Engine Durability

[rbt1548]

Hi, I have been offered a 1976 K6, which has had only 2 owners, looks in  good condition, nicely aged with a wee bit of wear at the rear of the tank where knees have worn the stripes.
As I'm not that knowledgeable of the SOHC 4 engine I was hoping someone could tell me if an engine with 57,000 miles may soon require attention, or can they go on for a good mileage after that?
I know the mileage can be relative to the treatment that an engine has had, services , general abuse etc., so any general opinions would be helpful.
I have rebuilt a number of bikes/engines over the years and I have a fairly well appointed workshop, so it wouldn't faze me having to do some work but I'd rather not have to do major things as I've got to a point where I'd rather just be riding than having to go though the process of rebuilding another one.

All opinions welcome.
Cheers

[ginger_jim]

Hi there, motors are definitely capable of mega miles as long they are maintained well.  Regular oil changes are a must! In reality you'd be lucky to buy a 37 year old bike without having to do something to it - I actually bought my 750 to fettle as I enjoy the challenge and would rather be in the shed than watching the brain numbing drivel on TV :-)

In my honest opinion, if you want something to ride day in day out get something newer, but if you want something that will require regular attention and repay your input with bags of character get the CB!

Good luck!

[rbt1548]

Hi there, motors are definitely capable of mega miles as long they are maintained well.  Regular oil changes are a must! In reality you'd be lucky to buy a 37 year old bike without having to do something to it - I actually bought my 750 to fettle as I enjoy the challenge and would rather be in the shed than watching the brain numbing drivel on TV :-)

In my honest opinion, if you want something to ride day in day out get something newer, but if you want something that will require regular attention and repay your input with bags of character get the CB!

Good luck!

Thanks, I also  enjoy working on my bikes, I have a 1965 BSA A65 Lightning Clubman which I totally rebuilt, and a 1992 Moto Guzzi 1000S, both which are keepers. I just wanted something a wee bit different from the twins I usually have and was thinking of the CB750, as I've never had a four before and they have a good reputation. It doesn't need to be a 'K' model as I also like the F1, I know a lot of people prefer the K with it's 4 pipes and original looks, but I'm lucky I like the look of both!
You are right in the respect that, for day to day running I could/should go out and get something  new or a few years old, that may yet happen, but since I retired I don't do half the mileages I used to and tend to use the bikes when the mood takes me so that was part of the reasoning for looking at the 750. It has a reputation of being reliable, good looking,(both Ks and the F1 in my humble opinion), good for spares, and they are not all that common on the roads.
Thanks for your opinion, that is why I asked , to get other's opinion to help me look out for a good one and what to look out for.
Cheers

[Green1]

Spot on ginger
I bought my 750 just over a year ago with 66,000 on the clock she has now covered just over 70,000.
I push her hard rain or shine and never do a round trip of less than 150miles.But always change the oil every 1000miles
So far all I have done is adjust t he cam chain and set the points.
Out of all my bikes she has been the most reliable and fun.

I never thought I would be playing around with a 42 year old 

[K2-K6]

Like the brain numbing programs spoken of "location, location location" gives a good pointer to this type of bike.....oil condition, oil condition, oil condition! it cannot be stated too storngly that they survive on good oil and will run mostly trouble free if that is looked after.

Given what you list as requirements, I think you'd really enjoy one of these and the F1 very similar to ride to the K so shouldn't restrict your choice.

If you are unfamiliar with the noises the motor makes at can be a great help to co-opt another ear to help you as some of them seem to be judged as a fault when that's not the case. have a good general look for butchered fasteners though which is the case with most old bikes anyway.

[Bryanj]

Cam and primary chains if it has not been looked after otherwise not much except that all the rubber bits are old and hard---dont we all wish---

[Waggles]

Agree with all the previous. 100,000 miles + is possible if well looked after and regular oil changes, only problem is you won't know how a 50,000 miler has been treated. Go for one with as low a mileage as you can find ( Waggles, specialist subject the bleedin obvious ) and as long as the chains seem OK ( no untoward noises ) you should be OK. Try to guess the way the motor has been treated by the rest of the bike.

My F1 is low mileage ( nearly 8,000 now! ) but is used everyday ( for 2 years ) and I find it an extremely practical and reliable bike. I have to say I am a confirmed F1-o-phile as I prefer the looks ( but know I am in the minority there and I do covet four pipes! ) and she performs like a K0, only thing I would say is as there are far fewer F1s around some parts ( like front brake caliper ) are now unavailable as there is less demand than for say a 400 four where they have been remanufactured.

I have seen a few 750s with around 20 - 25,000 on the clock so if you are lucky ........

[rbt1548]

Thanks for all the help!
Cheers

[Bryanj]

Just to reconfirm, I worked on a 125,000 mile old K where the bores, pistons, rings, crank and shells were all in spec, chains had been changed at 75,000 when a gear problem occured and was only stripped as the numpty had let the cam chain rattle a lot so it had eaten through the sides of the cam chain tunnel in the barrels.

Reson we knew the history is that it was originally the owners(of the shop) bike and he had serviced it for all its lift until the last numpty

[steff750]

  I have also got to the stage that id rather ride than rebuild ,back in the carefree seventies a lot of the bikes where run into the ground, so if its running now then you got a good one,I have seen loads of seized cams and knackered engines, i have lost count how many I have stripped for spares over the years
       one of my ko's is coming up to 55,000 If I can see 100.000 miles on that one without putting a spanner to it I will be a very happy bunny

[Bryanj]

Steff, you will probably find age knackers the rubber bits long before mileage does in the engine!!

[matthewmosse]

My 500 saw 180,000 before starting to jump out of gear in 1st and 2nd - it did most of that with minimalmechanical input appart from oil and filter changes and a quick check of the clearences on the camchain and tappets which were invariably in speck. Points rarely needed any attention. I only got issues after changing the engine due to the jumping out of gear issue. That was all as a sidecar outfit and I used it hard, carrying sometimes complete bikes i kit form across the country in one trip. Looked after they are tough.

[steff750]

yes I totally agree bryanj I have seen how hard those rubber bits get over the years and fall to bits , like cam chain tensioner  and wheels and I have seen oil pump strainers totally full of bits of rubber ,and that is the first thing I do with all engines is drop the sump pan Im still trying to find the magic formula to soften stuff like the carb rubbers