear upshifting or could also be over rev down shifting ( large tree jumping out in front of me).
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howdy folks.
heres the situation im facing. i have a 92 that i have done a top end job on. i had the cylinder re-plated and used a wiseco piston. since then the bike just doesnt seem to run right. at first it had unstoppable low end power but no top end rev. i discovered that i had the power valves timed wrong so that cured that issue. it will now rev and still has decent low end but it actually sounds like it misses at low rpm. i have a 94 that runs completely different. i would consider it "normal" since my brothers 95 and my friends 97 all seem to run about the same. the timing is set at stock on all the bikes mentioned and the jetting is all similiar, within a size or 2. pipes differ a little, one stock, one fmf desert and one fmf woods. all in all none the bikes are mostly stock so im wondering what can make such a difference? any thoughts at all??
oh and i have not done any leak down or any tests like that.
Who did you have do the plating on the cylinder?
DoldGuy
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Missing on the low end huh? What about jetting and plug? Maybe the plug got bumped and messed up the gap (or fouled). The bike with the woods pipe will have more bottom end than the others though and maybe run a bit cleaner down low. I know my bike sounds like its running pretty clean but then when it comes on the pipe, the whole pitch changes and it runs cleaner than an EFI bike (top end pipe).
Also what about the reeds?
Is it hard to start?
Also, check the kips without touching the top end. Just take the pipe off and look in there with a flash light. Pull the little arm and watch it operate. That lets you see if the cylinder parts are doing their job. Then you can rev it with the cover off to see if the actuator is doing its job.
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i believe millenium did the plating.........
as for the kips actuator it is fine, never had a prob. always where it belongs.
i have jetted it up and down based on the jetting of my other 500 and the other 500s i have access to. however.........it has been blowing a lot more oil out of the exhaust lately so i removed a 162 main and put in a 155. i am at 2800ft by the way....... i would like a 158 but i will have to go buy one. i have run a couple different plugs at variousl times..........going back and forth between the 9es and the 8es..........it seems to prefer the 9. the reeds are brand new boyesen. it is never hard to start. 2 or 3 kicks.
i have done the visual check of the powervalve that is how i found out it wasnt opening the secondary ports. i think i may have put it too far the other way. it seems to do what its supposed to when you do it by hand but not sure whats happening when the engine is running.
so far im thinking its a combination of jetting and powervalve. the weather here hasnt been great but its clearing up so ill probably be out messing with stuff this weekend. i also have a rad valve and a 10mm spacer to try. the rad valve didnt seem to make a huge difference on my 94 and that bike runs like its supposed to in my opinion.
thanks for all the input so far from everyone.
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New rings and plate doesn't mean anything... Comp test it..
AND leakdown
What's the ohm specs on coil and stator?
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A 155 main sounds way too small even for 2800 ft. What are you using for premix?? Fuel?? Have you checked your reeds? If your are getting stuff out the tailpipe is it black or is it real runny? I blew a head gasket and it had quite a bit of brown runny stuff coming out the tailpipe. Head gaskets are cheap. Do a test like Motorrad said.
You had nothing better to do this week anyway right :wink:
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Float level being too high comes tommind also... Blubbery bottom, having to lean out main....
Always check float level externaly.. Like climer says (piece of hose)
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A 155 main sounds way too small even for 2800 ft. What are you using for premix?? Fuel?? Have you checked your reeds? If your are getting stuff out the tailpipe is it black or is it real runny? I blew a head gasket and it had quite a bit of brown runny stuff coming out the tailpipe. Head gaskets are cheap. Do a test like Motorrad said.
You had nothing better to do this week anyway right :wink:
Always do the "BIG 4"..
these tests point you to the problem every time... no guessing, wasting parts, or time etc... dont even need to buy gaskets to do them.... and if anything can save you alot of money from melting down a good motor.
Step back, take some time, and do some tests... if anyting, you may discover other problems that are hurting power besides the major one at hand...
The big 4
Compression check
Fuel Level check (external)
Ignition System check (Ohm the coil, and stator) only takes about 15min
Leakdown test
Also a VIDEO works great... we can tell alot by how it sounds..
and if you could pull the pipe, and snap some pictures of the kips drums... that would be helpfull...
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i didnt do compression cuz as i said the rings are new and the cylinder is new. it will try and break your foot off if you dont have boots on when you start it. i do believe it is still in the kips valve. i was just wanting some fresh ideas before i buy another top end gasket kit.
I understand what you said. The reason I suggested a compression test is because you are assuming because your top end is "new" it's good. We have read many posts here over the years about a member that has a "brand new top end" only to find out after a compression test that the compression is poor. Like Motorrad commented, a compression is a very simple, quick and definitive test. Granted you've done it right by seeking the services of a well known and competent company such as Millenium Tech so most likely your compression is fine. HOWEVER taking a compression test, and writing the number down for future reference after a fresh engine is broken in is a smart move in the sense that now you have a baseline compression PSI, so that in the upcoming years you have a comparative number if you have future running issues.
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ill do the compression tonight.....ill have to make the stuff for leakdown. i do not suspect any probs in that area but i have not made any sort of ignition tests at all so my ignition could be weak. also have not looked at float......both good suggestions that i will do first.
i agree the 155 seems lean. however my best friend bought a 97 recently and it had a 158 in it. i have put in what you would assume the bike SHOULD have but it doesnt seem to be what it wants to run right.
this bike will run with any of the other 4 500s that i ride with......it just sounds different and delivers power different. no lack of power at all however. the stuff coming out the pipe is oil......nice and black.
also since i probably wasnt clear about this in the first post......... i didnt put this bike together recently.......i did the top end originally about a year ago........ thats when it had the tractor bottom end power but no top end. i rode it this way for about 7 months. thats when i retimed the kips. now it revs and still has good low end but not tractor like.
ill do some checks tonight and let you know what i find.
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however.........it has been blowing a lot more oil out of the exhaust lately
I wonder if the right side crank seal could be causing your troubles.
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
If you find you have transmission oil dissapearing and you see no external leaks, this is a tell tale sign you have a bad crank seal as well and might explain your excessive smoking. Don't know what you are premixing at, but I recommend 42:1 for the average weekend play rider.
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
Ive always wanted to find another set of cases, to "work on" ...
as Id like to be able to change the seals from the outside...
I think its doable... with alot of work
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however.........it has been blowing a lot more oil out of the exhaust lately
I wonder if the right side crank seal could be causing your troubles.
That's what I'm thinking. Leak down test for sure.
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it doesnt use trans fluid but that doesnt mean the seal is 100%. i have read the thread on crank seals and the leakdown tests........the seals that seem good but are not but heres the issue with that............. suppose you change the seals and they are 100%..... but after a few weeks/months/what ever they no longer pass these tests again but the bike still runs decent. you trying to tell me that your goign to change those seals at every instance that you feel the seal is not right? its all good in theory but thats not always real world feasible. this bike prob hasnt had crank seals replaced in at least 5-6 years if ever. ill update what i find as i have time to work on it.
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Crank seals don't see any transmission oil. The only lube they get is from the premix that gets sucked down there before being sucked into the cylinder. If they haven't been changed in 5+ years I'm betting that is the cause which can lead to other failures.
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Crank seals don't see any transmission oil. The only lube they get is from the premix that gets sucked down there before being sucked into the cylinder. If they haven't been changed in 5+ years I'm betting that is the cause which can lead to other failures.
Doesn't the RH primary side crank seal come in contact with trans oil the resides in the clutch cover housing ?
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Crank seals don't see any transmission oil. The only lube they get is from the premix that gets sucked down there before being sucked into the cylinder. If they haven't been changed in 5+ years I'm betting that is the cause which can lead to other failures.
Doesn't the RH primary side crank seal come in contact with trans oil the resides in the clutch cover housing ?
Yes
And shelf life of a nitrile seal is 5 years. Living on a climate controlled shelf away from heat oil and sunlight... How long do ya think life in a motor is??
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
Ive always wanted to find another set of cases, to "work on" ...
as Id like to be able to change the seals from the outside...
I think its doable... with alot of work
I did the lower end in my '97 KX250, and if I remember correctly there is a series of casting lips around the OD of the crankcase seal bores that only allow the seals to be installed from the inside of the case. You could bore those nubs off and be able to install seals from the outside, but then my only concern thereafter would be the imfamous KX500 kickstarting "backfire" blowing the seals clean out of the bore(s) ! :-o
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
Ive always wanted to find another set of cases, to "work on" ...
as Id like to be able to change the seals from the outside...
I think its doable... with alot of work
I did the lower end in my '97 KX250, and if I remember correctly there is a series of casting lips around the OD of the crankcase seal bores that only allow the seals to be installed from the inside of the case. You could bore those nubs off and be able to install seals from the outside, but then my only concern thereafter would be the imfamous KX500 kickstarting "backfire" blowing the seals clean out of the bore(s) ! :-o
That would be step one.. The easy part if you will...
The lot of work part would be making some kind of retaining system like Honda uses..
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well i have found the problem.................. i have an FMF spark arrestor installed. i was doing some swapping around while servicing the suspension and found a loud rattle when i was moving the sub frame around. turns out the pipe down the middle was broken off so the tail of the silencer was filling with exhaust and not moving out. thats where the oil and goop was coming from. i put on the stock silencer and its much better. sounds crisp again and missing like before. i havent had the silencer off in quite some time so no idea how long i was trying to tune around this issue. so anyway just goes to show ya...............start with the simple stuff.
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it is not out of the question!!! if it were a honda id just change them and not give it a thought....
Ive always wanted to find another set of cases, to "work on" ...
as Id like to be able to change the seals from the outside...
I think its doable... with alot of work
I did the lower end in my '97 KX250, and if I remember correctly there is a series of casting lips around the OD of the crankcase seal bores that only allow the seals to be installed from the inside of the case. You could bore those nubs off and be able to install seals from the outside, but then my only concern thereafter would be the imfamous KX500 kickstarting "backfire" blowing the seals clean out of the bore(s) ! :-o
A set of locking plates would fix that problem.
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well i have found the problem.................. i have an FMF spark arrestor installed. i was doing some swapping around while servicing the suspension and found a loud rattle when i was moving the sub frame around. turns out the pipe down the middle was broken off so the tail of the silencer was filling with exhaust and not moving out. thats where the oil and goop was coming from. i put on the stock silencer and its much better. sounds crisp again and missing like before. i havent had the silencer off in quite some time so no idea how long i was trying to tune around this issue. so anyway just goes to show ya...............start with the simple stuff.
Glad you found the culprit. So the pipe inside the silencer was broke and causing a blockage?
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well i have found the problem.................. i have an FMF spark arrestor installed. i was doing some swapping around while servicing the suspension and found a loud rattle when i was moving the sub frame around. turns out the pipe down the middle was broken off so the tail of the silencer was filling with exhaust and not moving out. thats where the oil and goop was coming from. i put on the stock silencer and its much better. sounds crisp again and missing like before. i havent had the silencer off in quite some time so no idea how long i was trying to tune around this issue. so anyway just goes to show ya...............start with the simple stuff.
Awesome ! Ususally most people that come here asking why their bike runs like crap stems from a junk top end. Glad to read that you have a simpler to fix issue. Reminds me back in the 80's when I was racing MX , i left a paper towel in the carb to keep dirt out, and in a frenzy slapped the air filter back in without removing the towel ! The bike ran like $hit ! I was dead last in that moto took me an hour to figure out what a dumba$$ mistake I made ! :?
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well the broken tube inside the muffler wasnt necessarily causing a blockage.............it just wasnt allowing the exhaust to flow directly out of the silencer. all the packing was blown out so the rear compartment was filling up before pushing the rest of the exhaust out.
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ride update.................
the bike ran superb. ive been trying to get it to run like this for quite sometime. the response was immediate and on a nice dry day in the desert traction was impossible..........just the way youd expect a good running 500 to behave.
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ride update.................
the bike ran superb. ive been trying to get it to run like this for quite sometime. the response was immediate and on a nice dry day in the desert traction was impossible..........just the way youd expect a good running 500 to behave.
Get your 500 on some traction friendly hardpack dirt and the sheer brutal acceleration will literally horrify you (in a fun way). You sand guys are leaving a ton of traction potential on the table... too bad ! :cry: