Crank question

[arakyle]

So after I disassemble the cases replace the mains in the case, how do you reinstall the crank into the press fit left case? To get it out I used a press... not sure if that is the best idea for putting it back in. Also I have heard people talk about floating the crank in the bearings... anyone have any ideas on this?

[96_banshee_96]

I would also like to know. I am about to put my motor back together as soon as I get my cases back from the powder coater.

I have heard of people putting the crank in the freezer because metal contracts when cold and its supose to just drop right in but I dunno if it realy works.

The guy I work with pulled my cases apart with a puller.

[Dave83]

Just slide the crank into the bearing on one side(freezing it will help) and then start the other side on.The case halves will get fairly close to each other and you can start some of the bolts.I start the longer ones first and snug them down then start a few of the shorter ones.Start in the center snugging the bolts(I tap the cases with a rubber mallet lightly also).Keep this up until the halves are sealed and the bolts are torqued properly.

[Rich250RRacer]

Originally posted by Dave83
Just slide the crank into the bearing on one side(freezing it will help) and then start the other side on.The case halves will get fairly close to each other and you can start some of the bolts.I start the longer ones first and snug them down then start a few of the shorter ones.Start in the center snugging the bolts(I tap the cases with a rubber mallet lightly also).Keep this up until the halves are sealed and the bolts are torqued properly.

This method will put unnecessary stress on the crank and possibly knock it out of "true". If you don't have the correct tool, freeze the crank and use a heat sink (a small block of steel heated to 400-500 degrees). Rest the heat sink on the inner race for about 5 minutes. If your quick, the crank will drop right in.

This is the correct tool.

http://i228.photobucket.com/albums/ee108/rich250rracer/motor%20rebuild/mot15.jpg

[LONG-ROD]

I froze myu crank for like 30 min and but my cases in the oven on the lowest setting for about 10 min slide right togather.

[Dave83]

How would my method knock the crank out of true?It works no different than that tool pictured.Pushes the bearings on the crank,not driving the crank into the bearings.That tool threads into the crank and pushes the case/bearing onto the crank ,correct????

[Rich250RRacer]

Originally posted by Dave83
How would my method knock the crank out of true?It works no different than that tool pictured.Pushes the bearings on the crank,not driving the crank into the bearings.That tool threads into the crank and pushes the case/bearing onto the crank ,correct????

It is way different from your method. The tool threads on the end of the crank and pulls the crank into the bearing. Your method is putting force on both sides of the crank weights and can actually push the crank together, especially in the area where the rod pin doesn't support the weights. The crank should never be forced into the bearings and like I've said on here many times before, NEVER, EVER use a hammer of any kind to tap the cases together.

[atvmxr]

Originally posted by LONG-ROD
I froze myu crank for like 30 min and but my cases in the oven on the lowest setting for about 10 min slide right togather.

x 5 or so.... night before put the crank in the freezer (wrapped in plastice wrap). put the case in the oven on lowest setting (175-200 or "warm") for about 30-45 minutes.. take out the case and quickly drop in the frozen crank. works great. ;)

[C-LEIGH RACING]

Wagner hot air heat gun, left side case, heat the case around the bearing hole, drop the bearing in.
Put the crank in a cold place, then heat the bearing inner race, drop the crank in.
Heat the right side case where the bearing hole is at, drop the bearing in.

Rule of thum,
when heating the case halfs to install the bearings, when you have the case hot enough that you cant touch the rear of the case half where the rear engine mounting hole is at, then the case is hot enough so the bearing will drop in freely.

While the crank is sitting in that cold place, allow some of the case heat to soak into the bearing & then start heating the inner bearing race, keeping in mind you need high heat for the race to expand enough so the crankwill slip in easy.

You may need some high heat gloves if you've never done this before.

IF, you have an OEM Honda TRX250R crankshaft, the machining on the crank will allow a slip fit into the bearing on the clutch side, so no pressing in is needed when putting the two case halfs together.
Aftermarket Hot Rods & Wiseco cranks, the machining on them is different & are press fit into the clutch side bearing.
Neil

[Rich250RRacer]

Originally posted by C-LEIGH RACING
Wagner hot air heat gun, left side case, heat the case around the bearing hole, drop the bearing in.
Put the crank in a cold place, then heat the bearing inner race, drop the crank in.
Heat the right side case where the bearing hole is at, drop the bearing in.

Rule of thum,
when heating the case halfs to install the bearings, when you have the case hot enough that you cant touch the rear of the case half where the rear engine mounting hole is at, then the case is hot enough so the bearing will drop in freely.

While the crank is sitting in that cold place, allow some of the case heat to soak into the bearing & then start heating the inner bearing race, keeping in mind you need high heat for the race to expand enough so the crankwill slip in easy.

You may need some high heat gloves if you've never done this before.

IF, you have an OEM Honda TRX250R crankshaft, the machining on the crank will allow a slip fit into the bearing on the clutch side, so no pressing in is needed when putting the two case halfs together.
Aftermarket Hot Rods & Wiseco cranks, the machining on them is different & are press fit into the clutch side bearing.
Neil

The heat gun is a good idea Neil, which will work great for tranny bearings too. I use a press for the crank bearings, but not everybody has access to one, and they should be used carefully, otherwise you could end up with cracked cases. As for the clutch side, I've run into an OEM crank that was tight enough to use my crank tool on. I've also come across a brand new OEM crank that didn't have a punch mark to line up the primary gear.

[C-LEIGH RACING]

Been using that ol heat gun for a bunch of years now, shes looking ruff though.
Neil

[norcalduner]

Originally posted by Rich250RRacer
This method will put unnecessary stress on the crank and possibly knock it out of "true". If you don't have the correct tool, freeze the crank and use a heat sink (a small block of steel heated to 400-500 degrees). Rest the heat sink on the inner race for about 5 minutes. If your quick, the crank will drop right in.

This is the correct tool.

http://i228.photobucket.com/albums/ee108/rich250rracer/motor%20rebuild/mot15.jpg

Where can I get this tool ?

[Rich250RRacer]

Originally posted by norcalduner
Where can I get this tool ?

It's OEM Honda. The part numbers are in the factory service manual. Each piece has it's own part number and they have to be ordered individually. The numbers in the book are older, so there may be updated numbers for them. CR's use the same tool (with different numbers), so if there's a problem I can get you those.

[machwon]

Its hard to stress the importance of that honda tool. The tool works awesome and in case the hot/cold method doesn't work or if it gets stuck half way. The tool can finish the job. Better yet it does it right the 1st try.