stl360+450
Veteran Member
I'm leaning towards the big bore at the moment. Plenty of time to mull it over.
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1971 CB350 . . . 40 year hibernation
- Thread starter stl360+450
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I'm leaning towards the big bore at the moment. Plenty of time to mull it over.
CrazyPJ know what pistons to use if you go that route
Even without any other mods you will notice a fair increase in overall power.
stl360+450
Veteran Member
Mentioning PJ sent my mind immediately to CB360s and I just realized that the 350 and 360 have the same stroke: 50.6mm. The bore on the 360 is 67mm. Would I be able to use 360 pistons in the 350???
If so, it will make for a funny coincidence because a friend sold me some 360 spares, including a pair of 2nd over pistons that I've been saving for a rainy day. How does one go about getting an oversized head gasket?
Edit: I read elsewhere that the wrist pin diameters are different, so, if it is possible to use the 360 pistons, it wouldn't be a straightforward swap.
I wasn't aware of the different wristpin size. Typically, big bore kits come with the appropriately-sized head gasket. The difficulty can be getting another one of the engine has to be rebuilt for some reason in the future, so buying pistons from a solid, reputable source is a must when going big. I bought THR (Todd Henning Racing) pistons for the drag bike project, they're Wiseco forged and come with head gasket and teflon wristpin buttons if you ask for them. I just did some searching and the options for the 350 are less than I expected considering the popularity of the bike for road racing. And of course, the bigger you go the higher the price.
good price (sold each so you'd need 2 sets) but no mention of head gasket
https://www.z1enterprises.com/wisec...s-motorcycle=Honda/CB350 Twin/all-models/1971
from THR, includes everything
https://www.ebay.com/itm/265382263106?hash=item3dca03f942:g:6okAAMXQ9MVRhIyQ
not from THR, but apparently a THR kit of max size at 67.45mm, head gasket available on request
https://www.ebay.com/itm/393792648398
good price (sold each so you'd need 2 sets) but no mention of head gasket
https://www.z1enterprises.com/wisec...s-motorcycle=Honda/CB350 Twin/all-models/1971
from THR, includes everything
https://www.ebay.com/itm/265382263106?hash=item3dca03f942:g:6okAAMXQ9MVRhIyQ
not from THR, but apparently a THR kit of max size at 67.45mm, head gasket available on request
https://www.ebay.com/itm/393792648398
stl360+450
Veteran Member
(ancientdadI wasn't aware of the different wristpin size.
I'm getting 15.0mm on the 350 pistons and about 15.9mm on the 360 pistons with my calipers.
Thanks for looking up some of the options for me. I'm starting to lean back towards plain old 2nd over 350 pistons. The cost is about five times less and I don't have a good justification for spending more on the big bore kit.
I'll still notice a big increase in overall power since this one came to me as a non-runner with zero compression. =)
wentwest
Veteran Member
Just a thought. I discovered that Starrett, makers of all sorts of very expensive machinist's measuring tools, has a clearance part of its website where they sell what appears to be last year's models. If you go to their website and scroll down to the bottom of the page you can find a link to a page called "promotions". Click that and go shopping, keep your credit cards in another room. The discounts are very deep.
stl360+450
Veteran Member
Thanks for the suggestion. Are there any specific measuring tools you would recommend?
At this point I have [non-digital] Vernier calipers, four micrometers (covering 0-4"), and a couple sets of feeler gauges. I was kicking myself for not ordering metric micrometers, but probably don't need both.
wentwest
Veteran Member
Not really any suggestions on what to buy. The website is pretty old and slow and it can be frustrating, but it is legitimate. I bought a micrometer and it showed up.
stl360+450
Veteran Member
I'll have a look!
stl360+450
Veteran Member
Wheels are in motion. My friend helped her parents complete the title paperwork to get it in their name. Once they receive the new title from the state we can proceed with a legal sale.
ballbearian
Veteran Member
Great feeling, isn't it? I had three titles in the wind a short time ago. 2 have shown up. Promise the parents a ride, it'll make their day.
stl360+450
Veteran Member
Sounds like a good plan, although they might prefer to go out for dinner. We'll see! It's a huge relief given that the title should have been put in their name 40 years earlier.
I'm also excited about the next steps in the parts gathering, which is going to involve a bundle deal with the local salvage yard. The owner has treated me really fairly over the 10 years I've known him and this figures to be my biggest purchase to date.
ballbearian
Veteran Member
Being on good terms and doing the right thing by folks always pays. And, that is something you can take with you.
Good to hear you can move forward. Another fun project we can watch, since I know you'll post plenty of pics so we can follow along.
stl360+450
Veteran Member
Brief update: I made a trip to the local salvage yard yesterday and picked up a number of pieces, including a complete 350 parts motor and the triple tree and forks from a 360. The purchased motor turned over this morning on the kick start, so I'll probably check compression before deciding what to do next. The original lower case has some damage, so I'll at least be using that along with parts of the top end.
Is it me, or does that engine look like a 350...?
stl360+450
Veteran Member
Poor wording on my part - the motor is from a 350. The front end is from a 360 to be used on this 350 project.
stl360+450
Veteran Member
I also picked up an undented CB350 gas tank in my bundle deal at the salvage yard. It is missing one of the cross-over spigots and I am considering cutting off the other one and sealing both of the holes with tank weld. Cross-over tubes are kind of a pain and some bikes (e.g., CB360) didn't have them out of the factory. I'll lose some range, but I think it's a fair trade-off.
Are you running Champion plugs? If so then switch back to the original NGK's. I know the B8ES is now replaced by the BR8ES plugs so the plug end caps have to be changed to non resisted but I've cured more driveability problems throwing Champions in the garbage can that I can count.
stl360+450
Veteran Member
Those plugs had been in the junkyard 350 motor that I just brought home, which was pulled from the pictured bike with the fairing. I only included the picture because the plugs don't look half bad to me. I couldn't see anything about the bike that would tell why it was parked/junked and I'm hoping to find some usable parts inside. The original motor was missing enough pieces that I chose to buy a parts motor rather than source parts individually.
I'm not sure those Champion plugs are even available now, but I am currently experimenting with Nippon Denso W24ESU plugs on my dohc 450. The FSM specifications actually list ND W24ES along with NGK B8ES starting with the K5, so I figured it was worth some investigation before switching over to non-resistor caps and BR8ES.
While I was still in the shops we saw some bikes with ND plugs in them, can't recall whether they ran properly with them or not. I do know the W24ES is supposed to equate to the B8ES so they might work out as an alternative.
stl360+450
Veteran Member
I put a compression gauge on the junkyard motor today. Much to my surprise, both cylinders made it up to 150psi. I didn't kick beyond that. If not for the decades old gaskets and seals, I'd be tempted to use this motor as is.
That's good news. Probably/hopefully means a teardown for cleanup and a fresh set of rings (hopefully still stock bore), and maybe other items depending on inspection, along with fresh gaskets and seals would make a solid engine for the 350 project.
stl360+450
Veteran Member
This weekend I stripped the bike down to the frame. The frame has some pretty serious damage on the lower left frame tube, where the step bar mount uses bolts on the bottom of the frame. The step bar was definitely tack welded on this side at some point in the past, but it was hanging loose on that side when I acquired the bike. I believe the frame damage is the biggest obstacle I will face on this project, so I want to sort it out before doing anything else.
The next four photos illustrate the state of the lower frame tubes on the left and right sides.
Left:
Right:
I have a freshly powder coated step bar thanks to Jim (LongDistanceRider), which allows me to evaluate the frame damage by mocking up the stock part on the damaged frame. The next photo shows the two step bars side by side. I wonder if the step bar that was on the bike came from a CL350.
The nice step bar does not line up with the one remaining bolt hole on the lower left frame tube, which seems to further confirm the fact that this part of the frame is bent. It looks like it suffered an impact from below that dimpled the tube slightly.
I recently found a welder who has a lot of experience and who seems willing to work on the frame. I plan to ask him how he would like to go about it, since I think that will likely yield the best results. My initial thought would be to have him cut out the damaged part of that lower tube and replace the tube only, then fabricate and weld on the mount for the step bar.
Any and all advice is welcome.
The next four photos illustrate the state of the lower frame tubes on the left and right sides.
Left:
Right:
I have a freshly powder coated step bar thanks to Jim (LongDistanceRider), which allows me to evaluate the frame damage by mocking up the stock part on the damaged frame. The next photo shows the two step bars side by side. I wonder if the step bar that was on the bike came from a CL350.
The nice step bar does not line up with the one remaining bolt hole on the lower left frame tube, which seems to further confirm the fact that this part of the frame is bent. It looks like it suffered an impact from below that dimpled the tube slightly.
I recently found a welder who has a lot of experience and who seems willing to work on the frame. I plan to ask him how he would like to go about it, since I think that will likely yield the best results. My initial thought would be to have him cut out the damaged part of that lower tube and replace the tube only, then fabricate and weld on the mount for the step bar.
Any and all advice is welcome.
Domscustom
Veteran Member
Check your Honda dealer for the B8ES plugs, mine has a bunch, $3 bucks each. I was surprised what I could still get there, been so conditioned to get stuff online, sometimes brick and mortar is a better bet.
Sent from my iPhone using Tapatalk
Sent from my iPhone using Tapatalk
stl360+450
Veteran Member
Thanks, Dom! I'll give that a try.
The good right side appears to be bent as well, it should be a straight line front to back so that need correcting first as it may change the other side some.
The bad side appears to be bent up and in.
I think I would see about finding someone with a frame jig since this frame is so damaged. That way the steering head is perpendicular to the ground and the swing arm axis can be adjusted so it is parallel to the ground and the rear of the frame is centered on the steering head. That's really the only way to be sure this bike will roll straight and turn left/right equally.
Or you can build one https://www.custom-choppers-guide.com/motorcycle-frame-jig-blue-prints.html
The bad side appears to be bent up and in.
I think I would see about finding someone with a frame jig since this frame is so damaged. That way the steering head is perpendicular to the ground and the swing arm axis can be adjusted so it is parallel to the ground and the rear of the frame is centered on the steering head. That's really the only way to be sure this bike will roll straight and turn left/right equally.
Or you can build one https://www.custom-choppers-guide.com/motorcycle-frame-jig-blue-prints.html
stl360+450
Veteran Member
Thanks, Jim. I'll ask around about the frame jig. The shop I use for power coating and vapor blasting is probably my best bet. Hopefully they have one or will be able to point me in the right direction.
ballbearian
Veteran Member
Simplest way, since you need a new bracket on the frame, would be a donor frame tube with bracket.
stl360+450
Veteran Member
stl360+450
Veteran Member
I do have access to frames at the junkyard, but Jim points out that this may not adequately address alignment concerns. It's a shame that titles are linked to frames -- I could probably get a good frame for $100 or less.
I would go ahead a get a donor frame ahead of time.
I don't know if that shop will handle round steel tubing, they're used to the squared exo-skelton frames and might get lost in old stuff. :lol: But won't hurt to check.
I don't know if that shop will handle round steel tubing, they're used to the squared exo-skelton frames and might get lost in old stuff. :lol: But won't hurt to check.
wentwest
Veteran Member
VIN numbers are linked to the headstock, not the entire frame. No one at the DMV is going to notice that your frame is made up of several donors. Just smile, point to the VIN plate when they ask and say nothing.
The 350's have the VIN stamped into the headstock as well as having the VIN plate on 1970 and later frames.
ballbearian
Veteran Member
Alot of alignment can be done with straight edges, string and cheap lasers. I've staightened a few high end steel racing bicycle frames in my day, usually by cold setting (blocks, levers and hydralics). Welding your titled head stock to a nice donor would probably be cheaper and give better results. It may be true that your frame was tweaked in an accident causing the rear end/swingarm area to be out from the head tube/ steering centerlines, but spending a grand on an alignment job sounds prohibitive to me.
A nice long gentle downhill, at speed, no handed was one way to verify frame trueness.
that your frame was tweaked in an accident causing the rear end/swingarm area to be out from the head tube/ steering centerlines, but spending a grand on an alignment job sounds prohibitive to me.A nice long gentle downhill, at speed, no handed was one way to verify frame trueness.
When my Dad (professional body and paint guy) used to rebuild totaled bikes he used a porto-power and a string/plumb bob setup. Afterward, I'd ride the bike toward and away from him and he'd sight the wheels to see if it was dog-tracking. He used it to straighten bent siwngarms too. My first Gold Wing (a '75) had a tweaked frame neck area, slightly bent forks and steering stem and I rode that bike over 100 many, many times after it was finished with no issues.
ballbearian
Veteran Member
Find an old school chopper frame builder. That's what they did, neck stretching.
stl360+450
Veteran Member
Thanks, Tom (both ancientdad and ballbearian)! I'll definitely explore options starting with the lowest cost and work my way up as needed. I sent an email to that frame repair shop - half the time I don't get a response when I do that, so we'll see. I'll also try to stop in at the local custom shop where I have done previous business for powder coating and vapor blasting. The guy there has been in the industry a long time and his services listed include fabrication and welding. He would be powder coating my stuff once the frame gets sorted, so it would be great if he was up for this job as well. (Or has an appropriate contact.)
I think there are chopper guys around and if I can find one that works on metric bikes, so much the better. I'll save that idea until other routes have fallen through.
I think there are chopper guys around and if I can find one that works on metric bikes, so much the better. I'll save that idea until other routes have fallen through.
stl360+450
Veteran Member
That's a really cool picture. The porto-power looks like a tool best left to the professionals, such as your dad. I hope I am lucky enough to find someone half as capable to do the work on my frame.
Thanks, but sadly (as I'm sure you can tell) it is a 35mm slide that I managed to (poorly) illuminate from behind with a fluorescent lamp to take a picture of it in 2013, hence the time stamp that didn't match up. Picture was actually taken in late '75. I have many of those that need to be professionally converted. And, I have the porto-power that he used, he still had it in the big metal case it came in when I was cleaning out his garage after he passed in 2016.
stl360+450
Veteran Member
How did you convert the old home movies? Could the same place digitize the slides?
My grandmother gave me audio reels of an interview one of my uncles did during the Vietnam War that was broadcast by the local radio stations in Milwaukee, WI. I got it converted to cassette in the 90s and digitized it myself later. It was so cool to hear a relative that I had never met and the content was really interesting as well.
That's an awesome thing to have, like a bit of a time capsule. I'm quite sure there were many things he wanted to say about that period during that interview but chose not to bring up, it was a very controversial era. I've always been fascinated with video and audio from before it was commonplace, there's a raw aspect of it that feels more like history than the trillions of typical videos today. I wish I had some audio content from some of my older family members. I never met either of my grandfathers, one was a mechanical engineer who passed in the early '30s and the other was a blue collar worker born in the early 1880s who passed 2 months before I was born. Both would have been interesting people to talk to. My father rarely talked about his childhood, only in short segments once in a while. As for the slides, yes, the place that digitized the Super 8 video can do them but it's an expensive process as was the cost of doing the video (about $300 for roughly an hour of video total). And, you have the very time-consuming task of viewing each and every one of them to see which ones are worth adding to the group to be converted, and I have many hundreds of them. Apparently it was less expensive to get slides developed from 35mm film back then, or perhaps it was my father's choice for viewing. I actually have a slide projector and bought a 100 slide carousel for it, but the task of loading it (and correctly as well) just to view them larger, and then locating those you want to get converted afterward, is an effort in itself.
stl360+450
Veteran Member
I neglected to mention that he was serving as a pararescue technician out of Da Nang AFB at the time of the interview. Apparently they did interviews like this to send home for airing on the local radio stations. It was more a recounting of events than anything subjective/political.
I digitized my grandmother's entire photo collection around 2006 when she asked me to serve as the caretaker. This allowed me to share it digitally with the entire family, but it was at least a two week enterprise.
stl360+450
Veteran Member
I visited the local shop today and showed the owner pictures of the frame damage. The current plan is for me to bring the frame for him to evaluate in person, but he thinks he can fix it. I plan to snag a lower tube for the heavily damaged side from the junkyard tomorrow and then I'll deliver everything to the shop. That will give him a couple of options.
Sounds good and his willingness to inspect before committing shows he has some knowledge and appreciation of the problems.
stl360+450
Veteran Member
Thinking more about it, I'm going to get an entire frame and leave it intact for comparison with the damaged frame. I just bought a junkyard motor from another K3, so it's the likely frame donor.
That is a good idea, he may decide that swapping out the steering head will be the best repair.
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stl360+450
Veteran Member
Another dilemma for your thinking pleasure -- I really appreciate everyone's input as this project tries to get off the ground.
Recap: I recently bought a spare 350 motor at the salvage yard near me. Surprisingly, the salvaged motor has good compression. The frame on my bike has significant damage to the lower rails. So I returned to the salvage yard this morning to acquire the frame that held the motor I bought last week.
New info: The owner and his wife realized they have a salvage title for that frame. I thought that would be wonderful -- ditch the bent frame and use this one. But, it's a salvage title for a reason. I believe it was totaled by insurance. I didn't see anything wrong as I pulled the motor, but, after removing the steering stem and top bridge, I believe the collision or whatever must have damaged the front. See pictures below.
This frame doesn't seem too bad to me and I'm planning to use a 360 stem, bridge, and forks already. Incidentally, I laid the step bar over this frame and it seems to fit perfectly.
The Dilemma: Do I use part of this frame to repair the original or fix this frame and proceed with the salvage title?
Recap: I recently bought a spare 350 motor at the salvage yard near me. Surprisingly, the salvaged motor has good compression. The frame on my bike has significant damage to the lower rails. So I returned to the salvage yard this morning to acquire the frame that held the motor I bought last week.
New info: The owner and his wife realized they have a salvage title for that frame. I thought that would be wonderful -- ditch the bent frame and use this one. But, it's a salvage title for a reason. I believe it was totaled by insurance. I didn't see anything wrong as I pulled the motor, but, after removing the steering stem and top bridge, I believe the collision or whatever must have damaged the front. See pictures below.
This frame doesn't seem too bad to me and I'm planning to use a 360 stem, bridge, and forks already. Incidentally, I laid the step bar over this frame and it seems to fit perfectly.
The Dilemma: Do I use part of this frame to repair the original or fix this frame and proceed with the salvage title?