Victoria! Zeke's CB175 Build

If you want to improve cam chain tension you have to figure out a way to increase tension with rpm.
The OEM's do it with a hydraulic assist. Parasitic drag is minimised at lower rpm where motor spends most of it's time on the street and increases as revs (and oil pressure) go up
Maybe adapt a mini hydraulic damper then replace parts 5&6? (HD used non pressurised hydraulic lifters for a long time)
If you figure out an oil feed the adjusters used in early Victory motors are (relatively) tiny, they fit into the rocker tip
Larger idler wheel will increase tension very slightly but will also totally change the dynamic movement of chain
You can see pictures of motorcycles with drive chain coming onto rear sprocket in weird directions, the inertia of chain coming off front sprocket, lubrication and sprocket sizes all play a part
 
crazypj said:
If you want to improve cam chain tension you have to figure out a way to increase tension with rpm.
The OEM's do it with a hydraulic assist. Parasitic drag is minimised at lower rpm where motor spends most of it's time on the street and increases as revs (and oil pressure) go up
Larger idler wheel will increase tension very slightly but will also totally change the dynamic movement of chain
Click to expand...
so are the slipper type tensioners hydraulically assisted?


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Nope, they just suport a lot more of the chain run. You'll have to re-read my previous post, I edited it a bunch more times
 
crazypj said:
Nope, they just suport a lot more of the chain run. You'll have to re-read my previous post, I edited it a bunch more times
Click to expand...
Will you help me understand what this tensioner is doing or not doing at high rpms?


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This is what it does at high speeds... (chain too loose)

http://www.cisco-eagle.com/fieldoperations/maintenance/maintenance-tips/figure21C.jpg

The long blade style tensioner ensures that the chain is guided straight to the next sprocket.
 
acm177 said:
This is what it does at high speeds... (chain too loose)

http://www.cisco-eagle.com/fieldoperations/maintenance/maintenance-tips/figure21C.jpg

The long blade style tensioner ensures that the chain is guided straight to the next sprocket.
Click to expand...
thanks I understand that but why is it happening with this tensioner? Is the initial spring tension tuned for a specific rpm? Could more tension with a stronger spring take out the slack at high rpms in other words tune the tensioner to high rpm?


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200 cam chain tensioner wheel is probably larger to adjust for the amount of freeplay they ended up with when they changed number of cam links and raised the head (taller barrels) and changed number of teeth. I doubt it was anything more sophisticated than that.

Racers replace hydraulic tensioners with fixed to try to eliminate chain whip.

At low speed the chain almost follows the same path that you see when you build the motor. As revs rise the chain starts to follow the sprocket and peels off later. That means that even the straight side is not straight. The chain also is subject to harmonics and has waves. So as revs rise and fall, the chain whips around - gets floppy if you will.

That is why manufacturers typically use full length chain supports. Look at say CB200, CB350, 360 and then modern motors to see how the front guide got longer and is now full length.

Even a tight chain whips
 
More tension might help a tiny bit... But there would be a limit. The point where you statically stretch the chain.
Once its locked in place, the spring doesn't do anything. So its only there to set the initial tension without stretching the chain.

I don't think its additional tension that you are looking for, but smoother control of the chain at speeds that would start to distort the chains path to the next sprocket.
 
acm177 said:
More tension might help a tiny bit... But there would be a limit. The point where you statically stretch the chain.
Once its locked in place, the spring doesn't do anything. So its only there to set the initial tension without stretching the chain.

I don't think its additional tension that you are looking for, but smoother control of the chain at speeds that would start to distort the chains path to the next sprocket.
Click to expand...
this my fault I am not asking the right question but you are making me ask a better question. How did Honda determine how much tension the chain needed?


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Given the weight of the chain, the expected slack, and redline of the engine, you can calculate the centripetal forces and determine the amount of chain tension necessary to overcome it.
 
Sonreir said:
Given the weight of the chain, the expected slack, and redline of the engine, you can calculate the centripetal forces and determine the amount of chain tension necessary to overcome it.
Click to expand...
i knew you knew :)


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So the slipper style tensioner takes centrifugal forces out of the equation or do they just contain them?


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Texasstar said:
this my fault I am not asking the right question but you are making me ask a better question. How did Honda determine how much tension the chain needed?


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Click to expand...

basically they are only taking out the slack and putting very ltltle "tension" on it
the chain will actually loosen up slightly as the engine reaches temp so it is never "tight"
 
Texasstar said:
So the slipper style tensioner takes centrifugal forces out of the equation or do they just contain them?


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Click to expand...

Just contain them.

You want the chain just tight enough to not slip a tooth or allow the chain to fly around like crazy inside the cases. More than that and you're robbing power from the engine.
 
teazer said:
200 cam chain tensioner wheel is probably larger to adjust for the amount of freeplay they ended up with when they changed number of cam links and raised the head (taller barrels) and changed number of teeth. I doubt it was anything more sophisticated than that.

Racers replace hydraulic tensioners with fixed to try to eliminate chain whip.

At low speed the chain almost follows the same path that you see when you build the motor. As revs rise the chain starts to follow the sprocket and peels off later. That means that even the straight side is not straight. The chain also is subject to harmonics and has waves. So as revs rise and fall, the chain whips around - gets floppy if you will.

That is why manufacturers typically use full length chain supports. Look at say CB200, CB350, 360 and then modern motors to see how the front guide got longer and is now full length.

Even a tight chain whips
Click to expand...
that is the picture I needed to see in my head! So the chain doesn't ride on the slipper at high rpm it is just used as a starting place at low rpm?


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Thanks for not getting exacerbated with me. I needed to get the picture in my head.


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Texasstar said:
that is the picture I needed to see in my head! So the chain doesn't ride on the slipper at high rpm it is just used as a starting place at low rpm?
Click to expand...

It should ride the slipper all the time, especially at high RPM. The spinning is forcing everything outward. As engine speeds increase, chain tension increases.
 
y5a5y6a7.jpg
so the flap is taking place on the long straight side of this chain


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