stainlesscycle
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yes, but when water is introduced into the crank case via the intake, i would think it would be forced through the sealed bearings via hydraulic pressure.
Ignition side crank bearing failure?
- Thread starter wence
- Start date
yes, but when water is introduced into the crank case via the intake, i would think it would be forced through the sealed bearings via hydraulic pressure.
GMP
Active member
Thats a good point. Possible as there is undoubtably an air space along with grease in the bearing. We don't know what type of seal they have, I don't anyway, so its all speculation. Either way dirty water in the lower end means trouble if the bike is drained, restarted, and ridden.
widebear
Banned
That may be true but the courser particulate will still be denied access to the inner bearing itself and depending on the type of seal the bearing may be salvagable. But like Glen pointed out we dont know whats in there for certain, may be ceramic for all we know, so this is all academic.
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GMP,
Thanks for the referral to Worlwide Bearing and the HD bearing number. I called and ordered a couple of those, they were only $29 each, not bad at all. They actually have a ceramic bearing that "should" outlast a steel bearing but besides it being $115 each, the gentlemen at WB said that there is something not right about the bearing, crank, case design of these 10+ year old bikes like mine that may cause the ceramics to eat into the races and cages even faster than a steel bearing generally wears out on these bikes. He did mention that the HD bearing he sells as a replacement is actually not classified as a high speed bearing like the 6306 is, but going off what you have said and his recommendation, I went for them anyway.
I will report back after I get the engine buttoned back up and get to riding for a while.
Thanks,
Matt
Thanks for the referral to Worlwide Bearing and the HD bearing number. I called and ordered a couple of those, they were only $29 each, not bad at all. They actually have a ceramic bearing that "should" outlast a steel bearing but besides it being $115 each, the gentlemen at WB said that there is something not right about the bearing, crank, case design of these 10+ year old bikes like mine that may cause the ceramics to eat into the races and cages even faster than a steel bearing generally wears out on these bikes. He did mention that the HD bearing he sells as a replacement is actually not classified as a high speed bearing like the 6306 is, but going off what you have said and his recommendation, I went for them anyway.
I will report back after I get the engine buttoned back up and get to riding for a while.
Thanks,
Matt
GMP
Active member
Some of the '99 - '00 bikes had crank journal tolerance issues causing too tight or too loose press fits. If tight they could eat bearings. Some guys also thought there may have been some misalignment and had the cases line bored to solve the problem.
I'm sure that WWB will send you C3 or C4 clearance spec parts. Look up the bearing's data sheet and recommended press fit. take your crank and cases to a shop with GOOD measuring tools (no cheap calipers), and have them measured. Calculate the press fit and see if your in spec.
The M306 is fine, I could be wrong but I thought it was a 10KRPM part. WWB supplied Ty Davis, and I was told he ran these same bearings in his YZ426s at the time he was racing them. I think they rev higher than a 250/300 GG.
I'm sure that WWB will send you C3 or C4 clearance spec parts. Look up the bearing's data sheet and recommended press fit. take your crank and cases to a shop with GOOD measuring tools (no cheap calipers), and have them measured. Calculate the press fit and see if your in spec.
The M306 is fine, I could be wrong but I thought it was a 10KRPM part. WWB supplied Ty Davis, and I was told he ran these same bearings in his YZ426s at the time he was racing them. I think they rev higher than a 250/300 GG.
Good info, i will make sure to do thatprior to installation.
Id like to get your opinion on one thing i have been on the fence about. I am not sure wther i should have the crank rebuilt. Inspecting it by sight and with hand, the crank has zero up and down movement in the big end rod bearing, it is very smooth running and has minimal radial movement. The bearing doesnt look damaged from what i can see as well. I am of the " if it aint broke dont fix it" camp so that is why i am on the fence about having it pressed apart and reassembled.
GMP
Active member
Matt,
How many hours? Riding style? Are the needle bearings visible through the slot in the rod at all blued? Ever drown the bike? Oil and ratio?
If this is just a typical high hour rebuild, and you plan to keep the bike, then do it and you will have a totally fresh lower end. If this is a fix for a main bearing failure at relatively low hours, I would first determine if the crank journal is of the correct size. If it is not then I would have it split, remachined to size, and rebuilt. I did this to a 125 that had a main fail (seize) and damaged the crank journal. The bike had a lot of hours though.
What were the press fits like upon disassembly? Was it a PIA to get the crank out or bearings out of the cases? Thats a clue.
For reassembly, I use heat/cold and as little force as possible.
RB Designs rebuilds cranks. Ron's work is of the highest quality.
How many hours? Riding style? Are the needle bearings visible through the slot in the rod at all blued? Ever drown the bike? Oil and ratio?
If this is just a typical high hour rebuild, and you plan to keep the bike, then do it and you will have a totally fresh lower end. If this is a fix for a main bearing failure at relatively low hours, I would first determine if the crank journal is of the correct size. If it is not then I would have it split, remachined to size, and rebuilt. I did this to a 125 that had a main fail (seize) and damaged the crank journal. The bike had a lot of hours though.
What were the press fits like upon disassembly? Was it a PIA to get the crank out or bearings out of the cases? Thats a clue.
For reassembly, I use heat/cold and as little force as possible.
RB Designs rebuilds cranks. Ron's work is of the highest quality.
Glenn,
First of all, thank you so much for the insite and info. You are really helping me make the right decisions and check all the right things to get this bike right, which is great, because its a great bike.
A little history about the bike:
It was originally owned by Russell Bobbit and from what I was told, this bike was his practice bike. I am not sure how many hours he put on it or when he sold it to the second owner.
The second owner was a friend of a friend who was in his early 50's at the time of purchase I believe, he raced the bike in Hare Scrambles and was from I have been told, a very particular person when it came to maintenance and upkeep on the bike. He sold the bike to my good friend Adam when he bought a new KTM200.
Once my buddy Adam got a hold of the bike we took it out and rode it a couple times at local parks and just play rode on it. One day when I was not around, he took the bike out and rode it, he later told me it was making whirring sound but he did not stop to look into it. Obviously it was the left side crank bearing begining to fail. The cage eventually let go and the bearing locked up. Looking into the engine now, it appears the only damage was that it ate into the area where the crank seal seats, but only on about 1/2 of the diameter and in a cresent shape and not very deep. I may have a picture of it I can post.
So in short, I am not sure of the total number of hours on the bottom end, or if it had ever had any previous failures or rebuilds.
On to what I saw during the tear down:
Starting Up Top:
The cylinder shows signs of flaking, mostly around the exhaust port but also some on the intake side, the piston shows this also with the very minute but consistent scratching along the skirt. The top of the piston had an even coating of carbon build up, and the bottom side of the piston head had a very small brown spot in the center. The power valve had moderate carbon build up and the bearings feel a little rough.
The Bottom End:
When splitting the case the left side bearing which failed, stayed locked onto the crank and of course pulled out of the case as it was being split. I eventually removed it from the crank using a puller tool. The opposite side bearing slid very easily off the crank as I gave the crank end a couple very light whacks with a piece of wood and a dead blow hammer. In other words it came off a lot easier than I expect it should. That bearing was fairly easy to remove from the case using a very large socket and a dead blow hammer once the locator dowels where removed from the case half and the case laid flat on the work bench.
Looking down onto the big end rod bearing, I can not see any bluing or signs of scoring or wear marks, it looks to be in good condition.
The journals on the crank I have no idea about, as I have very little experience with cranks and what normal wear looks like. It does not have any deviations in the surface, as far as being able to feel anything with your finger nail. The color on them is not uniform. I will get a picture of it this evening and post it on here.
First of all, thank you so much for the insite and info. You are really helping me make the right decisions and check all the right things to get this bike right, which is great, because its a great bike.
A little history about the bike:
It was originally owned by Russell Bobbit and from what I was told, this bike was his practice bike. I am not sure how many hours he put on it or when he sold it to the second owner.
The second owner was a friend of a friend who was in his early 50's at the time of purchase I believe, he raced the bike in Hare Scrambles and was from I have been told, a very particular person when it came to maintenance and upkeep on the bike. He sold the bike to my good friend Adam when he bought a new KTM200.
Once my buddy Adam got a hold of the bike we took it out and rode it a couple times at local parks and just play rode on it. One day when I was not around, he took the bike out and rode it, he later told me it was making whirring sound but he did not stop to look into it. Obviously it was the left side crank bearing begining to fail. The cage eventually let go and the bearing locked up. Looking into the engine now, it appears the only damage was that it ate into the area where the crank seal seats, but only on about 1/2 of the diameter and in a cresent shape and not very deep. I may have a picture of it I can post.
So in short, I am not sure of the total number of hours on the bottom end, or if it had ever had any previous failures or rebuilds.
On to what I saw during the tear down:
Starting Up Top:
The cylinder shows signs of flaking, mostly around the exhaust port but also some on the intake side, the piston shows this also with the very minute but consistent scratching along the skirt. The top of the piston had an even coating of carbon build up, and the bottom side of the piston head had a very small brown spot in the center. The power valve had moderate carbon build up and the bearings feel a little rough.
The Bottom End:
When splitting the case the left side bearing which failed, stayed locked onto the crank and of course pulled out of the case as it was being split. I eventually removed it from the crank using a puller tool. The opposite side bearing slid very easily off the crank as I gave the crank end a couple very light whacks with a piece of wood and a dead blow hammer. In other words it came off a lot easier than I expect it should. That bearing was fairly easy to remove from the case using a very large socket and a dead blow hammer once the locator dowels where removed from the case half and the case laid flat on the work bench.
Looking down onto the big end rod bearing, I can not see any bluing or signs of scoring or wear marks, it looks to be in good condition.
The journals on the crank I have no idea about, as I have very little experience with cranks and what normal wear looks like. It does not have any deviations in the surface, as far as being able to feel anything with your finger nail. The color on them is not uniform. I will get a picture of it this evening and post it on here.
GMP
Active member
Matt,
It sounds like the bike was run a fair amount of hours with no problems, some of them likely very hard. You also have no idea if the bike ever sucked water or dirt, which could kill a bearing easy. Considering that I'd guess that the fits are fine. When they are not the bearings fail quick and often. If your keeping the bike I'd have Ron do the crank and you will have a new motor. It would suck to have to pull it apart again next year for a rod bearing!
Also, when you press the new crank seals in, do not go past flush as you can block the oil hole in the cases. This was another bearing failure theory some time ago.
It sounds like the bike was run a fair amount of hours with no problems, some of them likely very hard. You also have no idea if the bike ever sucked water or dirt, which could kill a bearing easy. Considering that I'd guess that the fits are fine. When they are not the bearings fail quick and often. If your keeping the bike I'd have Ron do the crank and you will have a new motor. It would suck to have to pull it apart again next year for a rod bearing!
Also, when you press the new crank seals in, do not go past flush as you can block the oil hole in the cases. This was another bearing failure theory some time ago.
I think I will wait until the bearings come in, and then send the crank and new bearings up to RB Designs for a fitment check and crank rebuild.
Should I just go ahead and replace all the bearings in the transmission and clutch and such as well?
I plan on getting a new water impeller and bearing as a preventive measure.
Should I just go ahead and replace all the bearings in the transmission and clutch and such as well?
I plan on getting a new water impeller and bearing as a preventive measure.
stainlesscycle
Site Sponsor
i replace ALL bearings and seals, no matter condition, when motor is apart. it might be a bit of overkill, but you really don't wanna have to do it again later. and you know that it's a complete and total rebuild. that being said, trans bearings rarely go bad...unless you have clutch problems (wobble/runout/unbalanced/etc.) or you run your chain too tight..
GMP
Active member
I do the same, all bearings. Thats why I said do the crank too because my time splitting cases is worth more than a few bearings. I clean the case with old bearings up real good, put it in the oven up to 200 deg or on top of my pellet stove for a half hour, and they tap out real easy. Do the same for install but freeze the new bearings in dry ice. I use liquid nitrogen as I have access to it at work and they will just fall in place, but dry ice works good too.
The waterpump/PV shaft bearings in the side cover are a PIA to remove due to the small ID and blind hole. I ground a special set of jaws for my slap hammer puller to do it.
The waterpump/PV shaft bearings in the side cover are a PIA to remove due to the small ID and blind hole. I ground a special set of jaws for my slap hammer puller to do it.
Well, its a good thing that this GG 200 is worth it in my eyes, because its going to get the royal treatment. I am going to replace every bearing and seal on the bottom end. Hopefully she should be good as new when I am done.
Thanks for all the help and direction guys, I tend to let my wallet control my "know better".
I'm going to start a rebuild thread this weekend and would love for you guys to keep an eye out on what I'm doing. I want this bike to be as good as new when I'm done since I'm going to make the full investment.
Thanks for all the help and direction guys, I tend to let my wallet control my "know better".
I'm going to start a rebuild thread this weekend and would love for you guys to keep an eye out on what I'm doing. I want this bike to be as good as new when I'm done since I'm going to make the full investment.
stainlesscycle
Site Sponsor
blind bearing puller works for the blind bearings - you can 'rent' it for free at some auto parts chains...
also, freezing bearings in freezer works if you don't have dry ice access..
i have a small convection oven i bought at a flea market i heat cases/bearings etc. in.
also, freezing bearings in freezer works if you don't have dry ice access..
i have a small convection oven i bought at a flea market i heat cases/bearings etc. in.
The new sealed crankshaft bearings should may be fix a problem with condensate and following bearings corrosion in some special cold regions.
My only 9 month old bearings causes me many problems.
The sealings were open and the grease was gone.
This is normally no problem but in this issue you can't ride the bike in normal way.
You can recognise this when your engine don't work well from 1/2 throttle.
It depends may be from the "green" petrol with alcohol.
good luck
My only 9 month old bearings causes me many problems.
The sealings were open and the grease was gone.
This is normally no problem but in this issue you can't ride the bike in normal way.
You can recognise this when your engine don't work well from 1/2 throttle.
It depends may be from the "green" petrol with alcohol.
good luck
ignition side crankshaft bearing failure
i have a 99 and this bearing has failed 2 times on me in the 15 years of use at the time its failed it also needed pistons and rings I am a skilled mechanic but usually prefer to use my bike mechanic who was a distributor for several lines here in canada , bottom line these bearings are too large for what they were intended to do speed ratings limitations are too close to the rev ranges of my bike ec250 and i concur as everything that i have had in the past used a much smaller bearing . my failure has been cage disintegration first time fatigue failure more recently cage failure (looked like lack of lube) as an experiment to lube failure we reassembled this build with a similar but narrower bearing to to the 6205 that is used in early production with the appropriate spacer as required we also changed the way its assembled allowing the crankshaft to be free on one side so as to not allow bearing loading from case or crankshaft temperature growth. The thinking here was dead air space to see if a reserve of oil theoretically will support longer bearing life anyhow sorry to say will have to wait on this to report out riding now!
i have a 99 and this bearing has failed 2 times on me in the 15 years of use at the time its failed it also needed pistons and rings I am a skilled mechanic but usually prefer to use my bike mechanic who was a distributor for several lines here in canada , bottom line these bearings are too large for what they were intended to do speed ratings limitations are too close to the rev ranges of my bike ec250 and i concur as everything that i have had in the past used a much smaller bearing . my failure has been cage disintegration first time fatigue failure more recently cage failure (looked like lack of lube) as an experiment to lube failure we reassembled this build with a similar but narrower bearing to to the 6205 that is used in early production with the appropriate spacer as required we also changed the way its assembled allowing the crankshaft to be free on one side so as to not allow bearing loading from case or crankshaft temperature growth. The thinking here was dead air space to see if a reserve of oil theoretically will support longer bearing life anyhow sorry to say will have to wait on this to report out riding now!
