Father Son 75 CB200T Rise From the Ruins

[teazer]

180 degree re-phase is easy. There's a 180 crank and matching cam sitting here waiting for me to finish a few other rebuilds.

Let's not forget that a CB200 piston is long and it's heavy and the rings are thick. For high revs you want a light, short , slipper piston with thin rings.

You also need to stop the cam timing from flip flopping like a politician. Better control is always a good idea. Rods are more than long enough already, so move on. Nothing to see here. Intakes probably flow more than enough with a slight clean up but exhausts need some work to make them, well... work.

 

[Texasstar]

180 degree re-phase is easy. There's a 180 crank and matching cam sitting here waiting for me to finish a few other rebuilds.

Let's not forget that a CB200 piston is long and it's heavy and the rings are thick. For high revs you want a light, short , slipper piston with thin rings.

You also need to stop the cam timing from flip flopping like a politician. Better control is always a good idea. Rods are more than long enough already, so move on. Nothing to see here. Intakes probably flow more than enough with a slight clean up but exhausts need some work to make them, well... work.

Teazer I know I am chewing the cud on a few of these items especially the pistons. (We have been talking to Tbolt Phil he wants to move to Texas so we made him an hon'ry Texan) We have parts on the shelf that need to be addressed first. The detail work always takes the longest. Mom said we would have to curtail our motorcycle related activities until after Zeke got his science fair project finished so Zeke got his science fair project changed to aerodynamics and the teacher approved taking Lucky to school. So our hypothesis, material list, and procedure is due tomorrow. We really think our new cam and new carbs will decrease our drag coefficient

Just trying to work our way down the engine in comparing the 175 and 200. Looking for those lost family joules. Found a few grams.

 

[Texasstar]

Rich brings up a really good point with the 360° engine configuration. Check out some of kopcicle's topics on the rephasing of his XS650. He's working to overcome many of the same issues you'll be facing on the CB200.

It might also be worth pointing out that a 360° engine configuration contributes to the crank case breathing issues Rich mentioned. Below-piston pumping losses are often overlooked, but they're a real source of parasitic loses for an engine, especially as RPMs increase.

this is one that I am chewing the cud on from back in October. Will the 180 rephase take care of the below piston pumping losses at high revs and what is gained by a 277 over 180 and why is that Hughs' most popular rephase in lieu of the 180?


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[Texasstar]

this is one that I am chewing the cud on from back in October. Will the 180 rephase take care of the below piston pumping losses at high revs and what is gained by a 277 over 180 and why is that Hughs' most popular rephase in lieu of the 180?


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[teazer]

It's the big bang effect of getting two bangs close together and then the rear tire has time to relax before the next bang arrives.

Remember the CB72 Hawk and CL72 came in 180 degree (type1) and 360 degree configurations. 180 made more top end and revved higher than the 360 crank version with the same cams and carbs.

 

[teazer]

Oh and of course cams and carbs will reduce Coefficient of drag by creating a much larger negative pressure around the motor which will assist the laminar flow over the rider with reduced flow separation over the rider. ;-)

 

[Texasstar]

Teazer we found a purpose for our cb200 pistons! With the circlip in place it puts the perfect compression on the rod to hold the paper towels!

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[Texasstar]

We are ready to resume building! Thanks RichardB for introducing us to the 5S methodology.
Before....

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[Texasstar]

Mom told us our little shed is a "golden rectangle" because of its Fibonacci numbers.

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It was given to us after a homeless guy set it on fire and burned two holes in the floor. It is 9 by 15.

 

[Texasstar]

http://youtu.be/ycYyH86uZKE


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[ACE125toy]

Great thread!

Just inspired me to get my man room cleared and sorted so i can use it to work on my bike.

Thanks Liam

 

[Texasstar]

Great thread!

Just inspired me to get my man room cleared and sorted so i can use it to work on my bike.

Thanks Liam

thanks Liam we are finding out the cleanliness is next to godliness but the devil is in the details and so is the speed


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[Texasstar]

Been reading AG Bell. What do y'all think of these Arias we found for a cb200? I thought the sharp edges were taboo?

interesting solution for flame propagation. Weigh 133.5g.


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[Texasstar]

Teazer also because of bell I understand why you do what you do to your pistons. Proven material at speed. The meat is in the top of the piston. Decking piston lightens and places the compression ring closer to the top to dispel the heat and I bet you dropped one ring and modified the skirt. Bell said not to hold squish tolerances too close because of the fluidity of the charge....


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[Texasstar]

Teazer also because of Bell I think I understand why you do what you do to your pistons. Proven material at speed. The majority of the meat is in the top of the piston. Decking piston lightens and places the compression ring closer to the top to dispel the heat and I bet you dropped one ring and modified the skirt. Bell said not to hold squish tolerances too close because of the fluidity of the charge....and I bet there is 10 grams that can be dropped off that stock piston with out dropping 400 bucks for the Arias.


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[Sonreir]

Sharp edges on aluminum aren't a huge deal. On iron or steel they'll kill your engine in short order, however.

 

[Texasstar]

Was researching an intake swirl generator and stumbled across this declassified defense document from the 60's. http://www.dtic.mil/dtic/tr/fulltext/u2/408926.pdf


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[Texasstar]

Makes you wonder how our tax dollars are being spent...lol. Here are some highlights. The internal fin before the valve has the highest swirl generation even more than a shrouded valve.

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[Texasstar]

So after the intake valve is ported per Vizard and Bell can a small aluminum fin be epoxied in place as a swirl generator for the charge?


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[Texasstar]

Volumetric efficiency drops by 3%

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