1977 r75 timing chain question

BarryT · 12-29-2009, 06:08 PM

i am going to replace my timing cover seals because they are weeping. my bike has about 65k on it. should i do the timing chain while ik in there? should i do the crank sprocket also?

barry

Renner · 12-29-2009, 07:05 PM

yes, replace the chain.

You probably don't need a new crank sprocket. Check it's condition when you get there. They can be very challenging to remove.

Be sure to get a chain that has a master link and is not the "endless" variety that doesn't have one.
Your current chain likely has no master link and will need to be cut off, not difficult using a dremel with abrasive cut-off wheel.

I recommend using a master link with the long single clip as opposed to the two e-clip variety.

Nice R75/7 you have there.
Love the twin ATEs

bmwrench · 12-29-2009, 07:45 PM

If the seals are leaking, they may be renewed without removing the cover. If the gasket is leaking, then by all means, renew the chain while you are there. A bolt cutter makes short work of the old chain.

Wirespokes · 12-29-2009, 09:08 PM

Quote:

Originally Posted by bmwrench

A bolt cutter makes short work of the old chain.

And doesn't leave metal dust everywhere.

Andy-Gadget · 12-29-2009, 09:20 PM

Make sure that you line up the timing marks BEFORE cutting the chain, the main way I have found the timing chain change is buggered up is by the "I'll just put the new chain on where the old one came off".
This is the best way to get it a tooth out that I have found, the point where the timing marks line up is the least energy point of the cam, and it should stay at this point.
BTW, the boxer motor is so unstressed (very mild cam) that it needs at least two teeth out before things start to hit things the weren't designed to hit, and you usually can't get it to time (ignition) right at two teeth out.

As to the need to changing the chain, I would just because it is about 80k that I think twin row chains start to flap, it depends on how many idle / commuting the bike does.
Bike that do mostly highway miles are less hard on their chains, IMHO.

carpetburn · 12-29-2009, 10:13 PM

when i did the timing chain on my 75/6 i used a 2legged puller and a 3legged puller simultaneously[one per sprocket], i didnt need to cut the chain. It was a lot easier to do than i was lead to believe.

Renner · 12-30-2009, 06:02 AM

by all means use a bolt cutter if one is available.

if you use a dremel, grind the heads off a couple adjacent link pins and pull a link apart.

If there's any danger of foreign stuff getting into/on the engine then protect it/mask it off somehow.

If the sprocket is worn, it will wear the chain

12-29-2009, 06:08 PM	#1
BarryT ^OP Studly Adventurer Joined: Jul 2009 Location: Edwards AFB California (Rosamond CA) Oddometer: 546	1977 r75 timing chain question i am going to replace my timing cover seals because they are weeping. my bike has about 65k on it. should i do the timing chain while ik in there? should i do the crank sprocket also? barry __________________ 1977 BMW R75/7 2004 Kawasaki Ninja 250R (Wifes) 1977 RD400 (for sale) 2006 Buell Ulysses

12-29-2009, 09:20 PM	#5
Andy-Gadget Any bike can go anywere Joined: Jul 2006 Location: Hobart, Tasmania Oddometer: 1,251	Make sure that you line up the timing marks BEFORE cutting the chain, the main way I have found the timing chain change is buggered up is by the "I'll just put the new chain on where the old one came off". This is the best way to get it a tooth out that I have found, the point where the timing marks line up is the least energy point of the cam, and it should stay at this point. BTW, the boxer motor is so unstressed (very mild cam) that it needs at least two teeth out before things start to hit things the weren't designed to hit, and you usually can't get it to time (ignition) right at two teeth out. As to the need to changing the chain, I would just because it is about 80k that I think twin row chains start to flap, it depends on how many idle / commuting the bike does. Bike that do mostly highway miles are less hard on their chains, IMHO. __________________ "If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest" Benjamin Franklin. '95 Sport 1100 Guzzi,'84 Cali 2 Guzzi, '95 Guzzi mille, '84 R65LS, '84 R100, '82 R100RS, '05 DL650, '72 Bultaco Sherpa T 350, '78 Montessa 348, "00 XR650R

12-30-2009, 06:02 AM	#7
Renner combustophile Joined: Jul 2007 Location: sunny SoCal Oddometer: 1,556	by all means use a bolt cutter if one is available. if you use a dremel, grind the heads off a couple adjacent link pins and pull a link apart. If there's any danger of foreign stuff getting into/on the engine then protect it/mask it off somehow. If the sprocket is worn, it will wear the chain Renner screwed with this post 12-30-2009 at 06:56 AM

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12-29-2009, 07:05 PM	#2
Renner combustophile Joined: Jul 2007 Location: sunny SoCal Oddometer: 1,556	yes, replace the chain. You probably don't need a new crank sprocket. Check it's condition when you get there. They can be very challenging to remove. Be sure to get a chain that has a master link and is not the "endless" variety that doesn't have one. Your current chain likely has no master link and will need to be cut off, not difficult using a dremel with abrasive cut-off wheel. I recommend using a master link with the long single clip as opposed to the two e-clip variety. Nice R75/7 you have there. Love the twin ATEs

12-29-2009, 07:45 PM	#3
bmwrench Beastly Adventurer Joined: Nov 2006 Oddometer: 1,457	If the seals are leaking, they may be renewed without removing the cover. If the gasket is leaking, then by all means, renew the chain while you are there. A bolt cutter makes short work of the old chain.

12-29-2009, 10:13 PM	#6
carpetburn Gnarly Adventurer Joined: Dec 2009 Location: brisbane Oddometer: 110	when i did the timing chain on my 75/6 i used a 2legged puller and a 3legged puller simultaneously[one per sprocket], i didnt need to cut the chain. It was a lot easier to do than i was lead to believe.