Left head wiped out-Advice needed

[EB02GS]

OK, techniclally a '12 camhead. I just bought this as a projcet or part-out. Looking for some advice. BTW: I am decent with a wrench and have a service manual for the bike.

• Bike is '12 r1200gs Rallye with 38K miles​
• Bike went down hard on the left side​
• Left cylinder head with cover, coil, valves and cam sprokets are wiped out. Timing timing chain is also broken​
• Lower cam rail looks OK​
• Thinking of installing a used head with cams and timing chain​
• Can this be done in the bike, or does the engine need to be split?​
• If so, does it make more sense to just part out or install a used engine?​

Advice and guidance from those wo have done it apreciated.

 

[TLSgazza]

I'd love to see a photo of that !

Apart from that not a lot of help sorry

 

[autogs]

What is this "part out" bollocks that seems to be common language now ffs

Sent from my SM-A226B using Tapatalk

 

[Baked Bean]

I think it's like a part exchange but it's out ?

 

[Santa-2512]

Breaking for spares .... hes merican

 

[crumbles]

I would imagine it would be a full strip out...Ho sorry...
A full strip down too see if there are bits gone internally into it..

 

[Smiffypr]

OK, techniclally a '12 camhead. I just bought this as a projcet or part-out. Looking for some advice. BTW: I am decent with a wrench and have a service manual for the bike.

• Bike is '12 r1200gs Rallye with 38K miles​
• Bike went down hard on the left side​
• Left cylinder head with cover, coil, valves and cam sprokets are wiped out. Timing timing chain is also broken​
• Lower cam rail looks OK​
• Thinking of installing a used head with cams and timing chain​
• Can this be done in the bike, or does the engine need to be split?​
• If so, does it make more sense to just part out or install a used engine?​

Advice and guidance from those wo have done it apreciated.

If valves have hit the piston, it would be advisable to check the piston, con-rod and big end shells.

 

[Neil W]

Depends if it is a keeper you are doing for yourself to use or something to quickly fix up at the lowest price (or in English terms bodge up ) and sell on for maximum profit.

If it was a keeper I would find the newest, cheapest, lowest mileage undamaged used motor and stick it in the bike, keep the old one for spares or strip it at your leisure and decide what to do with it

 

[Deleted account 251024001]

Probably be worth checking for damage to the engine case where the cylinder connects. I would guess an engine swap would be more cost effective in time and parts.

 

[Gelandestrasse]

We call them twin-cams over here, good buddy! For translations purposes Spanner = Wrench. Nm is FtLbsluginches. Our gallon gets us much further than yours. Part-out is break for spares. Trunk = boot. Hood = bonnet. Fender is much more descriptively referred to as mudguard (or bumper for a car). Gas is actually petrol. Football is football and played only with your feet. The World Series is actually only played in USA. And until the recent emergence of more imaginative craft beers, our beer was far superior, if warm.

I'd welcome additions to the compendium of translatory articles. Just to assist our cousins across the pond.

 

[EB02GS]

Breaking for spares .... hes merican

LOL. True that.

 

[EB02GS]

I've bore-scoped the cylinder through the mangled head and the valves do not appear to have made contact with the piston (yeah). No foreign bits detected inside either, and only "internal" damage is a clean break of the left timing chain, with all pieces present and accounted for. Guide rails and tensioner appear fine as well. I am likely going to attempt a complete used head swap inc. valves, cams, timing chain, etc. with the only tricky part being extracting the old and broken timing chain and installing the new one without pulling the engine. I've seen it done by "breaking" the new chain, attaching it to the available end of the old one and carefully rotating the new one around the rear inner sprocket. Afterwards, re-assembling the chain. No doubt a delicate operation. Anyone here ever tried splitting and reattaching a timing chain?

 

[EB02GS]

I'd love to see a photo of that !

Apart from that not a lot of help sorry

I've bore-scoped the cylinder through the mangled head and the valves do not appear to have made contact with the piston (yeah). No foreign bits detected inside either, and only "internal" damage is a clean break of the left timing chain, with all pieces present and accounted for. Guide rails and tensioner appear fine as well. I am likely going to attempt a complete used head swap inc. valves, cams, timing chain, etc. with the only tricky part being extracting the old and broken timing chain and installing the new one without pulling the engine. I've seen it done by "breaking" the new chain, attaching it to the available end of the old one and carefully rotating the new one around the rear inner sprocket. Afterwards, re-assembling the chain. No doubt a delicate operation. Anyone here ever tried splitting and reattaching a timing chain?

Looks like I'm having a conversation with myself here. I modified a chain break tool for smaller pins and was able to remove the damaged links from the cam chain. I will replace them from a used chain and reattach it together. After that, the head swap.

 

[landmarkjohn]

Sounds like a plan, I guess the key to success will be the quality of the chain joint. You are breaking new ground I imagine. Best of luck with it

 

[dashfixer]

How will you break the chain? If you use a standard chain link extractor my worry would be the damage to the chain pin which you would then have to re-rivet to join the chain. Steel work hardens, which means that when you attempt to re-rivet the pin it wont be soft and therefore deform correctly. I think that for peace of mind while riding I would bite the bullet and strip the engine down enough to fit the chain properly without splitting it. Unless split links are available for the cam chain.

 

[The Other PaulG]

... was able to remove the damaged links from the cam chain. I will replace them from a used chain and reattach it together. After that, the head swap.

Why not instal an all-new chain (using your breaker method)? It sounds like the timing mechanism came to a catastrophic halt - I'd rather take the risk of a new chain not immediately seating 100% perfectly on 38k mile sprockets, than the risk of using a chain that could have suffered significant stretch during the drop.

 

[EB02GS]

Why not instal an all-new chain (using your breaker method)? It sounds like the timing mechanism came to a catastrophic halt - I'd rather take the risk of a new chain not immediately seating 100% perfectly on 38k mile sprockets, than the risk of using a chain that could have suffered significant stretch during the drop.

Well, I found a very low mileage used head, complete with valves, cams, sprockets, etc. and it is on it's way to me now. I also bought (2) very low mileage used cam chains to experiment with. The plan at this point is to replace the entire cam chain with a good used one using the "split and reassemble process", attaching the "new" chain to the old one and rotating it through the engine. My chain tool is equipped with both extraction and staking bits, and I have already been successful using it to extract a pin without grinding or otherwise damaging the cam chain links. After re-staking the replacement chain, for added security, I can also carefully MIG a small spot on the end of the extracted and re-inserted chain chain pin. I have watched the process on video a few times now and am confident it's going to work! I wouuldn't call it a bodge repair. I have broken, reattached and restaked many drive chains before, and th cam chain doesn't seem much different, aside from the size of the links and pins.

 

[EVskiy]

What is this "part out" bollocks that seems to be common language now ffs

Sent from my SM-A226B using Tapatalk

I also want to know what is a “projcet”

 

[EB02GS]

I also want to know what is a “projcet”

OK, thanks for pointing out my typo EVskij . Yes, it is a "project" bike.

1. I was able to successfully break the new cam chain without buggering it up. Study the process. I finally resorted to using a couple of small nuts on the garage floor, a sharpened punch and a very small awl to drive the pin out. I practiced several times on a length of the old chain first, just to get my technique down. If you are unable to break the replacement chain without damaging it, you're probably done.
2. I attached the new chain to a good link of the old chain (that was broken and still inside the engine) and rotated it through. It was necessary to grab the broken chain end with a long, hooked piece of wire coat hanger to pull while rotating the engine. With spark plugs out, I rotated the crank via the front crank pulley nut just enough to be able to get to the end of the broken old chain, and then rotated the joined chains clockwise through the engine. I used a small piece of wire coat hanger to temporarily join both new and old chains together for this exercise.
3. Once the new, but separated chain was fully rotated through the engine (with equal lengths of the new one showing out of the head's cam chain tunnel), I removed the old chain by removing the cotter pin or wire used to temporarily join them.
4. Re-attaching, (re-pinning and re-staking) the new chain in situ is really the hardest part; very difficult for me due to the angles and 65 year old eyes, but doable with enough patience, excellent lighting, tools, etc.
5. followed-up by lightly MIG welding the pin on the separated/re-joined link (on both sides) just to be fail safe, followed by grinding any excess weld off with my dremel tool and polishing the link afterwards.
6. I'm awaiting a few more parts to finish the job, but I have high confidence that this so-called "impossible" job (replacing a cam chain in situ) will hold. If anyone else is trying this, my advice is probably don't. But if you do, be very patient with the entire process and resist "over-staking" the removed and re-installed pin, as that will make a stiff link that is prone to excess heat and eventual failure. Would I do it again? Well........................... certainly not without MIG'ing the pin on both sides afterwards for added assurance, as otherwise I would certainly have lower confidence in a "re-staked cam chain".

Epilogue: If I only could have sourced a removable master link like they use on drive chains, this process would have been a snap! They make these for older BMW airhead timing chains, but none that I could kind for these cam chains on the DOHC engine.

 

[Pukmeister]

I replaced the worn camchain on my old Yamaha Thundercat YZF600R years ago and the new camchain was supplied split and provided with a peenable pin in the kit from Yamaha. Replacement was the same method as you used to link old and new chains and draw the new chain through the crank. The old chain could be bent in a full semicircle sideways it was so badly worn.

I'm surprised BMW don't supply new split camchains with peenable links as standard ?