Topic: Timing hesitation? *updated with video*

[gregripko]

Cb550k

I tried to retime the bike today and now it hesitates from a dead stop at 1/4 throttle....picks up with more throttle and then pulls hard.... I had new springs attached a long time ago making them stiff so I'm guessing my timing mark is in a different spot. Any suggestions? My idle increases as I advance the plate further as well

[phil71]

You're guessing. Get the book out, and set it step by step. Just shooting from the hip, what you're describing could be caused by fuel or spark, so eliminate spark being a problem first
Springs will not move the timing , they will just insure that the mechanical advance returns to idle more quickly.

[BobbyR]

Phil is right. You may want to see if the advancer is stuck. They lube dries out in the heat.

[gregripko]

Ok any suggestions for advancing lube? Just high heat lube right?

[BobbyR]

Ok any suggestions for advancing lube? Just high heat lube right?

Yes, take it out free up anything stuck and a little lube.

[gregripko]

Just trying to figure out why timing plate adjustments seem to only affect the first 1/4 of the throttle... If I go WOT throttle it picks up great.... Just hesitates from dead stop only... It def could be lube issue but could be the springs I put on a whole ago that are making things more difficult than having stock springs and of course I can't buy new ones that are oem

[bjbuchanan]

Set the timing "right" and then check out the 1/4 turn hesitation. Too much guess work as other guys said. In my experience that 1/4 hesitation was my needle clip one notch too lean, the transition made it stumble. I'm not saying that is exactly your problem but you have to be systematic with that stuff

[gregripko]

Ok Ty... I'll set it to spec and go from there I guess

[gregripko]

What's the best lube to use for the cam? I know there's some things to stay away from but I heard even using light motor oil is good? My manual calls for high temp grease but no specification as to what type

[BobbyR]

If you go to a Harley dealer they still have grease that will work for points and the advancer. 

[phil71]

You don't need any special harley grease. That is a dry chamber, and it doesn't get all that hot. Take the points cam off the advancer (make sure you know its orientation) clean the shaft with fine sandpaper or a wire wheel, run some emery through the inside diameter of the points cam. Run a light smear of grease around the shaft, and put it back together. Make sure it moves freely, and returns quickly by itself.
The "why" about 1/4 throttle is that if the advancer is sticky it may fling open late when centrifugal force overcomes the rust.
If that doesn't make sense to you,

[gregripko]

That makes sense to me and I hope it's that simple! It's either that or my springs are too stiff (I put on new ones a while back).... Either way the cleaning and lube will help

[lucky]

What makes you think the hesitation is from the timing?

[lucky]

What makes you think the hesitation is from the timing?

[gregripko]

Because that's the only thing I changed, the hesitation minimizes at a specific timing spot... Too retarded and it lags like mad.... But more advanced and the hesitation minimizes.. I wish I had some stock springs to eliminate that possibility but perhaps it just needs to be relubed as I used a lower temp grease 6+ months ago (think it was rated to 170 degrees)

[bjbuchanan]

The lubr is useful but more important is that freely moving advancer. No rust there at all is more important than the lube

Check with a timing light when it advances fully and compare to rpm. You may not need stock springs maybe just a tweaking. Either way you wanna see that smooth advancer action

[PeWe]

If you timed the ignition with sloppy springs, replaced the springs afterwards without check with timing lamp it will probably be wrong.
My CB750 had sloppy springs which became very visible with PAMCO ignition (rotor rotate freely without counter force from the points). Almost full advance at 1500rpm, spitting gasoline thru the carbs. Sorted by cut 1/2 turn off the spring on the arm side, shaped it with a plier. 
Make sure that the ignition is correct at idle and check at which rpm you see full advance marks.

[gregripko]

Just to verify is the idle mark the mark to the left of the F as seen below?


   | |
 T    F 14


Which is correct idle timing?

    |
  | |
T    F 14


Or

      |
  | |
T    F 14

[gregripko]

It advances at 2,700 - 3,000rpm but it doesn't advance gradually.... It advances from idle and then revs up and advances very sudden.... Maybe that's normal idk ... If springs advance too early it means springs are too loose and if they advance late it's too tight correct?

[Vinhead1957]

Correct but they also need to advance with no binding.   Little lube in there to keep things smooth

[gregripko]

Got the timing pretty good I think... It'll have to do for now I guess... Cleaned and greased, advances at 2700-3000 area right to the advance marks.... It's so bizarre... Lags only from a dead stop... Hmm

[BobbyR]

I have read and observed that these things do advance very fast and since we run them at 3 or more, it is advanced all the time. Without an accel pump they sort of lag until the vacuum get enough gas pulled out of the carbs.   

[gregripko]

I think the hesitation is coming from idle screws possibly... At least that's what I've been guessing at this point... Two tired has a little test involving putting the bike in top gear while running and putting it at a idle speed and opening the throttle half way... It should, as he says, have slow smooth acceleration but it in fact hesitates and burbles.... Almost chugging sound

[bjbuchanan]

You want it to have no "float" just dead pegged in the no advance position to like 1300ish rpm and have full advance in somewhere around 2600. This has that snappy return to idle at a stop and smooth advance. It seems like you have stiff @ss springs on there, stretch one of them just a bit and see what happens. You can stretch just one, you don't have to do both. If one doesn't do it, stretch the other just a little.

I like the 1300 mark because that is usually just above idle on a sorted bike and without super fine tuning you can nail some type of 2600 rpm zone where you smoothly advanced. I think your sudden advance is stiff springs.

With no accelerator pump you can only realistically twist fast thru a half throttle grab. The carbs just can't make it happen at anymore than roughly a half twist. That is why you see people who just have to slam that sport bike type rev fall flat on their face because the compensation just isn't there.

If you haven't done a lot of "real" mods then go to stock settings and work from there. It is easy to get far off base with a little tweak here and there and just can't make that magic happen.

Air screw around 1 turn, I like to start at 1. Stock needle position and see what happens. There is a big rush to change jetting to make that 4-1 work, or really that k&n flex that usually isn't necessary.

Hesitation and then sorta freight train type response is usually indicative of a lean to richer step. Burbling and bogging then clearing up usually indicates rich to leaner

[gregripko]

What do you mean "1300 mark"? I strobe time at 1100 rpm if that's what you're referring to