classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: dynamic on November 28, 2021, 10:39:26 AM
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I have just fitted a new concetric 626R 300 carb to my machine & it has become a very reluctent starter taking 10+ kicks to start
I have a 108 pilot jet & 200 main jet needle is on bottom notch , I do prime the engine ie. tickle throttle fully open then 3 kicks ignition off
a choke is fitted but makes no diffrence at all at any position
I do get cylinders firing but it just does not chime in
taking the plugs out they are barey wet , fuel flow is perfect I have both taps on to start ignition (Pazon) is spot on
once initially started hot starting is no problem the only thing not checked is float height I have not touched this from receiving the carb
all input gratefully received "worn out of North Wales "
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Does this have a "proper" pilot jet or merely a bushing? If the latter, make sure that all drillings are clear. Where did you buy it as apparently some on the market are not too good.
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A 626/300 (non-Premier) has the standard fixed pilot bush.
http://amalcarb.co.uk/rh-26mm-4-stroke-mk-i-carburettor.html
Do you mean 108 needle jet? The original '68 T100(C?) carb (626/8?) and generic 626/300 would have a 106 needle jet?
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my carb has an actual pilot jet came with the 108 size purchased from a store I have used for many years with no problems
maybe I have a "dud" ? at the moment soaking it in carb cleaner before poking/blowing the pilot circuit through
will post results
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my carb has an actual pilot jet came with the 108 size purchased from a store I have used for many years with no problems
The 626/300 (non-Premier Mk1) has a pilot bush, therefore, does not require a screw-in pilot jet?
http://amalcarb.co.uk/rh-26mm-4-stroke-mk-i-carburettor.html
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Details for RH 26mm 4 Stroke MK I Carburettor
This carburettor is built to a standard specification which provides approximate settings for this bore size and carburettor type. Ideal for anyone who wants to tune their machine themselves.
Comes fitted as standard with:
3 Cutaway Slide
160 Main Jet
106 Needle Jet
Pilot Bush
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http://amalcarb.co.uk/rebuilding-mark-1-concentric-carburetter
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Pilot Circuit
Mark 1 Concentrics are equipped with two types of pilot jets. '2 Strokes' use a removable pilot jet which should be replaced if it is damaged or shows signs of oxidisation. '4 Strokes' generally use a pressed in bush pilot jet in the gallery behind the pilot air screw.
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looks like im naming the pilot jet in error so I have a 108 needle jet screws in above the main jet
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Should be below the main jet ;) and normally a 106.
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Should be below the main jet ;) and normally a 106.
The needle jet is above the main jet.
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I was being ironic, hence the ;)
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I was being ironic, hence the ;)
Glad you said so as it made no sense to me, ironic or otherwise.
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after soaking my carb body in carb cleaner overnight( sealed over with clingfilm) and probing/blowing the pilot airways through re fitting carb to my machine
it started a very healthy third kick along with a nice "purring" tickover at last
I think maybe just a small amount of debris was restricting the airways even though this is a new carb
thanks to all members input "I am now educated"
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I think maybe just a small amount of debris was restricting the airways even though this is a new carb
It's not unknown for a new carb to still have some debris in it, however, modern fuel also blocks the pilot bush if the bike isn't started for a couple of weeks when fuel has been left in the carbs so I occasionally have to clear a pilot bush (see Bushman's link, below).
http://www.bmoc.ca/Tech%20Info/Bushmans%20Carb%20Tuning%20Update%202015.pdf
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thanks for the info LAB intresting read 4*here will ride till I cannot feel my feet