71 CB175 Project Lily Faye

[SeekingZero]

Nice progress so far. Really good work with that rear hoop. Also the soda blasting made that engine look great. Keep it up. I love these little bikes

Thanks. The soda blasting did a good job cleaning but I will still need to paint it.

300 bucks and it ran? where did you find that thing! looks like someone had a lot of fun throwing things together. like a sad baby frankenbike

great welding job, too! should be a fun bike for your wife to ride. you should see if she'll help you out with the rebuild!

South of Indy, and yes, very sad. I told her that she gets to help fiberglass a new seat pan. She said she'll hand me a wrench. :

 

[SeekingZero]

So I have started to rebuild the engine and did not realize how involved it was going to be.

Does anyone have a step by step, or a rebuild guide, or a book for this engine. I mainly want to get everything cleaned up and make this engine like new so I don't have to deal with it the way it was.

 

[Bert Jan]

http://www.mediafire.com/?tej2xyizztm

get it while it's still there!

 

[SeekingZero]

http://www.mediafire.com/?tej2xyizztm

get it while it's still there!

Thanks! I also found this guy's blog rebuilding a SL175 for anyone's reference. http://jaredyates.com/pages/sl175engine/sl175engine.shtml

 

[SeekingZero]

I got to disassembling the engine and have some questions.

First, should this side chain for the starter be this loose? I know it may be hard to tell, but anyone with some experience please chime in.

Also, the exhaust valves look a little banged up around the edges. From what I can tell they seat fine, but I just wanted to make sure this was alright.

And here are some images of the pistons and valves. I've got them cleaned up now.

 

[teazer]

starter chain is fine - they always have a ton of slack in them.

Valve is not so fine and should be removed and cleaned up

 

[SeekingZero]

starter chain is fine - they always have a ton of slack in them.

Valve is not so fine and should be removed and cleaned up

I did clean the valves up but I didn't remove them. That image of the exhaust valve is after cleaning. The edge is just banged up, and I'm not sure why. Should I replace them? Or put it back together and do a compression check first?

 

[Bert Jan]

Not sure on the valves, but they look very similar to the cb200 im doing. Wondering how the hell it's possible that there seems to be space between the valve and seat. Has to be tight fit when the springs are in (and they are cuase you didn't remove them) I even might dare to say the valves are from another (smaller) model cause the seats look way bigger then the valves. Also, as far as my knowledge goes, exhaust valves are smaller then inlets, like so, on my cb550f

yours seem to be the other way around.. oddly enough
long shot, but is it possible some redneck tried to fix the engine and ended up putting the valves in the wrong holes? (inlet in exhaust ans vice versa) If so, the damage to the valves is easily explained...

and starter is fine, as teazer mentined also. You can remove the little gear from the starter motor by sliding and check the chain for wear. Just be sure it can't hit the casing when engaged. That way it could take a chuck out of it.

 

[Bert Jan]

and waddap with this?

think you better get a new head man!

 

[SeekingZero]

and waddap with this?

think you better get a new head man!

I was worried about that too. In the picture it looks like damage but its actually white powder. I spent about 15 minutes thinking about what would cause white build up in the cylinders, and then in dawned on me that it was baking soda from the soda blasting!

As far as the valves go, does anyone have some pictures of what cb175 valves should look like in the head? A comparison would be nice. At this point I may just take them out and take them into a mechanic and see what he thinks.

 

[Bert Jan]

i would definatly take the head to a machinist, the lower right valve looks really far out on the pic i shopped..not good at all with the springs in it.

 

[SeekingZero]

Well I put the engine back together and did a compression check. I got 90 in the left cylinder and 109 in the right cylinder. 140 is what they should be at and anything lower than 114 indicates a leak. So I put some oil in one cylinder to seal the rings and did another compression check and the compression went over 300. So what now. Is it the valves? Rings? Both?

 

[interceptor]

Sounds to me like your rings are shot. How much oil did you put in there? 300 seems really high. Should only put about a teaspoon in. If there was no difference then there is something going on with the valves. Are your carbs back on too?

 

[SeekingZero]

Sounds to me like your rings are shot. How much oil did you put in there? 300 seems really high. Should only put about a teaspoon in. If there was no difference then there is something going on with the valves. Are your carbs back on too?

I didn't measure, I just poured. Maybe a tablespoon. Its only the engine, no carbs.

 

[teazer]

A tablespoon is about the size of that combustion chamber. LOL.

Pull the head and barrels off and inspect it all. Sounds like rings are stuck and valves could probably use a lap. At least with teh top end off, you will be able to see and measure it.

 

[SeekingZero]

Anyone know where I can find aftermarket valves for this bike? Ebay only has exhaust valves, unless I want to order from Asia, and I don't.

 

[teazer]

Kibblewhite are probably the best, but you can probably get valves from Toad Town or BoreTech and maybe M3.

 

[SeekingZero]

Kibblewhite are probably the best, but you can probably get valves from Toad Town or BoreTech and maybe M3.

Great! Kibblewhite is just a hour from me. I'll just ride over and pick em up. Thanks so much!

Also an update on the head and valve situation. I have the head at a local mechanic, and the valves are bent, they don't close fully with the springs in. So I need new valves at the very least.

 

[SeekingZero]

An update on the project overall:

As with most projects that take any amount of my time, I change my mind often. So I discussed with the wife and we decided to build it back up as a not so perfect bike that she can just throw around or lay down like Clarkson did with the Vespa in Vietnam...

She loved the general look of the CB350 from The Girl with the Dragon Tattoo, and being that it would be fairly easy for me to replicate that since its far from a perfect looking bike, I was all for it.

So the list of things to do is:

Finish engine rebuild
Refinish/Paint frame and parts
Purchase parts I still need - cables, levers, etc.
Reassemble
Ride

 

[teazer]

BTW, both heads in those pics are correct. Exhaust valves in both are smaller than the intakes. That's correct.

For a cheap or low cost alternative to Kibblewhite valves, you could get another second hand set or a complete head fairly cheaply or look on ebay for valves. Any 157 or 200 valve will fit but 160 are smaller.

Get a valve spring compressor from H.F. and you can pop those puppies in at home. No point in paying to have someone do that for you. You will need a m/c shop to surface the valves and cut the seats if they are bad, or just lap them in if they are not bad.