Maintenance & Technical > KX500 Original
Plethora of Questions
NastyNick:
Hey all, I have a bunch of newbie mechanical questions that I hope you can answer for me.
background:
I own, among others, a 93' KX5 what has worked really well for my type of riding, but the previous owners didn't do much to it as far as maint goes. So, I am in the process of rebuilding it. I CAN make it faster and stronger. hopefully it won't take 6 millions dollars to do it. ;)
Super newbie question 1: Whats the hole (drilled in the side) for on my new Tusk drain plug?
newbie question 2: Is it easier to do a top-end rebuild (see question 3) while the motor is in the frame? I have to pull it out anyway (frame welding job), but I read in my Clymers that it's sometimes easier to just leave it in the frame. Whats your experience?
newbie question 3: I am going to attempt my first top-end rebuilt myself. I am pretty good with a wrench, but have never cracked to top off a motor. Anybody have any suggestions or should I just take it in to the shop and let somebody else do it. Keep in mind that I have blown my "new bike" (kx250f) and my "upgrade" budgets for this year. Any more and my wife is gonna get reeaally mad. :)
I have already purchased a new Wiseco kit (pistion, wristpin, rings, circlips, etc), an engine gasket kit, and oil-seal kit and I think I have all the tools I will need.
newbie question 4: The previous owner of this k5 used belRay H1R at a 50-1 ration (one small bottle of oil to 5 gallons is what he told me). I used that same ratio all last year and it didn't seem to hurt anything, but with the new pistion and such, I am wondering if I should change things around. Keep in mind I don't ride the beast to it's full potential (yet).
newbie question 5: jetting? I order a new reed cage and reeds for it and am thinking I should change back to the stock jets. The previous owners had some goofy jets in it, but the motor ran fine. Strong through the whole powerband and didn't blubber or loadup. My qustion: What jets sizes should I use? I think the stock ones are a #60 pilot and a #168 main. I live and ride anywhere from 3500 feet to 5k in Montana. My problem is that I hate dinking with the jets after I have everything back together. I suppose the stock ones are a good place to start though. Does anybody think I should change them at all with the new reeds?
Any and all help would be appricated.
Thanks!
NN
mikesmith:
The hole in the plug is so you can saftey wire it to the frame so theres no chance of it falling out,be carefull tightening the plug,it can strip easily-just snug with the safety wire.You can do the top end ethier way,if you make a stand from 2x4's it's just as easy on your work bench if not easier.If you feel you can do it,buy a manuel,take pictures as you take it apart.If your worried and have your doubts have some one who knows how help or take it to a shop and pay them.I run 40:1 Maxima Super-M and like it,you can find some one to bad mouth just about any thing-so if your happy with Bel-Ray,run it,but I do like Maxima prouducts.Jetting is something you need to learn as your jetting can change with the weather,altitude,humidity,and tempature.I cant give you the jet #'s you need,but startring with stock and experimenting is where to start and how to learn how it affects your bike.Hope this helps some.
kawdude:
--- Quote from: NastyNick ---Hey all, I have a bunch of newbie mechanical questions that I hope you can answer for me.
background:
I own, among others, a 93' KX5 what has worked really well for my type of riding, but the previous owners didn't do much to it as far as maint goes. So, I am in the process of rebuilding it. I CAN make it faster and stronger. hopefully it won't take 6 millions dollars to do it. ;)
Super newbie question 1: Whats the hole (drilled in the side) for on my new Tusk drain plug?
newbie question 2: Is it easier to do a top-end rebuild (see question 3) while the motor is in the frame? I have to pull it out anyway (frame welding job), but I read in my Clymers that it's sometimes easier to just leave it in the frame. Whats your experience?
newbie question 3: I am going to attempt my first top-end rebuilt myself. I am pretty good with a wrench, but have never cracked to top off a motor. Anybody have any suggestions or should I just take it in to the shop and let somebody else do it. Keep in mind that I have blown my "new bike" (kx250f) and my "upgrade" budgets for this year. Any more and my wife is gonna get reeaally mad. :)
I have already purchased a new Wiseco kit (pistion, wristpin, rings, circlips, etc), an engine gasket kit, and oil-seal kit and I think I have all the tools I will need.
newbie question 4: The previous owner of this k5 used belRay H1R at a 50-1 ration (one small bottle of oil to 5 gallons is what he told me). I used that same ratio all last year and it didn't seem to hurt anything, but with the new pistion and such, I am wondering if I should change things around. Keep in mind I don't ride the beast to it's full potential (yet).
newbie question 5: jetting? I order a new reed cage and reeds for it and am thinking I should change back to the stock jets. The previous owners had some goofy jets in it, but the motor ran fine. Strong through the whole powerband and didn't blubber or loadup. My qustion: What jets sizes should I use? I think the stock ones are a #60 pilot and a #168 main. I live and ride anywhere from 3500 feet to 5k in Montana. My problem is that I hate dinking with the jets after I have everything back together. I suppose the stock ones are a good place to start though. Does anybody think I should change them at all with the new reeds?
Any and all help would be appricated.
Thanks!
NN
--- End quote ---
Hey, welcome. I've got a 94 that I'm currently rebuilding. It's been fun and spendy. The guy who owned this didn't do any maintenance as far as I can tell. With some of the wear in the bottom end I'd be surprise if the oil was ever changed.
1.Hole is used to attach a piece of wire from the hole to the frame so it doesn't fall out.
2. I haven't done the topend in the frame. I pulled the motor. Not hard to do. Probably the hardest part is the swingarm bolt. Make sure everythings supported BEFORE you pull that bolt. Basic tools should do it. Oh, you'll need a in.lb. wrench and a ft.lb. wrench. Make syre you look at the plating in the cylinder. It may be wore out.
3. Top end is easy. Bottom gets tougher but it's not bad either. Don't waste you money on a shop charge. If you get stuck post it here and it will be answered ten fold. This place is like your own personal mechanic.
4. 50:1 is too "something". I use 32:1 and I know some guys here use 40:1. I'll defer to someone that has more knowledge on this. For the new top end I would stay at what the factory wants but that's just my opinion. Again, I'm out of my element with this question.
5. For jetting start with the FAQ's. This chart gives an idea to start with. My KX has a 162 and a 62. I ride at about a 1000ft. Mine is not jetted correctly and ran like crap. I'll defer this one also. Do you need new reeds?
NastyNick:
--- Quote ---saftey wire
--- End quote ---
doh! I knew it had something to do with that. The Tusk plug appears to made out of aluminum and not a big fat steel bold like the original.
--- Quote ---With some of the wear in the bottom end I'd be surprise if the oil was ever changed.
--- End quote ---
The DFO (dreaded former owner) didn't have that problem. He had a leaky o-ring and seal on the counter-shaft side. He went through 6 quarts of gear lube a summer, just riding it once a week for a couple hours. It leaked all over his floor. Didn't make monetary sense tho, at 7 bucks a pop for the oil, a 6.95 seal and pennies for the o-ring. Then again, he never had to change the fluid. :)
--- Quote ---I use 32:1 and I know some guys here use 40:1
--- End quote ---
I tried experimenting last summer and U found it splooged way bad with any thing other than 50:1. maybe a carb issue?
--- Quote ---Do you need new reeds?
--- End quote ---
Yeah, probably. i pulled them out and they were cracked and appeared to be "burnt". Burnt isn't the right word...more like discolored.
Thanks for the help guys...I'll think I'll pull the motor out tonight and get started on it.
Rick:
Well, since you have answers on most of your questions, I'll not chime in on any of those. However, here are a few additional items.
1. Bel-Ray at 50:1 - H1R is a synthetic oil, and can be run at 50:1 without any damage to the motor. Other oils with different molecular structures require different ratios. Stay with Bel-Ray and you will be fine.
2. Top end job will take less than an hour if you leave the motor in the frame (I've probably done a hundred this way). However, if you have to take the motor out anyway to accomplish frame repairs, change the top end with the motor on the bench. If this is the first time for you, you will be able to watch the process better on the bench.
3. A top end job DOES NOT require taking the head off the jug. If the head is not leaking, and mods are not going to be done, leave the head on the jug. This will require a little more wiggle to clear the frame when you pull the jug while still in the frame, but just rotate the piston all the way to the bottom of the stroke and you will have enough clearance. When you put the jug back on the motor, have someone else sitting on a stool on the other side of the bike to help guide the jug down as you sqeeze the rings together. The piston has a ring locater pin in each ring groove, so extra help with jug installation helps avoid damage to the rings.
4. While the jug is off, clean the power valves. I have a couple of posts on the process on this site, but if you can't find them, just say the word.
5. The counter shaft oil leak can probably be fixed with a thicker o-ring. Paul can post the part number from Home Depot. However, even if the seal is the culprit, it can be changed without pulling the motor.
6. While the motor is out, grease all the suspension. You will probably need a lower shock bearing (I go through a couple a year), but just change the bearing unless other parts are damaged. I have a post on how to change the bearing without any special tools and without pulling the suspension part.
7. While your changing pistons, stuff some rags into the crank chamber. This is easier than trying to fish for the piston pin clip.
This should get you started. Post up with any problems.
Enjoy.
Rick
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