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Author Topic: which Jets to upgrade to?  (Read 1689 times)

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Offline CBR954AD

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which Jets to upgrade to?
« on: February 03, 2016, 08:25:59 AM »
hello,
So two days ago I got my engine running for the first time since it was fully rebuild. It has all new OEM parts as far as bottom end and top end. I will be running pods, and a 4-1 exhaust. what size main jet will I need? or in which ball park at least? I am really low on cash and jets are 7 bucks a pop.
the exhaust is a MAC 4-1 with canister here is image.
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Offline sbeckman7

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Re: which Jets to upgrade to?
« Reply #1 on: February 03, 2016, 09:29:52 AM »
Hopefully someone more experienced will chime in here, but from what I've read re-jetting is not required for the mods you have installed.  Only tuning.
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Offline Farley121

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Re: which Jets to upgrade to?
« Reply #2 on: February 03, 2016, 03:13:12 PM »
  It would help any and all reading this to give all the info required.

Bike model
Year
Any internal mods done during rebuild
Stock carbs?

And yes, the pods will require re-jetting.
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Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #3 on: February 03, 2016, 05:58:42 PM »
sorry, I have stock carbs, fully rebuild, stock Internals all OEM parts w new rings. Head has been port and polished. stock cam.
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Offline Restoration Fan

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Re: which Jets to upgrade to?
« Reply #4 on: February 03, 2016, 06:16:20 PM »
Quote from: CBR954AD on February 03, 2016, 05:58:42 PM
sorry, I have stock carbs, fully rebuild, stock Internals all OEM parts w new rings. Head has been port and polished. stock cam.

CB550, CB500, CB750, CB400, CB350?  That model will matter a lot.
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Offline 70CB750

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Re: which Jets to upgrade to?
« Reply #5 on: February 03, 2016, 06:20:30 PM »
Moving the needle up or down counts for 1.5 jet size.  Once you get to the end fo the jet interval, get bigger jets.
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Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #6 on: February 04, 2016, 07:28:48 AM »
LOL sorry 79 CB650. I dont think I can move the needle on these carbs. on top of them it looks like a rocker arm.
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Offline Farley121

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Re: which Jets to upgrade to?
« Reply #7 on: February 04, 2016, 05:04:14 PM »
  Remove the cap from the top of each carb. 
Look down and you will see a linkage and two small screws at the very bottom. 
Take out the small screws, lift out the linkage and pull the slide out. 
Turn the slide upside down and the needle will fall out. 
Remove the circlip and replce it one slot lower.
Reassemble in revers order.
Go see how you did.
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Offline Retro Rocket

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Re: which Jets to upgrade to?
« Reply #8 on: February 04, 2016, 05:08:06 PM »
Leave the stock airbox on and you won't have to change a thing...
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If You can't fix it with a hammer, You've got an electrical problem.

Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #9 on: February 04, 2016, 05:13:58 PM »
manual said on all 79 CB650 needle jet is non adjustable
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Offline Retro Rocket

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Re: which Jets to upgrade to?
« Reply #10 on: February 04, 2016, 05:15:31 PM »
Quote from: CBR954AD on February 04, 2016, 05:13:58 PM
manual said on all 79 CB650 needle jet is non adjustable

All the more reason to leave the airbox stock, it will be easier....
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750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #11 on: February 04, 2016, 05:16:00 PM »
Quote from: Retro Rocket on February 04, 2016, 05:08:06 PM
Leave the stock airbox on and you won't have to change a thing...
I like the look of the pods on the bike. I would like to keep the cafe racer look.
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Offline Retro Rocket

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Re: which Jets to upgrade to?
« Reply #12 on: February 04, 2016, 05:18:57 PM »
Quote from: CBR954AD on February 04, 2016, 05:16:00 PM
Quote from: Retro Rocket on February 04, 2016, 05:08:06 PM
Leave the stock airbox on and you won't have to change a thing...
I like the look of the pods on the bike. I would like to keep the cafe racer look.

Sorry to say that building for "looks" leads to other problems well documented on the forum, its up to you of course but if you want an easy bike to tune and don't want the associated problems with pods, then go right ahead..  If pods worked well, Honda would never have spent a small fortune designing the box to work with the carbs, its that simple..... Thats all I have to add....Its your bike...
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750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #13 on: February 04, 2016, 05:42:45 PM »
yes I agree. and it is true.
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Offline SOHC4 Cafe Racer Fan

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Re: which Jets to upgrade to?
« Reply #14 on: February 04, 2016, 08:04:12 PM »
If any of my bikes came with an airbox, I'd probably use it.
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Offline Retro Rocket

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Re: which Jets to upgrade to?
« Reply #15 on: February 04, 2016, 09:00:04 PM »
Quote from: CB750 Cafe Racer Fan on February 04, 2016, 08:04:12 PM
If any of my bikes came with an airbox, I'd probably use it.

I'm trying to work out just how big an airbox i can fit in a 750, maybe make it out of Aluminum and powder coat it.... ;)
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750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline CBR954AD

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Re: which Jets to upgrade to?
« Reply #16 on: February 05, 2016, 08:07:25 AM »
I bought the bike pretty much in a box. There was no air box and a lot of other things missing. It is a lot cheaper to install pods that but a air box I think. Anyways. Its not the first bike which I have to re jet. I had a 02 sv650s I installed a exhaust and re jet it. I was just asking if anyone knew on top of their head what size jet to use with pods and exhaust since I'm on budget and each jet is 6.99 for main or aftermarket for 3.49.
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Offline Retro Rocket

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Re: which Jets to upgrade to?
« Reply #17 on: February 05, 2016, 01:53:44 PM »
Quote from: CBR954AD on February 05, 2016, 08:07:25 AM
I bought the bike pretty much in a box. There was no air box and a lot of other things missing. It is a lot cheaper to install pods that but a air box I think. Anyways. Its not the first bike which I have to re jet. I had a 02 sv650s I installed a exhaust and re jet it. I was just asking if anyone knew on top of their head what size jet to use with pods and exhaust since I'm on budget and each jet is 6.99 for main or aftermarket for 3.49.

You need to tune it to find out, thats what sucks with pods, what may work on one bike, won't work on another, things like compression in the cylinders and type of pod make differences, just buy a couple of sizes bigger than stock and try them out. Its trial and error, thats what makes the airbox worth its weight in gold... ;)
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750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.
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