Dead cylinder method

[DaveO]

I've never done it, but always assumed that you removed the plug. I've read several accounts of the dead cylinder method, and none mention removing the spark plug on the dead cylinder. So plug in or out? Or does it not matter?

Sorry if this is a stupid question.

Dave

 

[arcticXS]

Question is ok, but the method is quite silly.

 

[TX650A Van Islander]

You're referring to syncing carbs presumably? If so, spark plug stays in, but be careful if you have electronic ignition to ensure the loose spark plug wire lead is grounded through another spark plug secured to the engine to avoid damaging your ignition. There are several references on this site from people far more knowledgeable than myself about this.

 

[DaveO]

Thanks @TX650A Van Islander, got my dummy plug all set up.

 

[arcticXS]

10 m of clear plastic tubing with 4 mm ID, a board, some cable ties and a small amount of ATF is all I ever used for synching carbs.

 

[Mailman]

I've never done it, but always assumed that you removed the plug. I've read several accounts of the dead cylinder method, and none mention removing the spark plug on the dead cylinder. So plug in or out? Or does it not matter?

Sorry if this is a stupid question.

Dave

I have done the dead cylinder method on my XS2 , because of the earlier unlinked carburetors. I used a heavy gauge solid copper wire and made a loop around the spark plug thread and a hook on the other end, so I could hang it on the little post in the fins, that’s right under the spark plug hole. I left the spark plug in the engine and used a spare plug to be plugged into the spark plug wire. I used this because I had an electronic ignition.

On later carbs, such as my ‘77, that had linked carbs and vacuum ports on the carbs, I always used my homemade manometer to balance the carbs.

The whole dead cylinder method is really only pertinent to unlinked carbs that might be difficult to balance.

Here is a good discussion on carb balancing, started by @DogBunny ,

https://www.xs650.com/threads/simple-carb-mixture-screw-and-sync-adjustments.33791/

Youve already read up on the dead cylinder method, but this simple summary might help someone else reading this,

 

[jpdevol]

$27 https://www.amazon.com/Motorcycle-Vacuum-Gauge-Balancer-Synchronizer/dp/B08F35KDVF/ref=sr_1_24

 

[Mailman]

Oh, you’ve never seen my high dollar, yard stick with transmission fluid manometer!

 

[DaveO]

Just to set the scene ....

I have the EX500 Kawasaki carbs. These are, of course, linked carbs @Mailman. When I first got the bike running, I had a problem with a seriously rising idle and was advised to check and set the mixture screws which I did, and this fixed it. I think they are both set to 1.5 turns out. (I'd have to check my folder - don't laugh, I worked in IT and like to write things down.)

Now that I'm riding the bike more, I seem to be mentally compiling a "to do" list. I've mentioned this before, but I have to say, although it starts right up on the electric start I am sometimes at a loss to start it kick starting. At first I thought it was old age and my generally weedy frame. But now I'm a bit more adept I think it is more than that. So, it's on my list to look at.

The carbs were initially balanced on the bench.

My intention was to use the dead cylinder method to set the air mixture screws.

After that I intend to balance the carbs using a manometer.

Things I have checked or am happy with:

Bike charges fine and battery is healthy
Plugs are fine and I have a healthy spark,
I've used a spark tester. I'll post a picture and the spark jumps a fair gap.
Float levels are fine (checked with clear tube method)
Fuel is fresh
Good compression (in fairness not measured)

cam chain, valve lash and timing all set, and in that order.

So, am I right setting the air mixture screw setting using the dead cylinder method?

Dave

 

[jpdevol]

Dead Cyl. for fuel screws:
You can use that method - and sometimes it'll produce better results, esp. with worn parts - or you can start at 3/4 turn ('75 carbs) each mix screw and fiddle it by ear, keeping both set equally. I'm lazy, so I use the latter unless results aren't satisfactory.

 

[DaveO]

@jpdevol I've seen those but was suspicious that something so cheap would be any good.

@Mailman That's brilliant. I've seen similar with mercury but not transmission fluid. I've all the bits for a bottle type manometer. How do you stop the fluid all ending up in the cylinder? Is there more off camera?

Reading back through "get 'er done" (my "build" thread") I suddenly thought "I bet it is the bl**dy battery again". But I've popped out to the garage, and I get 12.9V across the battery and 14.4V with the bike running. Not had a problem with electric starting, even after multiple starts. So, I'll count that as a load test.

Dave

 

[WideAWAKE]

$27 https://www.amazon.com/Motorcycle-Vacuum-Gauge-Balancer-Synchronizer/dp/B08F35KDVF/ref=sr_1_24
View attachment 225538

But only if you have vacuum ports.

Or put some in.

 

[DaveO]

Dead Cyl. for fuel screws:
You can use that method - and sometimes it'll produce better results, esp. with worn parts - or you can start at 3/4 turn ('75 carbs) each mix screw and fiddle it by ear, keeping both set equally. I'm lazy, so I use the latter unless results aren't satisfactory.

@jpdevol my original (75B) carbs are in a cardboard box. They had been well used. Crossed threads and knackered enrichener. (They were of course twin cable and unlinked. I've got the EX500 carbs now. Linked.

So, the correct setting for number of turns out is a matter of investigation. I set it as advised and was happy to get down the road. Now I have a few miles under my belt I'm still a happy bunny but, as I say, things could be improved.

I've got a two into one exhaust so no listening to each side or lolly sticks.

Dave

 

[jpdevol]

@jpdevol I've seen those but was suspicious that some so cheap would be any good.

I go both ways......lol.....and they both work. The key is to adjust either of them the same (on one cyl.) and with the gauges, adjust the air valves to get a proper needle swing.

 

[DaveO]

But only if you have vacuum ports.

Or put some in.

I bought the appropriate boots at the time complete with barbs. EX500 carbs don't fit into the 75 boots. When I got the carbs ... EBays finest ... they had barbs too.

 

[mike in idaho]

If you really want to do the "dead cylinder" method, with points, you don't need to be pulling off plug wires. Just short one set of points, at a time, to ground with a screwdriver with the engine running to do a quick cylinder balance check.

 

[DaveO]

If you really want to do the "dead cylinder" method, with points, you don't need to be pulling off plug wires. Just short one set of points, at a time, to ground with a screwdriver with the engine running to do a quick cylinder balance check.

I've a Boyer Bransden. I'll not be running the coil without load though.

 

[DaveO]

I've used a spark tester. I'll post a picture and the spark jumps a fair gap.

Tested out at about 25KV.

Dave

 

[bosco659]

Oh, you’ve never seen my high dollar, yard stick with transmission fluid manometer!

Well that looks awfully familiar! Used 2 stroke oil in mine. Need to be careful. Of too far out of sync the oil will get sucked into the carbs.

 

[bosco659]

I go both ways......lol.....and they both work. The key is to adjust either of them the same (on one cyl.) and with the gauges, adjust the air valves to get a proper needle swing.
View attachment 225540View attachment 225541

Just sold my SyncPro. Wouldn’t work on my 2 stroke motor. Was also a bit of a pain calibrating it before each use. Accurate though.