Dwell Readings and Timing Question

[Chrondor]

Hello,
I set the Dwell reading on my bike to 23 on the 4 cylinder setting and it seems to be running worse. The timing is a bit behind using a timing light and when I try and reach the "F" the bike will die and not idle.
Any ideas where to start on this? Thank you.

 

[5twins]

I'm going to assume you're working with the top set of points and trying to time the right cylinder. You should be doing this one 1st. Is the timing currently matched or close to being matched between the cylinders? I'm thinking it's not, with the left cylinder's timing being even farther off. When you move the whole backing plate to adjust the right cylinder's timing, that changes the left cylinder's timing too. That could be making it too far off and that's why the bike is stalling. Also, changing the points gap changes the timing. That may be why it's running worse now after setting the points gap.

 

[Chrondor]

It seemed to be running better with a lower dwell reading. Like around 20. Is that an okay setting for it. Or should I keep it at about 23?

 

[5twins]

What you have to know when using a dwell meter is that the reading is inversely related to the size of the points gap. In other words, a higher reading indicates a smaller gap, smaller reading a larger gap. The dwell value for the 650 is 93°± 5° which would be 88° to 98°. That would be 22° to 24.5° on the 4 cyl. scale. So at 20°, your points gap is too big. It may or may not run consistently well like that. The wimpy stock ignition may not have enough power to consistently fire that larger points gap. As I just mentioned, changing the points gap to 20° has changed your timing too. Maybe that's why it's running better.

 

[Chrondor]

Okay. I'll leave it at 23 and check it again when my battery charges back up.

 

[5twins]

The ideal setting would be 22°. That's the largest in spec gap. When points wear, they usually wear closed. Having the largest acceptable gap to begin with means they'll stay in spec longer as they slowly close up.

 

[grizld1]

Chrondor, you might save yourself some time and frustration if you do a static timing adjustment with your ohm meter while your battery charges, then finish adjustment with the strobe.

 

[Chrondor]

I have the meter. I'm assuming it will register higher Ohms where I should set the timing at "F"? Is there a specific Ohm reading? Then I can fine tune it with my strobe when it's running, or is it precise? No frustration, I'm enjoying putting these puzzle pieces together. It was running okay before, but I know I can get it running better. Pops a little on Deceleration and when I checked the timing it was a bit behind. When I set the gaps to the dwell meter all hell broke loose. HAHA Thanks to both you guys for the responses BTW

 

[grizld1]

Right, resistance should go to infinity when the points open. Static timing gets you close, use the strobe to finish. Many set full advance a bit short of the 40* mark; I like 38*, some use 36* and report good results.

 

[Chrondor]

Runs much much better at 22 on the dwell. Thanks for your help guys! -Chrondor

 

[kopcicle]

Late to the party but remember this Old Fart ?

Well the manual doesn't do a very good job of explaining this so ...

Set one set of points to the proper gap and place a dwell meter on that set of points and take down the reading .
(doesn't really matter what the number is or how many cylinders because you are going to make the other set the same . Just pick a setting that gives you a reading around mid scale)
Now get the bike running and set the other set of points to the same reading .
Ok now the almost kinda tricky part . Connect a timing light to the bike and moving the entire breaker plate assembly place the timing mark (usually for 1 & 4 ) within the 1/8" or so that is the full advance mark .
You will notice that one set of points is "usually" solidly connected to the breaker plate assembly (again usually 1&4 but not always ) and the other set (2&3) will move not only in advance and retard but in gap also .
Switch the timing light to 2&3 and again place the mark in the 1/8" that is full advance .
go back and check dwell for both 1&4 and 2&3 . if the dwell and the timing is reasonably the same for each set within a couple of degrees you are done .

Special cases . On older bikes the advance mechanism may have been abused and even though the timing is correct at full advance the static or full retarded timing may be way late . limiting the advance by adding a bit of metal to the advance stoppers is preferred to attempting to bend them as they often break . Worn or loose advance springs will cause indistinct timing at just off idle to around 2,200 hundred rpm .
Adjust the valves . I can't repeat this often enough . Adjust the valves or all the work that goes into adjusting the timing has little or no effect on performance . By nature of the shim under bucket arrangement that Kawasaki used for the 650 and 750 they get neglected . Find either a reputable mechanic with a proven record with older bikes or attempt or your self . Just get it right .
Some but not all of the 650's had three adjustable carbs and one fixed , others had idle and air screws and some had accelerator pumps . All require different procedures for adjustment . How ever if the valve adjust is correct and the timing is spot on the carb sync should be a breeze . Have a talk with the folks around WiredGeorge before you mangle anything in and or around your carbs . if your manifolds are rotten and cracked talk to Z1 Enterprises, Inc. - Specializing in Vintage Japanese Motorcycle Parts Jeff and Co. will be more than happy to get you the right parts . Almost forgot . Get a trickle charger for the thing . The early charging systems arn't near as efficient as the newer models . They work and they are durable they just don't have great output .

Seems like stone knives and bear skins but I set one set with the feeler gauge and get the other close . That is usually close enough to start it . Then I make the dwell equal for both sets of points . Then I set the timing . Then I check and adjust dwell if necessary . Then go back to timing ...

Repeat the process till you get sick of it . Just checked my notes , I've been using 23 deg on a 4 cylinder scale for years . Mind you I have no idea why other than it works .

~kop

This was originally written for kz 650 I hope it makes sense

 

[gggGary]

Where are my shim under buckets?
(oops found them, they were cleverly hidden in the FJR!) No Cow suckers in my garage.
Dwell is not critical on these like it is on V8's Two separate sets of points, coils for two cylinders, you have all the time in the world for coil saturation before points opening, even at redline. A V8 with one set of points and coil has 1/4th the coil soak time available even at 1/2 the rpm........ More important to decent running than dwell is timing at full advance, then timing at idle. and smooth timing advance. Watch the light and listen for random misfires. When you get tired of all this monkey jacking with mechanical nightmares, go buy a pamco with e-advance. and enjoy the ride. I currently have one XS each way. The points bike does run well, for now. Per the manual gapped one set of points vary gap on second to more or less match timing. The points spend the majority of the revolution closed (coil soak) the gap is mainly making up for the inaccuracies of the mechanical flivver a point mechanism is.

 

[Chrondor]

I'm going to set the timing right first, but for future time spent is the pamco going to save me that much time? If so it would def be worth buying. Also which kit would be best for a '73 tx650 (MikesXS has a few different kits and I already have NGK plug caps and cables)? If it doesn't save a bunch of time I don't mind getting the timing right the old fashioned way.

 

[gggGary]

Nah you don't HAVE to swap. If you are happy with how it starts and runs with points and don't mind an afternoon now then checking and setting and prolly fresh parts about every 10K stick with em. When the time comes, compare a complete set of good quality points parts with a Pamco...