CB175 valve train replacement

T

triplesNtwins

Louder the pipes, the safer you'll be.
So as some of you may know, the valves in these little 175's are pretty much garbage . Im just looking for guidance as to what valves I should be looking for. It would be nice to find some stainless steel that wont cost me more than i paid for the whole bike itself. Is bateman racing the only place i can find these valves. Any help is appreciated.

T.
 
Bateman or Kibblewhite. Pretty much anything other than stock is gonna cost you though........
 
I'm not sure why you think that stock sucks. SUre they drop a head from time to time but to be fair, we ran three different motors for years on stock (lightened) valves and only failure we had was when my rider tried to catch a CB350 up the main straight at Road America and severely over revved it. 13,000 will do that to a valve eventually.

I have looked at Kibblewhite valves and agree that they are a nice insurance, but they also have a life and need to be replaced from time to time.

For a street motor I would use whatever valves came out of the motor - clean them up and you're good for another decade or so. For a race motor, I'd still have a hard time justifying the investment Titanium valves are good with a 180 degree crank, full re-design of the cam tensioning arrangement and suitable seats and guides, but my pockets are not that deep.

I used to get valves machined up from stainless blanks to my own designs for a CB77 but the cams I used beat them to death so I started to use stock valves and with a slight head re-design they made more torque and more power than the old SS oversized valves.

Now what was the problem you were alluding to?
 
teazer: that was the response I was looking for, and yes INSURANCE was probably the reason why I was asking this question. I don't have a lot of experience with the CB's and from what Ive read is that the valve train is garbage. But your right, my pockets aren't that deep, but I want new ones because I have a brand new head that I would prefer to put new valves in. Just wanted somebody's opinion on the topic.

Also what does anyone know about ignitions for these cbs? I want to ditch the points.

Thanks T.
 
This isn't cheap, but I suspect you'll have a hard time finding better:

http://www.probe-eng.com/servlet/the-Honda-CB160-fdsh-175/Categories
 
You'll be hard pressed to beat this price for stock valves:

http://www.ebay.com/itm/Honda-CD175-CA175-CL175-CB175-SL175-CB200-Valve-in-ex-/230583099958?pt=Motorcycles_Parts_Accessories&hash=item35afd2e236&vxp=mtr

You may want to consider replacing the valve guides at the same time:
http://www.ebay.com/itm/HONDA-CB160-CB175-BRONZE-VALVE-GUIDES-/230661692166?pt=Motorcycles_Parts_Accessories&hash=item35b4821b06&vxp=mtr

I'd stay clear of any aftermarket valves for the CB175 though. They're available because the 175 is a popular vintage race bike, but most will require aftermarket springs, retainers, etc. It's going to be an expensive path the follow.
 
Or get a DYNA to fit a GL1000 and remove one of the two pickups and keep it as a spare. The DYNA backing plate is exactly the same size as a CB160/175/200 You will need a sleeve to fit the DYNA rotor in place of the points cam, but that's simple, and you may have to shorten the rotor slightly but that's a hacksaw and file job if you don't have a lathe handy.

Simple, not too spendy and effective even with a stock coil.

Or find a gently used/pre-loved DYNA S for any bike cheap and fit the pickup to your points plate. Slightly more work and even cheaper.
 
Triple, check out some of the links at the bottom of the first post:

http://www.dotheton.com/forum/index.php?topic=12552.0

And search around for Les Baker (or is it Barker?) - he is a great source for parts.
 
Rich, thanks for the help, those links will do me a lot of good when it comes down to it. Thanks everyone I think im off to a start with this. Ill set up a thread of my build once I get these parts gathered up. Just have to finish off my RD then its time to mess with a 4 stroke.
 
Sonreir said:
You'll be hard pressed to beat this price for stock valves:

http://www.ebay.com/itm/Honda-CD175-CA175-CL175-CB175-SL175-CB200-Valve-in-ex-/230583099958?pt=Motorcycles_Parts_Accessories&hash=item35afd2e236&vxp=mtr
Click to expand...

+1

Had these put in my head. I haven't fired the engine since the head rebuild but you can't argue with the cost, especially when you compare the price of Kibblewhites. I didn't have to get new glides, but I did replace the seals and caps procured from my local Honda shop.
 
Honda valve guides rarely seem to need replacing. We fitted CB200 valve guides to our 175 race bikes just to get better valve stem seals.
 
teazer said:
I'm not sure why you think that stock sucks. SUre they drop a head from time to time but to be fair, we ran three different motors for years on stock (lightened) valves and only failure we had was when my rider tried to catch a CB350 up the main straight at Road America and severely over revved it. 13,000 will do that to a valve eventually.

I have looked at Kibblewhite valves and agree that they are a nice insurance, but they also have a life and need to be replaced from time to time.

For a street motor I would use whatever valves came out of the motor - clean them up and you're good for another decade or so. For a race motor, I'd still have a hard time justifying the investment Titanium valves are good with a 180 degree crank, full re-design of the cam tensioning arrangement and suitable seats and guides, but my pockets are not that deep.

I used to get valves machined up from stainless blanks to my own designs for a CB77 but the cams I used beat them to death so I started to use stock valves and with a slight head re-design they made more torque and more power than the old SS oversized valves.

Now what was the problem you were alluding to?
Click to expand...

To clarify, would you recommend sticking with stock valves in the 175 over fancy ones from Kibblewhite for racing?
 
That depends on how hard you rev it and how often you race it. If you run it until the valves bounce, fit Kibblewhites. If not just replace stock ones every couple of years at the annual teardown. That's what I do. If you're risk averse, fit Kibblewhite and know that you are relatively safe.
 
teazer said:
That depends on how hard you rev it and how often you race it. If you run it until the valves bounce, fit Kibblewhites. If not just replace stock ones every couple of years at the annual teardown. That's what I do. If you're risk averse, fit Kibblewhite and know that you are relatively safe.
Click to expand...

Do you have any idea what the lifetime of the Kibblewhites are vs. stock for racing? My thinking is go with the Kibblewhites and you can skip more replacements at the tear downs and be relatively safe.
 
No idea. We had one failure of a stock exhaust in 10 years of racing including Daytona and Road America and RA Superbike School on the same old used valves out of one of our junk motors. I have no idea how to extrapolate that to any one else's situation.

You could do the analysis and testing I suppose, but that would be more expensive than replacing valves every season. Ask K/W what they recommend for replacement times. They may not know, but it's worth asking. The answer might be 500 hours at less than say 11,000 and immediate replacement if motor went past 12000 or some such. Life depends on so many variables including revs, cycles, and temperature and let's not forget that excessive clearances make the valve slam back onto the seat and that shortens life dramatically too.

The real issue is not the cost of valve replacements or even piston, crank and barrel replacement, but how much is invested in the head. We ruined a CL175 sloper head and had to fit the one from my only other motor and that will be expensive to weld up and machine. Our heads are ported and flow tested and machined for different squish etc and that all takes time and other scarce resources.

The smart thing to do is to fit K/W valves on a racer and keep a good race log. All parts have a fatigue life and will fail eventually. The trick is knowing when and swapping them out before that point.
 
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