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Discussion Starter · #1 ·
My 500t started to run rough so I checked the timing and the right cylinder was very advanced idle at the full advanced markings. Tried normal adjustments and could not get it any where near right. Fitted new Daiichi points, used these before and had good results, but still the same. Checked auto advance that is OK.
I am at a loss the only thing I can think of is the cam shaft bearing worn, seems to be OK but I thought I would ask if anyone has had a similar problem before I start to pull it all apart?
 

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Sensei
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Re: Ignition Timing Mistery

Before you tear into it, recheck the cam chain tensioning.....I have seen a high rev back it to a previous "stop' spot.....Loose chain allows advance....
 

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Discussion Starter · #3 ·
Thanks Steve, I will have a look, but the mystery is that the left cylinder timing is spot on and the right is very far advanced. This is at idle speed 1200 rpm.
 

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Sensei
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How about a worn points cam?....(on the advance)
The only other thing I can figure is either badly manufactured points, or a mis-positioning of the points on the plate (holes drilled/worn wrong)....Usually Daiichi parts are OK (although I always preferred the Kokusan) but you could have got bad ones.....Will it statlc time in exactly ? (sometimes a bit of work with jewelers files on the slots/holes will fix it)... ;)... Have you tried a different plate?
 

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Discussion Starter · #5 ·
Thanks again for you help Steve, The bike has done about 1000 miles since last service and the timing was perfect then, so something has changed in that time. The points I replaced were quite good and I would normally have left them in for longer. I will think about it till the weekend then have another play with it. Allan
 

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Sensei
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Allan... Did you find a cause for this yet?....I cannot picture a scenario where only one side would be advanced while the other remains in time (assuming it's not the points, plate, or advance unit themselves) One side retarding could be a broken/missing roller or kink in the camchain, worn/sheared tooth on the cams or crank, etc....But advancing?????.....You have me stumped.... Steve
 

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Discussion Starter · #7 ·
Thanks for your interest Steve! The answer is yes and no, I have fixed the problem. I did the timing the old way with battery and light bulb and got it very close and then did the final adjustment with the bike running and a timing light to get it spot on. The mystery of why it it all happened remains. A friend who knows electronics thinks it could possibly have been a problem with the timing light? Don't know but I now know how to overcome it if there is a repeat. Allan
 

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Sensei
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Well Allan....You have proved to me that the basic "static" timing with a light bulb, THEN fine tune advance with a strobe (which is the way I learned to do it) is ultimately the correct method.... But who would have thought you could get those "advance" indications just from skipping the static timing?.... One would think the strobe would be as accurate at idle as at full advance...... Live and learn.... :D
 

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My approach with 450's has always been to static time - then I check with a strobe to see if the advancer actually functions and the timing advances to anywhere between the advance marks.
I never use the strobe at idle on a 450 - it's been my considerable experience that they run much better with a static time, it gives you the crisp throttle response off idle that we all seek.

My two cents worth - if you paid me to tune your 450, that's how I'd do it........
 
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