Father Son 75 CB200T Rise From the Ruins
- Thread starter Texasstar
- Start date
Couple of thoughts:
That "fin" around the guide looks to our eyes as a great way to get gas flow but it turns out that it's not so good. Gas passes easiest around a round object. With a wedge, it splits the flow and flows less than if it were rounded off slightly. That guide would flow better if it had a long tail after it to smooth the flow.
The "fire ring" is what we call a squish band or in car terms a Quench area. If that were my head, I would re-cut that area and then mill the head to get the width back to 56mm. Your machinist will need the barrels to center the cutting tool. Do not assume that the combustion chambers are perfectly aligned. They may be, but often they are not.
The inlets will flow more air stock than the motor can use, but for a race motor, we would shorten the guides and clean things up a little and that's about it. The exhausts are not all that good but only need a clean up to make them work well at higher lift.
Car guys like huge port volumes but our little motors like high port velocity. Big ports hurt rideability. A stock bike engine is small and relatively high state of tune. A mildly tuned 200cc motor makes around 100-120Hp/liter. That's the equivalent of a 500-600HP Chevy 350. Unlike a 350 Chevy, we don't have much low end to mid range and we have to optimize the few horses we do have.
That's why 99 times out of 100, car guys come up with solutions that are not appropriate for our little toys.
BTW, nice little TA125.
That "fin" around the guide looks to our eyes as a great way to get gas flow but it turns out that it's not so good. Gas passes easiest around a round object. With a wedge, it splits the flow and flows less than if it were rounded off slightly. That guide would flow better if it had a long tail after it to smooth the flow.
The "fire ring" is what we call a squish band or in car terms a Quench area. If that were my head, I would re-cut that area and then mill the head to get the width back to 56mm. Your machinist will need the barrels to center the cutting tool. Do not assume that the combustion chambers are perfectly aligned. They may be, but often they are not.
The inlets will flow more air stock than the motor can use, but for a race motor, we would shorten the guides and clean things up a little and that's about it. The exhausts are not all that good but only need a clean up to make them work well at higher lift.
Car guys like huge port volumes but our little motors like high port velocity. Big ports hurt rideability. A stock bike engine is small and relatively high state of tune. A mildly tuned 200cc motor makes around 100-120Hp/liter. That's the equivalent of a 500-600HP Chevy 350. Unlike a 350 Chevy, we don't have much low end to mid range and we have to optimize the few horses we do have.
That's why 99 times out of 100, car guys come up with solutions that are not appropriate for our little toys.
BTW, nice little TA125.
Texasstar
Can't is a four letter dirty word
teazer said:
Thanks for being so gracious but my buddy Boris @ RPM Dallas just rolled his eyes and said very dryly "you never listen to car guys" oh well we had a good time. Boris also sold me his Super 3 triumph years ago. He is also a Japanese vintage guy. He said not to Serdi cut, lap the valves, assemble motor, use stock gaskets, and do a leak down test. He said there is no one he would trust to do that job right of repairing the chamber. So plan b this motor is gonna be more stock. You just saved us some money and we appreciate it!
Texasstar
Can't is a four letter dirty word
the bike is at Big D's in Dallas. Keith's son Jared is a vintage road racer in the 750cc class and told us about it. Jared said they raced in Louisiana this past weekend. I ran into across a gal on tumblr #555 that raced a 160 there also this weekend. They have 3 vintage factory race bikes. My office is right around the corner. I'll find out at lunch time Monday. Do you recognize this bike?teazer said:
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Texasstar
Can't is a four letter dirty word
Texasstar
Can't is a four letter dirty word
Why? Why was there a shorty on the right but a longer reverse on the left? Now Nixon was brilliant and got the glory but it was his tuner that got him there. Did one carb have different jets than the other? Did it impact the tuning of the carbs? We're the header sizes different? It apparently gave him an advantage to earn 300 bucks that day. He got paid a 1000 for riding the 2 stroke screamer 250 Yamaha that weekend...148mph. 5 port engine??? And look at that fairingteazer said:
What about duel overhead cams four our little girls and vtec timing? It seems to me this would be an answer to increasing volume flow for more top end amd keeping velocity flows for idle and midrange torque????
Now here is another stupid question. With electronic ignition and electronic valve timing can you turn a 4 stroke into a two stroke in theory doubling the revolutions firing and doubling power?
This article is above my engine knowledge pay grade the evolution sohc to rev to vtec
http://world.honda.com/motorcycle-technology/vtec/p3.html
Please be reminded our ancestors sat in a bar one night and one said, "hell yes we can push back the sea and build a garden for you honey."
Lucky says, " I am a 200cc bike on the outside but I have a 400cc heart."Attachments
Texasstar
Can't is a four letter dirty word
Lucky told us she is 200cc on the outside but she has a 400cc heart. Every set back has a pit of Gold at the end if the rainbow after the storm passes. We have had a change of plans with this head. No porting, serdi cutting, no change in compression. We have been advised not to by some very smart people. Honda overengineered the head to handle 250cc of jug. So my son is gonna learn how to lap valves today and install valve keepers the old fashioned way. We are in the process of using the other part of the front fender to make a rear tire hugger to protect the carbs.
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Any idea what year this pic is from? Wouldn't mind having a closer look at some of the racing leathers. I have a set that are similar in design - just without the stripes (solid color body with different color sleeves). I went back and forth on having stripes on the arm - but didn't. Anyhow - wouldn't mind trying to find more pics.
Texasstar said:Please be reminded our ancestors sat in a bar one night and one said, "hell yes we can push back the sea and build a garden for you honey."
Texasstar
Can't is a four letter dirty word
I think 1967. I googled Gary Nixon Daytona 1967Tim said:Any idea what year this pic is from? Wouldn't mind having a closer look at some of the racing leathers. I have a set that are similar in design - just without the stripes (solid color body with different color sleeves). I went back and forth on having stripes on the arm - but didn't. Anyhow - wouldn't mind trying to find more pics.
In the first pic, the T100 has its original discolored pipe and short meg and that looks to have been replaced with a shiny new pipe and long megaphone. If that is really Nixon's bike, it would probably be a good idea to leave it as it was - it's a piece of history. Change it and it's just another pile of shiny parts on an old bike. :-\
You want the seat to be around 1mm on inlets and say 1.5 on the exhaust. That's why it's easier and quicker to get them cut on a Serdi machine. But for a stock motor, this is as good a way as any.
You want the seat to be around 1mm on inlets and say 1.5 on the exhaust. That's why it's easier and quicker to get them cut on a Serdi machine. But for a stock motor, this is as good a way as any.
