Question about Timing

jensey · Post by **jensey** » Fri Jul 20, 2012 3:43 am

This also works :http://www.elektronik-sachse.de/ZDG3/HO ... /index.htm

russ · Post by **russ** » Sat May 10, 2014 7:58 am

got it figured out .

Tim Miller · Post by **Tim Miller** » Sat May 10, 2014 7:12 pm

Russ,

Setting your timing light to 0 it should fire at "F" mark or 5 degree BTDC at 1000 rpm. Then at 3000rpm and up should fire between the 2 marks or 45 to 48 degree BTDC. If it fires any sooner than 48 degree's it will likley seize under full throttle / high load.

Or you can set your adjustable timing light to 5 and it should fire at "T"mark or TDC at 1000 rpm. Then adjust timing light to 48 and it should be at about "T" mark @ 3000 & +rpm.

If you don't have at least 5 deg. advance at idle it will be very sluggish but unfortunately most advancers are shot and they will over shoot the 48 deg mark.

When I rebuild my advancers I make larger stopper to shorten the curve. I like 10 deg at idle and 42 deg at full advance.

Tim

russ wrote:I bought a nice timing light for 40 bucs, it shows rpm / 2&4 cycle , also has a knob for presetting advance .now to backstep a bit , I thought this thread would be best place to ask my question as it's the same . I want to set timing on my 305 dream at 3000 rpm/ which is where book tells me full advance should be . now my question/ should I leave the light set on 0 to do this or set it to 5 degrees . 5 degrees before TDC is what book says timing should be set at 1000 RPM . when I got light I set advance on it at .5 and did timing at 1000 rpm . bike was great in town and on 30 or so mile rides, on highway at 55 MPH with headwind in 4th gear couldn't keep that speed. reset at 3000 RPM .5 on light . seems better but still not quite right . should I leave time light on 0 when making this adj. ?the light can be set from .whatever to whole numbers . reading these posts have made me ? if I am scewing up a simple thing by not having another head to help me reason it all out . I have the E-Ign from Probe installed by their directions , plenty of room each way to Adv/retard the timing the eng is orig as best I know , no issue with carb , coil rebuilt with new solid core wire . close to 10000 miles on eng . thanks for any help . can turn cam and feel the adv mech working , it springs back just fine .

russ · Post by **russ** » Sun May 11, 2014 7:08 am

thanks. what I did yesterday was to set light to 0 and use F mark as I realized it was the advance position. I have a bit of fluctuation in the timing , so today I will recheck the chain tensioner. I played with it till I gave up . confident I'm real close to where I need to be at 1000 rpm . have trouble getting a smooth and steady idle to be 100 percent . I see full advance about 2500 rpm's , a bit before the 2 advance marks . rode down highway and seemed responsive and strong . maybe something in this post will resonate with someone and help me better understand what all I need to do to get her just right before my AMA trip in july. thanks again for info on light and settings . time chain tensioner looks new and seemed stuck , all freed up and reinstalled turned engine over slow by hand as I felt tensioner for movement and retighten lock nut adde mystery oil and pb blaster to gas , will ride and see what comes of it . does seem smoother idle

mike in idaho · Post by **mike in idaho** » Sun May 11, 2014 6:51 pm

I seldom worry about it if the spark advancer doesn't produce a perfect setting on both ends of the scale, set the full advance right on the money and don't worry about a degree or two at idle, it's going to be running at full advance 95+% of the time anyway. If you're concerned about points pitting or oxidation get one of these transistor ignitions: http://sohc4shop.com/catalog/product_in ... ucts_id=32 . For less money, you could build your own: http://www.cs.berkeley.edu/~wkahan/TransIgn.pdf .

russ · Post by **russ** » Sun May 11, 2014 8:01 pm

so it would be more important to get full advance at 3000 rpms? I have the probe elec ign .

Tim Miller · Post by **Tim Miller** » Sun May 11, 2014 10:07 pm

Russ,

It's important to recognize that your total full advance at whatever RPM it registers, that you never exceed 48 degrees maximum advance. The problem with 50 year old advancers is that the rubber-coated stoppers have shrunk up, allowing more timing curve which in turn may allow your timing to idle at less than 5 degrees; resulting in poor throttle response.

Tim

russ wrote:so it would be more important to get full advance at 3000 rpms? I have the probe elec ign .

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