Carbmate Sycrhonizer

[cheesy]

Here's the promised review of the Carbmate. $95US from Amazon.

Piece o' cake to set up and use. Connect to a 12v power supply; I used the CX battery. Calibrate to '0' by turning the left knob to 0.5"hg and turning the right knob until the center green LED lights steadily. Any blinking of that LED indicates that it ain't dialed in yet.

Connect up the vacuum hoses, making sure that the left hand hose is attached to the 'reference' carb. That's the carb with the throttle cables to it. In my case, it is also the left carb.

Fire up the bike, let it warm up, and adjust the idle to spec. The CX is 1000, + or - 100rpm.

First pic is of the initial reading of the 'bench synced' carbs. Not too shabby for 'eyeballin'.


Second pic is showing idle speed with my electronic tach. It's a heck of a lot more accurate than the mechanical tach.


Getting there. This is zeroed in at 2"hg between the carbs, which is the low end of the resolution, the left knob being turned fully to the left. Honda spec calls for a max of 1.4"hg, which means there is more futzing needed. The idle dropped a bit, but is still within spec.


Bingo. The carbs are now balanced within 0.5"hg of each other. The procedure calls for adjusting at 1.5" and 1" before attempting 0.5"hg. I showed no difference in balance, though, until I got down to 0.5". So, pretty simple.


Now the caveats.

Number one. Not against the Carbmate, this thing is stupid simple to use and wish I'd bought one years ago. However, syncing the carbs on the CX is kind of like, 'lather, rinse, repeat and repeat and repeat and repeat. Honda, in their infinite wisdom, must not have thought the CX carbs would ever need to be synced because there ain't a hell of a lot of access to that adjusting screw and locknut. Makes a five minute job take 30 minutes.

Number two. This is against the Carbmate. Made entirely of plastic, including the hose nipples. I can see these getting broken off with not too much rough handling. If that happens, the unit is rendered useless and will have to be sent back to the manufacturer for repair. Or Macgyvered.

Now for the results of the carb syncing. Starts with less choke. Beautiful idle. Still having acceleration issues, though. Got an entire new electrical system. Went through the carbs again the other night and got both floats set at 15.5mm per spec. Replaced both air cut off valve assemblies. Dead nuts on carb sync.

Because of what happened on the shake down today, I'm back to thinking that one, or both, vacuum pistons are sticking. I pulled onto a four lane from a two lane and started to accelerate. And had nothing. Eased up on the throttle and I had one cylinder start firing. Managed to get up to speed on the one jug to 7 grand when the other cylinder kicked in. Lemme tell ya, 7 grand to 11 grand in approximately one second only needs to be experienced once. I think my stomach is still laying out on IL 47. Along with my heart, cuz that dropped out after the front wheel came back down.

Hey, I jacked my own thread.

[2LZ]

Good review! That unit does look super easy to use....and easily readable for us with old "reading glasses" eyes.

[SpudRider]

Thanks for posting the detailed, informative review, Cheesy.

[Mudflap]

Cheesy, You've been fiddling with the carbs for quite a while but the problem persists. I've had similar problems with a CX cutting out with the throttle open which turned out to be a bad spark plug cap. I was able to verify the problem by removing the rubber piece that covers the spark plug hole, then going for a ride in the dark. Looking down in the hole while accelerating reveled sparks jumping from the cap to the valve cover, effectively knocking out one cylinder. A new set of plug caps solved the problem.

BTW there is a tool made to easily reach in and adjust the carb sync. I still use a 40+ year old mercury stick to balance carbs.

[cheesy]

Originally Posted by Mudflap

Cheesy, You've been fiddling with the carbs for quite a while but the problem persists. I've had similar problems with a CX cutting out with the throttle open which turned out to be a bad spark plug cap. I was able to verify the problem by removing the rubber piece that covers the spark plug hole, then going for a ride in the dark. Looking down in the hole while accelerating reveled sparks jumping from the cap to the valve cover, effectively knocking out one cylinder. A new set of plug caps solved the problem.

BTW there is a tool made to easily reach in and adjust the carb sync. I still use a 40+ year old mercury stick to balance carbs.

Today, out of frustration(read:Po'd), I finally drew a bead on the issue. This morning, Aki from Finland (Andy62 on the CX500 forum) and I went through everything I've done in the past year and eliminated the entire electrical and ignition systems. It's all new anyway. That left the carbs. And I found the left vacuum piston was indeed sticking. There were some nasty score marks on the engine side of the slide. Some deep enough to snag a finger nail. The piston would catch on the way up. I couldn't find any score marks in the bore of the carb and it felt smooth. The piston had a lot of slop in the center of the cap, which probably caused the problem

So, I had a set of low mile Keihin VB carbs for a smaller twin that used the same pistons and caps. I swapped out the needles for the CX ones and installed them. 90% of the problems went away. I still have a slight stumble around 4-6000 rpm that is dependent on throttle position. That tells me that there is a blockage in a passage somewhere in one or both of the carbs. I'll run a few tanks with some Seafoam and see if that clears it up. Otherwise, back into the ultrasonic cleaner with the bodies.

What is this tool you speak of? I have a right angle screw driver that's kind of like an old GM dwell tool. Doesn't work worth a poop for it. I was thinking of making something along the lines of this old valve lash tool I have. Worth a try, anyway.