Camshaft bushes and breather

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pierodn

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Dear All,
soon I will start to remount my 750 n. 13.... engine and I wanted to get from you two Councils.
The first: should I replace both camshaft bushes??? or or and do I check that the old are still good?;
The second: isappropriate close the camshaft breather and fit a breather body elsewhere?
Thank you and an happy new year.
Piero


Camshaft bushes and breather


Camshaft bushes and breather


Camshaft bushes and breather


Camshaft bushes and breather
 
Re: Camshaft bushes

Are your cases split and the cam out? The way to check would be the measure the difference of the cam journal and the ID of the bushings. If within specs, you should be good to go.

Journal being .8750
Bushing ID .8735
Difference of .0015

These are standard measurements. I do not know what the outside tolerance would be but I am sure some one will chime in.

If you need to replace these bushes, it will require some outside service to line bore to true.

As far as the breather goes, I would leave the the breather you have and add one on the mag boss on the timing chest.
 
Re: Camshaft bushes

pvisseriii said:
As far as the breather goes, I would leave the the breather you have and add one on the mag boss on the timing chest.
Click to expand...

Hi Sir,
The mag boss on the timing chest means maybe the CRANKCASE BLANKING PLATE?
If i replace the old camshaft bushes with news standard do you think i could have trouble?
Thanks.
Ciao.
Piero
 
Re: Camshaft bushes

Piero
On early 750s there is a blanking plate where the magneto on dominators when later commando have just plain casting.

Regarding camshaft bushes, if you replace them you'll have to ream them , this requires specific tools as the 2 half crankcases should be machined together to be sure they are in line.
 
Re: Camshaft bushes

Cam bushings don't wear too fast unless there were contaminants in the oil. Lots of people changed cam shafts to upgrade the ignition/points system so commandos had a variety of variations in cam journals and bushing sover their production span. There were scrolled bushings and cam journals and unscrolled bushings and cam journals . Some bushings had shoulders and some required thrust washers. Presumably this was all assembled correctly prior but just sayin you need to check what your combinations are.

Your bike is lookin great!
 
Re: Camshaft bushes

pierodn said:
Camshaft bushes and breather
Click to expand...

Speaking from personal experience, those handlebars are going to give you aching wrists very quickly.

You need some pullback angle in handlebars for better natural ergonomics, otherwise your wrist joints will be stressed at all times.
 
Re: Camshaft bushes

pvisseriii said:
Are your cases split and the cam out? The way to check would be the measure the difference of the cam journal and the ID of the bushings. If within specs, you should be good to go.

Journal being .8750
Bushing ID .8735
Difference of .0015

These are standard measurements. I do not know what the outside tolerance would be but I am sure some one will chime in.

If you need to replace these bushes, it will require some outside service to line bore to true.

As far as the breather goes, I would leave the the breather you have and add one on the mag boss on the timing chest.
Click to expand...


Thats 0.0015'' INTERFERENCE
 
Re: Camshaft bushes

standard values in mm are
Bushing ID 22.225
camshaft OD 22.187
difference 0.038

could be easier for us poor guys not living in UK or (former) British Colony :D

have an happy new year and ride safe
 
Re: Camshaft bushes

JRD said:
Piero
On early 750s there is a blanking plate where the magneto on dominators when later commando have just plain casting.

Well, but the mag boss chest is the blanking plate?

If i have understand well, i can fit on blanking plate another breather.

Ciao.

Piero
Click to expand...
 
Re: Camshaft bushes

Best after market breather is probably Jim Comstock's (comnoz), fits in sump plug, but be careful if you have a 68-70 frame, the frame brace may not allow fitting. I think sold now by CNW in Colorado. Read through this which-the-best-comnoz-breather-t14210.html

I'm just using the timed breather out of the cam end into the oil tank and a catch bottle from the oil tank breather to prevent spreading oil.

But if you have the blanking plate that may help too. Mine has no blanking plate, just solid casting, but would work the same. Some drill extra holes into the crankcase from inside the timing area to increase air flow into/out of crankcase.

Dave
69S
 
Re: Camshaft bushes

grandpaul said:
pierodn said:
Speaking from personal experience, those handlebars are going to give you aching wrists very quickly.

You need some pullback angle in handlebars for better natural ergonomics, otherwise your wrist joints will be stressed at all times.
Click to expand...
Click to expand...

You are right, This should be really inconvenient handlebar much worse than the ... ... Lambretta!.
The handlebar is almost straight.
I built myself with a stainless steel tube.
I liked the idea of a handlebar as possible like to that of the first fastback but I couldn't find it on the market.
The handlebar, the source was even lower, but since I was not able to mount the master cylinder that touched on upper yoke I had to lift it up.
I am rebuilding this bike in honor and in memory of two dear friends norton owner unfortunately disappeared.
I don't know if I'll use this bike but I hope to have a lot of time looking at it.
Ciao.
Piero
 
Re: Camshaft bushes

I don't want to make it too easy, but would not fit the blanking plate another breather equal to that fitted on the left crankase halve?
Ciao.
Piero
 
Re: Camshaft bushes

pierodn said:
I don't want to make it too easy, but would not fit the blanking plate another breather equal to that fitted on the left crankase halve?
Ciao.
Piero
Click to expand...
Hopefully. Although it works, your current breather can be considered inadequate. The simple addition at the blanking plate may make a big difference without the big expense.

A side benefit is that you will maintaining some originality. With a 69, this would be significant.
 
Re: Camshaft bushes

But if I mount another standard breather on blanking plate where do I send it the vent?
If i join the two vents on the tank of oil does not risk a return in one each of the other?
Thanks for the advice.
 
Hi Piero
Firstly let me say your bike looks great. It reminds me of my first Commando which was a black 1972 Fastback. It had flat handlebars and rearset footpegs and I found it quite comfortable, even on long distances. But I was younger then.
Regarding the breather, there have been quite a few opinions given about the best way to improve it. My bike has the camshaft breather and I agree that it is inadequate.
The Comnoz breather sounds excellent, but because it attaches directly to the crankcase it breathes some oil as well as air. That's OK if the breather goes to the oil tank as original, but I don't like to do that.
I have nearly finished a different breather arrangement so that it will breathe from the magneto blanking plate (this required drilling some holes through the timing case into the crankcase, which your bike will probably need if it has camshaft breathing and you want to change to timing case breathing.)
I have made a catch tank which fits in the cradle between the engine and gearbox. I have fitted a MikesXS reed valve to the top of this tank and the engine will breathe into that. The outlet from this tank will go to the air filter. I'm hoping it won't be too oily. My oil tank will also breathe into this catch tank, instead of dribbling oil into the air filter as it used to do because it has the central oil tank.
Because I am using the reed valve, I will block off the camshaft breather. I don't want anything to dilute the pressure pulses going to the reed valve.
I hope to post some photos soon.

Cheers
Martin
 
Re: Camshaft bushes

pierodn said:
But if I mount another standard breather on blanking plate where do I send it the vent?
If i join the two vents on the tank of oil does not risk a return in one each of the other?
Thanks for the advice.
Click to expand...
I run one to the oil tank and one to the atmosphere via a tube running down the frame tube. Many people use a little vented catch bottle. I rarely see, if any, oil coming from the timing side breather.
 
If the bike wet sumps easily or it sits for a while and most of the oil is in the sump, there will be an ounce or so of oil come out the breather upon start up. I would use a catch bottle no matter how you do it. I have one off my central oil tank and no more oil dripping over the gearbox.

Dave
69S
 
Re: Camshaft bushes

grandpaul said:
pierodn said:
Camshaft bushes and breather
Click to expand...

Speaking from personal experience, those handlebars are going to give you aching wrists very quickly.

You need some pullback angle in handlebars for better natural ergonomics, otherwise your wrist joints will be stressed at all times.
Click to expand...

What I would do is rotate the bars he has forward.
 
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