Cam bearing surface damage.

[CH_R1]

Hi Folks
Looks like I've got some damage to one section of the camshaft bearing surface on the inlet cam at cylinder 1. Had trouble getting two of the cam followers out on either side of this section of the bearing as the bearing surface has worn causing a slight lip on either side. What pees me off most is that aside from this section of bearing surface on the head and very slight wear to the corresponding bearing cap everything looks brand new! I could go and check it with plastigauge but from what I can make out if its worn beyond spec the head is junk. I am thinking of deburring, cleaning up the surfaces and and putting it back together with a few prayers to the gods of top end lubrication! Just wondering if anyone else has had this problem? The motor had no worrying noises and was getting oil through the pressure check bolt after about 20 seconds. I have only just bought the bike. It's got 23,000 miles on it, it's been regularily serviced (oil + filters etc) but I think this has been the first time the valves have been checked. The only suspicious thing I noted was that the 4 bolts holding the cam cap did not seem to be at the same tightness- one seemed a tad looser than 10Nm. (Not sure if they can be wrongly torqued from the factory?) Anyway any help or advice much appreciated. Thanks in advance.

[phuk72]

Hi Folks
Looks like I've got some damage to one section of the camshaft bearing surface on the inlet cam at cylinder 1. Had trouble getting two of the cam followers out on either side of this section of the bearing as the bearing surface has worn causing a slight lip on either side. What pees me off most is that aside from this section of bearing surface on the head and very slight wear to the corresponding bearing cap everything looks brand new! I could go and check it with plastigauge but from what I can make out if its worn beyond spec the head is junk. I am thinking of deburring, cleaning up the surfaces and and putting it back together with a few prayers to the gods of top end lubrication! Just wondering if anyone else has had this problem? The motor had no worrying noises and was getting oil through the pressure check bolt after about 20 seconds. I have only just bought the bike. It's got 23,000 miles on it, it's been regularily serviced (oil + filters etc) but I think this has been the first time the valves have been checked. The only suspicious thing I noted was that the 4 bolts holding the cam cap did not seem to be at the same tightness- one seemed a tad looser than 10Nm. (Not sure if they can be wrongly torqued from the factory?) Anyway any help or advice much appreciated. Thanks in advance.

Strictly speaking, the service intervals for valves ar 24k so it could be that they have never been checked. But it sounds like someonbe has had a go and fecked it up!

Getting a spare head is gonna be tricky so hopefully it is salvagable.

Sorry this post is not actual help

[CH_R1]

Doubt that anyone's ever seen the valves. The bike's had one owner from new. Got a full service history- book with sevices/milages, receipts except for 600, 3000mls, got receipts for everything- no sign of valves being checked. Think I'll risk it and sort the shims, clean up the dodgy bearing surface (carefully) and pretend I saw naaaaaathing! Bad practice I know, but life's too short and the bike probably would've run perfectly for thousands of k's/mls before I started interfering anyway!

[dandywarhol]

Watch you don't loose oil pressure from the excessive bearing clearance

[CH_R1]

Good point. I may check it with plastigauge after all. Just can't face replacing/sorting the head after all of a couple of weeks of owning the bike! I figure if there was a problem with the oil pressure due to the bearing wear, there would be coresponding wear to other parts of the cams/valvetrain. Question is: if I don't sort it now, will the bearing keep wearing to the point where it does start to affect the oil pressure? As the journal in question is one of the inside ones out of four on that cam it may be ok for thousands of miles or until such a time as other parts need atended to due to normal wear. Either way I'm pissed off about it cos everything else looks like it's just been run in! Ach well...

[andre]

Mine was exactly the same, same cam same cylinder. I cleaned the burrs up reshimed and put it back together. that was at about 38000 km. Redid it at 60000, and guess what, same again. this time i managed to get a complete head with cams. I posted about this prob at the time, suggesting it was a common fault, but most dimissed this. But if you read through old threads it pops up a bit. Me thinks the head is made of best gorgonzola. Be careful touquing the cam bolts up, 10nm i think it is, definately no more. Oh and when i got the replacement head from apparently a 20000m engine, that to was showing the same signs but of a much lesser extent, due to lower miles. Good luck

[CH_R1]

Hmm, this kind of makes me suspect possible inconsistancies in manufacturing tolerances from the factory.

The other issue I came accross was when I replaced and retorqued the inlet cam: Basicaly I did everything as per the Haynes manual but after tightening the bearing cap bolts I found that the cam wouldn't turn. I'd used Kent cam lube on all of the journals and only torqued to 10Nm with a good quality torque wrench but it was totally unmoveable! In the end I undid everything and tightened the cam cap bolts by hand, without the torque wrench, to the point where the cam would turn reasonabley freely (though to me this felt like a lot less than 10Nm.) Now, when the motors running, there is a slight squeeking noise which I am sure is comeing from the cam in question. To be honest, I'm sure I should be re-stripping the motor to have a look and see whats going on but to be quite frank I can't be arsed! I'd not even driven the bike before I did the valves! I reckon the only thing I can do to sort it is to replace the head and possibly even the cam(s) but I now think that it may run fine for quite a while and in the end I'll have to do the same work anyway- just (hopefully), a year or so from now! Anyway, either way it's kind of annoying when the bike has obviously been well looked after and every other part of the motor is virtually like new! Ach well.

Just out of interest, when you rechecked at 600000 was the damage to a diferent journal on the same (inlet) cam? How was the initial suspect cam surface looking?

Cheers for the info!

[CH_R1]

Oops, that should've read 60,000 miles! (Reckon you'd expect a bit of bearing surface wear after 600,000!))

[andre]

It was 60000 kilometres, mine is an import. Yes it was exactly the same journals. Folk on here said i must be using crap oil. No not at all, decent semi synthetic every 6000km. Some folk love these bikes so much there cant possibly be anything wrong with em. I think its a great bike, and enjoyed all the 5 years i have had it, including the 5 trips abroad. Only thing its lacking is hondas bomb proof engine quality and another 20 or so bhp. I would clean it up reshim and enjoy. And when the time comes try to get hold of a second hand head. Cause if you only do 5000m a year, thats a good few years use.

[andre]

Forgot to add, i had same prob with cam not turning when torqued to 10nm. Give the problem journals a rub with some fine emery paper, and i think i tightened mine to 8nm instead. And the other thing, the replacement head came from a 96 tdm. Paid £120 with cams and valves, and postage.

[CH_R1]

Yup, thats what I did. Cleaned up the bearing surface and put it back together. Now wishing I'd threadlocked the cam cap bolts tho. Keep thinking that they could loosen up as they weren't done up to the specified 10Nm. Oh well, probably would have happened by now if it was going to happen. How much worse were the bearings when you replaced the head at 60,000kms? How many of the four bearing surfaces on the inlet cam were shot? Was it just the original single surface that had worsened or was it several? Was it getting noisy? Just trying to gauge how long I've got before I need to do the same. If pos, I'd like to put it off til I need to do the piston rings at the same time. Guess it'll vary from bike to bike anyway. Anyway, thanks for the info!

[andre]

The same journals around the middle inlet valve. As bad again the second time. I was tempted to just shim it up again and carry on, or sell it. But i couldnt sell it like that, i certainly wouldnt like it done to me. And i cant afford anything else yet. I think i would open it up and do the threadlock, as if they loosen i would imagine there would be some premature wear.

[SDN]

There are options, though they may be expensive

Remove the head, strip all valves ect and take to an engineering company

1 skim each side of the bearing journal on a milling machine and bolt the journal to the head

2 bore out with a horizontal boring machine to the desired diameter

Or - You may be able to bore out oversizes and fit some white metal bearings this would be good

Or you could weld up the worn areas and bore out back to size

Just some thought from an engineer

hope it helps

[andre]

Or buy a better bike bike, much as i love the TRX, the engine is shit. A bit negative, but i have had mine 6 years now, and if i could afford to change it i would. But i keep saving the bloody baaaarstard from from the brink of disaster.

[Mincehead]

Or buy a better bike bike, much as i love the TRX, the engine is shit. A bit negative, but i have had mine 6 years now, and if i could afford to change it i would. But i keep saving the bloody baaaarstard from from the brink of disaster.

I can assure you there`s been MANY worse from the land of the rising sun Andre.
Think `toffee` cams on VF`s,Kawasaki Z series twins and their horribly inefficient oiling to the cam and valve gear, cam chain tensioner issues on more models than you can shake sticks at and generally poor QA across the board!
Oh yes, in comparision the TRX/TDM motor is a peach.