Hi Everyone- I have a 74 cl360 (stock engine) that is currently using mikuni vm32 carbs (PO put them on). When I first bought the bike I had it tuned on a dyno and it ran ok, but the PO had open ended exhausts and I recently put reverse cone mufflers on, which changed the carb dynamics. Since I put the mufflers on, I've never been able to dial in the jetting on the vm32s properly. The best I've been able to do is get the bike to idle ok and run pretty well in the right temp / humidity, but its always finicky and never idles/runs smoothly.
In the back of my mind I always knew I'd need to downsize the carbs (everything I've read says vm32's are way too big for a stock 360 engine), and I'm in the process of planning how I'd like to do this. After reading alot on DTT and other forums, I've basically come up with two options that I'd like some advice on if anyone can help.
1 - vm28 roundslides - https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetors-mikuni-28mm-001-022.html
Upsides
-Easier to tune
-Better size for a ~28-30 bhp cb360 per the mikuni manual (see image)
Downsides
-For me the main downside is that it there aren't alot of comments on base jet settings on the forums (there are way more comments on vm30s), and I'd basically have to source all of the parts myself (ie intake boots, air filter, throttle) vs ordering a "complete kit". This isn't necessarily a huge problem if I can make sure I get the correct parts before ordering. I was also planning on ordering several sizes of jets so I could try to
The vm28s from DCC come with the following
Main 200
Pilot 60
Needle jet 169 N8
Needle ???
Air jet 30
Valve 2.5
Per this post: http://www.dotheton.com/forum/index.php?topic=62687.0 , raptormeat is running the following settings for a vm28 on a cb360 (at almost 7000ft elevation):
Main 180 (but suggested going to 200 if you aren't at his elevation)
Pilot 30
Needle jet 175 P2
Needle 5DP7 2nd notch down
Valve 2.5
1.6mm adjustable air jets
Based on these, I was thinking of starting with something like a 200 main and 25 pilot. Once I get those dialed in I can start working on the needle jet and needle.
2 - vm30 roundslides - https://www.dimecitycycles.com/the-coveted-mikuni-vm30-carburetor-complete-kit-for-honda-cb-cl-350-360s.html
Upsides
-Way more comments on the forums about other users' jet settings, so hopefully I have more information to dial in the jetting if I'm struggling.
-Complete kit, so I know I won't have to confirm the intake size, boot size, etc.
-Also comes with several sizes of main and pilot jets.
Downsides
-Slightly oversized for a cb360 (but from what I read they can still be jetted to work properly)
-Maybe not enough of a downsize from the current vm32's (if I'm struggling to get vm32's to work properly, is dropping to vm30's really going to make that big of a difference??)
I'm also planning on ordering several sizes of main and pilot jets to get myself close to dialed in when I order the carbs. I was wondering if anyone has feedback on the following jet sizes to get close to dialed in?
Pilot Jets - 25, 22.5, 20 (I already have 50, 45, 40, 35, 30 from previous attempts with my vm32's)
Main Jets - 220, 200, 190, 180, 170, 160
So basically, I have a few main questions for anyone that can help:
1. Would you recommend getting:
vm28
+ 25, 22.5, 20 pilot jets
+ 220, 200, 190, 180, 170, 160 mains
or getting the vm30 kit?
Would you recommend getting any other sized jets to start with?
2. Will this K&N filter fit the vm28 (RU-2690) - https://www.knfilters.com/search/product.aspx?prod=ru-2690
3. Will this "Mikuni specific carb boot" fit the vm28 and fit the intake port of the cb360 - https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-intake-parts-honda-cb-350-mikuni-rubber-carb-boot-002-053.html
-Also, will that boot need to be modified to fit the cb360 bolts since it is designed for a cb350.
4. Is there a suggested 2 into 1 throttle for the vm28 (or is there a better one for the vm30 since I've read some negative reviews). Would it be possible to re-use the throttle I'm currently using for the vm32's and just attach that to the vm28's or vm30's?
5. Does anyone have a good basic starting point for getting the vm28's running? Of note, I am currently at sea level in an area that is typically very humid.
Thanks to everyone for reading this long post, and for any feedback you can help with. I really appreciate it.
In the back of my mind I always knew I'd need to downsize the carbs (everything I've read says vm32's are way too big for a stock 360 engine), and I'm in the process of planning how I'd like to do this. After reading alot on DTT and other forums, I've basically come up with two options that I'd like some advice on if anyone can help.
1 - vm28 roundslides - https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetors-mikuni-28mm-001-022.html
Upsides
-Easier to tune
-Better size for a ~28-30 bhp cb360 per the mikuni manual (see image)
Downsides
-For me the main downside is that it there aren't alot of comments on base jet settings on the forums (there are way more comments on vm30s), and I'd basically have to source all of the parts myself (ie intake boots, air filter, throttle) vs ordering a "complete kit". This isn't necessarily a huge problem if I can make sure I get the correct parts before ordering. I was also planning on ordering several sizes of jets so I could try to
The vm28s from DCC come with the following
Main 200
Pilot 60
Needle jet 169 N8
Needle ???
Air jet 30
Valve 2.5
Per this post: http://www.dotheton.com/forum/index.php?topic=62687.0 , raptormeat is running the following settings for a vm28 on a cb360 (at almost 7000ft elevation):
Main 180 (but suggested going to 200 if you aren't at his elevation)
Pilot 30
Needle jet 175 P2
Needle 5DP7 2nd notch down
Valve 2.5
1.6mm adjustable air jets
Based on these, I was thinking of starting with something like a 200 main and 25 pilot. Once I get those dialed in I can start working on the needle jet and needle.
2 - vm30 roundslides - https://www.dimecitycycles.com/the-coveted-mikuni-vm30-carburetor-complete-kit-for-honda-cb-cl-350-360s.html
Upsides
-Way more comments on the forums about other users' jet settings, so hopefully I have more information to dial in the jetting if I'm struggling.
-Complete kit, so I know I won't have to confirm the intake size, boot size, etc.
-Also comes with several sizes of main and pilot jets.
Downsides
-Slightly oversized for a cb360 (but from what I read they can still be jetted to work properly)
-Maybe not enough of a downsize from the current vm32's (if I'm struggling to get vm32's to work properly, is dropping to vm30's really going to make that big of a difference??)
I'm also planning on ordering several sizes of main and pilot jets to get myself close to dialed in when I order the carbs. I was wondering if anyone has feedback on the following jet sizes to get close to dialed in?
Pilot Jets - 25, 22.5, 20 (I already have 50, 45, 40, 35, 30 from previous attempts with my vm32's)
Main Jets - 220, 200, 190, 180, 170, 160
So basically, I have a few main questions for anyone that can help:
1. Would you recommend getting:
vm28
+ 25, 22.5, 20 pilot jets
+ 220, 200, 190, 180, 170, 160 mains
or getting the vm30 kit?
Would you recommend getting any other sized jets to start with?
2. Will this K&N filter fit the vm28 (RU-2690) - https://www.knfilters.com/search/product.aspx?prod=ru-2690
3. Will this "Mikuni specific carb boot" fit the vm28 and fit the intake port of the cb360 - https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-intake-parts-honda-cb-350-mikuni-rubber-carb-boot-002-053.html
-Also, will that boot need to be modified to fit the cb360 bolts since it is designed for a cb350.
4. Is there a suggested 2 into 1 throttle for the vm28 (or is there a better one for the vm30 since I've read some negative reviews). Would it be possible to re-use the throttle I'm currently using for the vm32's and just attach that to the vm28's or vm30's?
5. Does anyone have a good basic starting point for getting the vm28's running? Of note, I am currently at sea level in an area that is typically very humid.
Thanks to everyone for reading this long post, and for any feedback you can help with. I really appreciate it.