Jump to content
Sign in to follow this  

What do i need to know before getting a crank re-built?

Recommended Posts

I'm going to get a falicon rod put in my crank but im having a hard time deciding where to get it re-built at, How do i know who can do a good re-build ?

What do i need to know about truing a crank, I have read about a crank being 5thousands of an inch out... What does that mean, 5thousands out of what and what is considered good truing ?

There is a place near to where i live that re-builds cranks and i want to take it there, I just want to get info online first.

Thanks

Share this post


Link to post
Share on other sites

Know that Honda cranks are difficult to rebuild and many shops wont do it. The crank will not be rebuildable if someone hammered it out of the cases and damaged the the center hole at either end.

Share this post


Link to post
Share on other sites

Know that Honda cranks are difficult to rebuild and many shops wont do it. The crank will not be rebuildable if someone hammered it out of the cases and damaged the the center hole at either end.

What is different on honda cranks ?

I know a shop that will re-build the crank for me but i just don't know if they can do a good job...

And i sure wouldn't hit the crank out with a hammer !

Share this post


Link to post
Share on other sites

There is a company called Mr. Crankshaft, I believe, that does a good job at a reasonable price and comes recommended by several of the members here. Google.

Crank truing is the process of aligning the two sides of the crank with each other so that the shafts on both sides are on the same center. In order to rebuild the crank. it is pressed apart, then the new crank pin pressed into place in one side, rod installed, and the other half of the crank onto that. There are no keys or splines to guide the assembly back to its perfect alignment, so this has to be done after the assembly is made.

The center holes at the crank ends are not used for the truing process in most cases. The crank is placed in a stand that supports it by resting the main bearing journals on thin edged rollers running on ball bearings. Dial indicators are used on the flywheels of the crank to detect any out of round or asymmetry conditions, which are then corrected before calling the job done. If the crank does not have flywheels with a cut surface around the entire circumference, it becomes necessary to use the center holes to support the crank and apply the dial gauges to the bearing journals. This is a more difficult approach as far as getting precise readings goes.

Share this post


Link to post
Share on other sites

I have a feeling that Mr. Crankshaft has the proper jigs and measuring setups to do the job right. What you want to avoid is someone who is winging it.

Share this post


Link to post
Share on other sites

What is different on honda cranks ?

I know a shop that will re-build the crank for me but i just don't know if they can do a good job...

And i sure wouldn't hit the crank out with a hammer !

Shops that rebuild a lot of cranks have fixtures to press them together with. Many shops do it on a lathe. The centering holes offer a true center to use to build cranks without any special fixtures. After the crank has been pressed together a hammer and wedges are used to true the crank. The trouble with Honda cranks is that they use sheet metal shrouds around the crankshaft to take up volume in the cases. Any attempts to true the crank with a hammer or wedges will dent and desroy the shrouds. So, the cranks have to be pressed together true to begin with. This can be done on the lathe without fixtures but you have to stop and check it many times on the way.

Now, I said the problem with Honda cranks are the sheet metal shrouds but maybe they're not? A new factory crank for a contemporary Honda 2-stroke runs around $240. Cost to rebuild a crank with OEM parts is $100 +$90 in labor. Other manufacturer's (Yamaha) cranks cost $350+ for new replacements.

Share this post


Link to post
Share on other sites

Now, I said the problem with Honda cranks are the sheet metal shrouds but maybe they're not? A new factory crank for a contemporary Honda 2-stroke runs around $240. Cost to rebuild a crank with OEM parts is $100 +$90 in labor. Other manufacturer's (Yamaha) cranks cost $350+ for new replacements.

I agree you're not much money ahead on a Honda crank, only good reason is if you are using a custom rod or a special rod or are in some way not happy with the factory original.

Share this post


Link to post
Share on other sites

There is a company called Mr. Crankshaft, I believe, that does a good job at a reasonable price and comes recommended by several of the members here. Google.

Crank truing is the process of aligning the two sides of the crank with each other so that the shafts on both sides are on the same center. In order to rebuild the crank. it is pressed apart, then the new crank pin pressed into place in one side, rod installed, and the other half of the crank onto that. There are no keys or splines to guide the assembly back to its perfect alignment, so this has to be done after the assembly is made.

The center holes at the crank ends are not used for the truing process in most cases. The crank is placed in a stand that supports it by resting the main bearing journals on thin edged rollers running on ball bearings. Dial indicators are used on the flywheels of the crank to detect any out of round or asymmetry conditions, which are then corrected before calling the job done. If the crank does not have flywheels with a cut surface around the entire circumference, it becomes necessary to use the center holes to support the crank and apply the dial gauges to the bearing journals. This is a more difficult approach as far as getting precise readings goes.

Thank you so much for that reply, It is exactly what i wanted to know.

And thanks to everybody else for your answers also, They have all helped me out.

Now to find a good place to get my crank built !!

Share this post


Link to post
Share on other sites

Google turned up this place

http://www.jktuning..../crankshaft.htm

That place is over 2 hours from where i live, I am hopefully going to find a good place within an hour...

There is a place 20 minutes away that does cranks but i just don't know how well they do cranks, They seem to do all sorts of sports bike and MX bikes cranks so i think they will do a good job... Looks like i will find out soon.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×
×
  • Create New...