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Discussion Starter · #1 ·
Hi everyone, thanks for taking the time to read this. I've finally found some time this later Winter - early Spring to dive back into my '72 CL350. I'm new to working on these motorcycles and am looking for a little guidance. I've just cleaned my carbs and checked the jets.

The PO had different jets in each carb body (#105 main jet in one side and #100 in the other). The bike came with original air boxes and new air filters, but the PO was running 6" UNI foam filters and said it drove well. How/why would he use different sized jets? Or was he just a bonehead?

Because the jets were different I figured that I'd just buy a rebuild kit from Common Motor and start from scratch. From what I have found out, please tell me if I am mistaken, is that the main jet primary for this particular carb is #68. The Common Motor kits comes with a #70. Will this still work?

I know the old timers and purists only use the air boxes/filters (and probably for good reason) - which is the plan - and say you can't get these motors running really well with pods. So how come so many owners use the pod/foam filters and how do they know what jets to use?

Thanks Fellas & look forward to reading some responses.

Cheers
 

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Your last question first:

Folks use pod/foam filters because:
1. They look cool (in their opinion)
2. Any modification has to improve performance. Hey, they wouldn't sell that stuff if it wasn't better than stock.
3. They don't know what jets to use until they put the package together. Then, if they can read the spark plugs, it is possible to come up with the best jets for that particular combination of parts.

The PO may have used different jets because his plug readings showed one side leaner/richer than the other (probably due to some other undiagnosed problem). Or he may have poor eyesight and couldn't read the numbers. Maybe he didn't know there were numbers.

This will tell you about the stock carbs:

http://www.hondatwins.net/forums/49...nformation-cb-cl-sl-350-s-cb-cj-cl-360-s.html

And this will tell you how to proceed:

http://www.hondatwins.net/forums/49-fuel-supply-carburation/20667-cb350-carb-rebuild.html

Aftermarket carb kits don't always come with the correct parts (especially jets) so be sure you have the right stuff before you tear into it.
 

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On this forum the intake question gets asked over and over. As an old timer I will give you the same answer. The Honda 350 engine is highly tuned. The head flows well, the length of the exhaust is proper for a street bike and the intake is designed to provide a balanced source of air with a properly tuned intake length. The intake, carb throat diameter, cam profile and exhaust are matched. The designers created this bike with the objective to provide a high performance motorcycling experience. If you have ever ridden a well sorted out CB350 you will understand what that means. The CL exhaust is a compromise. The CL does not put out as much power as the CB.
The problem with Uni filter is they do not have an air balance tube between them. The CV slides will not go up and down together and it is impossible to properly tune the stock CV carbs. Some folks have put a lot of effort to make them run almost as good as stock. The only hope for Uni filter or other individual style filters would be to ditch the stock Keihin CV and get a set of throttle slides like Mukunis. Yu can get away with this if you live in the flat lands and the bike does not see much elevation changes. The stock Honda filters are very well designed. They have velocity stack intake runners and huge filter surfaces. This makes them big. Big is not stylish, but you can chose between pretty or a well tuned bike.
How does your CL350 run? It should idle well at 1100 RPM and pull very strongly past 10,500 RPM.
 

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Your last question first:

Folks use pod/foam filters because:
1. They look cool (in their opinion)
2. Any modification has to improve performance. Hey, they wouldn't sell that stuff if it wasn't better than stock.
3. They don't know what jets to use until they put the package together. Then, if they can read the spark plugs, it is possible to come up with the best jets for that particular combination of parts.

The PO may have used different jets because his plug readings showed one side leaner/richer than the other (probably due to some other undiagnosed problem). Or he may have poor eyesight and couldn't read the numbers. Maybe he didn't know there were numbers.

This will tell you about the stock carbs:

http://www.hondatwins.net/forums/49...nformation-cb-cl-sl-350-s-cb-cj-cl-360-s.html

And this will tell you how to proceed:

http://www.hondatwins.net/forums/49-fuel-supply-carburation/20667-cb350-carb-rebuild.html

Aftermarket carb kits don't always come with the correct parts (especially jets) so be sure you have the right stuff before you tear into it.
That line though... :D the PO is the ultimate off-screen villain, I tell you.
 

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Discussion Starter · #5 ·
Thank you JT for the info and links. I’ve read them both - great stuff in them. And thank you James as well for taking the time to explain again why these bikes are built the way they are. Just looking for some reassurance that I’m going about this the correct way before I go purchasing parts. Not so much concerned with how the bike looks as I am with wanting a well run machine.
 

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I've run stock boxes, stock boxes with uni foam, and foam pod filters.
Being said, on my current bike are stock boxes with foam and I have no plans to install pods... However the bike ran well enough with pods. They are more maintenance though, and need to be cleaned more frequently and replaced sooner. If tomorrow my air boxes fall off and all I have is pods, I'll use the pods til they needed replacement. I never did any jetting changes with pods, but it seems stock jetting was a little rich with pods.
 

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stock jets are always better than aftermarket...more accurate ratings.

70 could work but 68 is likely better...read the plugs to know which is best for your bike in your location.
 

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I'm in a situation where the PO cut all the airbox mounting tabs off of the frame, so unless I weld new ones back on, I can't easily use the stock filters, which also didn't come with the bike anyway. So more than likely I'll be going with the Mikuni VM30 carbs, and some pods.

I wonder though, Cognito Moto makes a few air intake boxes for certain bikes, where it's like the pods have been combined into one larger filter. Would that style be better than individual pods? Seems like it might solve some of the pod filter problems, namely the lack of air balance tube that Jim mentioned above.
 

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I dont see how the balance tube has any effect other than increase filter area, which indicates Honda didn't want to be restrictive at all. 180 twin, and the right cylinder will want air immediately after the left. The way the runner directs air into the carbs and its jets is something pods won't emulate either.
 

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Discussion Starter · #11 ·
Thanks for all your input guys. Basically I’ve learned from your comments and reading is that whatever I use there will be tuning involved. That’s not a bad thing as I’ll learn as I go despite being a “I want it yesterday” kind of person.
I still have the stock muffler too - it is in great shape in appearance but the PO said it was starting to get loud. No remedy to re-pack the old mufflers from what I understand.
Thanks again fellas!
 
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