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    AD

1971 CB350 . . . 40 year hibernation

Thank you AD and BB (ballbearian) for the parts cleaning advice. I'll hopefully get to the cleaning soon.

I received my micrometer set today and just checked the intake lobe on the cam. My measuring skill is likely still developing, but I found the base diameter to be 1.301" and the lobe diameter to be 1.561" for a lift of 0.260". The spec is 0.271". The scuffing already suggests repair or replacement, but how bad is that number? And do these measurements sound reasonable for the later cams? (The odometer shows 10,000 miles and I think they were hard miles.)
 
If you’re going to use mics and calipers it’s (in my opinion) a really great investment to get a reference standard (about $20, something like this https://www.ebay.com/itm/1340689657...o2D0Et7Qlq&var=&widget_ver=artemis&media=COPY) to get the “feel” right.

You can easily be off by a few thou by forcing a measurement - much worse with calipers, but mics aren’t idiot proof either.

Re: parts washing, you can also grab a 5 gallon container of ZEP, simple green, etc, any degreaser really and just dump it in a bin to use with a scotch brite, wire brush, whatever.

We have a 20 gallon tote in the shop I’m at now that works just as well as the parts washer that was at the old place I was at. It’s just a tub with a pump and a spout at the end of the day.


-Ed
1972 CL350
1985 VF700F
 
If you’re going to use mics and calipers it’s (in my opinion) a really great investment to get a reference standard.
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My set came with three reference standards, so I'll try to get some practice with the feel. As with many skills, I can only hope to get better with experience.



Re: parts washing, you can also grab a 5 gallon container of ZEP, simple green, etc, any degreaser really and just dump it in a bin to use with a scotch brite, wire brush, whatever.
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This sounds like a good way to go. I have a cheapo HF pump that I bought for a one-off task and, for my current needs, I could probably use an oil pan of Simple Green and Scotch Brite to get started cleaning the cylinder and head.
 
stl360+450 said:
I have a cheapo HF pump that I bought for a one-off task and, for my current needs, I could probably use an oil pan of Simple Green and Scotch Brite to get started cleaning the cylinder and head.
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This sounds like a good low budget way to go, I just hope the Simple Green works well enough for you. My experience with it on my 450 bottom end parts wasn't very impressive, which is why I ended up buying the petroleum based stuff later.
 
stl360+450 said:
Thank you AD and BB (ballbearian) for the parts cleaning advice. I'll hopefully get to the cleaning soon.

I received my micrometer set today and just checked the intake lobe on the cam. My measuring skill is likely still developing, but I found the base diameter to be 1.301" and the lobe diameter to be 1.561" for a lift of 0.260". The spec is 0.271". The scuffing already suggests repair or replacement, but how bad is that number? And do these measurements sound reasonable for the later cams? (The odometer shows 10,000 miles and I think they were hard miles.)
Click to expand...
Numbers aren't actually bad. The FSM numbers don't seem to match reality and since Honda was revising their cams continually the one time printed spec may not apply for lift.
Here's an 060 cam profile
107a7c20c31862030adfa0a6f5e20a02.jpg
 
I removed the pistons (standard size) and inserted the top rings into each cylinder to check the ring end gap. Found them both to be around 0.018" to 0.020" while the standard range is listed at .008" to .016" and the service limit is .032". The cylinders show many little scratches and scuffs, but I don't see anything that looks deep.

z128WjP.jpg


The pistons measured 2.516" (63.90mm) and 2.519" (63.95mm), but no one should put too much stock in my ability to accurately use a micrometer at this point. Again, there is no unusual wear on the pistons, so I would like to think that standard pistons and cylinder honing will be sufficient for the rebuild.

1fmK6Xs.jpg
 
So far so good. You want to check the ring gap with the rings @1/2" from top and @1/2 way down the cylinder. Pistons should be measured top, middle and bottom.
Looks like a light hone and new rings.
 
If you are planning to re-use your pistons, and you decide to vapour blast your stuff, make sure you throw your pistons in as well. Personally, I never re-use pistons, I always bore to the next stage and put new ones in. Make sure you replace your rings, pins and clips. Buy some extra piston pin clips, and try to get one in quickly and swift. If it takes longer then a 20-30 seconds to put one in, throw it away, and start with a new one. I have seen too many damage due to a weak clip. There is only one way to put the clips in, the good way, must people underestimate this tiny part, with a lot of damage as a result.

If you have new piston pins, please check your small end play.
 
jensen said:
If you are planning to re-use your pistons, and you decide to vapour blast your stuff, make sure you throw your pistons in as well. Personally, I never re-use pistons, I always bore to the next stage and put new ones in. Make sure you replace your rings, pins and clips. Buy some extra piston pin clips, and try to get one in quickly and swift. If it takes longer then a 20-30 seconds to put one in, throw it away, and start with a new one. I have seen too many damage due to a weak clip. There is only one way to put the clips in, the good way, must people underestimate this tiny part, with a lot of damage as a result.

If you have new piston pins, please check your small end play.
Click to expand...

Thanks for the advice, especially as regards the wrist pin clips and small end play. I have been on the fence about reusing the pistons. The ring end gap is a bit large, which made me wonder how much of that typically results from ring wear vs. cylinder wear. It makes sense to me that the ring wear would be greater than the cylinder wear, but differences in the hardness of the materials could change my expectation. If the cylinder wear tends to be greater, I'd rather go to +0.25mm.

I see that 4-into-1 has a +0.25mm aftermarket kit that is around $100. Should I be able to trust such a kit or should I be looking for Honda parts? Wiseco seems to offer kits in the +1.0-2.0mm range.
 
stl360+450 said:
Thanks for the advice, especially as regards the wrist pin clips and small end play. I have been on the fence about reusing the pistons. The ring end gap is a bit large, which made me wonder how much of that typically results from ring wear vs. cylinder wear. It makes sense to me that the ring wear would be greater than the cylinder wear, but differences in the hardness of the materials could change my expectation. If the cylinder wear tends to be greater, I'd rather go to +0.25mm.

I see that 4-into-1 has a +0.25mm aftermarket kit that is around $100. Should I be able to trust such a kit or should I be looking for Honda parts? Wiseco seems to offer kits in the +1.0-2.0mm range.
Click to expand...

I would have no problem using your pistons as long as the ring grooves are completely clean and show no excess wear. Always replace the wristpins and clips of course, and checking the small end of the rod for pin fit is a basic requirement as well. For me, it isn't the cost of the parts as much as the other aspects of piston replacement when you go oversize, and the primary part of that is the quality of the cylinder boring available to you in your area. If you've never used the machine shop that you choose to do your boring, the results could be good or not so good and you have to live with that while spending money for the labor and for brand new parts that might not equate to a good overall outcome. I'd closely inspect your pistons and if they're as good as they look, buy a new set of 1st over rings and file the end gaps to the low end of spec, give the cylinders a light hone and be done with it. There will be minimal break-in as well.
 
ancientdad said:
I would have no problem using your pistons as long as the ring grooves are completely clean and show no excess wear. Always replace the wristpins and clips of course, and checking the small end of the rod for pin fit is a basic requirement as well. For me, it isn't the cost of the parts as much as the other aspects of piston replacement when you go oversize, and the primary part of that is the quality of the cylinder boring available to you in your area. If you've never used the machine shop that you choose to do your boring, the results could be good or not so good and you have to live with that while spending money for the labor and for brand new parts that might not equate to a good overall outcome. I'd closely inspect your pistons and if they're as good as they look, buy a new set of 1st over rings and file the end gaps to the low end of spec, give the cylinders a light hone and be done with it. There will be minimal break-in as well.
Click to expand...

Thanks, Tom. I have used two local machine shops based on recommendations from friends. It turns out that the motorcycle shop where I took my rims for powdercoating last summer uses one of those shops as well, so that gives me a little extra confidence in them, although neither shop has let me down so far.
 
I agree with AD about the pistons, if useable, use them, don't worry, don't spend too much money on things that are more or less ok, since you have other, more important things to look at and invest in. I gave my personal opinion about re-using pistons, since I have the tools to bore and plateau honing them at the office.

Already some news about the paperwork of this bike ?
 
jensen said:
Already some news about the paperwork of this bike ?
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My friends should be back from a long trip this week. I've avoided bothering them during their travels, but I will reach out this week if I don't hear from them first. I don't want to go any deeper without securing the title.
 
ancientdad said:
I would have no problem using your pistons as long as the ring grooves are completely clean and show no excess wear. Always replace the wristpins and clips of course, and checking the small end of the rod for pin fit is a basic requirement as well. For me, it isn't the cost of the parts as much as the other aspects of piston replacement when you go oversize, and the primary part of that is the quality of the cylinder boring available to you in your area. If you've never used the machine shop that you choose to do your boring, the results could be good or not so good and you have to live with that while spending money for the labor and for brand new parts that might not equate to a good overall outcome. I'd closely inspect your pistons and if they're as good as they look, buy a new set of 1st over rings and file the end gaps to the low end of spec, give the cylinders a light hone and be done with it. There will be minimal break-in as well.
Click to expand...



Thanks Tom for these comments. Good motivation and perspective for me to address the machine shop issues I've been avoiding. Also, good to know about using oversize rings on standard pistons, I had no clue that was possible.
 
ballbearian said:
Also, good to know about using oversize rings on standard pistons, I had no clue that was possible.
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You can always go up one size to ensure you get a good tight gap within spec. A bit of cylinder wear would make for a gap at the farther end of spec with standard rings. Can't safely go more than one size over without concerns about the proper curvature at the ends.
 
I checked in about the paperwork and learned that one of the parties involved had to isolate/quarantine this week. The plan is to address the title after that is over. So, I'm not doing a whole lot with the bike right now, but hope to soon.

I'm curious, though, about the prospects of getting this big dent popped out of the tank. Can it be done? I don't need the tank to be perfect, but this dent is a bit large for my taste.

ywWywVD.jpg
 
wentwest said:
These folks in Santa Rosa, CA claim they do paintless dent repair on tanks. At least check them out.

https://motopdr.com/
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Thanks, Bob, I checked them out and they do seem to be pros at this, although I'm guessing it's an expensive service once you include shipping both ways. I like learning new things, so I think I'm going to try pulling the dent myself. Depending on how badly I fail, it could make for an even greater challenge for the professionals!
 
I got all the old paint off the tank today. It was a lot of work, especially in the areas where two HONDA bumper stickers were placed. I got a little heavy handed with my grinder after I tired of the paint remover, but I'll worry about smoothing the surface out a bit later on. There are three dents that I hope to pull out, one of which was hidden by Bondo under the left side badge. The tank feels much nicer to me already, now that the old paint and stickers are gone.

rJXq0tt.jpg
 
Earlier today, I dropped off most of the top end pieces for vapor blasting with a local motorcycle shop. The cylinders and valve guides will be evaluated and they'll hone the cylinders if that's all they need. They said it would take about two weeks.

sBKHmE7.jpg


I ordered a set of three JIS screwdrivers on eBay a couple of years ago without realizing they were designed to work with a 15mm socket/wrench. I use a hand impact 95% of the time, but occasionally I'll use my HF impact tool with one on a stubborn pan screw. Helped with the one toughie today on the insulator boots.

In the afternoon, I rebuilt the 3D carburetors using kits from 4-into-1. I installed all of the new internal parts that came with the kit, so the only original internal parts will be the jet retainers, floats, and float pins. The float heights checked out at 26mm, so I made no adjustment. I also installed new throttle shaft felts that I bought on eBay. The original internal pieces will be kept in case I run into any issues if/when the bike is operational.

aSzS8MU.jpg


The chrome tops cleaned up well. All I had to do was send about $40 to the good folks at 4-into-1 for replacements.
 
haha! It's amazing how shiny things get when money is used to polish them.
 
Did you get the cracked overflow tubes soldered up in the carbs? I did mine this weekend.

brassy.jpg
 
Title is still in progress, so things are moving slowly. This morning I picked up the parts I had vapor blasted at a local shop. The valve guides and cylinders were inspected and the guides checked out okay, while the cylinders did not. I was told that the piston to wall clearance was 0.005" and that I should probably go 1st or 2nd over. I'd like to investigate that further before committing to oversized pistons.

GWI6v7p.jpg

I also picked up a reprint of the parts manual for the CB/CL350K3, which came from the UK.

cQv4DgR.jpg
 
I played around with feeler gauges this afternoon to see if I could learn any more about the condition of the cylinders. I don't have any specific directions or experience here, so I'm sure there is a better approach, but here goes.

hrwyc3L.jpg


The table below shows observed ring end gap versus depth. Does this give any useful/credible information about taper?

xqROZV7.png


I also found that I could insert a 0.006" gauge on the sides of the piston (no rings) with little resistance. The same gauge would become tight more quickly when inserted in the front or back. I did this with the piston top about 1" below the top of the cylinder.

Is there anything else I could reasonably measure without the aid of a machine shop?
 
Is that table from the FSM? The engine's stroke is just under 2" (50.6mm), so the chart in inches shows cylinder depths far greater than the stroke of the engine. Since the pistons are cam-ground they always have more clearance on the sides than the thrust faces front or back. If a .005" feeler fits reasonably easily on the thrust faces then the bore is pretty sloppy
 
ancientdad said:
Is that table from the FSM? The engine's stroke is just under 2" (50.6mm), so the chart in inches shows cylinder depths far greater than the stroke of the engine. Since the pistons are cam-ground they always have more clearance on the sides than the thrust faces front or back. If a .005" feeler fits reasonably easily on the thrust faces then the bore is pretty sloppy
Click to expand...

The table consists of measurements of ring end gap in terms of the depth in the bore. I wanted to get some information from different depths to see how it varied.

The 0.006" gauge goes in without much resistance, but it's obviously snug. Sounds like I should be thinking about oversized pistons.
 
stl360+450 said:
The table consists of measurements of ring end gap in terms of the depth in the bore. I wanted to get some information from different depths to see how it varied.
Click to expand...

Right, but it seemed odd because at 3.5" of depth you'd be down in the area well beyond where the rings even ride, and close to halfway down where the skirt rides in the lower part of the sleeve. And at 1" down those numbers look like the maximum end gap or somewhere near it

stl360+450 said:
The 0.006" gauge goes in without much resistance, but I'd obviously snug. Sounds like I should be thinking about oversized pistons.
Click to expand...

Either Cruzin Image or Scrambler Cycle will be a good choice

https://scramblercycle.com/collecti...350-piston-kit-2-sets-5mm-0-50mm-os-new-repro

https://www.cruzinimage.net/2017/08/17/68-73-honda-cl350-0-5mm-oversize-pistons-set/
 
ancientdad said:
Right, but it seemed odd because at 3.5" of depth you'd be down in the area well beyond where the rings even ride, and close to halfway down where the skirt rides in the lower part of the sleeve. And at 1" down those numbers look like the maximum end gap or somewhere near it
Click to expand...

That's fair. I didn't think too hard about the stroke or ring locations on the piston when I was taking measurements.

Is it typical to see more wear near the top of the piston travel, as the measurements suggest?
 
stl360+450 said:
That's fair. I didn't think too hard about the stroke or ring locations on the piston when I was taking measurements.

Is it typical to see more wear near the top of the piston travel, as the measurements suggest?
Click to expand...

Jim of thousands of engine builds would know this better than I, but I know the wear is always greater at the top and bottom because of the rotational forces. That's one of the reasons he asks about taper.
 
Your actual ring gap numbers will vary depending on if you are using your old ring or a new one but you will get an idea of relative variance.
I know you are weighing your options. I was in the same spot with my build, which I still have not finished (project log Blue Dream CA78), long story.
Your piston fit (.006) sounds consistent with your machinist recommendation.
 
ancientdad said:
Jim of thousands of engine builds would know this better than I, but I know the wear is always greater at the top and bottom because of the rotational forces. That's one of the reasons he asks about taper.
Click to expand...

Thanks. I may have jumped over the bottom of travel area in my amateur approach, but the toys have not yet been put away, so I could check a bit more for curiosity's sake.

Edit: I checked the gap at 2" depth and found 0.017" on the left cylinder and 0.020" on the right. Beyond that, it seems to tighten up.

ballbearian said:
Your actual ring gap numbers will vary depending on if you are using your old ring or a new one but you will get an idea of relative variance.
I know you are weighing your options. I was in the same spot with my build, which I still have not finished (project log Blue Dream CA78), long story.
Your piston fit (.006) sounds consistent with your machinist recommendation.
Click to expand...

Thanks for the tips. I'm using the old rings, so that should be factored in, but it sounds like any further measurements will be for my edification only (which is something I enjoy along with the practical decision making information).
 
stl360+450 said:
I'm using the old rings, so that should be factored in, but it sounds like any further measurements will be for my edification only (which is something I enjoy along with the practical decision making information).
Click to expand...

Nothing wrong with checking the gaps on the old rings, it's yet another indicator of overall wear. I'm often curious about it when the bore isn't as worn
 
In my experience I've found that over square engines have more taper at the top than under square engines. An over square engine is one where the piston bore is larger than the stroke.
I've only dealt with a couple of actual square engines and they were tapered top and bottom.
Your last measurement shows what the actual bore size was originally before any wear took place. So your left cylinder has worn .007" and the right is worn .010"
Yeah it's time for 1st over pistons minimally but given that the right side is .010" over to begin with I would go with 2nd over so between the boring and honing you'll have fresh clean surfaces. .010" is .25mm, 1st over.
 
LongDistanceRider said:
In my experience I've found that over square engines have more taper at the top than under square engines. An over square engine is one where the piston bore is larger than the stroke.
I've only dealt with a couple of actual square engines and they were tapered top and bottom.
Your last measurement shows what the actual bore size was originally before any wear took place. So your left cylinder has worn .007" and the right is worn .010"
Yeah it's time for 1st over pistons minimally but given that the right side is .010" over to begin with I would go with 2nd over so between the boring and honing you'll have fresh clean surfaces. .010" is .25mm, 1st over.
Click to expand...

Thanks, Jim. That's interesting information about the squareness of the bore and stroke and with the 350 being over-square, the greater wear/taper at the top seems to fit.

Second over only gets to 330cc. It might be nice to get it up to at least 350cc if I need new pistons...
 
stl360+450 said:
Thanks, Jim. That's interesting information about the squareness of the bore and stroke and with the 350 being over-square, the greater wear/taper at the top seems to fit.

Second over only gets to 330cc. It might be nice to get it up to at least 350cc if I need new pistons...
Click to expand...

As you have seen from my 450 - forget the compression ratio for a minute - you can safely go as far as 4mm over on the stock Honda sleeves, and that will get you well beyond 350cc (367.5)
 
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