Crankshaft: Replace or not?

[VZTech]

Hey everyone I need some advice. I bought a 86r completely original and stock about a yr ago I have finally got around to working on it. When I got it the left side case was busted from the chain coming off,so I have the engine at the shop getting the new case put on and new top end ,basically while it was there and apart getting the engine completely gone through. They told me that the crank is good and nothing is wrong with it but while it was apart I might want to think about putting a new one in it. I don't know what to do.I bought the bike from my cousin and the shop told me that the standard bore piston is still in it and it doesn't need bored so we are putting a stock piston back in. Just from that wouldn't the engine have to be in good condition as old as it is? The bike has never been raced or modified,will I be ok to put the crank back in or not? I really don't want to spend the extra money for a new one if this one is good. Any opinions or advice would be appreciated. Thanks in advance.

[250r4life]

if they said it is still good, i would probably leave it in there... i hope they checked the clearances on it...

of course, it depends on if you plan on modding it in the future... if youre going to leave it stock, it will have pretty mellow HP and should be able to run for a long time...

if you are going to mod it, obviously it will wear out sooner...

thats a hard one... i guess it depends on how much that extra $275 is going to hurt you. you can get a whole new OEM crank and rod assembly for $275

[86 Quad R]

if the crank checks out ok and there isnt any up n down movement or side to side i say run it but, i would atleast change the crank bearings on it. as for the bore. i'd atleast go one over with it to be on the safe side. twenty years on a stock bore is a lotta running for it "NOT" to be out of round or have a slight taper to it.

[250r4life]

yah... thats a good idea... spend $45 and get some new bearings...

[kiesta00]

If I were you i'd go ahead and change all the bearings/seals/gaskets in the bottom end while you're at it. Saves you some headache down the road, do it while its apart.

[86 Quad R]

changing all of the bearings is not a bad idea but, not really necessery. a thorough inspection of the remainder of the bearings is important and by doing so will tell if they need replacing or not. a good method is to clean the cases and bearings. afterwards, physically rotate then with your index finger and check for abnormal slack.

[kiesta00]

woops didnt mean ALL bearings, meant that for gaskets and seals lol

[peeping TOM]

yer those bearing that the gear shafts run on seem invinsible !!!!!!!

[Saint18z]

www.mrcrankshaft.com he will regrind your crank and make sure its trued i got mine done by him w/ a new hot rods rod for 170 shipped