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Discussion Starter · #1 ·
OK after completely refurbishing my bikes ignition system I am trying to dial in the ignition timing. I have been using a light to do this. Something I notice was that the bike idles much smoother when I set the mark a bit to the advanced side. If I try to line up right on the fire marks the make starts to idle roughly.

I was riding it around timed somewhat advanced (but not knocking or pinging), and noticed the bike seemed to loose power after a while like it was getting hot. I have been also playing with the fuel mix so it may have been simply too lean.

Anyway what I'd like to know is how would a slightly advanced spark effect the engine as compared to a slightly retarded one. I can see that a late spark would probably result in a loss of power. Can I hurt anything running slightly advanced as long as I'm not knocking or pinging? If I had complete confidence in the 30-year old advanced mechanism I'd probably just time it to the marks and leave it at that. I can see it's advancing the spark, but not too sure it's the right amount at the right rpm.
 

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Sensei
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You should be able to get a steady idle (@1100 to 1300 RPM) by static timing the bike EXACTLY on the index marks......If not, something (else) is wrong.....
So, First we'll need some info.......
What are the compression readings?
Did you clean/lube/check the advance unit?
Are you trying for too low an idle? (what/where are YOU setting the idle speed?)
Is your "timing" light a bulb or a strobe?

As for advance settings, racers run with the units locked at full advance, but they won't/don't idle well (if at all)
 

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450's respond best (in my experience) to a simple static time with a little light bulb, described here -

http://www.hondatwins.net/forum/viewtopic.php?f=18&t=883

If that's done properly, any other running problem is usually dirty carbs or something.

The risk of arbitrarily advancing the timing is predetonation, which will cause bad stuff to happen.
A running 450 is a symphony of different noises, and a slight predetonation may go totally unoticed. It can put a hole in a piston without even knowing it's happening.

Racers do tend to advance the timing a bit, but they spend all their time at 9,000 rpm and tear down their engine after every race.

Do like Steve says and collect your basic diagnostic info, like compression, etc...........
 

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Discussion Starter · #4 ·
OK here goes:

I haven't been able to take compression readings, but the bike had 8K miles on it when I got it for whatever that's worth.

The advance unit is what is causing me the concern about this. I was having all sorts of issues with dialing in the Dynatek electric ignition, and at one point I played with the springs on the weights. There was no tension on the weights at all in their relaxed state, so I was worried idling at 1200 RPM I was seeing advance too early. Should the springs be essentially relaxed when the cam lobe moves the first few degrees?

My timing light is a strobe, but I initially timed the bike by watching the plug and cranking it by hand.

Is it not normal for the idle to rise as I advance the timing? Like I said I am still playing with the carbs some, and had the mix screw over 2 turns out before reading that 3/4 is the place to start. So that could be a factor.

I guess what I'm looking for here is a bullet proof way to be sure my advance is working properly. NOS springs seem to be a pipedream. Isn't there some spec as to the tension of these springs? When I strobe the marks the timing looks a bit tiny bit advanced at idle. When I up the RPM the marks seem to move in the advance direction but bounces around a lot.

Bottom line: Do I time the bike static, and not worry about the advance screwing it up? Or do I time the bike right on with the strobe regardless of how it runs and hope for the best with the advance unit?
 

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Hey, you didn't day anything about a Dyna system.
Lots of people have trouble with that......

If you're worried about your advancer, Mike's XS shop sells advancer springs that (by all reports) are identical to 450 advancer springs.
 

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Discussion Starter · #6 ·
Yeah I'm pretty sure I had a bad plug wire and/or a weak connection with the POS 3m splicer that came with the Dynatek. I ended up replacing both coils, wires, and plug caps from the ones at Mike's. I also put a fresh set of plugs in it. The motor is running well now, I'm just trying to get it dialed in.

I'd have ordered the springs too if I knew they worked with the Honda.
 

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Sensei
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Bulletproof way to be assured the advance unit is working correctly.... Buy a NOS one.... $50+ at minimum... IF you can find one... Probably more like one and a half times to double that price.. They appear occaisionally on eBay....
IF the springs are right, the center should gently but quickly "snick" back to the retarded position when manually spun advanced and released......
 

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Discussion Starter · #8 ·
I tweaked the springs until there was no slop when the cam was fully retarded, but snapped back fairly gently from advanced position. I then static timed the bike by pulling the plugs and watching/listening for the spark.

It fired right up and is popping a bit on one cylinder at idle but I think that's carb related. It pulls nicely through the gears and is idling at around 1400. I think my next step is to build a manometer to get the carbs right on.

Thanks for the help guys.
 

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Timing and advance: Attach a strobe timing light to #1 cyl. and start the motor. Adjust for the LF mark to appear at the pointer at idle. raise the RPM - the timing should begin to advance at 1800 rpm and not before. If the advance starts around idle speed it will make it impossible to set a fixed idle speed and means the springs are weak. The advance should continue until 3200 or a little higher and the pointer should be positioned within the maximum advance marks at this point - and should go no higher at higher rpm. If the marks on the alternator rotor are dancing around under the strobe light, check for wear in the exhaust camshaft bearings (can you move the ignition cam laterally? test it with a dial gauge). It could also mean a loose timing chain or damaged guide rollers. Not having a steady timing mark is not a good thing.
 

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Discussion Starter · #10 ·
Made a little progress I think. I locked the cam lobe down by removing a washer so there was no way it could turn and advance the timing. I checked the timing at idle and it was dead nuts on for both cylinders, with a nice stable mark. This lead me to believe that the weights were giving me the erratic readings and showing advance at idle. I tweaked the springs and was able to get a stable timing at idle, but still have some issues with advance. At this point I'm writing the springs off as a loss since they are unable to give me a smooth predictable advance.

Oh and I checked my cam chain tension and have no play in the cam bearings. Since the mark is stable at idle I feel pretty confident these aren't issues.

Now if I could get a confirmed case of someone using the XS650 springs with good results I'll be in business.

Thanks for the help guys, these forums are great!
 

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last time i tried to order the xs650 springs they were out... maybe a month ago?
 
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