K75 neglected for two years

[Laitch]

I'm going to buy a new valve and get a quotation for a head and valve resurface
Any more suggestions?!

Get the head analyzed by somebody who is experienced. Cylinder #1 is compromised. You're likely to need more parts than just one valve.

it matters... thats why i use e3 exclusively...

I bought cubic zirconia-tipped plugs from Alibaba and saved 20%.

[Martin]

Sometimes it is cheaper to get a good 2nd hand head, engine or whole bike than reco a cylinder head.
Regards Martin.

[alexg]

 I would not do anything until after you clean the thing and are sure that there is not a crack in the valve seat where the it burned. Sometimes the seat gets damaged as well, and then you are for an expensive repair.

Also, with high compression engines, I am not fond of resurfacing heads unless there is no way to reinstall successfully. Why resurface the head? Is it warped or corroded? A good bead cleaning should be enough. Take all the valves, not just the burned one.

[Rokah]

Managed to borrow for a few minutes a BMW Valve Removal tool

After cleaning, this is the state of my exhaust valves and valve seats. What are your opinions? Is there a way I could avoid the BMW tax of around 150€ for the cracked exhaust valve?

I am also worried about the valve guides being too loose. I removed the Oil seal and when open the valve can wiggle around 0.5mm  :S

[Laitch]

I can't get much from those two photos. Many profiles of each part should be taken and identified by cylinder and function. You probably should consult an engine machinist for an accurate assessment. Try consulting one that isn't a BMW technician.

Download the K75 K100 2V manual from this site. Go to its Engine section index. Go to the Specification section within that index. In that section are listed the allowed clearances of parts throughout the engine. If your description of both the part and its clearance is accurate, your measurement seems to indicate excessive wear.

Watch this video for measurement technique. It isn't child's play and needs accurate measurement tools and technique. Let us know your results.

https://www.youtube.com/watch?time_continue=91&v=LIL1lV_xtHI&feature=emb_title

[alexg]

The valve stem is worn out probably. Try measuring with a micrometer at place where the valve guide rides and near the end of the stem, where there is no wear. You can measure the diameter of the valve guides with a series of # drills. I agree with Laitch, the play is excessive.

Changing valve guides is repair shop territory: warming up the head in a control temperature oven (not over your kitchen range), driving the old guide out without banging anything else, driving the new guide all the way to the spec height w/o misalignment, and then, machining the seat to have it concentric with the new guide, and shaving it to spec width. Not impossible, but requires practice, and a lot of special tools.

I agree that the price of an exhaust valve is exorbitant, but for an exhaust ventile, might not be  :(

Curious: how many miles in this bike; for the wear of the valve seal surface, a lot.

[The Mighty Gryphon]

By removing the head and getting the valves out, you have done the worst part of a valve job.  Take the head and the valves to an automotive machine shop for a quote rebuild the head.

Another option would be to look for a used head with good valves.  You should be able to get the head squared away for the price of a couple good tires.

[riots100]

Any shop that rebuilds cylinder should be able to take care of yours.  I had a local machine shop rebuild mine from my K75 and it went smooth as silk.  The shop I went to also offered cleaning bath as well.  The only parts that were replaced were the valve guides.

[Rokah]

Thanks for all the answers, I had the head in the trunk of my car waiting to be taken to a friend of mine that has access to a CMM (coordinate measure machine) but I took it to the machinist directly as he was not going to trust my measurements anyway.... As soon as he saw the valve play he mentioned changing the guides. So I asked him to give me a quote on replacing all the valve guides and doing the seats. I've seen at realoem.com that the valves have a +Core note beside them (plus core charge (possibility of a return of the old part)) I will try to contact the mothership to see if they offer discounts for bringing the old in.

I agree that the price of an exhaust valve is exorbitant, but for an exhaust ventile, might not be  :(

Curious: how many miles in this bike; for the wear of the valve seal surface, a lot.

97k miles according to the dash (157k KM)

By removing the head and getting the valves out, you have done the worst part of a valve job.  Take the head and the valves to an automotive machine shop for a quote rebuild the head.

Another option would be to look for a used head with good valves.  You should be able to get the head squared away for the price of a couple good tires.

It has really been a breeze up to now! Both with a few workshops in Madrid an with you guys. Lets see how well the machine shop quotation treats me.

looks like we are having parallel stories.
Any shop that rebuilds cylinder should be able to take care of yours.  I had a local machine shop rebuild mine from my K75 and it went smooth as silk.  The shop I went to also offered cleaning bath as well.  The only parts that were replaced were the valve guides.

[Rokah]

While the head is in the machine shop, i've been inspecting a few other parts.

What do you think about these parts. Should they be replaced?

Chain tensioner (plastic part)

Chain tensioner (metal part) Is that dent normal? should I worry?

I believe this pump shaft is OK

State of rubber screw gaskets

pump shaft seal

[Rokah]

I've bought a set of pistons+rings from a guy that used to run a BMW dealership. Quick question, do the big end connecting rod bolts need to be replaced once the are loosened? I am aware that they are torqued on an angle basis but they seem to be a bit hard to remove from the conrod.

[Laitch]

. . . do the big end connecting rod bolts need to be replaced once the are loosened?.

The bolts don't need to be loosened. Are you using a manual?

[Rokah]

The bolts don't need to be loosened. Are you using a manual?

Then how do you remove the pistons?!

I'm on step 5 of this page: http://www.bmw-k100rt-page.eu/manual/Engine/examinationEngine_22.htm

[Laitch]

Then how do you remove the pistons?!

You remove the nuts on the ends of the bolts. The bolts stay in the rods, the piston is pushed out of the cylinder by pushing against the inside of the piston with a hardwood dowel or any suitable object fit for the purpose that won't damage metal parts. This is explained in Part 10, steps 6 and 7 and illustrated by a photo show the bolt in place.

The first rule of performing any procedure is read the entire procedure first—maybe a couple of times—then think about it, answer questions you might have about it, then start it.

[riots100]

I did not replace the connecting rod bolts or nuts when I replaced my bent connecting rod.  Just torqued it to spec.  All has been good since.

[Rokah]

Engine done! It started on the first try! Thanks for the help!

[The Mighty Gryphon]

Can you tell us what was done and parts that were replaced? 

[Rokah]

of course!

Piston + Rings (I got a deal)
Big end bearing shells
Big end bolts
Full head(All 6 valves+guides+guide reaming+ seat recut + surface)
New head gasket
new original pump seals

and then the basic maintenance pack, filters(air + fuel + oil)

All o-rings and seals were also changed including the copper ones.

[The Mighty Gryphon]

Nice!  It sounds like you're riding on a new engine now!