Author Topic: Carb Jet sizes  (Read 267 times)

Offline ogri211

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Carb Jet sizes
« on: March 13, 2018, 06:55:55 AM »
I'm just about ready to overhaul my carbs, my bike had a Motad 4 into 1 fitted from what I can remember Motad olways advertised that you don't need to up your jets. I have managed to procure a standard set of headers which I am getting rechromed and I have got a Marshal deep tone tailpipe which is what I wanted as it is the same as what I had in 1982 ( my profile picture) does anyone have any ideas of what size of jets I should fit as for obvious reasons I don't want to be pulling the carbs on and off.
Triumph Rocket3, Suzuki GT 750A, Kawasaki H1B, Honda 400 Four, Triumph Speed Triple

Offline Bryanj

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Re: Carb Jet sizes
« Reply #1 on: March 13, 2018, 07:40:21 AM »
With the correct screwdriver and smallish hands you can get the floatbowls off in situ and swap jets, I would try standard first as i fitted a marshall to a 550 and it ran fine on standard

Offline ogri211

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Re: Carb Jet sizes
« Reply #2 on: March 13, 2018, 08:54:08 AM »
Unfortunately, my hands are rather large but im going to put capheads on the carb boals when I do them o the should be easy to take off I will go with the standard jets first and take it from there. Thanks for your advise. 
Triumph Rocket3, Suzuki GT 750A, Kawasaki H1B, Honda 400 Four, Triumph Speed Triple

Offline hairygit

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Re: Carb Jet sizes
« Reply #3 on: March 13, 2018, 09:40:13 AM »
Unfortunately, my hands are rather large but im going to put capheads on the carb boals when I do them o the should be easy to take off I will go with the standard jets first and take it from there. Thanks for your advise.
Be very, very careful not to do capheads  too tight, the carb body is really rather fragile where the screws go in, threads strip for fun, and the entire screw area can snap off if you don't tighten them gradually and evenly. Sad to say I've seen it happen a few times, but these days you can't just nip to a breakers and get a full bank of carbs from a running bike for a tenner! (There some good things about the 80's eh?)
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Offline andut

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Re: Carb Jet sizes
« Reply #4 on: March 13, 2018, 03:01:27 PM »
I would agree with Bryan's caution with those float bowl screws - you may want to check how good the threads are in the carb castings and consider helicoiling them all before fitting the carbs if you're expecting to be changing jets or float heights as part of your tuning.  Cap heads will definitelty make removal / refit of the bowls easier once the carbs  are on the bike, but go steady when tightening them up !

Offline Nurse Julie

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Re: Carb Jet sizes
« Reply #5 on: March 13, 2018, 03:19:31 PM »
I have gone from Allen screws to machine screws on my CB550 and Trig helicoiled every thread as many of them were stripped bare   ::) ::)
« Last Edit: March 13, 2018, 03:42:32 PM by Nurse Julie »
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Offline ogri211

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Re: Carb Jet sizes
« Reply #6 on: March 13, 2018, 05:25:04 PM »
No prob I have done plenty of carbs but I will check the threads and helicoil them is needed and fortunately I happen to have a spare bank of carbs hopefully help the Alzheimers when im putting my original ones back together.
Triumph Rocket3, Suzuki GT 750A, Kawasaki H1B, Honda 400 Four, Triumph Speed Triple

Offline Greg65

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Re: Carb Jet sizes
« Reply #7 on: March 14, 2018, 07:28:43 AM »
I had much fun and games with a Suzuki GS 1000 that had been podded and badly jetted as well as two of the four carbs damaged. In my general reading at most you will need is to go one jet larger for an exhaust mod. I found this web site invaluable for helping me set up my carbs and as its general advice I’m sure it will be useful.

http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

Have fun as it requires lots of road testing.

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