Author Topic: T 100 68 carb/starting problem  (Read 504 times)

Offline dynamic

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T 100 68 carb/starting problem
« on: November 28, 2021, 10:39:26 AM »
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 "

 

Offline iansoady

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Re: T 100 68 carb/starting problem
« Reply #1 on: November 28, 2021, 11:03:02 AM »
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.
Ian
1952 Norton ES2
2008 Yamaha X-Max 250

Offline L.A.B.

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Re: T 100 68 carb/starting problem
« Reply #2 on: November 28, 2021, 11:16:32 AM »
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? 
L.A.B.

Offline dynamic

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Re: T 100 68 carb/starting problem
« Reply #3 on: November 28, 2021, 04:32:31 PM »
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

Offline L.A.B.

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Re: T 100 68 carb/starting problem
« Reply #4 on: November 28, 2021, 04:41:36 PM »
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
"
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

"
http://amalcarb.co.uk/rebuilding-mark-1-concentric-carburetter
 "
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.

"

« Last Edit: November 28, 2021, 04:51:53 PM by L.A.B. »
L.A.B.

Offline dynamic

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Re: T 100 68 carb/starting problem
« Reply #5 on: November 29, 2021, 08:53:28 AM »
looks like im naming the pilot jet in error so I have a 108 needle jet screws in above the main jet

Offline Rex

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Re: T 100 68 carb/starting problem
« Reply #6 on: November 29, 2021, 05:45:10 PM »
Should be below the main jet ;) and normally a 106.

Offline L.A.B.

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Re: T 100 68 carb/starting problem
« Reply #7 on: November 29, 2021, 06:13:25 PM »
Should be below the main jet ;) and normally a 106.

The needle jet is above the main jet.
L.A.B.

Offline Rex

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Re: T 100 68 carb/starting problem
« Reply #8 on: November 29, 2021, 09:24:48 PM »
I was being ironic, hence the  ;)

Offline L.A.B.

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Re: T 100 68 carb/starting problem
« Reply #9 on: November 29, 2021, 09:33:46 PM »
I was being ironic, hence the  ;)

Glad you said so as it made no sense to me, ironic or otherwise.
L.A.B.

Offline dynamic

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Re: T 100 68 carb/starting problem
« Reply #10 on: November 30, 2021, 10:00:20 AM »
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"

Offline L.A.B.

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Re: T 100 68 carb/starting problem
« Reply #11 on: November 30, 2021, 10:19:29 AM »
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
 
« Last Edit: November 30, 2021, 10:21:47 AM by L.A.B. »
L.A.B.

Offline dynamic

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Re: T 100 68 carb/starting problem
« Reply #12 on: November 30, 2021, 12:05:44 PM »
thanks for the info LAB intresting read    4*here will ride till I cannot feel my feet