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Discussion Starter #1
all right i have a couple of questions to throw out here in regards to my sl350 street bike in the works

first, i'd like some opinions as to what a reasonable price would be for a nos 68' cb350 cam.

second, i'm thinking of piecing an engine together from an sl and cl. the bottom end of the sl is geared lower than the cb/cl model for more low end torque. i was planing on using the top end from the cl because it's in better shape and because i can install a set of 32mm mikuni's easy enough. my understanding is that the new carbs will cause some power loss on the bottom but add some to the top. anyone done this or know enough to speculate on what the results will be?

...connoisseur of slack...
 

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Snork,

Let me try answering some of your questions.

A NOS 68 cb350 cam is going to be expensive. If you can find one. I'm only guessing but probably $250 or more. Your better bet might be going right to Megacycle and getting a cam.

There are two different flavors of SL350 motor. One version came with an electric start and one didn't. The one that has the electric start is the same as the cb350 motor. No changes to the transmission. The one that didn't come with the electric start would have a different transmission but that motor (bottom end) won't fit into a CB350 frame. So if you have a stock cb350 frame and motor and a spare sl350 engine that you want to swap parts around you've got your work cut out for you. If you just want to get lower gearing couldn't you just change the counter shaft sprocket or rear sprocket? Might get you the results you're looking for with a lot less work. The power loss, on the bottom end, due to mikuni 32 mm carbs will only be felt on a dyno.

The question I've got back to you is what are you trying to do? Is this for a race motor or a street bike?

Craig
 

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Discussion Starter #3
well you make the $150 price tag for the the cam i found sound like a deal. is the difference really enough to warrant it?

let me provide more detail and a question or two more... the bike is a 71' sl350 frame originally modified in the 70's for flat tracking. the sl engine is the later version, no starter and 28mm direct linkage carbs. the top end from the sl was previously sandblasted with the wrong media and is heavily pitted as well as having broken fins from a wreck so i'd like to swap it just based on that.

the cl top end comes from an all original bike i bought. old man hondas site is down so i can't compare the engine serials but the tach on this bike is of the older 68'-69' verity with the higher redline would that imply that the cam is also the older? i know that there were sometimes bleed over from one year to the next when it came to updating the models and that they also replaced the body work of last years unsold bikes with the body work from the next.

as to intent i am not interested in making performace enhancements that make the bike any less stable or reliable.
i'll take all the top end i can get but not at a significant loss loss at the bottom beacuse that is where a lot of my riding will be. maneuverability is more desirable on austin roads in my opinion than high speeds and the highways here have some of the highest incidents of vehicular death in the nation so i won't be hitting I35 too often.

by the time this bike hits the road it will have the front end from a cb500t, new rear suspension, an extended swing arm and bronze bushings.




...connoisseur of slack...
 

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There were two different flavors of cam as well. Make sure the cam you picked up will work with the rocker arms you've got. The early cam won't work with the later rockers. And the early rockers won't work with the later cam. The early cam should have a 286 marked on it and the later one a 312 marked somewhere. Same with the rockers.

Since the SL frame you've got already had the SL engine you've got in it you are in good shape. The CB/CL head and cylinders should bolt right up to the SL bottom end. According to the parts book I've got the early cam was in SL bikes up to serial # 1026008. After that it was the later cam.

One more thing, the SL swingarm is already longer than the CB swingarm. You may not need to lengthen it.

I've been to Austin. I know what you mean about I35. I rented a Harley for a weekend and road around the hill country south and west of Austin. Lovely country.

Craig
 

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Discussion Starter #5
craig, i'm guessing your parts book will also tell you what the last serial was with the older cam for the cl's if you would check that for me i'd appreciate it.

the sl does have a longer swing arm but just by a quarter inch or so and i'm looking to stretch it an inch and a half.

...connoisseur of slack...
 

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The early cam goes up to serial # 2072209.

The SL swingarm I had used was about an inch an a half longer than the CB swingarm. And of course the parts book I'm looking at doesn't show the swingarms. I only have part #s for the engine. The longer SL swingarm was also wider - at the axle - than the CB swingarm. Another way to tell them apart.

Craig
 

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Discussion Starter #7
thanks for looking up that info. the serial from my cl is 204???? so according to the serials you provided my 70' cl does have the older model cam.

it's not my intent to challenge your knowledge of these bikes because i'm sure to lose but i went out tonight i went out and rechecked my measurements of the swing arms from my cl, my sl and a spare sl arm that i have. measuring from the same points this is what i came up with. cl-50cm, sl.1-50.5cm, sl.2-52cm. so the spare sl arm is just under 1 inch longer than the cl arm. i'm not sure what year sl the spare is from but the other is from my 71'. unfortunatly the wheel mounts on the spare are bent out of true so i won't be using it as it is.


thanks for your help, i'm sure to have more questions come up



...connoisseur of slack...


Edited by - snorkelfork on Oct 05 2007 01:30:13 AM
 

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huh. Tannermatic has my old sl swingarm so I was just going from memory. Which must be failing. I could have sworn it was about an inch and a half longer. But you've got the pictures to prove my memory is not what it used to be. :)

Just ask. I'll try to help whenever I can.

Craig
 

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How much benefit is to be had from the earlier cam? I have a '68 or '69 cl350 & the points cover has type I stamped into it. My understanding is this identifies it as the more desireable cam setup - I haven't checked the serial#. Really, I only bought the bike for the carbs. Sorry Snork, I'm not selling - yet. I'm hanging on to it for a race bike project, provided the benefit of that cam is worthwhile.
 

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Discussion Starter #10
no worries, from the info craig provided i was able to confirm what i already suspected, that my 70' cl still has the earlier cam. back then when a honda was sold the title listed the bike as what ever year it was sold not the year it was manufactured.

i'm not sure what noticeable difference there is in the cams. my understanding is that the older cams caused the cv carbs to work harder and put small perforations in the diaphragms from the stress. i also heard it had some thing to do with honda realizing that they couldn't compete with the 2-strokes looked to make the 350 a practical work horse rather than a sport bike. both of those stories may be little more than bullshite.

...connoisseur of slack...
 

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The easiest way is to look under the top cover of the motor. Early cams were fat where they bolt to the cam gear, later ones are pretty uniform in the center cention between the lobes. You can swap cams between motors as others have said as long as you have the rocker arms to go with them but the cam boxes are different too. It can be a bitch trying to get a late cam in the earlier box due to some of the castings. This is work best done if you're stripping the motor for a rebuild.
 

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150 is a steal. megacycle charges like 300 to resurface. i would have expected near 300 for a nos one. but ebay surprises the shit outta me sometimes. youll need the followers, like eveyone has said. those are harder to get as they will pit too. megacycle will resurface those for 60 each. the 70s did not have the fat cams. bfd was right, the early cams had a fatter section int he middle leading to the sprocket land. theres no real difference in hp. ive found 350 cams that all look very different and have different numbers cast or stamped into them. its power delivery more or less. something else to note, the early heads had 6mm exhaust studs. the later had 8. the head is as important as the cam and followers. the fat cams only came in the type1 motors, and only with the 6mm exhaust studs.

the sl swing arm is longer by about an inch or so.

ive been waiting for this topic to come up. craig, you opened a huge can of worms buddy. the sls came with 28mm mikunis. so, technically, if i was to get a set of 28mm mikunis, and run them on my fcb bike, those would be considered leagal??? i know one guy with wera who did it. thoughts?

the sl bottom and cb/l swap is doable. craigs right about the frame and motor gig though. the sl had narrower gears. toe cases were narrower.

jc
 

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Discussion Starter #13
joe i'm pretty sure you mean the sl's had direct linkage carbs, they are keihins not mikunis. and perhaps honda did not pay much attention when cutting pipe for swing arms because as i said neither of my sl swingers are even an inch longer as can be seen in the photo i posted.

i'm interested in seeing where this thread goes, for once it's information that's applicable to my bikes.

...connoisseur of slack...
 

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hmmm, the SL swingarm I have is longer. I'll have to measure it. Maybe the swingarm changed when the frame did? you know, from single to twin downtubes.

Joe,
I would say YES that is 'legal' if you were to get actual SL carbs. Why not? It would be within the letter of the law.

BORN TO LURK, FORCED TO WORK.
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Discussion Starter #15
here is a photo of the rocker box from my 1970 cl350 on the right compared to the box from a 73 cb350. i measured my exhaust studs and they are 8mm but you tell me if that isn't the older cam. honda was not so cut and dry when it came to design changes in their bikes.


i just have to add, i woke up this morning hungover to find some fuck stole my bike out of my garage...


and no i didn't black out and leave it somewhere, at least i don't remember doing that...

...connoisseur of slack...

Edited by - snorkelfork on Oct 07 2007 09:47:17 AM
 

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Snork,

Can you take one of the rockers out for each of the two top ends your showing us in the latest picture? Take a picture of the side view of the rocker arms. There should be a pretty clear difference in the two rocker arms.

Craig
 

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the one on the right is definitely a fat cam. why its in a post 69 bike is definitely freakish. i have never ever found a fat cam in a post 69 bike that was still sealed.

jc
 

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Discussion Starter #18
sure craig, i'll try to do that today.

the frame is packed pretty deep in my garage, if i can get to it with out spending an hour i'll get the serial off of the neck.

the original owner laid it down not long after he bought it and didn't ride it again for 34 years. when i bought it there were less than 4000 miles on the bike. i used it as a daily rider for a year before it developed a severe oil leak in the top end. when i pulled the engine out the old gaskets were fused to the surfaces and so brittle that i had to use a wire wheel and razor blades to scrape them away layer by layer, gasket remover didn't work for shti.

...connoisseur of slack...
 

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Discussion Starter #19
so over the weekend i watched an auction for a nos set of roller bearing cam mounts from grizzly sell for $255. it seemed to me like it wouldn't require much sweat to have the old mounts machined to fit roller bearings for a lot less than that. has anyone ever done that before?

...connoisseur of slack...
 

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Discussion Starter #20
sorry guys, i started to pull the rocker arms so you could compare them but there were way to many screws and since the case is split i couldn't get good leverage to break them loose. not worth the effort just for a few photos.

but on another note. today i pulled the engine out of my SL and cracked the case open. at first i was very pleased to see that it too had a 68'-69' rocker box till i noticed that one side of the cam was bone dry and burnt. turns out when they rebuilt the top end, they used blue RTV in abundance and clogged the oil channel leading to that side. hence the odd grinding noise i had previously mentioned in my project thread.
check out the wear on this rocker arm




...connoisseur of slack...
 
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