Author Topic: Honda CG125 engine classes falls into pushrod?  (Read 4703 times)

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Offline ChengFNGWORKS

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Honda CG125 engine classes falls into pushrod?
« on: August 23, 2018, 01:54:30 PM »
Hello,

I would like to ask a question,

In the rulebook, it stated "shall have pushrod operated valves with camshaft located at least one crankshaft stroke below the OEM cylinder deck position or utilize OEM pushrod length at least twice the crankshaft stroke."

I dont quite understand what it really means as English is not my everyday language.

Could anybody enlighten me on this?

Does Honda CG125 engine falls into the Pushrod classes?

I have attached a photo of Honda CG125 engine

Offline ChengFNGWORKS

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #1 on: August 23, 2018, 02:02:19 PM »
The camshaft and its shaft located just below the cylinder block.

Attached a few pics to show the location of.

And im sorry if my English is hard to understand.

Offline mtiberio

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #2 on: August 23, 2018, 05:15:42 PM »
I owned the 229cc Zhongshen version of this motor. The cam placement is no more elevated relative to the crank than in an American pushrod V-8. The lower rocker arms do it mean it is not pushrod. That rule is in place to prevent cam-in-head motors with short pushrods/folllowers from running in the pushrod class. As long as the top of the piston (nominally the cylinder deck height) doesn’t dip below the cam centerline, you are within the rule. I’m not an inspector, but I’d say you are good to go.

Offline Koncretekid

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #3 on: August 23, 2018, 09:50:01 PM »
That looks like the same motor that was in the bike that the boys from England that pitted with us in 2016 at the BMST raced with and set a new record. I don't recall ever seeing that model in the U.S.
Tom
« Last Edit: August 23, 2018, 09:53:41 PM by Koncretekid »
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Offline mtiberio

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #4 on: August 24, 2018, 07:36:55 AM »
That looks like the same motor that was in the bike that the boys from England that pitted with us in 2016 at the BMST raced with and set a new record. I don't recall ever seeing that model in the U.S.
Tom

There was no need for Honda to import it to the USA. We change our oil. The CG (pushrod) motors were developed for 3rd world countries where people do no maintenance on their motors (they only take them to the dealer when they stop). The CG will run with almost no oil or oil that has turned to goo. When Honda studied why they were having OHC motor failures in these countries, they decided to design a bullet proof motor which could survive with no maintenance.  Wikipedia and this Honda tech article explain it.

https://world.honda.com/history/challenge/1975cg125/index.html

https://en.wikipedia.org/wiki/Honda_CG125

CSC (California Scooter Company) imports the TT250 which uses a 229cc chinese clone of this design. There is also the Hawk 250, a similar 229cc dual-sport type bike. Both are sub $2K, and while they work well enough, you get what you pay for in terms of running gear. The motors are bullet proof, air cooled, carbed and will probably survive the next nuclear war (if only they had points).




Offline ChengFNGWORKS

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #5 on: August 24, 2018, 01:28:33 PM »
I owned the 229cc Zhongshen version of this motor. The cam placement is no more elevated relative to the crank than in an American pushrod V-8. The lower rocker arms do it mean it is not pushrod. That rule is in place to prevent cam-in-head motors with short pushrods/folllowers from running in the pushrod class. As long as the top of the piston (nominally the cylinder deck height) doesn’t dip below the cam centerline, you are within the rule. I’m not an inspector, but I’d say you are good to go.

I believe the Zhongshen is the improved version of the CG125 as it has bigger cc and engine balancer in front of the crankshaft.

what does this line means? = "or utilize OEM pushrod length at least twice the crankshaft stroke."

should i measure the pushrods length?

That looks like the same motor that was in the bike that the boys from England that pitted with us in 2016 at the BMST raced with and set a new record. I don't recall ever seeing that model in the U.S.
Tom

yes from the photo you shared, it is the same model, Honda CG125

That looks like the same motor that was in the bike that the boys from England that pitted with us in 2016 at the BMST raced with and set a new record. I don't recall ever seeing that model in the U.S.
Tom

There was no need for Honda to import it to the USA. We change our oil. The CG (pushrod) motors were developed for 3rd world countries where people do no maintenance on their motors (they only take them to the dealer when they stop). The CG will run with almost no oil or oil that has turned to goo. When Honda studied why they were having OHC motor failures in these countries, they decided to design a bullet proof motor which could survive with no maintenance.  Wikipedia and this Honda tech article explain it.

https://world.honda.com/history/challenge/1975cg125/index.html

https://en.wikipedia.org/wiki/Honda_CG125

CSC (California Scooter Company) imports the TT250 which uses a 229cc chinese clone of this design. There is also the Hawk 250, a similar 229cc dual-sport type bike. Both are sub $2K, and while they work well enough, you get what you pay for in terms of running gear. The motors are bullet proof, air cooled, carbed and will probably survive the next nuclear war (if only they had points).





it was indeed a bulletproof engine and i intended to tune it and run it at Bonneville!

Offline mtiberio

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #6 on: August 24, 2018, 02:49:59 PM »

what does this line means? = "or utilize OEM pushrod length at least twice the crankshaft stroke."


in the rare case that you have a high camshaft engine, the rule makers want it to be able to run if the pushrods are long/heavy/springy enough to give the bike no rpm advantage (my interpertation). I cannot imagine an engine that could take advantage of this clause. No way the CG engine has pushrods twice the length of the stroke. Just concern yourself with the first part of the rule:

 camshaft located at least one crankshaft stroke below the OEM cylinder deck

you should know the stroke of your engine. Measure down from the head gasket surface (cylinder deck) the distance of your stroke. If that point is above your cam centerline (and I believe it is), you meet the rules.

Done forget the big slotted screw you see on the side of the cylinder is the lower rocker arm pivot, not the cam shaft. The cam shaft is below the base gasket surface on a CG motor.

Offline mtiberio

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #7 on: August 24, 2018, 02:55:00 PM »

it was indeed a bulletproof engine and i intended to tune it and run it at Bonneville!

If I remember correctly the 229cc Zhong motor I had would spin to over 8000 RPM stock which is pretty good for a pushrod motor. Good luck, it should be fun stuffing a hot cam and big carbs on that thing (unless you are running production)

Offline ChengFNGWORKS

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Re: Honda CG125 engine classes falls into pushrod?
« Reply #8 on: August 24, 2018, 03:18:50 PM »

in the rare case that you have a high camshaft engine, the rule makers want it to be able to run if the pushrods are long/heavy/springy enough to give the bike no rpm advantage (my interpertation). I cannot imagine an engine that could take advantage of this clause. No way the CG engine has pushrods twice the length of the stroke. Just concern yourself with the first part of the rule:

 camshaft located at least one crankshaft stroke below the OEM cylinder deck

you should know the stroke of your engine. Measure down from the head gasket surface (cylinder deck) the distance of your stroke. If that point is above your cam centerline (and I believe it is), you meet the rules.

Done forget the big slotted screw you see on the side of the cylinder is the lower rocker arm pivot, not the cam shaft. The cam shaft is below the base gasket surface on a CG motor.

thanks for the explanation, really appreciate it


If I remember correctly the 229cc Zhong motor I had would spin to over 8000 RPM stock which is pretty good for a pushrod motor. Good luck, it should be fun stuffing a hot cam and big carbs on that thing (unless you are running production)

I am planning to run it in the A-PG 175 class.

I have a lot more to ask, should i just ask the questions here or should i start a build diary already?