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Post by boosted81 on Sept 15, 2020 13:45:16 GMT 1
I have an Rd250LC(4L1) with around 60k km on the clock. The bike needs it's top end replaced, but I also want to clean the bottom end while I'm at it.
The crankshaft is in great condition, it spins freely, doesn't have any wobble or play so I am not planning to do anything with it. Not sure about the crank bearings and seals tho since I bought the bike as a non runner.
My first question here is: Can I somehow clean the bottom end without splitting the casses?
Another question is: If I were to split the cases, can I put them back together using sealents such as Honda Bond instead of genuine gaskets?
Last question is: Are parts like crank bearings, crank seals a generic part? Meaning I can go into a store that sells bearings and seals and buy one for my application. (asking this because I have poor accessibility to RD parts, since im not from the UK or any other EU union country..)
Thank you guys!
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Post by boosted81 on Sept 15, 2020 13:45:33 GMT 1
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Post by boosted81 on Sept 15, 2020 13:45:49 GMT 1
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Post by boosted81 on Sept 15, 2020 13:45:59 GMT 1
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Post by arrow on Sept 15, 2020 13:48:45 GMT 1
Wekcome to the forum. Where are you based?
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Post by midlifecrisisrd on Sept 15, 2020 14:01:09 GMT 1
Hi
At 60km it may feel ok but if that's an original crank then it will no doubt be past it's best
Also lying for long periods is not good for the bearings. It tends to cause small pits where the rollers have been sitting
This means it feels ok but can self destruct after a few hundred miles
Your crank seals will be well past their sell by date and need replacing which needs the cases split as there is a lip around the middle of them
Only use genuine Yamaha crank seals. There are a lot of cheap ones out there that can fail very quickly
Honda bond is fine to rejoin the case halves. Let's face it they were all made by Threebond
An air leak from a failing seal or a half chewed bearing roller exiting via you nice new top end can be fatal
Do it right, split the cases, new seals and a full crank build and have price of mind
Steve
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Post by boosted81 on Sept 15, 2020 14:18:45 GMT 1
Hi At 60km it may feel ok but if that's an original crank then it will no doubt be past it's best Also lying for long periods is not good for the bearings. It tends to cause small pits where the rollers have been sitting This means it feels ok but can self destruct after a few hundred miles Your crank seals will be well past their sell by date and need replacing which needs the cases split as there is a lip around the middle of them Only use genuine Yamaha crank seals. There are a lot of cheap ones out there that can fail very quickly Honda bond is fine to rejoin the case halves. Let's face it they were all made by Threebond An air leak from a failing seal or a half chewed bearing roller exiting via you nice new top end can be fatal Do it right, split the cases, new seals and a full crank build and have price of mind Steve Thanks for the reply Steve! I am really not in the best circumstances to rebuild the crank at the moment. A) Financially B) Shops in my country don't do a good job of repairing cranks and balancing them.. In regards to the same topic, what is it that the crank can fail even tho it seems solid after inspection? The previous owner filled the entire bottom end with 2 stroke oil before leaving the engine out of the bike for almost 10 years so I don't see how any sort of moving part would've seized? Im not a mechanic tho, so correct me if I'm wrong. |
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Post by midlifecrisisrd on Sept 15, 2020 14:44:14 GMT 1
The seals harden so don't seal, the pins the big ends run on wear or pit. Other than that it's just general bearing wear
Think the seals from Yam in the UK are £28 but may be cheaper via Yam in other countries
The outer mains wear the most and at a push can be changed DIY
Check the side float on the big ends and the rod deflection at the small end and compare it to the tolerances
If your crank measures well it would suggest it has been serviced before
Here in the UK cranks usually failed between 20 and 30 thousand miles
Steve
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Post by boosted81 on Sept 15, 2020 15:23:29 GMT 1
The seals harden so don't seal, the pins the big ends run on wear or pit. Other than that it's just general bearing wear Think the seals from Yam in the UK are £28 but may be cheaper via Yam in other countries The outer mains wear the most and at a push can be changed DIY Check the side float on the big ends and the rod deflection at the small end and compare it to the tolerances If your crank measures well it would suggest it has been serviced before Here in the UK cranks usually failed between 20 and 30 thousand miles Steve Well, I guess the best thing to do is open the crankcases at this point.. I would ASSUME that they've serviced the crank at some point, since as you stated, they fail at 30k, and mines got 60k on the clock,but I will take the measurements to confirm for sure. In regards to the seals and bearings: It's a pain in the arse for me to get parts from the UK, I've gotten a few bits a month ago and the shipping cost me an arm and a leg(£50+). So changing the big/small end bearings on the crank won't be an option at least for now... In regards to crankshaft bearings(left and right bearing) as far as I know they are a universal part(SKF, NTN, KOYO probably make bearings with those dimensions). But I wonder if the seals are also the same deal( is there such thing as a generic seal with the same dimensions as the original in the RD)? |
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Post by tony2stroke on Sept 15, 2020 15:40:36 GMT 1
The seals harden so don't seal, the pins the big ends run on wear or pit. Other than that it's just general bearing wear Think the seals from Yam in the UK are £28 but may be cheaper via Yam in other countries The outer mains wear the most and at a push can be changed DIY Check the side float on the big ends and the rod deflection at the small end and compare it to the tolerances If your crank measures well it would suggest it has been serviced before Here in the UK cranks usually failed between 20 and 30 thousand miles Steve In regards to crankshaft bearings(left and right bearing) as far as I know they are a universal part(SKF, NTN, KOYO probably make bearings with those dimensions). But I wonder if the seals are also the same deal( is there such thing as a generic seal with the same dimensions as the original in the RD)? Absolutely!! the numbers are stamped on them, you can then look them up. |
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Post by tony2stroke on Sept 15, 2020 15:46:45 GMT 1
Hi At 60km it may feel ok but if that's an original crank then it will no doubt be past it's best Also lying for long periods is not good for the bearings. It tends to cause small pits where the rollers have been sitting This means it feels ok but can self destruct after a few hundred miles Your crank seals will be well past their sell by date and need replacing which needs the cases split as there is a lip around the middle of them Only use genuine Yamaha crank seals. There are a lot of cheap ones out there that can fail very quickly Honda bond is fine to rejoin the case halves. Let's face it they were all made by Threebond An air leak from a failing seal or a half chewed bearing roller exiting via you nice new top end can be fatal Do it right, split the cases, new seals and a full crank build and have price of mind Steve Thanks for the reply Steve! I am really not in the best circumstances to rebuild the crank at the moment. A) Financially B) Shops in my country don't do a good job of repairing cranks and balancing them.. In regards to the same topic, what is it that the crank can fail even tho it seems solid after inspection? The previous owner filled the entire bottom end with 2 stroke oil before leaving the engine out of the bike for almost 10 years so I don't see how any sort of moving part would've seized? Im not a mechanic tho, so correct me if I'm wrong. Oil is hygroscopic, If engine has been in a damp place the oil will absorb water, this is the enemy, it may well be OK, its a risk though that most don't want to take. |
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Post by boosted81 on Sept 15, 2020 16:58:32 GMT 1
Alright so I am definitely going to tear down the entire engine... I need to ATLEAST make a close inspection before I put my fresh top end.
The engine has definitely been sitting in a humid placea and you definitely have a point about the hygroscopicity of oil.
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Post by tacky1 on Sept 15, 2020 17:11:53 GMT 1
Honda Bond will be good for the crankcase halves to be fitted back together, You just need a light smear, get the cases together pretty quick as Honda Bond sets fast, there is no gasket there from factory, I would recommend Threebond 1211 for the cases if you can get it, Its what I use on all my engines and it designed for crankcases.
Oh, And use genuine yamaha seals for the crank, Not Yambits or any other shitty brand...
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Post by boosted81 on Sept 15, 2020 17:23:12 GMT 1
Honda Bond will be good for the crankcase halves to be fitted back together, You just need a light smear, get the cases together pretty quick as Honda Bond sets fast, there is no gasket there from factory, I would recommend Threebond 1211 for the cases if you can get it, Its what I use on all my engines and it designed for crankcases.
Oh, And use genuine yamaha seals for the crank, Not Yambits or any other shitty brand...
Thanks for joining in the discussion! |
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Post by steeley on Sept 15, 2020 17:54:57 GMT 1
Welcome to the forum . Good luck with your project , i have a list of part numbers some where for bearings and seals ect i will dig it out and have a look .
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Post by jon on Sept 15, 2020 18:03:11 GMT 1
The seals are not a generic size like the bearings.
As mentioned before only use genuine seals.
Most gaskets are OK to use any pattern ones, apart from the head. Ideally genuine, or Athena as a second choice.
Jon
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Post by boosted81 on Sept 15, 2020 18:07:01 GMT 1
Honda Bond will be good for the crankcase halves to be fitted back together, You just need a light smear, get the cases together pretty quick as Honda Bond sets fast, there is no gasket there from factory, I would recommend Threebond 1211 for the cases if you can get it, Its what I use on all my engines and it designed for crankcases.
Oh, And use genuine yamaha seals for the crank, Not Yambits or any other shitty brand...
Speaking of sealeants I see three bond offer an array of them. The 1211 as you suggested might be a good choice, but I also see another one from them the 1184 for which they claim that it is ideal for surfaces with poor flatness and small gaps. However its listed as a semi drying sealer. The only reason im asking this is because I don't know if the 40 year old casses are flat enough to use a thin coat od sealent... I don't know if this bike was abused or anything so there might even be a massive air leak on the engine as it is now.. |
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Post by 4l04ever on Sept 15, 2020 19:03:05 GMT 1
Welcome to the forum.
You can perform a leak down test once the engine is back together to confirm you have no leaks to save an expensive blow up.
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Post by tony2stroke on Sept 15, 2020 19:12:09 GMT 1
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Post by rich on Sept 15, 2020 19:13:35 GMT 1
You can get a rough idea how fresh the crank is by the colour of the flywheel webs. If it's original at 60k (around 40k miles) they will be pretty black from blow by. if it's fresher, they are more likely to be a lighter grey colour.
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Post by midlifecrisisrd on Sept 15, 2020 19:20:09 GMT 1
If you can get 1184 that should be fine
Personally I prefer 1215 as it's slower setting than 1184 and is petrol resistant
Steve
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Post by tony2stroke on Sept 15, 2020 20:21:27 GMT 1
+1 for threebond 1215
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Post by tacky1 on Sept 15, 2020 21:38:16 GMT 1
Honda Bond will be good for the crankcase halves to be fitted back together, You just need a light smear, get the cases together pretty quick as Honda Bond sets fast, there is no gasket there from factory, I would recommend Threebond 1211 for the cases if you can get it, Its what I use on all my engines and it designed for crankcases.
Oh, And use genuine yamaha seals for the crank, Not Yambits or any other shitty brand...
Speaking of sealeants I see three bond offer an array of them. The 1211 as you suggested might be a good choice, but I also see another one from them the 1184 for which they claim that it is ideal for surfaces with poor flatness and small gaps. However its listed as a semi drying sealer. The only reason im asking this is because I don't know if the 40 year old casses are flat enough to use a thin coat od sealent... I don't know if this bike was abused or anything so there might even be a massive air leak on the engine as it is now.. Im sure the 1184 will work, Ive used the 1211 for a lot of years on 350s, 500 gammas and RD500s etc. and never a prob, I also smear a little on the intake gaskets as they can be a biatch to seal sometimes. I dont think youll have a case problem, Smear it on and tighten her up......
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