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Stiff brand new crankshaft

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Hello everyone, I installed a brand new crankshaft on my kx100 and it feels a little stiff.

I'm not sure if this is normal or no ... I think my bearing seal might be misplaced. I don't know how how stiff is a crankshaft usually so I can't really compare.

Any ideas?

https://streamable.com/vgv6f

 

Thank you

71084391_2393129550961779_8390027967727665152_n.jpg

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After you've mated the cases, the crankshaft must be centered in the cases.

Measure the play between each counterweight and case with a feeler gauge,

 

Ideally use a crank puller tool but you can carefully tap the appropriate end of the crank with a plastic hammer to center it.

Edited by mlatour
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Stiff crank usually means there is an axial load on the main bearings.  It can also mean the crank is significantly out of true. 

Something is definitely not right with that crank seal.  It appears to be cocked at an angle and not fully seated.  Might also be too large on the inner diameter, it doesn't appear to be even touching the top of the crank.

Aftermarket parts?

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Good observation on the seal Dan, 

centering was the first thing that came to mind as it was the problem on my 1st ever engine refurb.

but yes as suggested there a few possibilities other than that.

 

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28 minutes ago, turbo dan said:

Stiff crank usually means there is an axial load on the main bearings.  It can also mean the crank is significantly out of true. 

Something is definitely not right with that crank seal.  It appears to be cocked at an angle and not fully seated.  Might also be too large on the inner diameter, it doesn't appear to be even touching the top of the crank.

Aftermarket parts?

I have centered the crankshaft. It goes a little bit better but still stiff.
I think it's the seal. 

What are my options? do I have to split it back open? 

Edited by Freedom45

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Unfortunately that design will need split again.

Did you put seals in dry? Maybe when pulling crank in it rolled the seal lip a little

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19 minutes ago, Smoking 2's said:

Unfortunately that design will need split again.

Did you put seals in dry? Maybe when pulling crank in it rolled the seal lip a little

&%$#@!! That is what I thought.

Do I need to change the seal or I can reuse it? It is brand new

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14 minutes ago, Freedom45 said:

&%$#@!! That is what I thought.

Do I need to change the seal or I can reuse it? It is brand new

If it fits proper I'd say it's probably fine but truly I wouldn't risk a $12-15 seal over having to pull it completely back apart later. If it was Yamaha I'd say go with it but those are easily replaced in mins if it tore

Really at this point I'd be more concerned with crank bearing damage, it'll need to come out also to replace seal

Edited by Smoking 2's
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3 minutes ago, Smoking 2's said:

If it fits proper I'd say it's probably fine but truly I wouldn't risk a $12-15 seal over having to pull it completely back apart later. If it was Yamaha I'd say go with it but those are easily replaced in mins if it tore

Would there be a way to pull back the seal into its place? It only the top part that is not fully centered. Like dan said.
If splitting is the only option ill do it. I saw the Yamaha and it is away easier to change.... ?

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1 minute ago, Freedom45 said:

Would there be a way to pull back the seal into its place? It only the top part that is not fully centered. Like dan said.
If splitting is the only option ill do it. I saw the Yamaha and it is away easier to change.... ?

No man, gotta pull it again. Only good thing is you'll never make a mistake like that again, check, double check and sometimes for a 3rd

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14 minutes ago, Smoking 2's said:

No man, gotta pull it again. Only good thing is you'll never make a mistake like that again, check, double check and sometimes for a 3rd

You are right... Very sad mistake. I won't do it again. I was able to pull back seal with a screwdriver. still a little cocked at angle tho. I guess im just losing my time trying to fit the bearing from the shaft..?

You edited your post up there. I have to change bearings too ?? They are brand new ... Cant I tell if they are still good when I see it? I dont want to put bad part on my bike but don't want to waste money either changing brand new parts if they are in good conditions.

Edited by Freedom45

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Just now, Freedom45 said:

You are right... Very sad mistake. I won't do it again. I was able to pull back seal with a screwdriver. still a little cocked at angle tho. I guess im just losing my time trying to fit the bearing from the shaft..?

You edited your post up there. I have to change bearings too ??

Only way of getting it out that I can think of would be to hit or pull on center race which can damage the ball bearings.

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1 minute ago, Smoking 2's said:

Only way of getting it out that I can think of would be to hit or pull on center race which can damage the ball bearings.

You are right. Ball bearing will get damaged. I will split it back open. 

Thank you for the help man. I'd rather do the job twice but have it perfectly setup up.. Just a little bit disappointed XD...
Last question, what parts should I changed. Both crankshaft bearing and seals..? If I have too I will do it but I did it like a week ago. They are new. 

 

I know the cocked bearing has to be changed. Should I just buy a kit only and both ..?

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1 minute ago, Freedom45 said:

You are right. Ball bearing will get damaged. I will split it back open. 

Thank you for the help man. I'd rather do the job twice but have it perfectly setup up.. Just a little bit disappointed XD...
Last question, what parts should I changed. Both crankshaft bearing and seals..? If I have too I will do it but I did it like a week ago. They are new. 

 

I know the cocked bearing has to be changed. Should I just buy a kit only and both ..?

If other side was square and seal looks good then I'd just replace the one side bearing and seal, other side should remain in place by itself, just check it out real good

Oil or I use white lube assembly grease on everything before going back together.

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You can get a main bearing and seal kit for about $40. When installing the seals, they need to bottom out completely against the 3 casting lips on the outer edge. Once you get the cases together, tap on both ends of the crank to center it and remove any stress on the bearings so it spins freely. Use your lube-du-jour on the sealing lips to help reduce the drag. That can help it to spin freely. 

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Read this with interest, I am also having a crank issue a mech installed. Afraid to start mine before another talk with the mech. Good luck Freedom!

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Whack the crank a couple times with a RUBBER mallet from each end if it is stiff after install. Should be an immediate improvement if everything else was done right but crank doesn’t spin nice and easy.

Flame suit on. 

Edited by Jethrobolas
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