Author Topic: Keihin Main Jets  (Read 2135 times)

Offline martin_uk

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Keihin Main Jets
« on: May 07, 2021, 08:19:36 AM »
Genuine jets are expensive but Motorcycle Products do sets of 5 for £7.68


https://www.motorcycleproducts.co.uk/keihin-105-brass-jets/1/016688



Keihin 105 Brass Jets

    Head size 6mm
    Thread 5mm
    Pitch 0.80mm
    Overall length 9mm
    Thread length 5mm
    Made in Japan

Many other sizes and for other carb manufacturers

Ideal if you need to try different sizes
1977 CB750F1
1977 CB750f1 836
1978 CB750F1
1975 CB500K1

Triumph Street Triple 675R
Ducati 800 Icon Scrambler
Triumph 3TA
AJS 350 mod16
BSA BantamD1
Honda C90zz
Honda CB500X
BSA WD B40 350

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Keihin Main Jets
« Reply #1 on: May 07, 2021, 08:30:52 AM »
Handy link, thanks.Do any of the Keihin carbs fitted to CB SOHC/4's use screw in jets 🤔
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline martin_uk

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Re: Keihin Main Jets
« Reply #2 on: May 07, 2021, 08:37:36 AM »
Handy link, thanks.Do any of the Keihin carbs fitted to CB SOHC/4's use screw in jets 🤔

Yes the main jets on CB750F1 and CB750K8 PD carb do for certain.

The PD carb slow/idle are push in.
1977 CB750F1
1977 CB750f1 836
1978 CB750F1
1975 CB500K1

Triumph Street Triple 675R
Ducati 800 Icon Scrambler
Triumph 3TA
AJS 350 mod16
BSA BantamD1
Honda C90zz
Honda CB500X
BSA WD B40 350

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Keihin Main Jets
« Reply #3 on: May 07, 2021, 08:39:23 AM »
Handy link, thanks.Do any of the Keihin carbs fitted to CB SOHC/4's use screw in jets 🤔

Yes the main jets on CB750F1 and CB750K8 PD carb do for certain.

The PD carb slow/idle are push in.
Ah, OK, far to new models for my knowledge base 😁
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Online Bryanj

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Re: Keihin Main Jets
« Reply #4 on: May 07, 2021, 09:30:55 AM »
Now nowJulie, all the 750 use screw in mains, ad pilots for that matter.

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Keihin Main Jets
« Reply #5 on: May 07, 2021, 09:35:15 AM »
Now nowJulie, all the 750 use screw in mains, ad pilots for that matter.
You're correct I'm sure Bryan 🙃🙃🙃 I don't do too much with 750 carbs, Graham knows I'm shite with them and only let's me loose on the 400/500/550 ones 😁😁😁
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Online Bryanj

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Re: Keihin Main Jets
« Reply #6 on: May 07, 2021, 10:17:46 AM »
I try not to do any of them and i wont even touch the damn PD ones any more, i think i got 2 or 3 sets of 750 ones (PD that is) if Graham wants them

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Keihin Main Jets
« Reply #7 on: May 07, 2021, 10:29:46 AM »
I try not to do any of them and i wont even touch the damn PD ones any more, i think i got 2 or 3 sets of 750 ones (PD that is) if Graham wants them
PD's have no place here, except in the skip. I think Graham would favour a hole in the head above 3 sets of PD's, thanks for the offer though and I don't stock any parts or rebuild kits for PD's either 😘😘😘
« Last Edit: May 07, 2021, 10:31:23 AM by Nurse Julie »
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline martin_uk

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Re: Keihin Main Jets
« Reply #8 on: May 07, 2021, 12:49:07 PM »
One of the key things on the PD is to remove/replace/clean  the pilot/slow jets and passages which tend to get blocked.

Also, make sure all accelerator jets squirting well and dont try to increase mixture too much with mains and needle.

Mine had 125 mains and 1.2mm  of washers under needle and pulled very poorly and hesitated.

Changed to 110 mains and 1 x 0.4mm washer under needle and runs great  :)
1977 CB750F1
1977 CB750f1 836
1978 CB750F1
1975 CB500K1

Triumph Street Triple 675R
Ducati 800 Icon Scrambler
Triumph 3TA
AJS 350 mod16
BSA BantamD1
Honda C90zz
Honda CB500X
BSA WD B40 350

 

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