Motorcycle carb sync/tuning tools.

[2ndGearRubber]

Picked up a new to me 1981 Kawasaki KZ440 LTD, about 22k miles.

It sat for most of the last 5 years, accumulating about 500 miles. It falls on its face about halfway through the rev range, I personally think it's an issue on the left side (chain side) cylinder, but that doesn't really matter. Popping and failing to continue to rev. Previous owner neglected it and removed parts, so I won't have tach readings until the middle of this week. Spark plug wire connectors are messed up, they will be replaced in two days or so. I did confirm the mechanical timing advance moves freely, and filled it up with seafoam and fresh 93. Valve adjustment when I change the plugs this week.



Left side plug is lean like a modern FI car, right side black and very rich. So I pop off the carbs, everything looks clean, nothing obviously nasty or clogged, really clean actually. Minor varnish spot in the right carb bowl, maybe the size of a quarter? Wiped right off with brake clean. I can rebuild the carbs in an hour or so, but would prefer not to. Having let it idle for 1-2 hours, and riding it around the parking lot at work, it is running significantly better.





ANYWAYS - the bike has twin carbs, which I will likely need to sync. I set the metering screws to match each other (they were not previously), and it runs better, so fine tuning is in order. Middle of this week I'll set the valves and swap plugs and wire ends.

Regardless, I want to be sure they're right, and would like to buy a new tool/toy. So what is GJ using to match carbs?



https://www.amazon.com/dp/B00T80OR52/?tag=atomicindus08-20

This caught my eye, I'm not super concerned about having to zero the gauges if needed. And with 4 gauges, I can test them with my mighty vac and I should get two working ones!

 

[1982fxr]

Most of the catalogs have one from Motion Pro, no clue how good either are...

 

[thinman]

Morgan Carbtune out of the United Kingdom is a great tool. Google it and comes right up. Dealership techs have mostly gone to electronic tools but last I looked they are spendy. Carbtune isn't cheap but works really well and has no batteries.

 

[Modern Garage]

Try trusting your ears. Maybe my hearing is odd but that's all I've done for years when tuning twins. You can usually crouch behind the bike and listen to the mufflers and hear if one is louder (carb throttle more open) and adjust as needed. I realize the exhaust has a crossover pipe but this still works. Doesn't cost anything to try.
Joe

 

[bwringer]

Morgan Carbtune. End of discussion.

Those dial gauges are delicate Chinese junk and **** royal balls in just about every way possible. For just a few bucks more you can get a Morgan Carbtune on your doorstep in about a week.

The Motion Pro sticks sucked even when they had mercury, and now they use some other fluid and they're even worse.

 

[vtcat]

Yes,Morgan Carbtune

 

[Shehzada]

Morgan Carbtune out of the United Kingdom is a great tool. Google it and comes right up. Dealership techs have mostly gone to electronic tools but last I looked they are spendy. Carbtune isn't cheap but works really well and has no batteries.

Yes....i bought it a while ago.

 

[mbshop]

Yea, on my bmw I used a mercury setup. Worked just fine. Course it had fi but the throttles still needed adjusting.

 

[Htscheg]

Ive used the motion pro with murcury, works well wnough for what I use it fir, that said the Morgan tool looks nice and compact!

 

[biggziff]

I've got a Twinmax and a Harmonizer, but I've used these for a long time and they're very accurate and easy to make.

http://www.powerchutes.com/manometer.asp

However, don't over-complicate this. A bench sync (google it) is almost always 95% close enough to the point you'll never notice any difference.

Also...this is a not-uncommon issue with this and other bikes of that vintage.
http://www.kawasakimotorcycle.org/f...-info/136283-popping-backfire-1982-kz440.html

A cold valve check would be wise (24 hours cold), don't let it idle for more than 10 minutes (bad idea for any bike) dump a can of Seafoam through it first and ride it for a week before you start tweaking.

 

[1foxracing]

I still use mercury sticks. I tried the Morgan Carbtune and tossed it in the garbage after 1 use, was not accurate or even close.

 

[2ndGearRubber]

I've got a Twinmax and a Harmonizer, but I've used these for a long time and they're very accurate and easy to make.

http://www.powerchutes.com/manometer.asp

However, don't over-complicate this. A bench sync (google it) is almost always 95% close enough to the point you'll never notice any difference.

Also...this is a not-uncommon issue with this and other bikes of that vintage.
http://www.kawasakimotorcycle.org/f...-info/136283-popping-backfire-1982-kz440.html

A cold valve check would be wise (24 hours cold), don't let it idle for more than 10 minutes (bad idea for any bike) dump a can of Seafoam through it first and ride it for a week before you start tweaking.

Lots of work done on the bike today.


All valves, intake and exhaust on both banks, were at 0 lash. They are now properly set, and I expect much happier.


The big one was the bench sync, just matching the throttle blades more or less by eye on the bench. Well, they were way out of sync. They're close now, plugs and end caps arrived today, exhaust should be here thursday.

So the plan is to get the tires on and the bike back on the ground, get it running again and see if I still need a balancing tool.




EDIT: And why is it bad to idle the bike? Air cooled related issue?

 

[MikeF2316]

Lots of work done on the bike today.


All valves, intake and exhaust on both banks, were at 0 lash. They are now properly set, and I expect much happier.


The big one was the bench sync, just matching the throttle blades more or less by eye on the bench. Well, they were way out of sync. They're close now, plugs and end caps arrived today, exhaust should be here thursday.

So the plan is to get the tires on and the bike back on the ground, get it running again and see if I still need a balancing tool.




EDIT: And why is it bad to idle the bike? Air cooled related issue?

An air cooled bike has no cooling when it's not moving. So it can overheat. But carb temperature affects the mixture, so if you set them perfectly at a condition they don't normally see, then they'll be wrong when you're riding around.

P.S. I have a mercury setup to balance carbs. Unlike cheap gauges, they can't go out of adjustment!

 

[gungatim]

I use 4 of the HF vacuum gauges when I had to sync the carbs on my Goldwing. the key is to get them all set the same, which requires taking them apart and moving some of them a tooth or two, since they are not all going to be zero'd exactly the same. not a big deal and they work fine. for fittings I used the plastic fish tank restrictors that you can push into the holes.

there are a few write-ups on most of the bike forums I used to be on where guys did this, so not my idea. I think you can do the whole setup for 4 bikes under $30, half that for a twin.

 

[1950mercury]

Buy some jis screwdrivers

 

[Git]

Another Morgan Carbtune user...
https://www.carbtune.com/

 

[bpjr]

Check the rubber connector for mounting carbs to engine. They get dry rotted, lose suction and make adjustment problems...among burned valves. My old 900 Kaw had this issue and I couldn't keep the carbs adjusted until replacing them.

I'll have to check my gauges to see what brand they are...but they came from Holeshot Performance Products in California and the needles can be dampended manually for easy reading. Work fine on my Suzuki Bandit 1200 carbs.

 

[speed bump]

The last time I did tuning I bought 20 ft of clear tubing, a yard stick, and put some gear lube in it. Worked well enough but my carbs were reasonably close.

The other thing I have played with is using an IR thermometer to get it the cylinders close. I'm not sure how well it worked because I didn't have a vacuum gauge but the bike ran better and the owner is still happy with it.

 

[gda659]

I've got a Twinmax and a Harmonizer, but I've used these for a long time and they're very accurate and easy to make.

The Harmonizer makes the job super easy. Works great for me when balancing the throttle bodies on my R1100GS. It's probably no more accurate than the mercury carb sticks (which I last used many years ago), but you don't need to fuss with hanging the stick or have any concern about mercury and it's super portable so you can take it with you on a road test (for example).

 

[2ndGearRubber]

Alright, got the bike basically finished (less tach cable) and have some new results.


First: syncing the throttle plates on the bench was a HUGE help. I didn't have a single thing small enough to sit under the throttle plates when closed, so I just set one at full close, then matched the other by eye. Night and day improvement, likely aided by new plugs and plug ends.

The only sputter now is what feels like the transition to the main jet coming through the RPM range. An italian tune up today for about 10 minutes seemed to help.



The current plan is to ride it a bit, get a tank or two of gas through it, and re-evaluate. I like that Harmonizer product. Perhaps I'll go up 1-2 jet sizes if it still runs a tad off (richen the problem away perhaps), and if not pick up one of the listed tools.

 

[bpjr]

Alright, got the bike basically finished (less tach cable) and have some new results.


First: syncing the throttle plates on the bench was a HUGE help. I didn't have a single thing small enough to sit under the throttle plates when closed, so I just set one at full close, then matched the other by eye. Night and day improvement, likely aided by new plugs and plug ends.

The only sputter now is what feels like the transition to the main jet coming through the RPM range. An italian tune up today for about 10 minutes seemed to help.



The current plan is to ride it a bit, get a tank or two of gas through it, and re-evaluate. I like that Harmonizer product. Perhaps I'll go up 1-2 jet sizes if it still runs a tad off (richen the problem away perhaps), and if not pick up one of the listed tools.

I checked my gauges and they are Holeshot brand made in Taiwan. Holeshot doesn't advertise it but the gauges can be calibrated before using them by turning a screw on each gauge. If memory is right the Kaw has ******* instead of screw in inserts for balancing but the gauges come with them anyway. http://www.holeshot.com/maintenance/tuning-tools

 

[cnk]

I still use mercury sticks. I tried the Morgan Carbtune and tossed it in the garbage after 1 use, was not accurate or even close.

Did you install the plastic reducers per the directions? That seems to be the only complaint I've seen with the Carbtune when folks don't install them. It results in a very difficult gauge to read. I just used one to sync my Yamaha FZ-09 and it was quick, easy, and accurate.

 

[Schurkey]

I'm going to spend some time looking at the Morgan Carbtune. I know that mercury is evil and the downfall of modern civilization...which means I'm having some trouble getting a small quantity to replace what's been lost out of my Carb Stix.

For now, I've used two mercury manometers. "Mine" ran low on mercury, I borrowed my friend's the last time I synched my Honda.

MY mercury carb stix use bored-glass tubes as would be used in a laboratory. Works great. I just love it, although it's old enough that I need to replace the plastic hoses that connects the glass tubes to the motorcycle intake ports. The hose has gotten old and hard. I got two sets of port adapters with it, one that fits Honda 4-poppers, and one that fits Yamaha (I think). The port adapters are cheap plastic, the only thing about the whole deal I disliked.

My buddy's mercury carb stix use ****** plastic tubing instead of bored glass. They've got an orifice at the top of each tube, stuffed into the vacuum hoses to dampen the gauges. Since he was missing one of the hoses, I had to fabricate another orifice to the same dimensions as the others. And even though they're notably cheaper than mine, the tool still works just fine.

 

[1foxracing]

Did you install the plastic reducers per the directions? That seems to be the only complaint I've seen with the Carbtune when folks don't install them. It results in a very difficult gauge to read. I just used one to sync my Yamaha FZ-09 and it was quick, easy, and accurate.

Yes I used the plastic reducers, still not as accurate as Mercury sticks.
For anyone that has a old set of Mercury sticks around you can still purchase Mercury separately.
https://www.grainger.com/product/8ZL32?cm_mmc=PPC:+Google+PLA&s_kwcid=AL!2966!3!166592707839!!!g!371261531964!&ef_id=V4E8GwAAALbkpmzP:20171026142144:s&kwid=productads-adid^166592707839-device^c-plaid^371261531964-sku^8ZL32-adType^PLA