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Central Oil Tank.Tough Enough?
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DogT
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I never had any issues with mine. Notice there are 2 types of central tanks. On one the return goes to that 'top hat' that sticks out above the tank, the the other version the return goes into the main tank itself right in front of that 'top hat' thing. They both work the same. The hole from the air box goes into the tank and bends up near the top of that 'top hat' thing. It's sort of a vapor separator. I actually made a catch bottle off that hole in the breather because it was always spitting oil out which got all over the gear box, etc. Probably from wet sumping. I can get pictures if necessary.
Notice you cannot just replace the newer tank with the central one. There's lots of differences, the battery tray is all together different.
Notice you cannot just replace the newer tank with the central one. There's lots of differences, the battery tray is all together different.
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Had that tank on my 70 and I feel it is actually a better design and setup than all the later ones that can crack underneath or separate at mounting points. It's a darn tough tank that never gave me any grief.
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Thanks for that.The tank is original to the bike.Its a 1970, I think this design was one year only.To be honest the design looks far more sturdy than later "improved" design, that crack & leak.No need for pic, thanks though!
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As you say.Its sturdy.No signs of distress anywhere!
o0norton0o
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I've had no problems with the central oil tank on my '70 commando. The breather is the hole facing forward, down low on the tank. There's a straw attached to that hole that goes up inside the tank, terminating in the top hat bulge in the tank in an attempt to suck only air to vent crankcase air pressure, rather than oil. That hole will weep small amounts of oil from the mist of oil inside the tank when the engine runs. I just ignore it and spray down that area every so often. (I'm a slob)
The oil feed banjo usually has a small oil line that comes off it that went to the chain guard to oil the chain. I removed that nonsense and plugged the line where it exits the banjo. One thing about the 70 oil system is it holds less oil than the later system with the different shaped tank and it's disposable oil filter and extra plumbing. Less oil means less cooling ability, so regular oil changes are important to monitor any particulate matter in your oil (remember, no paper filter) and compensate for oil breaking down faster due to it's smaller volume. You can also add the extra plumbing and oil filter to this system I believe too.
There's a lot of stuff you need to do to your '70, and quite a bit of optional stuff too. I'm sure at some point I could make you a list of the things that "I" think are must do modifications if you like.
The oil feed banjo usually has a small oil line that comes off it that went to the chain guard to oil the chain. I removed that nonsense and plugged the line where it exits the banjo. One thing about the 70 oil system is it holds less oil than the later system with the different shaped tank and it's disposable oil filter and extra plumbing. Less oil means less cooling ability, so regular oil changes are important to monitor any particulate matter in your oil (remember, no paper filter) and compensate for oil breaking down faster due to it's smaller volume. You can also add the extra plumbing and oil filter to this system I believe too.
There's a lot of stuff you need to do to your '70, and quite a bit of optional stuff too. I'm sure at some point I could make you a list of the things that "I" think are must do modifications if you like.
o0norton0o
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I'll make a list. I'll post it here in a few days.
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Get the tig out and do the olde Triumph Comp bit , where a bleedy great bulge increases the capacity somewhat .
Thio I ran a stiock one . Gets bleedy hot .
Thio I ran a stiock one . Gets bleedy hot .
o0norton0o
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here's your list...
modification list:
add directionals- not required on motorcycles in 1970 but it helps other motorists see your intended path *good option
keegler swing arm modification- My bike had very sloppy handling because of the poor design of the early swingarm tube *essential modification
swing arm oil feed tube- I added it to allow lube to drain into the swingarm. It makes a mess *not necessary, I've removed it
swap 19 for 21 tooth sprocket- 19 is too small. A 21 sprocket is about right for road riding *essential mod
add extra clutch plate- adjusting the clutch stack height lightens the lever pressure so normal humans can squeeze the clutch lever *essential mod
breather modification- Absolutely required. You can use either a Jim schmidt crankshaft breather mount or do a timing plate mount. (I have BOTH working together) It keeps your bike from being leaky. *essential modification
superblend crank bearings- '70 bikes have one ball and one roller bearing. They should be replaced with superblends. you should also pull the timed camshaft breather discs and plan to replace them with a reed breather. *essential modification
yamabond crankcase assembly- Using a good crankcase sealer on reassembly is smart. there are many available now. *good option
sleeved amals- Sleeving the old carbs kept them from gauling and freezing up. *good option once your carbs are worn
ammeter headlight mount- I like a guage *good option
new adjustable isolastics- The old shim style adjusters work, but have to be disassembled to readjust, the new style is easier to use *good mod
Early head steady >>box head steady >> to rose joint headsteady- The original headsteady WILL crack and break from vibration. The box style transmits a lot of engine vibration to the frame. The rose joint headsteady is a better choice than the other 2.
koni shocks- Just an upgrade with adjustable damping and preload. *good mod
points>>boyer ignition>> digital boyer- Points suck, get a digital ignition and call it good for decades *essential mod
dual lead 3 ohm dyna coil- increases spark quality '70 model has 12 volt coils in parallel which is the worst ignition set up. ditch it! *good mod
fibre glass >>steel gas tank- Glass tanks suck, get a metal tank. *essential mod
new dynodave clutchrod oil seal- smart little inexpensive part that keeps gearbox oil off your clutch plates *essential mod
new venhill nylon lined clutch cable- lightens the clutch pull on your lever *essential mod
replace non cush drive hub with later model cush drive hub- *good mod
Wider lightweight rims for modern tires- If you're buying new tires, then that is the time to consider changing rim sizes too. It can lighten your unsprung weight and put more surface area rubber on the road too. *good mod
Front wheel drum brake to disc swap- the disk is better, but obviously it's expensive to do. *good mod
add the oil filter and related plumbing- I've never done it, but it seems like a good idea *good mod
braided steel oil line to the head- good mod
Some of these modifications require some addtional reading to see all the options. Certainly, I am just one very opinionated data point, and it may be wise to seek other people's opinions. There may be other modifications that I missed (I'm forgetful sometimes) Maybe others will chime in on those.
modification list:
add directionals- not required on motorcycles in 1970 but it helps other motorists see your intended path *good option
keegler swing arm modification- My bike had very sloppy handling because of the poor design of the early swingarm tube *essential modification
swing arm oil feed tube- I added it to allow lube to drain into the swingarm. It makes a mess *not necessary, I've removed it
swap 19 for 21 tooth sprocket- 19 is too small. A 21 sprocket is about right for road riding *essential mod
add extra clutch plate- adjusting the clutch stack height lightens the lever pressure so normal humans can squeeze the clutch lever *essential mod
breather modification- Absolutely required. You can use either a Jim schmidt crankshaft breather mount or do a timing plate mount. (I have BOTH working together) It keeps your bike from being leaky. *essential modification
superblend crank bearings- '70 bikes have one ball and one roller bearing. They should be replaced with superblends. you should also pull the timed camshaft breather discs and plan to replace them with a reed breather. *essential modification
yamabond crankcase assembly- Using a good crankcase sealer on reassembly is smart. there are many available now. *good option
sleeved amals- Sleeving the old carbs kept them from gauling and freezing up. *good option once your carbs are worn
ammeter headlight mount- I like a guage *good option
new adjustable isolastics- The old shim style adjusters work, but have to be disassembled to readjust, the new style is easier to use *good mod
Early head steady >>box head steady >> to rose joint headsteady- The original headsteady WILL crack and break from vibration. The box style transmits a lot of engine vibration to the frame. The rose joint headsteady is a better choice than the other 2.
koni shocks- Just an upgrade with adjustable damping and preload. *good mod
points>>boyer ignition>> digital boyer- Points suck, get a digital ignition and call it good for decades *essential mod
dual lead 3 ohm dyna coil- increases spark quality '70 model has 12 volt coils in parallel which is the worst ignition set up. ditch it! *good mod
fibre glass >>steel gas tank- Glass tanks suck, get a metal tank. *essential mod
new dynodave clutchrod oil seal- smart little inexpensive part that keeps gearbox oil off your clutch plates *essential mod
new venhill nylon lined clutch cable- lightens the clutch pull on your lever *essential mod
replace non cush drive hub with later model cush drive hub- *good mod
Wider lightweight rims for modern tires- If you're buying new tires, then that is the time to consider changing rim sizes too. It can lighten your unsprung weight and put more surface area rubber on the road too. *good mod
Front wheel drum brake to disc swap- the disk is better, but obviously it's expensive to do. *good mod
add the oil filter and related plumbing- I've never done it, but it seems like a good idea *good mod
braided steel oil line to the head- good mod
Some of these modifications require some addtional reading to see all the options. Certainly, I am just one very opinionated data point, and it may be wise to seek other people's opinions. There may be other modifications that I missed (I'm forgetful sometimes) Maybe others will chime in on those.
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Hey thanks for this.In fact,am doing most of these.Breather en route from CNW as we speak, plus other parts.Ive already got "Pender" disc.I was considering the single coil.Is there a specific one youd recommend?
o0norton0o
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I use a "dyna" coil 3 ohms... it's worked good for 20+ years with no issues.
Just so you know, you may not be able to use the CNW sump breather because the '70 frame has a cross member under the engine which precludes the mounting of the Comstock (CNW) breather. If by some miracle you 're able to attach it, there has to be significant clearance to that frame cross member or else they may collide when the engine vibrates when it's running. If you are modifying your cases to mount the CNW breather in the "combat case" position, then you'll be fine. In the sump position, I'd bet it's not going to happen.
I did the old britts style timing side breather modification, then I added the Jim schmidt camshaft port reed breather hardware to the existing '70 timed breathing port. I doubled my air moving volume capabilities and have a reed valve seal on both air exit ports which helps to further lower the resulting crankcase vacuum pressure on the upstroke.
Just so you know, you may not be able to use the CNW sump breather because the '70 frame has a cross member under the engine which precludes the mounting of the Comstock (CNW) breather. If by some miracle you 're able to attach it, there has to be significant clearance to that frame cross member or else they may collide when the engine vibrates when it's running. If you are modifying your cases to mount the CNW breather in the "combat case" position, then you'll be fine. In the sump position, I'd bet it's not going to happen.
I did the old britts style timing side breather modification, then I added the Jim schmidt camshaft port reed breather hardware to the existing '70 timed breathing port. I doubled my air moving volume capabilities and have a reed valve seal on both air exit ports which helps to further lower the resulting crankcase vacuum pressure on the upstroke.
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It looks like you're not averse to modifications, so here's my mod. related to the subject of your original post, the central oil tank.
I modified the engine breathing by removing the timed breather and fitting a reed breather off the timing case. But instead of routing it to the oil tank, I fed it into a catch tank which nestles between the plates behind the engine.
With no engine breather going to the oil tank, I could let the oil tank vent naturally via the port that was formerly used for the engine breather tube.
Then I plugged the pipe that drips oil into the air filter. That fixed that problem.
I modified the engine breathing by removing the timed breather and fitting a reed breather off the timing case. But instead of routing it to the oil tank, I fed it into a catch tank which nestles between the plates behind the engine.
With no engine breather going to the oil tank, I could let the oil tank vent naturally via the port that was formerly used for the engine breather tube.
Then I plugged the pipe that drips oil into the air filter. That fixed that problem.
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DogT
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I found it impossible to add to the clutch pack height without a slipping clutch. OB sells a pack of additional shims you can add to the pack and if one works send the rest back for a refund. I find the clutch operation good enough, if a bit stiff, but if set up right, once you have the clutch pulled in, it should get real easy to hold. Like a compound bow. DynoDave has a whole page on setting up the clutch pack height, including his rod seal.
The breather mods are good. Get rid of the timed breather gizmo but there's still not enough of a hole in the cam to breathe properly. And yes, the sump breather will not fit on the 69/70 frame because of the frame tube right below it. There are also mods to the timing cover/crank holes to improve breathing and adding a breather off where the points were on the earlier bikes was.
Add real seals to the gearbox outer cover, also to the tach drive.
The breather mods are good. Get rid of the timed breather gizmo but there's still not enough of a hole in the cam to breathe properly. And yes, the sump breather will not fit on the 69/70 frame because of the frame tube right below it. There are also mods to the timing cover/crank holes to improve breathing and adding a breather off where the points were on the earlier bikes was.
Add real seals to the gearbox outer cover, also to the tach drive.
o0norton0o
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you're good to go with the breather, that's the top shelf application.
In regards to the coil I use, there's nothing special about dyna brand coils. Any dual lead coil will work. Most of them come in 3 ohm or 5 ohm resistance. 3 ohm seems to be the choice for boyer electronic ignitions. Depending on which EI you chose, you should see what resistance they recommend for optimum spark.
I use this coil. https://i.ebayimg.com/images/g/WCAAAMXQb29R3ze6/s-l300.jpg
In reference to the clutch stack height, I did buy a pair of metal plates in thinner thicknesses, so I could add a plate, and micro adjust the height of the stack by swapping a thicker one for a thinner one. This way I could adjust the tension to be as light as possible without slipping. I beleive dynodave's website has excellent instructions on just how that works and how to do it...
In regards to the coil I use, there's nothing special about dyna brand coils. Any dual lead coil will work. Most of them come in 3 ohm or 5 ohm resistance. 3 ohm seems to be the choice for boyer electronic ignitions. Depending on which EI you chose, you should see what resistance they recommend for optimum spark.
I use this coil. https://i.ebayimg.com/images/g/WCAAAMXQb29R3ze6/s-l300.jpg
In reference to the clutch stack height, I did buy a pair of metal plates in thinner thicknesses, so I could add a plate, and micro adjust the height of the stack by swapping a thicker one for a thinner one. This way I could adjust the tension to be as light as possible without slipping. I beleive dynodave's website has excellent instructions on just how that works and how to do it...
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A belt primary drive would provide a number of benefits, a couple of which have been touched on previously.
With no oil on the plates, the clutch stack can be adjusted to give a feather light clutch without slippage.
You can opt for a higher (numerically lower) primary ratio to change the overall gearing without the need to go to a 21 tooth sprocket. This avoids over stressing the poor old mainshaft.
The whole assembly is much lighter than the chain drive one, thereby reducing stress on the poor old mainshaft.
Kickstart effort is reduced.
No oil in primary = no leaks & no need to check/top up.
With no oil on the plates, the clutch stack can be adjusted to give a feather light clutch without slippage.
You can opt for a higher (numerically lower) primary ratio to change the overall gearing without the need to go to a 21 tooth sprocket. This avoids over stressing the poor old mainshaft.
The whole assembly is much lighter than the chain drive one, thereby reducing stress on the poor old mainshaft.
Kickstart effort is reduced.
No oil in primary = no leaks & no need to check/top up.
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