Author Topic: hot rods crank? (Read 9510 times)

jfwyatt1 · « **on:** July 05, 2013, 02:51:33 PM »

why do some people say you need the bearing ID turned down to install a new hotrods crank? is this a must or will i be fine using just the regular oem bearings? i understand you have to press the crank in on both bearings but will doing that be reducing reliability any. thanks guys

GO OVRIT · « **Reply #1 on:** July 05, 2013, 03:31:26 PM »

In my opinion this is one of those where there is not a right or wrong answer. I have one motor that I used the larger I'd bearing and the one before that I used stock honda bearings. I'm pretty sure it was pumashine that said he runs a slip fit on both sides. You just need to be confident that you know the difference between a slip fit and worn crank journals.

Polonda · « **Reply #2 on:** July 05, 2013, 06:06:03 PM »

Running the larger I'd bearing is about ease of assembly and disassembly. I myself have run slip fit on both sides on my motor with no issue. Most of the kart guys also slip fit both sides. When you are constantly splitting cases it just makes it easier. For a motor that is not planning on being split often I would keep the journals press fit for best longevity of the crank. IMO

jfwyatt1 · « **Reply #3 on:** July 05, 2013, 06:20:49 PM »

thanks guys just wanted to be sure before i build this thing again.

GO OVRIT · « **Reply #4 on:** July 05, 2013, 07:22:50 PM »

Quote from: Polonda;848

Running the larger I'd bearing is about ease of assembly and disassembly. I myself have run slip fit on both sides on my motor with no issue. Most of the kart guys also slip fit both sides. When you are constantly splitting cases it just makes it easier. For a motor that is not planning on being split often I would keep the journals press fit for best longevity of the crank. IMO

I couldn't remember if it was you or Tony that said they ran a slip fit on both sides, but figured whichever one of you it was would confirm it.

rsss396 · « **Reply #5 on:** July 05, 2013, 07:51:05 PM »

I run a slight slip fit just on the stator side to allow the crank to seak natural center when running if that makes sense.

But the hotrod cranks have a slightly tighter fit than a Honda crank so it's IMO a good idea to have one side atleast a little looser, does not have to be slip fit but looser than it is to allow for the crank to center itself naturally.

All250R · « **Reply #6 on:** July 06, 2013, 01:02:01 PM »

imo, the hot rods/wiseco cranks have a deficiency in that the right side journal is only larger than the ID of the bearing for ease/cost savings during manufacturing. The proper design is a slip fit crank on the right side and torqued into place by the crank nut. This way the crank can find neutral amount of lateral tension on it after installation. I would have the crank journal turned down to the OEM spec.

All250R · « **Reply #7 on:** July 06, 2013, 01:04:31 PM »

By the way, if you have good journals from an old OEM crank, this is the part number for the CR250R short rod rebuild 13200-KS7-830. It doesn't come with thrust washers and are discontinued from Honda, but ProX ones should be able to be sourced, last time I talked to LASleeve about it.

Tbone07 · « **Reply #8 on:** July 06, 2013, 01:58:07 PM »

For installation purposes, I don't think you would need the ID of the bearings ground if you have a crank puller tool. Tusk makes one and you can find it on www.rockymountainatvmc.com

I love this tool and it makes engine assembly/disassembly so easy. There are also 2 other Tusk engine tools I bought and those help a lot as well. Specufically the case splitter tool.

05450r · « **Reply #9 on:** July 06, 2013, 02:02:37 PM »

Is there more than one place to get the slip fit bearings?

udontknowme · « **Reply #10 on:** July 06, 2013, 05:10:10 PM »

talk with BDT about slip fits. i hear they got a new cnc mill

05450r · « **Reply #11 on:** July 06, 2013, 05:36:59 PM »

Ahahhahaha,good one!! Does anyone else do it?

mx250r91 · « **Reply #12 on:** July 06, 2013, 05:52:57 PM »

I reduced the journal OD on the right side of a hot rods stroker crank with Emory cloth until it measured the same as an old Honda crank to allow the bearing to slip fit. Crude, yes but it worked. Please don't scold me since I didn't do it to Honda spec and check it with their one off jig like they did in the 80s!!

GO OVRIT · « **Reply #13 on:** July 06, 2013, 08:33:42 PM »

Quote from: udontknowme;1223

talk with BDT about slip fits. i hear they got a new cnc mill

Call me a redneck if it makes you feel better, but I like that and just might build one for myself. Don't worry, I won't let it near the R just some woodworking.

jfwyatt1 · « **Reply #14 on:** July 07, 2013, 05:33:02 PM »

i was planning on using my crank puller to pull the crank into the right side case just shy of where it would go when you tighten up the crank bolt then just pulling it carefully onto the left case thus in theory centering the crank like it would be with a slip fit after i tighten the crank bolt. hopefully that makes sense to you guys. i have the means to put it on a lathe but like the idea of having a press fit on both sides.