givemethebighammer
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| posted on 9/1/07 at 11:36 PM |
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Honda Carburettor needles
Has anyone got any information about honda carburettor needles?
The Blackbird uses needles marked as J5FZ
The Fireblade uses two J5FS and two J5FR
I can't find any info anywhere about how these numbers relate to L1 length, taper etc or how they relate to the standard keihin part numbers
available from people like Allens Performance.
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ReMan
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| posted on 9/1/07 at 11:47 PM |
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All four needles in the fireblade dynojet kit are the same?
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givemethebighammer
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| posted on 10/1/07 at 12:01 AM |
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evening Col, up late too!
I found some info that says certain models of fireblade (and blackbird)also jet cyls 1+4 differently to 2+3, but only by a small amount, something
like 1+4=142 and 2+3=140. I guess it is the same thinking as the different sized trumpets to spread the powerband?. I know about the needle thing
because I picked up some fireblade needles from a bloke who had fitted dynojet ones. I have tried measuring them with the vernier to see how the
differ from the blackbird ones but I can't see any real difference. It must be subtle.
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Surrey Dave
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| posted on 10/1/07 at 09:45 AM |
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Any Good
found this chart , could be useful.
http://www.motorcyclecarbs.com/Keihin_PJ_PWK_Jet_Needle_Size_W52C495.cfm?UserID=395580&jsessionid=7e30314441168422117833
are you fine tuning with the LM1 etc?
it would be a miracle if any of the bike carb original needles worked out spot on for a different engine setup , I've found that even very small
changes on keihin /mikuni carbs make a difference.
On my GSXR carbs the original jets where 112 on the outer cylinders and 115 on the inner cylinders , I assumed this was to do with the fact that the
inner cylinders would probably run a little warmer , the intakes are the same length on the GSXR.
[Edited on 10/1/07 by Surrey Dave]
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givemethebighammer
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| posted on 10/1/07 at 10:53 PM |
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quote:
Originally posted by Surrey Dave
found this chart , could be useful.
http://www.motorcyclecarbs.com/Keihin_PJ_PWK_Jet_Needle_Size_W52C495.cfm?UserID=395580&jsessionid=7e30314441168422117833
are you fine tuning with the LM1 etc?
[Edited on 10/1/07 by Surrey Dave]
Thanks Dave I already found the above link and it doesn't have any relevance to the honda codes. I'm not really fine tuning, more just
playing really. I do have a slightly rich spot just off idle, not enough to cause the engine to bog down. In fact if I didn't have the the LC1 I
wouldn't have known it was there. Like I said I got a box of needles and jets for a fiver from a bloke who had upgraded his fireblade to a
dynojet kit and was going to bin the old parts and the remains of the dynojet kit he hadn't used. My thought were that perhaps needles from a
smaller bike might have a different taper etc on them. As it is I can't tell the difference between the blackbird ones and the fireblade ones
even though they have different part codes, hence this post.
thanks
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Surrey Dave
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| posted on 11/1/07 at 12:33 PM |
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Needle Jet
I think the needle jet is relevant to just off idle as the top portion of the needle is parrallel , although I believe also that the point at which
the needle goes from parrallel to tapered is higher or lower for different needles.
I guess needle jets would be expensive and probably not worth the hassle if it is not noticeable when driving
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