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  #1  
Old 29 Dec 2008
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Carb tuning

Hi
For xmas i got an arrow exhaust and stage 3 kn filters and dynojet kit for my kle500
i have installed the 134 jet supplied and the needle jet (didn't fancy drilling the slide) anyway heres the problem when at wot at about 8-9000rpm the engine hits a flatspot however if i close the throttle a bit it starts to pull again i think this means i need the 130 or 126 Main jet in to lean it off.
Am i correct or do i need a bigger jet?
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  #2  
Old 29 Dec 2008
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Go for a ten minute ride at WOT at the target rev range in question and do a plug chop.

Here are two websites I have found handy when trying to tune the Keihins on my Ural. Mine may not be a modern Japanese bike, but the principles should be the same...

https://www.johnsmotorcycleparts.com...uning_tips.htm

Spark Plugs

HTH
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  #3  
Old 29 Dec 2008
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More than likely the main jet is too small .
If you think about it ; when you back off the throttle the bike runs better , you are in fact reducing the amount of air ,the fuel delivery stays the same so the air:fuel ratio is where it should be .
If you have put a less restrictive exhaust or air filter on the bike ,you will need to jet up .
Do a plug chop to check out the mixture .
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Old 29 Dec 2008
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The standard jet is a keihin 92/93 different in each carb?

found this conversion
Keihin Jets -------- DJ Jets

Num / Thou. ------- Num / Thou.
92.5 / 0.035 ------- 92 / 0.035
95 / 0.036 ------- 94 / 0.036
97.5 / 0.037 ------- 96 / 0.037
100 / 0.038 ------- 98 / 0.038
102.5 / 0.039 ------- 100 / 0.039
105 / 0.040 ------- 102 / 0.040
107.5 / 0.041 ------- 104 / 0.041
110 / 0.042 ------- 106 / 0.042
112.5 / 0.043 ------- 108 / 0.043
115 / 0.044 ------- 110 / 0.044
117.5 / 0.045 ------- 112 / 0.045
120 / 0.046 ------- 114 / 0.046
122.5 / 0.047 ------- 116 / 0.047
125 / 0.048 ------- 118 / 0.048
127.5 / 0.049 ------- 120 / 0.049
130 / 0.050 ------- 122 / 0.050
132.5 / 0.051 ------- 124 / 0.051
135 / 0.052 ------- 126 / 0.052
137.5 / 0.053 ------- 128 / 0.053
140 / 0.054 ------- 130 / 0.054
142.5 / 0.055 ------- 132 / 0.055
145 / 0.056 ------- 134 / 0.056
147.5 / 0.057 ------- 136 / 0.057
150 / 0.058 ------- 138 / 0.058
152.5 / 0.059 ------- 140 / 0.059


so the 134 jet is equivalent to a keihin 145

put the 130 in and it seemed to rev a bit more freely although that was just a short burst in the backgarden

so i'll have to take it for a run tomorrow

dodger
"If you think about it ; when you back off the throttle the bike runs better , you are in fact reducing the amount of air ,the fuel delivery stays the same so the air:fuel ratio is where it should be ."

i know on the carbs on a norton commando mk2 amal's the final about 1/8th throttle only raises the needle some more as the slide is already fully open so the air flow is not affected

also on the kle its a cv carb so if you reduce the air flow the slide and needle close a bit because the venturi effect is reduced so the fuel delivery would be affected
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  #5  
Old 30 Dec 2008
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Flat spots usually indicate leanness .
Stumbling indicates richness .
Sometimes it can be hard to decide which is which .
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Old 30 Dec 2008
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flatspots probably not the best word to describe it more of a bog like if u turn the choke onwith the bike warmed up it bogs a bit
but doing this at the 8-9000rpm didn't help thats why i'm thinking its rich
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  #7  
Old 30 Dec 2008
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quick update 130 jet has improved will try the 126 tomorrow and see then its time to adjust the needle clip
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