Maintenance & Technical > KX500 Original
Port timing
kwakman:
Been flicking thru the manual and the port timing section has info that appears wrong to me. I'll post the whole lot in a while, but first a question.
For the 89 onwards 500, it gives two specs for the exhaust port, one for high engine speed (powervalve open), and one low speed(powervalve closed.
The 89 onwards model has the centre flap type port, which moves into a raised position at high rpm.This has the same effect as raising the exhaust port, which if I'm correct, gives a longer total exhaust duration to allow extra 'blow down' time for the cylinder which is needed at high rpm as there is less time to fill and empty the cylinder.
However, the manual,(Clymer covering 500 models 83 - 93) gives the high speed exaust open as 83.5 deg BBDC, and the low speed timing as 93.5 deg BBDC. Isnt this the wrong way round?
Anybody....
kwakman:
Sorry its crude, too busy fiddling with fives to learn computer stuff....
Year transfer transfer exhaust exhaust total total
open close open close inlet ex
BBDC ABDC BBDC ABDC DEG DEG
85 62 62 92 92 124 184
86 59.5 59.5 96 96 119 192
87 59.5 59.5 86.5 86.5 119 173
88 60 60 90 90 120 180
89on 60 60 H.S.83.5 83.5 120 167 High rpm
L.S.93.5 93.5 187 Low rpm
This Is How It Is In The Manual, But are HS and LS specs the wrong
way round????????
kwakman:
Also for your delectation, compression ratios by year... KX500
84 7.0 to 1 (US 6.7 to 1)
85 7.9 to 1
86 8.4 to 1
87 7.4 to 1
88 7.1 to 1
89 7.7 to 1 Low speed
6.8 to 1 High speed
90on 8.3 to 1 Low speed
7.4 to 1 High speed
If Stewart, BDI, Doordie or anyone can summarise the effect of the timing and compression for each model year as to how each should perform I'm all ears.....
My money's on the 86 but I am ever so slightly biased :roll:
doordie:
--- Quote from: kwakman on January 05, 2009, 10:46:23 AM ---Sorry its crude, too busy fiddling with fives to learn computer stuff....
Year transfer transfer exhaust exhaust total total
open close open close inlet ex
BBDC ABDC BBDC ABDC DEG DEG
85 62 62 92 92 124 184
86 59.5 59.5 96 96 119 192
87 59.5 59.5 86.5 86.5 119 173
88 60 60 90 90 120 180
89on 60 60 H.S.83.5 83.5 120 167 High rpm
L.S.93.5 93.5 187 Low rpm
This Is How It Is In The Manual, But are HS and LS specs the wrong
way round????????
--- End quote ---
Yes,HS and LS are wrong,Duration HS=187* and LS=167* (more duration,more rpm) :wink:
doordie:
--- Quote from: kwakman on January 05, 2009, 11:16:08 AM ---Also for your delectation, compression ratios by year... KX500
84 7.0 to 1 (US 6.7 to 1)
85 7.9 to 1
86 8.4 to 1
87 7.4 to 1
88 7.1 to 1
89 7.7 to 1 Low speed
6.8 to 1 High speed
90on 8.3 to 1 Low speed
7.4 to 1 High speed
If Stewart, BDI, Doordie or anyone can summarise the effect of the timing and compression for each model year as to how each should perform I'm all ears.....
My money's on the 86 but I am ever so slightly biased :roll:
--- End quote ---
-86 a wild beast with a low to midburst in power,need higher oktanrate to not pinging.Hard to ride! :evil:
-90 a slightly "tamed" beast in low to midrangepower.Easy to ride! 8-)
as always just my 2 cents :-D
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