[goodoltup]

All back together and looking good. Note that the engine now has a CD175 head including cam end covers, a CD175 stator and sprocket cover, and a CB200 clutch cover.

 

[goodoltup]

There are however some things to address in the near future. The cylinder head is in a slightly different position, so the muffler mounts don't line up. These will have to be remade. The new shocks don't have the correct bushing diameter or width, so a bushing will have to be made to suit. And, there is some bad rust in the typical spot behind the tail light.

 

[goodoltup]

I addressed the starter button as well. I bought a new button and spring from a CB750, drilled a hole in the CD175 housing, and manufactured a brass clip to hold it in place. I made the contact from a piece of Vero board by putting a solder glob on the front as a contact. Instead of routing the wire inside the bars where there is almost no room left, I covered it in heatshrink and ran it next to the brake switch wire. The starter button is tested and it works and feels exactly as it should.

Next, when it is not raining, is a test ride! I'll put a few miles on it, change the oil, reset the valve clearance and check the points, then this part of the project will be finished.

 

[01-7700]

if you didn't know the fin was chipped you couldn't tell at all

 

[goodoltup]

Ok bad news. After assembly and test running, the engine was making a noise that I didn't like. It was like a grumbling sound, coming from deep in the engine. Not exactly like a bad bearing, not exactly a ticking noise, something in between. I could not tell really if it was coming from the top end or bottom end. Sounded more like the bottom. Some observations:

• Sound is related to engine rpm
• Sound still happens when transmission is in gear, zero MPH. So it's not a transmission bearing.
• I removed the starter chain and sprag and ran it again, sound still there.

So I think it could be:

• Crank bearings
• Primary drive/clutch basket
• Oil pump
• Cam chain/idlers/tensioner
• Cam bearings

Really none of these seem likely. All these items looked good during assembly, and upon disassembly. There were no shavings or anything in the oil.

So, engine came out and apart. I did not find anything untoward.

As a matter of course, and for peace of mind, I ordered the following parts:

• Full gasket kit
• Crank radial bearing
• Crank Left Hand roller bearing (got a good deal on eBay)
• Cam tensioner wheel, the larger one
• New cam sprocket (old one had some damaged teeth, but would not have been the cause of the noise)
• New piston rings (I made the gap too big on the oil control rings, and the engine smoked a little
• Various other bits that I should have replaced the first time, but that also would not have contributed to the noise.

 

[goodoltup]

You can't buy the tensioner small wheel separately, and I can't find a new tensioner assembly. I'm sure that this part isn't the cause of the noise, but it's not ideal, so I may find a way to replace it anyway. I'm looking into buying something else a retrofitting it somehow.
First picture is the crank radial bearing. You can't just buy a 6305 bearing because it has a registration hole in it to line up with a dowel pin in the case. Too bad, because the Honda bearing is expensive.
All told, I just bought another almost £200 worth of parts.

 

[goodoltup]

I just noticed some differences between the tensioners. In the pictures below, the tensioner with the small roller removed is the CB200 part. The other one is the CD175 part. Note that the angle of the arm is different. I mocked both up in the engine, and this seems to have no affect on the tension of the chain or the final position of the roller, just the final position of the tensioner shoe and spring. Maybe something went funny there? To be safe, I ordered a used CB200 tensioner and new large roller from eBay.

 

[fxray]

This is some of the best work I have seen documented in a while, and it is a beautiful bike. Thanks for the pictures and for taking the time to describe your project.

 

[goodoltup]

This is some of the best work I have seen documented in a while, and it is a beautiful bike. Thanks for the pictures and for taking the time to describe your project.

Hello fxray,
Thank you for thanking me! I use this forum as a diary of sorts, so I can have the story of the work documented for future reference or just nostalgia. I'm a mechanical engineer so I guess I like to document. You may be interested in another project I did with a cb550 frame and KTM 690 engine

Project CB690 (KTM 690 engine in a CB550f frame)

I'm embarking on a project that I've had in mind for a long time, and finally have the funds to start. I want to make a bike that I would like to ride. A classic bike, with a standard riding position. A modern bike, with disc brakes and good suspension. A fast bike, but with torque and low end...

www.dotheton.com

Thanks again!

 

[goodoltup]

Here's a view of the camchain tunnel from the bottom. The chain touches the large roller on both sides, which I wasn't aware of and is kind of interesting. New roller is still on the way. I still don't think it is the cause of the noise, but it's getting replaced anyway.

 

[goodoltup]

Some new parts. Gasket kit. +1mm oversize rings, original Honda. The rings are because I messed up the oil control ring end gap previously, and I noticed that the LH cylinder smokes a bit, maybe this will correct that. New bearing. Perhaps not needed but I got a good deal on it, only £35 so why not. And the tensioner. It is in superb condition, but I already bought a big roller so that will get replaced anyway. Also a new (used) cam gear. The previous one had a dink in a tooth that I didn't like. I'm awaiting parts from CMSNL, so won't get to reassemble until next weekend. It should be noted that I really don't think that any of these items are the likely cause of the noise, but I'm replacing them anyway.

 

[goodoltup]

Final parts arrived. This weekend the engine will go back together.

 

[goodoltup]

Ok let's build the engine (again)! I replaced the big radial ball bearing on the RH side of the engine, and also the roller bearing on the LH side. An observation, the rollers fell out of the old bearing. The rollers stayed pretty firmly in the new bearing. Maybe the cage was worn? Bottom end assembly went smoothly.

 

[goodoltup]

After assembling the top end I had some trouble with the cam. This was the CB200 cam that I only used because it was easy. The cam lobe wear was interfering with the rocker. I'm not sure how I got away with it the first time the engine went together, maybe I used a different rocker that just fit it better. But in this case, the rocker is up on the worn lip of the lobe, and you can see daylight between them. So, I'll use the CD175 cam like I wanted to in the first place.

 

[goodoltup]

This is covered pretty well on a different thread..

Cl175 dropped on a beach rebuild (Now a running 200cc)

Re: Cl175 dropped on a beach rebuild Thanks for the support, this is the first time I've been this far down the rabbit hole

www.hondatwins.net

from Simo, so I won't go too deep. There is a 1mm gap (2mm diameter difference) between the CD175 cam and CB200 sprocket, so I made some 1mm shims out of steel and tack welded them to the sprocket. Instead of using a mill to widen or slot the holes I moved them 90 degrees. Now the timing mark will be 90 degrees off, I'll just have to remember that.

 

[goodoltup]

An updated cost list for this project is below. Parts in blue were ordered after the engine was assembled and the funny noise was discovered.

 

[Emil]

WOW! That's 1645.09 USD. You must really LOVE to tinker on that bike!

 

[goodoltup]

WOW! That's 1645.09 USD. You must really LOVE to tinker on that bike!

Hi Emil,
It got a little out of hand! I only paid £1200 for the bike, and I could probably only sell it for £1500, so it is a very bad investment. But, I did enjoy making a custom motor and upgrading the machine, and it kept me out of trouble over the winter.

 

[goodoltup]

Ok I've been NOT riding the bike lately because the noise is really bothering me. Last thing I can think of is piston slap. It is a bit of a clattery noise that increases with RPM, and never goes away under any conditions (clutch in, clutch out, neutral, under load, etc.) I did not check the work of the guy that bored the cylinders, maybe he got it wrong? Maybe the aftermarket pistons are funny? I don't know. To that end, I could take the pistons out and measure them, maybe I'll find something. But, I may as well just have a new set of pistons/cylinders to swap out, to minimise down time. So I bought a set on Ebay, but I found when I received them that they are already 1mm over, so the pistons better be good. I've cleaned and painted the cylinders and given a fresh hone to the bores. I'll install some weekend and will see if that fixes the noise.
Below are the cylinders. I made a small stand on which to paint them, which also keeps the weight off of the liners when putting them in the oven. Sometimes if you heat them up the liners will push out.

 

[goodoltup]

Cylinders have been installed. The bike has been assembled and test run. The noise remains!

As a troubleshooting method I removed the primary gear and ran the engine (for a few seconds only because the oil pump runs off the clutch basket, which is driven by the primary gear.) The noise remains!

Removing the primary drive gear completely isolated the oil pump, primary drive, clutch basket, and all transmission gears and bearings. Earlier in the project I removed the sprag clutch and starter chain and retested as well.

With those items isolated, below is a list of things that it COULD possibly be.

• Crank main bearings
• Big end bearings
• Pistons
• Small end bearings
• Cam chain
• Cam chain tensioner
• Cam bearings
• Tappets

That's it! Now a list of why all of those things are unlikely.

• Crank main bearings
  • I replaced the two outer main bearings. The inner two felt fine. Plus, it just doesn't sound like bearing noise.
• Big end bearings
  • I had the engine apart a few times, and they felt fine. Doesn't sound like big end noise really.
• Pistons
  • I swapped pistons and cylinders, the noise remained.
• Small end bearings
  • I swapped pistons, and the noise remained.
• Cam chain
  • New cam chain.
• Cam chain tensioner
  • New rollers.
• Cam bearings
  • No damage. Plus, this head/cylinder was used in my CD175, and it didn't make any noise then.
• Tappets
  • No damage. Plus, this head/cylinder was used in my CD175, and it didn't make any noise then.

When looking at parts lists, I found that for the CB200, some people are selling a 219T cam chain in 88 links, some with 86 links. CMSNL doesn't have any model year breaks for this. I can't verify how many links the chain I installed has. Is it possible that for some reason the cam chain is too tight? It would have been hard to install, and it wasn't. I DID notice however when assembling the engine that after assembling the top end and releasing the cam tensioner that it didn't move at all. Is the cam chain tensioner at the end of it's adjustment? Is the chain too tight somehow? Also, there is a difference between the CD175 and CB200 cam covers. Is the chain rubbing on the cover and I didn't notice?

I have ordered a new cam chain, 100 links, and I will cut to size and install a master link. I have ordered a CB200 cam cover. Next week I will pull the motor, replace the chain without splitting the cases, replace the cam cover, reinstall and test.

If that doesn't work I will replace the crank.

If that doesn't work I have no idea what to do.