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Discussion Starter #1
I recently caught the CB160 bug after reading a few well written articles. I plan to supercharge or turbo charge this motorcycle here is what I have so far:

I began searching for a bike, but there were none available in my local area. There were a three bikes within a couple hours ride from my home, with prices ranged between 400$ and 1500$ and were either too expensive or too whored out for my taste.
Planning to café this little bike meant that most of the stock parts on the bike, like the seat, rims, brakes, tank, wheels and so on would not be used.
A quick check on EBAY revealed the going rate for CB160 parts was very reasonable to ridiculously low. This meant that if I purchased one of the nicer bikes I wasn’t going to get much for the parts I wouldn’t use. I began to look around for a rolling chassis and found what was left of a 1968 CB160 at Pro Class Cycles in Richmond with no title. I paid the requested price of 75$ and began an immediate DMV title search, costing an additional 25$
The search revealed no title on record. I waited the required 21 days and posted my intent to title. I waited 21 more days and had the title in hand (Too Easy!)
I now had the donor chassis and began to collect some of the pieces I would need to for this project. I started with the transmission. I already had the CB160 engine and transmission, but the CB160 uses a 4 speed transmission and utilizes an ancient detent mechanism for shifting, this simply will not due for my purposes.

The first upgrade will be a 5 speed transmission from a CL/CB175. There are several ways to get the 5 speed to work and two different detent mechanisms.
1. The 1968/1969 CL/CB175 has a sloper case and utilizes a 5 speed transmission, but has the old style detent mechanism. The 68/69 lower unit is a direct bolt in for the CB160 chassis, but again uses the old style detent mechanism.
2. Machine, weld and modify the CB160 case to accept the 5 speed cluster from the 68/69 CL/CB175 again you are still stuck with the old detent mechanism.
3. Use a 1970 or later CL/CB175 vertical case 5 speed cluster and detent mechanism in the 68/69 sloper case. This requires just a little machining to make it work and you get the modern vastly superior detent mechanism.
I chose to use option 3. I sourced a 1968 CL175 lower unit from a junk yard in Georgia 150$ including shipping. The vertical CL/CB175 was sourced locally, I picked up a whole engine and transmission with seized pistons for 50$ I now have the all of the hard parts I need.

The next item to be sourced would be the cylinder jug, I plan to increase the bore to 56-57mm to get around 200cc of displacement, again the are several ways to go here with the selection.
1. Use the 160 head and jug and over bore the sleeves.
2. Use the 175 sloper jug and head and over bore the sleeves.
3. Use the 175 vertical jug and head and over bore the sleeves.
4. Use a CB200 vertical jug and head.
I selected the option 4 as the CB200 head is supposed to have better flow over the CL/CB160/175 pieces and requires less machine work. I have not acquired these pieces yet.

The CL/CB160/175/200 are all in the same motor family and many of the parts interchange between these engines. They all use the same 41mm stroke and add cc by increasing the bore size. All of these engines share the same intake and exhaust valve sizes 24mm Ex. and 28mm In. These valves are super cheap and in my opinion will need replacement for even a mild performance build.
Aftermarket valves are available from Kibblewhite at 240$ a set. Too rich for my blood I will be using a set of stainless valves from a Honda 1.6 car engine 25mm Ex. and 29mm In. (15.99 a piece) they are too long and will need to be shortened and re-grooved (15$ a valve. The final cost 124$ half of the Kibble white cost and I get to select what style keepers and locks to groove the valves for, allowing to select the best product for least cost.
The Kibblewhite springs are 40$ a set and are reasonably priced, but I will be cruising the spring catalogs to see if I can match something up for cheaper. I will let you guys know what I find.
I am still trying to decide turbo or supercharger. There are several options for a turbo sized for a 200cc engine available for around 200$ made by IHI with several compressor trims available. I have a couple of small super chargers in the shop A VW/Porsch smog pump (A real roots blower) and an Eaton M24 that could be shortened to ¼ it’s size to accommodate the small displacement. The Aisin AMR 300 could also be used, but I do not have one on hand.

This is what I have so far, I will be documenting this as I go with lots of pics and general build information.

Suggestions, foreseen problems or anything else you guys may have to share is welcome.
 

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Discussion Starter #3
The frame will be the stock CB160 sloper frame and swing arm with bracing added as needed. I was going to use Ceriani 32mm (cheap and available) for the front fork, but with around 40 expected HP I have decided to upgrade these to 35mm.
The rear suspension will remain as a twin shock set up. I will use some quality rear shocks and will know what they are when the right price comes along.
I plan to use a Harley Dual Disk hub from a 2.15 x 21” front wheel and vented and sloted rotors to reduce weight as much as possible. For the rear brake I will use a motorcross style disk brake. Something like a KX 500 or CR500 should do nicely.

Fuel will come by way of Microsquirt fuel injection. I am looking at a WR250 throttle body and injector, and have found a few around 200$ the going rate for one of these Yamaha items used on Ebay.

Thanks for your interest.
 

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Discussion Starter #4
Here is an 08 WR250 throttle body that is listed on Ebay. Perfect for my use, but at 250$ I will wait for something more reasonably priced, but as you can see it is a nice piece.



As you can see the Microsquirt should fit nicely under the seat. My brother is using Megasquit on his 9 second V6 Mustang and has had great success running ethanol and 23 pounds of boost with 0 detonation.



Were going to find out if Microsquirt has the same success with this little MC engine. Wish me Luck

Thanks for your interest
 

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obd? why bother just stick a turbo on it, reroute the pipes and plonk a bigger carb on there and your laughing! seriously tho it looks a good project, try looking at overseas sellers as they might do the parts cheaper
 

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Discussion Starter #6
Scuba,

I work with digitized information for a living and really enjoy what I do, plus there’s the whole retro vibe you get when adding new to the old…

I’m also married with children and the shop even with all the tools is a quieter place than the house.

Thanks for your interest.
 

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Discussion Starter #7
I’m still working to finish my SC DT175, but I have begun to collect parts for the little CB160.

The CB160 head and the CB175 cylinder head have been at the port shop for flow bench comparison. The porter will select the better flowing head to modify.

I expect the 175 will flow better, but I have seen some unexpected results from the flow bench before. I will post the results when I have them in hand.

I will use SV650 factory head parts for the conversion:

CB175 Cylinder Head Conversion Parts List

4 SV650 Base Washers ****
4 SV650 Double Springs ****
4 SV650 Valve Retainers ****
4 SV650 Valve Locks ****

Sub Total 71.99$
Picked up on Ebay. It should cover the above parts list.



4 SV650 4.47 guides Kibble White 12.75
4 SV650 Valve seals 1.46
2 SRAD 750 Ex. 25mm valves Kibble White 21.94
2 SRAD 750 In. 29mm valves Kibble White 21.94

The Kibblewhite guides are a bit pricey and the valves are a very low price for a Kibblewhite. They usually run 40-60$ a pop. The valve seals are 1.46$ a pop at BikeBandit.com

Sub Total 140.60

Total 216.59

I will hopefully have enough cash to order the Kibblewhite parts soon. The used SV650 head is already paid for.

The problem is waiting on the port guy. He has a large following and would normally not touch this little motorcycle head, but he and my brother swap hot rod favors and run at the track together.

He is doing it as a favor to my brother. Thanks Bro!

I also have picked up a 1972 CL175 lower unit for the modern shift mechanism and a 1969 CL175 lower unit for the 5 speed sloper cases.

Progress will be reported as it happens. Thanks for the interest.

“Slowly, but surely the Tortoise said to the Rabbit”
 

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Discussion Starter #8
News from the port shop! The heads will be taken apart today and I should have some maximum valve size numbers very soon.

His philosophy on this is no point in putting a valve in the head that is bigger than the intake tract after porting.

I am expecting these little heads to flow 40-50 HP worth of air (70-90 cfm) these are the target HP and air flow numbers the porter will making his decision from.

He will also tell you flow numbers mean nothing to him unless they all come from the same bench with an identical set up fixtures and parameters for each test,

or when comparing your new flow numbers to the old stock ones and again same bench with an identical set up fixtures and parameters.

I am really stoked about the port job. I couldn’t really afford his time if I had to pay strait up.

I will post his recommendations for the valves, which head he prefers hopefully some stock flow numbers Monday.

I will post pics of the port job whenever he gets around to doing it.

Thanks for the interest.
 

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So you are planning on running 45+ psi?
 

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Can't wait to see those flow numbers. 160 heads are not good for flow and peak at around .200" of lift IIRC. Ported they will continue to flow with more lift. 175 sloper heads flow much better, but not 70-90 cfm. A stock 175 sloper can flow that much on the intakes if you can get the valve open enough. A 200 head is basically the same as 175 vertical but has more fin area to dump heat and nice wells to retain oil (the oiling changed on that motor) 200 barrels are too tall to go with longer rods and taller pistons on the 200.

20 or 175 vertical head will handle all the airflow that motor could ever use. A bigger problem is getting it to rev and not generate more friction than power.

With a blower everything changes of course.

I'd suggest go with any 175 barrels you can get cheap plus a 200 head if you have one as the best place to start.

Either style of box works and the early one is an easier weld and machine job or keep your eyes open for a sloper 175 motor or set of crankcases.
 

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Discussion Starter #11
With a good intercooler maybe I can run 12-14psi on street gas.

Yes, 40+ HP I know this number seems high, and I have no experience with these little engines… but hear me out.

Over bore to 200cc:

100% / 160cc = .625cc per 1%

40cc X .625% = 25% increase in engine size.

Total percentage gained by overbore to 200cc = 25%

Stock CB160 advertized HP – 16.5 HP

100% / 16.5 HP = .165 HP per 1%

25% X .165 HP = 4.125 increase in HP

16.5 HP + 4.125 = 20.625 Total HP


Our bore increase has given us a new HP number of 20.625 HP for 200cc

Now if we add a free flowing exhaust, larger valves, and ported head, we should easily see an increase in HP.

These mods could very easily add 10% or more HP, but to keep everyone here honest we will call it 10%.

100% / 20.625 = .20625 per 1%

10% X .20625 = 2.0625 increase in HP

20.625 + 2.0625 = 22.6875 Total HP

Now add 2 atmospheres or 14 PSI to the mix and you should get roughly double the HP

22.6875 X 2 = 45.375 HP

These numbers are purely keyboard racing, but by the numbers 40+ HP should attainable. Throw in custom camshafts, valve timing and a good balance and general blueprint and you get some more HP.

The 175 head at the port shop is a vertical head, please tell me more about the longer rods mentioned earlier.

Thanks for all the interest.
 

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The very, very fastest 160's, taken to 212cc I believe, are making 22-ish HP and about 7 lbft. That is with high compression. Can you run high compression with you turbo? Does the 200cc's even move enough air to get a turbocharger to make a bar of boost?

I'm not any kind of expert with turbos, so I may be way off.

However, a stock 175 really only makes about 12-13 rwhp. My guess is you won't be able to bump compression when running a bar of boost. Stock is what, like 9:1 already? You may actually have to drop CR, especially considering this is an air-cooled engine. Lets say you were able to keep it at 9:1, your added displacement adds 1 rwhp, and you run a bar of boost. That gives you, at best, 30 rwhp.

Still a good number for a 160/175/whatever, but I think 45rwhp is quite a bit more than you can get without 'sploding the engine.
 

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Discussion Starter #14
Again, I am no expert on the subject of the CB160/175 or 200 motorcycle engines, but the numbers above are realistic.

If you ever looked down in the throat of one of these heads you’ll see there is huge room for improvement as they are very restrictive.

I have yet to see a ported and polished CB/160/175/200 head. I have yet to see any flow numbers of any kind, even though I hear a lot of people quote them and I have yet to see a Dyno sheet.

While I am no expert many of the people I do business with are... Ask them and they will tell you a 1” port/valve will easily pass 100 cfm worth of air.

People who go through the trouble and expense to have such modification and testing done usually post such information as I will in this thread when they are in hand.

You can’t really use the CB175 or 200 as a comparison. These engines are in an extreme state of de-tune compared to the little 160 with its giant in comparison tuned carburetors and intakes and race inspired design.

To add injury to insult the CB200 and CB175 carry the same valve size.

It sure seems this project has sparked some debate, I am in the camp that believes 40 HP is easily attainable. Others here do not believe it can be done.

I would like to point out Mr. Elsburg again. He is making 12-14 HP with a supercharged 50cc Honda engine and races it with success. (He is a world record holder)

I will shore up all the known weak links and durability issues that others have already discovered during their builds, but I’m sure the supercharger I will find some weak links very quickly.

As for compression I will leave it some where in the 9:1 to 10:1…. Shock and awe right?
I see cars at the track regularly who run 12-14 psi on pump gas with very good intercooling set ups.

I see no reason I can’t do it.

As for the Air/Oil cooling carrying heat to the turbo is a good thing and a little oil squirt on the bottom of the piston will keep the heat down to a reasonable hopefully detonation free temperature.

Thanks for all of your input, it really helps to work out bugs that I have not thought of yet.

What you guys don’t like the MegaSquirt????

Thanks for your interest.
 

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"I see cars at the track regularly who run 12-14 psi on pump gas with very good intercooling set ups.

I see no reason I can’t do it."

They do it with water cooled engines.

I've seen some dynos with the 160's. Again, the very fastest make 21-22 rwhp, 6 or 7 lb ft.

Even the best port jobs done on the 175 head don't flow enough air NA to fill the jugs at 212cc.
 

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Can I get the bore x stroke you're aiming for, intake valve diameter, intake valve lift and carb size?

I found most of the numbers for a stock CB200, cam lift is based on the mildest Megacycle cam available:
http://www.x386.net/TTR/tech/cgi-bin/motorsim2.cgi?cgibore=55&cgistroke=41&cgicylinders=2&cgicompratio=9&cgiintakemm=28&cgiintakecount=1&cgiintakelift=6.24&cgicarbdiameter=18&cgitranseff=90

My crude sim says 12hp is all that sucker's worth in it's stock config. For 40hp your talking about moving the peak HP past 12k RPM, much more intake lift and/or larger diameter. Throw the numbers into my even cruder supercharger sim, it's saying 18psi boost to hit 40hp at 12k.
 

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Scoobie,

leaving aside the rather long mathematical expose, don't forget that Modern auto engines are not at all like a sixties Honda in any aspect of their design.

Decent squish, 4 valve heads, water cooling and 3D mapping plus FE analysis on critical components makes for a very different starting point. 175 and 200 motors were not much softer than a 160 which was a terrible design in so many ways. Valve train sucks as does the cast iron skull combustion chamber hold over from the CB77/72 means they weep oil and don't seal well on a big bore motor and have terrible heat transfer. 175 was a better set of compromises but the 200 was deliberately softer to suit that market it was aimed at.

There are but two useful parts on a CB200. The head and oil pump plunger. The rest can be recycled. That's probably a little cruel but crank and barrels and pistons and transmission are useless to a 160/175 jockey as are the clutch and cases
 

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I'd be interested in that unit if it's suitable for the 15hp to 20hp range Hack. The only setups I know of are either expensive ($1000+) or require add ons (PC 3) to adjust.
 

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Discussion Starter #19
I had a little time last night to disassemble my donor SV650 head. I removed the cam covers and went to work.



A 5/8 deep well socket and a plastic hammer works nicely to remove locks and springs quickly without losing the tiny locks.



In 30 minutes or so I had most of the parts needed for my valve swap. Minus the valves. I could have the (31mm) intake valve heads resized if needed. The exhaust valve is 25.5mm and may work as is.



I will patiently wait for the port guy to give me some sizes for the valves. If I could use the valves by shortening the stem and re-grooving could easily save me 150$

In fact if I could use everything off the head including the valves, this would be one great deal. Even if I can’t use the valves the rest of the parts I salvaged are a small fortune if you order from Kibblewhite or Suzuki.

I could save another 60$ if I could re-use these guides. I am unsure if I can get them out without damaging them.

The lash caps would be nice to use as well, but I have to do some homework on the subject of using a lash cap in conjunction with a rocker arm vs. being actuated by a cam lobe.

Thanks for the interest
 

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Discussion Starter #20
I had a little time last night to disassemble my donor SV650 head. I removed the cam covers and went to work.



A 5/8 deep well socket and a plastic hammer works nicely to remove locks and springs quickly without losing the tiny locks.



In 30 minutes or so I had most of the parts needed for my valve swap. Minus the valves. I could have the (31mm) intake valve heads resized if needed. The exhaust valve is 25.5mm and may work as is.



I will patiently wait for the port guy to give me some sizes for the valves. If I could use the valves by shortening the stem and re-grooving could easily save me 150$

In fact if I could use everything off the head including the valves, this would be one great deal. Even if I can’t use the valves the rest of the parts I salvaged are a small fortune if you order from Kibblewhite or Suzuki.

I could save another 60$ if I could re-use these guides. I am unsure if I can get them out without damaging them.

The lash caps would be nice to use as well, but I have to do some homework on the subject of using a lash cap in conjunction with a rocker arm vs. being actuated by a cam lobe.

Thanks for the interest
 
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