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View Full Version : ot:getting a cr250 crank pin out



j king
10-26-2003, 05:27 PM
I figured someone would know how this is done. I am rebuilding my boy's fl250 honda{same as older cr250} and dont know how they press the crank throw pin out.As it holds both sides of the crankshaft together I figured it is shrunk in pretty tight.Also if you know the procedure of installing a new one. Thanks for any help. Jim

gamachinist
10-26-2003, 05:56 PM
You'll need some kind of fixture to hold it in a press.To reinstall,the wheels can be heated to allow the new pin to slide in.Then it will have to be trued.This is done on centers or v blocks off the stubs with a dial indicator on the od of the wheel.
It might be easier to take it to a shop that has all the fixtures and.(Try an independent Harley shop if the local dirt bike shop can't help you).
Robert.

motorworks
10-26-2003, 07:19 PM
Jim
I rebuild these and others in my shop.
Labour runs about $40-$75 Canadian for a single throw,but parts can be $$!!
Better to bring it to your local shop and have it done right.
regards
eddie

suomi
10-27-2003, 12:03 AM
I have done some work on snowmobile 2 stroke cranks and I sure that CR crank is no differnt. what you need is a steel plate about 12x6x.750 that you cut a U in. the U fits around the rod and supports the crank wheel. Then press away on the crank pin YOU NEED A GOOD PRESS (really tight). Reassemble in reverse order then put the crank on v blocks using a dial indicator to check runout wail away on the crank with a lead hammer till it is straight hope this helps.

Ragarsed Raglan
10-27-2003, 08:52 AM
Jim,

As Soumi says.... the press needs to be about 10ton force. Never heat the wheels, even though they probably run at close to 300*F when the engine is running, they could deform when split apart and the stresses are relieved.

Before splitting the flywheels scribe a line across both wheel rims, at the 180* point - opposite the big end, to aid re-assembly. Use this as a guide when fitting the pin into the second wheel on re-assembly. True the wheels on parallel knife edge straight edges (off the bearing diameters on the crank mainshafts) using a lead mallet to 'thump' the wheels into alignment (that scribe line will get you close but your still going to need to 'trim' the wheels to truth). Check alignment of wheels in the rotational axis; this will probably call for the wheels being 'wedged' open on the side opposite the pin.

It's an art to do this, but one which with patience, and some fore thought, is soon learnt.

RR

[This message has been edited by Ragarsed Raglan (edited 10-27-2003).]

j king
10-27-2003, 06:44 PM
Thanks guys.I think for what the parts cost I better get it a bike shop to do this. Jim

audrey
10-28-2003, 08:37 AM
Crankshaft Pins. Press must be heavy Duty. We used a Fifty ton Model from Princess Auto. I used to press out 40 mm crank pins on my Motorcycle. Good Idea to have a slide down safety screen to prevent parts from going through you like a bit of shrapnell. Measuring the space between the wheels and making up a suitablely sized block so to press it back together close to original factory speca also helps. This can be adjusted with suitably sized shims to get proper spacing. Then on the lathe and indicate and start whacking into shape. If out also a large c clamp can be used to move it a bit but with the block usually the flywheels are parallel. I hope this gives you an idea. Mike Auds old Man