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kevlarr

Crank bearing replacement

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Evening, I have to replace crank bearings on my ST 300 Factory 2016, I have been quoted silly money for labour to have a shop do the work so am thinking of doing my self. Any advice or tips would be helpful. TIA. Kev

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Does it need the bigend replacing or just main bearings?

Edited by suzuki250

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You do know its a pretty big job for the uninitiated? Do you have the tools to do it correctly? A flywheel puller, bearing puller

Are you sure its silly money?

Edited by faussy

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Bike was smoking and was told that bearing seals needed replacing , £200 later and still smoking . Now quoted £240 labour plus  parts for bearings if I take engine out,   I have access to pullers etc

I have never done it but thought this may be an ideal time to learn. I have no time limit, it takes as long as it takes. Thanks for your replies. 

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£40 more than just the seals sounds infeasible, but £200 to change seals is somewhat OTT I would have thought. I would expect RYP website to have a video but Sherco owners may give more detail.

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1 hour ago, kevlarr said:

Bike was smoking and was told that bearing seals needed replacing , £200 later and still smoking . Now quoted £240 labour plus  parts for bearings if I take engine out,   I have access to pullers etc

I have never done it but thought this may be an ideal time to learn. I have no time limit, it takes as long as it takes. Thanks for your replies. 

Cant you take it back to the guy that did the initial work and tell him his fix wasn't a fix? 240 with the engine already out is excessive, id be expecting around 150, to a bike mechanic its maximum a 3 hr job

Edited by faussy

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Well if you really feel the need to do it, it`s a good time of year to waste some time. Once you do it you feel confident to fix about anything in the future. First off leave the motor completely assembled in the frame. This will give you more leverage to get everything apart. Do the flywheel and stator first. Then everything off from the clutch side. The hardest thing and this point will be primary gear on the crankshaft. Take lots of pics and be organized about it. Do not take off the top end, untill you are ready to remove the motor. Now go watch as many u tube vids as you can. Cut up an old inner tube into 4 small strips to hold the transmission togerther once you have split the motor. It really is not hard to take it apart. Remember to always have the transmission in nuetral while splitting the cases and assembling the cases. What fun you are going to have!

Edited by lineaway
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What makes you think it needs a rebuild?Is it noisy with more than usual vibration?Does it start and run ok apart from the smoke?

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Original diagnosis and quote was for seals and didn’t know it wasn’t them until back together and running. Bearings are a little noisy and that is what they believe may be the problem. Starts and runs fine until riding to sections then smokes excessively 

Thanks for the tips Lineaway

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Can someone explain why slightly noisy mains would make it smoke excessively, especially if crank seals have just been replaced ?

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 Starts and runs fine until riding to sections then smokes excessively

If the exhaust is full of oil, it may catch fire and smoke excessively when riding to sections.  It will also run funny and have a weird smell, sort of like a rancid barbecue. You could be burning off the oil that built up from the bad seals.  There are some posts on here about cleaning out the exhaust.  Another way is just to run it hard and keep a lot of heat in the exhaust until it burns out.  This could be a long ride at the speed it starts smoking on the way to sections or a nice long hill climb.  Repeat until it stops smoking.     

 

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1 hour ago, b40rt said:

Can someone explain why slightly noisy mains would make it smoke excessively, especially if crank seals have just been replaced ?

 Too much play in the main bearings will cause the seals to leak. But while he is taking it apart I would make sure the seal is new and properly seated.

Edited by lineaway

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Mcman56, I did think about oil in exhaust packing as a cause of it still smoking . Do you guys think I should leave alone for a while and see if it calms down. I could change packing first I guess, cheaper option to start with. 

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