Topic: How can I test/set dwell on CB750K?

[Kaze]

I'm looking for a good tutorial on how to test and set the dwell on my CB750K6.

I have read a couple posts about dwell here, but didn't see one that out-right detailed how to do it. Is there a how-to about DWELL on this forum somewhere?

The manual talks about dwell angle and suggests using an outdated machine that I don't have (or plan to find).

How is dwell tested or adjusted? Aside from point gap and timing, I don't see anything in there that even has an adjustor. What am I missing?

[Gurp]

you can google how to test dwell with a multimeter. I remember youtube having some vids.
Getting a dwell meter is way easier though. they aren't too much on ebay and flea markets/estate sales

[Don R]

  Dwell is the measurement of engine rotation degrees when the points are closed and the coils are charging. If you don't have or don't want to get a dwell meter just set the timing and point gap properly and the dwell will take care of itself.

[PeWe]

This thread is rather complete
http://forums.sohc4.net/index.php/topic,147444.0.html

[newday777]

This thread is rather complete
http://forums.sohc4.net/index.php/topic,147444.0.html

Thanks for posting it Per and Mike for starting the thread.
Yes it is! I just read through it in my early awake time... That is a good refresher course. I haven't had to do it since the early 80s(my K5 has Dyna electronic).
I bought a tool box from an estate last summer that had a dwell meter and timing light in one of the drawers so I'm ready to go on my next project bike(K8) with the points still.

[Kaze]

Let me see if I am understanding correctly here. A dwell meter is essentially a precision tool for setting point gap? A step above the feeler gauge, so to speak? If so, I've misunderstood completely. This is why I prefer talking to people directly. I got the wrong idea that setting dwell was a whole other thing.

Google and Youtube are helpful, but some questions are best addressed by voices of experience, and this is where the experienced folks seem to congregate.

Thanks for the time and the link.

[PeWe]

You can get an auto multimeter with dwell for not much money.
I use one, see the photos in that thread. Yellow unit.

Good with auto multimeter is the current fuctionality. Mine handle up to 20A.
Costed under $100

[newday777]

I'm looking for a good tutorial on how to test and set the dwell on my CB750K6.

I have read a couple posts about dwell here, but didn't see one that out-right detailed how to do it. Is there a how-to about DWELL on this forum somewhere?

The manual talks about dwell angle and suggests using an outdated machine that I don't have (or plan to find).

How is dwell tested or adjusted? Aside from point gap and timing, I don't see anything in there that even has an adjustor. What am I missing?

What are you missing? The needed Dwell Meter to measure the dwell angle.
If you are going to run points you need to get a dwell meter for optimum performance.

[Gurp]

I only use my Dwell meter on my 61 GMC truck. I've never needed it on my bikes. As mentioned above it's good pretty much if your IGN timing and points are set correctly.

Sent from my LE2127 using Tapatalk

[PeWe]

The good thing with dwell meter is to set both points equal at idle.  1:4 vs 2:3.
You will also hear when that happens.

[bryanj]

I once had an apprentice tell me it was impossible to get points correct without a dwell meter so at lunch time we went outside in the car park and fitted new points and condenser into my 3.0ltr V6 Ford essex engine which i did wirh screwdriver, feelers and a spanner to allow me to move the dizzy.
Numpty then got out his dwell meter and strobe and had to walk away muttering to himself when all was spot on, experience beats gagetry 99% of the time!

[BenelliSEI]

The points gap setting is a “range”. In order to gap both points sets identically with a feeler gauge you need to be very lucky (I do this 90% of the time). Generally, if both coils are firing at the same point at idle and achieve total advance in unison (checked with a timing light), I’m done.

However….. when I see slight differences with the light, I pull out the dwell meter. No question it is the more accurate solution. Because it’s so accurate, it can also be a royal pain. Tightening a screw can make a huge change, so it requires practice too.

[gearsoup]

You can get an auto multimeter with dwell for not much money.
I use one, see the photos in that thread. Yellow unit.

Good with auto multimeter is the current fuctionality. Mine handle up to 20A.
Costed under $100

Do you have a current link to that unit, or an analog one if need be? I didn't think I needed yet another tool, but here we are! 

[Deltarider]

Analogue dwell meters read easier than digital ones. You can find them very cheap at flea markets and ebay*.
BTW, analogue meters are also much nicer to use reading rpm and voltages dynamically.
Important is the right working order.
An OEM ignitionplate will have the settings almost in the middle of the range. When not, set them there. It's a good starting point.
Realise that increasing the dwell (so narrowing the gap) will retard the timing, decreasing the dwell (so widening the gap) will advance the timing.
Doing the adjustment dynamically can be a pain: with things loose, vibration plays a role. You can choose to adjust, fasten, start the engine and see what it resulted in. Then stop the engine and with the knowledge I've put above, you will know which direction to go. Adjust, fasten, restart the engine and see what it resulted in. If needed, readjust. You may have to repeat the steps. Also, like Pewe said, listen.
* I have seen some which measure in % Duty Cycle instead of degrees. It should then be between 54,4 and 51,1%.

[PeWe]

I bought mine in a nearby shop in Sweden.
Same model must be available elsewhere under another name.
eBay, Amazon etc.
Price in SEK
https://www.biltema.se/en-se/car---mc/workshop-equipment/test-instruments/multimeters/digital-multimeter-car-2000024258

If it is not absolutely exact, enough if it wil show same result when it is about getting both points equal.

I like it for voltage and current measuring too.

[TwoTired]

Honda did not provide a precision dwell adjuster.  With the main points plate loose, it moves about from point spring pressure and cam position while doing the adjustment on a running engine.  The plate only stabilizes when the screws are tight.  It is possible to eliminate much of the slop of the points plate with some metal mashing. 
Most dwell meters don’t provide a range specifically for our SOHC4s, unless it has a 2 cylinder setting.  The wasted spark scheme behaves as a 2 cylinder engine would.  So if you’ve made the points plate into a precision fit in the engine bosses, you adjust the gap and attach the dwell leads to find the needle reading on the dwell meter in a range select that the meter provides.  Thereafter you can use the meter instead of the feeler gauge to adjust point gap using the meter, and ignore any pitting on the points that would alter a feeler gauge gap adjustment.

IMO, a better investment is a genuine points file which flattens the point contacts.  This makes the feeler gauge adjust as accurate as a dwell meter, and provides all the coil charge time that’s required to fire the spark plugs.

[MauiK3]

I've always struggled with using a dwell meter on my bikes. Tightening the screws really messes with the setting. It can be frustrating,

[MauiK3]

+1 on TwoTired!

[PeWe]

Important to ensure the plate sit tight.
I had to use mr hammer on my K6 to convince the bosses to hold the plate tight.
There is a link to that in the dwell thread Mike started.
https://www.motorcycleproject.com/text/sohcign.html

Found here where they have much good info.
http://www.hondachopper.com/garage/garage.html

I hammered the bosses straight on, not sideways to not risk boss to crack. It swelled on both sides.
Plate sit in place, bolts not tightened. Hammer a little on each boss going around to make sure it will tighten equally to keep plate in center.
A small sharp metal hammer.

This only if plate can be moved sideways-up- down.


TEC plate and points so 2:3 especially has a guide keeping it correct.

Cheap meter in USA according to eBay seller.
https://www.ebay.com/itm/374927505330?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=n5_go2jarz6&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY

I searched: car multimeter + dwell.

Whatever procedure used, that kind if multimeter is very useful.
I have compared the measurements with another digital I got from my job decades ago, not cheap and checked once a year.

The analog stuff is sometimes better.
But for my bikes, the cheapo works fine.

[Deltarider]

[...] Cheap meter in USA according to eBay seller.
https://www.ebay.com/itm/374927505330?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=n5_go2jarz6&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY
[...]

A Holdpeak - forgot which specific model - once came out good in a test. Yet I don't like measuring with an inductive clamp - always too much hassle and problems to come to a steady reading  - and therefore will always prefer the ignition's primary circuit for connecting. Both digital and both analogue meters I have, connect that way. Simple and reliable. The Optilux I once had, had an inductive clamp and I always had problems with it. 

[PeWe]

Very important when adjusting an idling engine, ignition or carbs, FAN.

I use a table fan running on full speed in front of engine cooling it.

I could not get my ignition right without cutting the advancer springs almost one wound each.
Both my CB750.

If advancer has a play when nut is not tightened, it show right T (and F) at most counterclockwise position.

[Kaze]

Yeah, that fan idea is pretty clever. I was going to have a gal out there with a fan, but she said no.

Guys keep telling me just to get electronic ignition. ...same jokers who think I should carry a telephone in my pocket.

[Bodi]

Dwell is important on a V8 where the points open four times per crank revolution and the coil charging time gets very short at high rpm. With our dual fire coils it's once. Totally insignificant. Have the gaps at spec and timing set and stop thinking about dwell.

[Gurp]

Dwell is important on a V8 where the points open four times per crank revolution and the coil charging time gets very short at high rpm. With our dual fire coils it's once. Totally insignificant. Have the gaps at spec and timing set and stop thinking about dwell.

My old 1961 GMC with its point dist has angered me before. First time i replaced the point and couldnt tune dwell by ear......
called my GF's dad ann him and "Cousin" Bill came over. they both lauged then bill set my dwell by ear and feel. Mangaed to get a dwell meter not longer and checked his work. 31 degrees.... pretty good I'd say

[Deltarider]

Dwell is important on a V8 where the points open four times per crank revolution and the coil charging time gets very short at high rpm. With our dual fire coils it's once. Totally insignificant. Have the gaps at spec and timing set and stop thinking about dwell.

True. Yet, when you like to have identical gaps on 1+4 and 2+3 (nice) and if you have a dwell meter lying around, you may as well use it. It can detect irregularities, a feeler gauge can not. If you don't have one, and you want one, my advise would be to buy a cheap analogue one second hand. Abstain from models which use an inductive pick-up clamp. The clamp itself is very fragile and easily damaged; just one impact is enough to make it useless. Also you'll have its wire (and your fingers) close to where it is hot (exhausts etc) and when you're not carefull, you may find the wire partly melted afterwards. Models which use the primary circuit are just as accurate.