Honda CX 500 Forum banner
1 - 20 of 23 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter · #1 ·
Just upgraded to Murray's Carbs which are amazing!!
I did just notice a slight bog down on sharp acceleration (only have started on stand so far as my battery isn't secured yet)

As to if this is "normal" I should note that my H Box is still in tact and the pipe extensions to enable H Box removal aren't here quite yet.. and.. one of my pipes has a small crack at the seam. Could this cause something like this?

I'm a novice to all of this, so any thoughts are greatly appreciated!

Video recording of this
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #2 ·
Also... I ordered new Spark caps as mine were pretty corroded. Could also be a culprit
 

·
Registered
Joined
·
252 Posts
I essentially have the same setup as you--murray carbs, hbox, leaky exhaust pipes...though i also have done the brass rod mod and have an ignitech.

If youre at a standstill and you go wide open, it will bog a bit. Slide carbs like you rolling into the throttle. Gotta remember--instead of controlling just the air flow like the CV carbs, you're now controlling air and fuel. The slide carbs will act a bit different from the CV's.

edit: ill watch the video when im home to see if anything funny is going on...or someone else will chime in.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #4 ·
I hear ya! interesting and makes total sense. Also.. i'm not going to often "floor it" when in neutral on a stand. I'll obviously get more used to it as I start riding it. Just gotta secure the battery
 

·
Registered
Joined
·
586 Posts
I would say your problem is those PODS. I had a z1900 that I had a Kerker pipe on and added those KN PODS as I liked the sucking sound. Worst performance hit I ever saw. Research told me the carbs needed to be rejetted for the proper fuel air mixture. I am guessing the carbs are setup for stock performance, (not sure how Murray handles special NON-STOCK) situations. I think you will be OK if yo either add the stock air system back on or have the bike professionally tuned to adjust the fuel/air ration to account for the PODS/Exhaust and any other mods you may have done.
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #6 ·
I would say your problem is those PODS. I had a z1900 that I had a Kerker pipe on and added those KN PODS as I liked the sucking sound. Worst performance hit I ever saw. Research told me the carbs needed to be rejetted for the proper fuel air mixture. I am guessing the carbs are setup for stock performance, (not sure how Murray handles special NON-STOCK) situations. I think you will be OK if yo either add the stock air system back on or have the bike professionally tuned to adjust the fuel/air ration to account for the PODS/Exhaust and any other mods you may have done.
Hey there!, My bike is pretty much stock for the most part, the Murray Carbs are the first major upgrade i've done aside from getting the gas tank repaired / painted and some of the front end speedometer and headlight replacement.

True on the "stock performance" part, however I tried to point out, i'm fairly certain Murray jets these with the H Box removal in mind. When ordering it explicitly says it's assuming Hbox removal. So that COULD totally be my problem that it's still there.
 

·
Super Moderator
Joined
·
5,339 Posts
I'd suggest a call to Murray unless he chimes in on this thread.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,454 Posts
Excessive resistance in the plug caps can cause poor off-idle response.
I haven't worked with direct slides for years, but I suspect they will cause a little delay if you hit the throttle too hard. That's the whole reason for constant velocity carbs. They're simpler to operate.
 

·
Registered
Joined
·
24,495 Posts
in a nut shell when you whack the throttle open at a dead standstill with dual 34mm mikunis (large for the engine/) you create a massive vacuum leak air velocity in the
venturi drops and it cant pull fuel so it falls on its nose don't do it
with cv carbs when you whack the throttle wide open it does nothing more that open the butterfly starting the acceleration you are not lifting the slide

now get on the bike and go ride within a week you and the bike will figure each other out and it will never be a issue
 

·
Super Moderator
Joined
·
23,404 Posts
Fuel is denser than air. It has greater inertia.

On a snap throttle opening air moves before fuel giving a lag.

This is called fluffing and it is what CV carbs were designed to prevent.

After riding your mik equipped bike for a while this will incorporate into muscle memory and cease to be an issue.

Smooth inputs. :p
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #12 ·
in a nut shell when you whack the throttle open at a dead standstill with dual 34mm mikunis (large for the engine/) you create a massive vacuum leak air velocity in the
venturi drops and it cant pull fuel so it falls on its nose don't do it
with cv carbs when you whack the throttle wide open it does nothing more that open the butterfly starting the acceleration you are not lifting the slide

now get on the bike and go ride within a week you and the bike will figure each other out and it will never be a issue
Perfect, thanks so much for the feedback everyone.
Didn't think it was a huge deal in practical use, but thought I'd ask!

Thanks also for the call the other day Murray. It ended up being a simple pinched fuel line. Rerouted it and shortened one of them a bit so it wouldn't kink. Fired right up, those things are amazing.
 

·
Registered
Joined
·
252 Posts
in a nut shell when you whack the throttle open at a dead standstill with dual 34mm mikunis (large for the engine/) you create a massive vacuum leak air velocity in the
venturi drops and it cant pull fuel so it falls on its nose don't do it
with cv carbs when you whack the throttle wide open it does nothing more that open the butterfly starting the acceleration you are not lifting the slide

now get on the bike and go ride within a week you and the bike will figure each other out and it will never be a issue
odd piggyback question--

on mine, with the engine off my throttle is smooth... heavy, but smooth. but with the engine running, it requires a lot of muscle to get the carbs off their initial idle position, then its back to it being kinda heavy..is that normal for the dual mikuni's?

the initial effort to get it off idle and the heavy input always takes my friends by surprise when they try my bike...
 

·
Registered
Joined
·
60 Posts
Discussion Starter · #14 ·
odd piggyback question--

on mine, with the engine off my throttle is smooth... heavy, but smooth. but with the engine running, it requires a lot of muscle to get the carbs off their initial idle position, then its back to it being kinda heavy..is that normal for the dual mikuni's?

the initial effort to get it off idle and the heavy input always takes my friends by surprise when they try my bike...
Is it possible your throttle line has a sharp turn in it or pinched somewhere?
Just wondering with someone sitting on it and pinching the line might make it harder.

Could experiment and have it OFF while sitting on it. If it's hard to pull that could be it
 

·
Registered
Joined
·
252 Posts
Is it possible your throttle line has a sharp turn in it or pinched somewhere?
Just wondering with someone sitting on it and pinching the line might make it harder.

Could experiment and have it OFF while sitting on it. If it's hard to pull that could be it
nope. ive already had to call murray about a high idle before when i first installed the carbs several years ago. everything is routed as decently as i can get it.

the issue is present regardless if someone is on it. throttle is smooth when its off, albeit a smidge heavy, but as soon as the bikes running, the throttle takes more effort to get the slides off idle smoothly, and throttle actuation is also heavier as well. it feels like theres a large spring pulling against the slides...which there is...but with my other slide carb experiences, its nowhere near as heavy as these murray carbs.
 

·
Registered
1978 CX500 "The Grub", 1983 GL650I "Nimbus"
Joined
·
11,454 Posts
Could airflow through the venturi be causing a low enough pressure to resist raising the slide?
 
1 - 20 of 23 Posts
Top