92 CR500 Rebuild

[ianj454]

I am currently in the process of rebuilding the bottom end of my 92. The crank bearing on the left side completely fail causing the crank to rub against the case. From the pictures what is your opinion on the damage to the crank and case, am I better off buying a used complete bottom end instead of going on with the repair?




Also I had to drill out the retaining screw for the bearing on the transmission, what is the best method to remove this, or am I better off bringing it to a machine shop?

[crashtestdummy]

I do not like to give my opinion without more information so I will guess at a couple of things.
1. You shut the motor off as soon as you heard the scrapeing noise.
2. You have some degree of mechanical talent and you possibly have more tools than the average home mechanic or someone else split the cases apart for you.

If it was my motor (I also have a 92 that I rebuilt after the right case split where the kickstart shaft is) I would determine if the strength of the case at the left hand bearing has been compromised, if I decided that a good buff job to smooth out the grooves on the case would be okay I would still replace the crankshaft. The crank is the one part that will grenade the whole engine if it fails. If I decided to reuse the crank I would have to have it turned down, checked for the trueness of the counter wieghts and balanced at a machine shop since I don't have my lathe anymore. Then I would still have a used crank, piston and connecting rod that had experienced some amount of abnormal stress.

I have removed broken bolts from many motors over the years. I would remember the times I tried to drill out a steel bolt free hand from an aluminum engine case and wishing I hadn't attempted it, although I have had enough succesful bolt extractions over the years to keep me dumb enough to try it again. I would find or make a new friend who has a drill press and some good extractor bits, not the ones that snap off with the slightest amount of twisting. If I had to take it to a machine shop and pay to have it done I would remember how much cheaper it would have been if I had went to the machine shop before I screwed up the aluminum engine case to begin with.

I am very fortunate that my son-in-law is a multi factory certified motorcycle mechanic who specilizes in dirt bikes. He has every specialty tool you can imagine in his garage. We can blow up an engine in the morning and if we have the parts we can completly strip a motor and be riding again in the afternoon.

[ianj454]

Thanks for your reply!

The bike was running like shit and very hard to start so I figured it had to be a crank seal gone. When i removed the stator case I noticed I could move the crank with my hand. I put the bike away and stuck with my cr125 until I had enough funds to continue with the 500.

As for experience I would not say I am an expert but I have done just about every repair minus the bottom end (this is my first). I have all the proper tools for splitting the cases and re-installing the crank. I was thinking my self to bring the case to a machine shop to remove the screw as I don't have a drill press.

I figured the crank was a loss, so I started looking at new cranks on ebay, anyone have any experience with hotrods cranks in 500's?

Also what would be the best way to remove the grooves from the case, water paper?

[scooter5002]

Hot Rods. Made in China. ProX. Made in Japan. Need I say more?
Go buy a kit and have your stocker rebuilt.

[ianj454]

I would go pro x but they only make connecting rods for my bike.

[BiPolar_Bear104]

I have a hotrod crank and connecting rod in my 95 cr500 and i have a really big bore. I have put about 60 hours on it and so far so good! I just had to replace my Pro X piston after 2 rides.. I had "cold seized" after letting it warm up to 120F. (Don't know how it happened but I personally will not buy any of there products anymore) Hope this helps your decision.

[crashtestdummy]

I have had a hot rods crank in my 500 for three years now. A couple of things that I had to watch out for;

As for me I would just remove the burrs and sharp edges on the case. I don't think it's nessacary to remove the grooves, just the stuff that may come loose.

When I had to remove the transmission gears there are shims that like to hide under the gears as I was pulling the gear set out and they might have fallen off if my son-inlaw had not made me aware of the issue. I go slowly on every transmission tear down and do my tolerance measuring as I go then I know what to order depending on how much money is in the toy fund. I also take pictures. I have had too many whacks to the head over the years to trust my memory.

Have the crank bearings installed at a machine shop in the cases not on the crank as you will not be able to push the cases together with the bearing on the crank unless they are perfectly aligned which will never happen. DO NOT pull the cases together with the bolts. Use a dead blow hammer softly until the cases are aligned and touching. If they wont go, take them apart, check things over and try again, repeat as necassary.

One little trick that I use is when I am at a point where I can rotate the engine I remove the spark plug then take my air impact wrench, turn the pressure down and spin the engine slowly while shifting through the gears, when I feel confident that things are okay I crank the pressure up(or use my 1/2" electric drill)and shift through the gears again. When I am happy that the engine and tranny are in good condition then I finish the assembly.

Best of luck to you.

[ianj454]

Thanks for your input!

I know of a very reputable machine shop that has done excellent work for me in the past. Ill have them install all the bearings that involve being pressed in. as for installing the crank I have the crank puller/installer tool so as long as i take my time with it and a rubber mallet I should be good.

As for the transmission I have two different work shop books for the 500, but I have made sure every shim has not stuck to the case and fall off when removing. I was also wondering is there any cheaper upgrades I can do while the cases are apart such as transmission work? I am putting this up against a 2012 CRF 450 when it is complete, and I would like to take that $13K 4 stroke to school.

[crashtestdummy]

I will let you in on my speed secrets.

Try different sprocket combos. I run 15/44 when I want to drag race since the 500 has the power to get my fat butt going. Some times someone will crawl ahead of me at the start but when the 500 winds up into the power band it's all over for them. I'm 6'4" at 290 so I have to feather the clutch on my starts due to the sprocket ratio.

When I get ahead of them I move over in front of them so they can look through my dust cloud. Sometimes they think I,m still in my lane and they will move over to the wrong side and have to hit the brakes. I never said I would play fair.

On my starts I have both feet on the ground in front of the foot pegs. This accomplishes two things; it keeps my legs from wanting to move backwards which, if you watch a lot of starts, the guys legs want to naturally move backwards which just unloads the front and takes you out of the forward/nuetral/balanced position. Secondly when I go for second gear I raise both legs straight up on their way to the pegs but I let off the throttle for just a fraction of a second, and snag the shifter with my boot on the way up. I don't use my clutch when I drag race unless you are a pro rider you can't shift as fast as I can using this technique, every time the clutch and throttle are used together you lose forward momentum. Ask around and find out what a 450 tops out at. I know my 500 can hit 125 with my son-in-law on it.

Of course I will try to jet the carb to fit the conditions, I also run my premix at 20:1 which allows more gas to be in the cylinder when it fires.
I have also found (by accident) that the length of the silencer has an effect on where the torque curve happens in the power band. I use a long silencer for the woods because I feel the motor has more torque lower in the rpm range.

I ride in the mountains mostly so I have no advice on racing a 450 on a track. I gave that up a long time ago in the interest of self preservation. I do have a nephew that can beat a 450 on a two smoke 125 at the track but that's because of his ability to go flat out on any bike he gets on and he is a very technical rider.
Practice,Practice,Practice until your tired of it and then practice some more.

[ianj454]

Thanks! Ill have to give your method a try. As for the race its just going to be a straight drag race, he would kick my ass on a track, as I don't race.

Done a bit more work today and found one of the shift forks looked bad, which explains why it was having trouble sometimes shifting in third gear. The gear that this shift fork moves also looks like it has suffered some minor damage. The side where the shift fork is located to looks darker than the rest of the gear almost like it was burned at one point. Also the teeth on the "burned" side feel a tiny bit rough, but nothing extremely bad.



This picture its a little hard to see but that is where the fork shifter is located. It all looks a little rough and scratched.



Notice the gear in the middle, one side of it is a bit darker.



Here is the shift fork. The metal is "peeling" off it in certain places.

My main concern is not the shifter fork but the gear. Do you think the gear can be re-used, or should I buy a new one? Keeping in mind a new gear for this would be over $100

[AlisoBob]

Dieter or Roosty can answer all your tranny questions... I would replace anything questionable.

If you do the crank and tranny right, the short block should last YEARS, I dont care how often or hard you ride.

[ianj454]

Thanks, Ill replace everything, if you don't do it right the first time, there is no point in doing it at all.

EDIT: Ordered a Hotrods crank kit for it. Going to start ordering the rest of the needed parts over the next little while.

Now to move on to the cylinder problems...