Cam bearing replacing

Hi and has anyone replaced the cam bearings on an 08 engine? A TXC250 to be specific ....

The two cams have 2 bearings each but the repair manual shows 2 bearings as a replacement and the other 2 bearings seem to be listed a unit with the cam shaft and gears ...

It is possible to just replace all bearings without buying a new cam?

It looks like they press on the cam...in fact they must.

I guess you cna get the bearing numbers and order a couple and press the new ones on?

Yes I was thinking that also but that gear must align with the lobes on the cam in some manner or the timing marks on the gear will be off ... So is it really possible to press a new bearing on the shaft and then re-align the gear correctly?

I just sent mine off to Up-Tite. George says that he can replace them with high quality bearings, but there is a risk that the gears could break coming off as they have to be pressed off. Considering each cam is about $250 and will come with the same crappy OEM bearings, I decided to take the chance.

The bearing on the intake side was just about to break apart on our 2009 TXC 450.

Interesting and at 250 per pop ...I certainly don't want to buy new cams .... I can get bearings here but not sure on how to re-align the gears on the cams ...

Thats the same bearing on my bike that is loose and squawking... Intake cam, bearing on the gear side ....

I wish I had taken a picture of mine. The bike had become very noisy. We actually did a piston/rings/cam chain because we thought the cam chain was worn out. Now I'm sure it was that bearing and I'm positive it was a mere ride or two from blowing to pieces.

If there is no keyway on the cam I would mark it with a scribe before removing and check the lobe center by degree wheel when you are done. I worked on an older Mercedes engine that had no marks, the cam gear fit on a tapered cone and had to be degreed in. I guess they wanted it perfect.

Not sure what is on the shaft but maybe the degree wheel is the known way for doing this type of work ..... I'd just like to confirm this the correct method ... Seeing the parts manual listing the parts is confusing to me ....

My bike got noisy in a matter of 1-2 40 mile rides ...

Got the cam out and found a clue on the gear

All 4 bearings had a little slack ... ~60 hrs ago at ~950 hrs , I replace the big-end bearing, mains, and at that time, I checked these bearings for slack ... zero was there at that time ...

I'd say you fund a good clue. Now you just need to do is get it apart and together without breaking something..... without a key or anything else to hold it, the gear must have a pretty tight interferance fit. you feeling lucky?

Lucky? Not really ... The guys over here once cracked a crankshaft of mine ... I'm a little more choosey now on who I allow to put a hydraulic press on my parts now ..

I'm off now to see about new bearings and see about a press guy who knows what he is doing ...

id be putting a bit of gentle heat on the gear, as stated there would have to be a tight tolerance if theres no keyway.
a little heat will give you a bit more clearance and wont affect the steels hardness
otherwise you will be putting alot of pressure on the gear trying to get the shaft out and it doesnt look like it could take alot

good luck let us know how you go

Got the bearings and dropped off the cams at a shop ... Monday they'll build some sort of jig for the removal ...

I talked with a UK friend of mine here who knows a little on this type of work ... There is an outside chance that the bearing race can be used to hold the cam while pressure is applied to the shaft to drive the gear off because a small lip exists at the bearing race over the shaft ...

OR maybe we can bust \ cut \ grind the bearing completely off the shaft, leaving the center area of the gear at the shaft open so a holding-jig can be applied at the very base of the gear for pressing the shaft out ...

If all fails, we will need a jig to fit the gear ... the issues here is that gear is not made flat and has rounded corners and some recessed area right above the round corners at it's base ...

We are gonna try to remove a single bearing off the opposite end of the shaft from the gear with a house-made jig for holding the bearing in place while the shaft is pressed out...Working on the end opposite end from the gear first seems a safer way to test what we are doing ... If they can remove the single bearing, the jig might can be used to drive off the bearing and gear without actually touching the gear with any thing other than some heat ...

Replacing the gear on the shaft should be the easiest part with heat applied to the gear ...

If anyone sees any issues here, please let me know ...

You can see the small, small lip here on the bearing race protruding away from the shaft ...

That's the way I'd do it
Also on assembly, chill the cam shaft and heat the gear, the cold camshaft and gently heated gear will give you the biggest tolerance without damaging the parts so you can get them aligned again easier.
Keep the piccies and progress coming
Cheers

http://www.ebay.com/itm/Professioal...otors_Automotive_Tools&vxp=mtr#ht_2771wt_1165

You can use one of these to catch the lip of the bearing and try to press both bearing and gear off together. Another option is to weld the valves shut and install some reeds. Brraaaap!

Keep us updated Ray, I suspect I will be doing this soon.

The bearings on the opposite end from the gear is not a problem ... Just pull it off with a standard gear puller ...

The gear end is another issue .. First attempt with the gear end on was notta ... They are gonna try to remove the bearing and get the jig on the very bottom of base of the gear next and try pressing that way ...

I'm not liking this design at all ... I've rode this bike ~2 yrs ... One very long road trip and a couple other lengthy trips, other than that, just your normal 30-70 mile per day rides ... And now, after 2 yrs, I'm looking at this ~$500.00 repair bill for parts? About 1,000 hrs total on the bike ... Next time maybe, only 800 hrs before this rebuild is needed? .... I'm not liking this at all ....

Are all bikes made with this cam design? I was looking for a 3rd party cam and found nothing available ....

By removing the bearing are you talking about cutting the outer race of the bearing on opposite sides and then letting the ball bearings fall out so that it leaves nothing but the inner race? (I've done this with a cutting torch before) At that point if you still couldn't get behind the gear to press it or pull it off you could carefully notch the inner race and crack it off. I have even carefully notched bearings and supported the opposite side and then cracked them with an air hammer and chisel. It really doesn't matter how much you tear up the bearing as long as you don't hurt the cam.

Right, we are hoping to remove the bearing race off the shaft ... Once you get that outer shell off and remove the balls, that race can be cracked off in some manner ...

I'm looking at ~2.5 weeks down time if I gotta send these back to the states ...

I haven't seen the finished product but word is these guys got the gear off the shaft ...

Here is a small video of how I found the the cam bearings were loose ... Just grabbed the cam gear and wiggled it really ... You should be able to see the bearings move also if any slack is present ....