Pilot Screw Adjustment.

[kev64]

Hopefully Hawk will be along soon and give you a proper techy reply as he s been messing
with these carbs for years also Carl is excellent but has gone missing of late !

[macca__macca]

Am i right in understanding that step 7 is saying to turn the idle speed screw to reduce the idle speed down to 1200rpm after raising it to the peak value in step 5, and likewise instep 10? Also since i have a DynoJet kit i assume I'll assume the final opening values for me will be the 2.5 turns as specified in the DynoJet install guidelines?

Hopefully! I guess my main query was around step 7 in my comment above? I.e step 5 results in a fast idle which you then reduce by turning the idle speed screw in step 7?


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[kev64]

Yes , when you screw your fuel screws in (or out ) when the mixture is correct your engine speed will
increase,, so when you have done both carbs the idle revs will be higher, its just saying to adjust
tickover back down to 1200

[kev64]

Also , i have Jack flash thumb screws and i will use this procedure later ,
i usually just set both screws to 1 turn front and back, so ill let you no how i get on !!

[macca__macca]

Great thank you!


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[Steve97]

I have dynajet kit fitted, followed the instructions to the letter, but changed my 45s for 48s fuel screws now set to 3/4 front 1 rear, goes like hell ! now and again pops a bit on the overrun so guess its maybe a little rich but I can live with that,

[macca__macca]

Steve that's a lot different from what dynojet specify! They say 2.5 turns front and 2.25 rear. Do you have a k&n filter and fairly open slip on pipes as well?

I get a fair bit of popping and am definitely running very rich


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[kev64]

So I warmed the bike up, did a few miles , found a quiet layby,
shut the engine down and followed what is said in the manual.
Screwd both mixture screws out to about 2 1/2 turns, screwed the front in
and then the back, no real engine speed increase, just got a bit smoother
really, in the end set them to 11/4 front, 11/2 turns out back.
Set the tick over back to about 1100, that's me done,
I'm hoping to get a bit more advice in wales this weekend

[kev64]

Also those figures of 2.5 etc are only a rough guide, as the manual says, each bike is different
screw them in till the revs pick up or things run smoother (and you cant smell fuel)
When I had my dyno jets and k&n fitted things went ok and my mixture screws were about what they are now !! The pilot circuit is always running right through the rev range

Have a read up on Hawk and Tony mons guide in the workshop section,(carb set up) this will help !!

[macca__macca]

Thanks guys! Looking forward to doing this and hopefully seeing an improvement in performance.


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[VTRDark]

It's quite simple really no matter what jet kit you use.

To set the fuel mixture screws you screw them in (leaner) until the revs drop and the engine almost cuts out. You them unscrew (richen) until you hear the revs rise and have crisp sounding. no fluffy exhaust note and then set the screw in-between two. Treat each carb separately. If you don't hear a change in note and/or you revs don't rise or drop then the other circuits are not set correctly. ie the needle and/or main.

http://www.vtr1000.org/phpBB3/viewtopic ... 14#p238528

Oh..... and yes the pilot circuit runs right through but it tapers off so it only trickles into the main circuit the further up you go.

(:-})

[bigtwinthing]

I've never followed the honda instructions as I don't have an inductive multimeter with an RPM pickup.

One day I shall buy myself one of these.
http://www.ebay.co.uk/itm/360450091851? ... 1423.l2649

I do my mixture by ear. Start at 2.5 turns out. Turn the screw in until you hear a change/drop in revs, then turn the screw out until you hear a change/drop in revs. Then set it between the two. You also have to listen to the crispness of the engine. Then verify with the blip test.
http://www.vtr1000.org/phpBB3/viewtopic ... 14#p238528

(:-})

Id have got you for for a Powerpoint presentation!

[bfarthing83]

No one appears to have noticed this in my previous post....

http://www.davidsilverspares.co.uk/part ... 084220201/

Also, am I to assume nobody knows the definitive answer as to why go through the idle drop procedure, only to end up at the same point in the end ( 1 turn out on front, 1.25 rear )

Hi is this the pilot jet screw? One had snapped off on mine and I’ve spent 2 hours extracting the b8stard. Was curious as I don’t know where to set it to
Cheers Ben



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[VTRDark]

Yes that's it. Not easy to get to with the carbs mounted to the bike especially the rear. With one snapped off I can only assume that it had been overtightened which is not good as it can damage the seat. You should have a spring, washer and rubber O ring on the end of the screw. Sometimes when you remove the screw the O ring get's stuck inside the hole but make sure all the pieces are there. As for setting it there is no definative answer as every bike will be slighlty diffrent.

FUEL SCREW/MIXTURE ADJUSTMENT

[bfarthing83]

Yes that's it. Not easy to get to with the carbs mounted to the bike especially the rear. With one snapped off I can only assume that it had been overtightened which is not good as it can damage the seat. You should have a spring, washer and rubber O ring on the end of the screw. Sometimes when you remove the screw the O ring get's stuck inside the hole but make sure all the pieces are there. As for setting it there is no definative answer as every bike will be slighlty diffrent.

FUEL SCREW/MIXTURE ADJUSTMENT

Thank you.
Yeah she was way too tight. I have a new jet on the way and wii be rebuilding on Wednesday. Should explain why it was under power and sounding like a 125 with an oversized exhaust.
Am I best to use a carb balancing kit or play it by ear and feel?


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