questions in a crank swap since mines bad

[peatree90]

so i spun a rod barring and it scored my crank and rod... so i was wondering if i bought a used crank and used rod and pistons would i have to have them balanced or would i just be able to slap it together and be fine??? or should i just buy a used motor and just put that in ..... second if i do buy used would 600rr parts fit in the 600f4i same year??? that might be a stupid question but i was just wondering bc im finding a lot of parts for the 600rr not that many for the f4i thanks for the help... ps i have a 2003 f4i stunted out

[WHEELIE]

1. You're going to have more money (with labor time) than
what it's worth, than just buying a motor and slapping it in.. IMHO
2. No the 600RR and the F4i are different too...


Good luck on which ever way you go

[~03~raven]

I'm sure there are different bearing codes so you would have to wait til you got the new crank in hand and figure out what main and rod bearings you need. Like with the Yamahas there are numbers stamped on the motor case, numbers on the rod endcaps, and numbers on the the outter must crank web. by using the numbers on the crank web and the numbers on the case you get the journal bearing code, using the crank web and the rod end cap number you get the rod bearing code. That make sense?

[Wheeliest]

for a cheap quick fix that could last 1 hr or 40k miles, u can throw in a used un-damaged crank and slap a used rod with new rod bearing. but in a perfect world, there are markings on the rod and cases that require specific bearing sizes (when assembled new) your actually suppose to plasti gauge the plane bearings (crank bearings/journals) but from what i seen in the different size crank bearings is not a real measurable amount. you will need to buy a new head gasket also.

[Wheeliest]

Quote:

Originally Posted by ~03~raven I'm sure there are different bearing codes so you would have to wait til you got the new crank in hand and figure out what main and rod bearings you need. Like with the Yamahas there are numbers stamped on the motor case, numbers on the rod endcaps, and numbers on the the outter must crank web. by using the numbers on the crank web and the numbers on the case you get the journal bearing code, using the crank web and the rod end cap number you get the rod bearing code. That make sense?

just so you know, most SS race built motors for club racing they use the thinnest factory bearings available for rods and crank. so its not necessity to match the codes.

for a perfect build, you would use a brand new crank, along with brand new cases and start completely fresh.

[peatree90]

thats what i figured about the motors but was just checking.... but i was planning on doing all the work my self im pretty good wit a wrench.. but if it has to be rebalanced then i think ill just do the used motor instead of going through all that trouble thank alot for the info.

[peatree90]

sounds like a bigger head ache then its worth rebuilding then buying a motor out a wrecked bike.... im good but no professional mechanic

[Wheeliest]

no "rebalancing" needed.

[JohnnyP]

Quote:

Originally Posted by Wheeliest just so you know, most SS race built motors for club racing they use the thinnest factory bearings available for rods and crank. so its not necessity to match the codes. for a perfect build, you would use a brand new crank, along with brand new cases and start completely fresh.

Thats not correct man, if the bearings arent the right size your rebuild will last 5 minutes...

There are numbers on the crank, engine cases and rod ends...Those are used to find the correct bearing size..And usually is more then one different size in one engine...

The chances of getting a used crank that shares the same numbers as your engine is like a million to one...If its too tight they will fail right away, if its too loose they will fail very soon also...

Running loose tolerance for a race engine is for power, but not for reliability...And theres a huge difference between running loose tolerance that has been measured and calculated and just using a different crank without the proper bearings or even checking the clearance

[Wheeliest]

I've built several 954 motors and 07 gsxr 1k motors, and believe me, you get the same plasti gauge numbers with every color bearing. even used un matched cases, those motors are still going strong. there is a shit load of lee way in the tolerances which you would think it would lead to catastrophic failure quite quickly and it doesn't.

Quote:

Originally Posted by JohnnyP Thats not correct man, if the bearings arent the right size your rebuild will last 5 minutes... There are numbers on the crank, engine cases and rod ends...Those are used to find the correct bearing size..And usually is more then one different size in one engine... The chances of getting a used crank that shares the same numbers as your engine is like a million to one...If its too tight they will fail right away, if its too loose they will fail very soon also... Running loose tolerance for a race engine is for power, but not for reliability...And theres a huge difference between running loose tolerance that has been measured and calculated and just using a different crank without the proper bearings or even checking the clearance