Author Topic: 1978, hondamatic, cb750a replacing the stock box????  (Read 4156 times)

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1978, hondamatic, cb750a replacing the stock box????
« on: December 20, 2008, 12:51:04 pm »
hi. I hate the stock air box on my bike. it is a pain in the ass to remove and put back when I want to do anything with the carbs. I want to rip it out for ever, and put in some great looking, easily accessible, individual filters from, say, k&n part#rc-2314. my questions are: 1 heard bikes can run "lean" with these filters on? but coating them with filter oil can help that? also a guy i know has a ton of old hondas, says he puts these on all the time and doesn't have to adjust anything? except he says the carbs throw sparks and catches cheap foam ones on fire? 2 there is a vacuum hose that plugs into the stock box, what would I do with that if i replace the box with individual filters?

thank you for your help.


  • Guest
Re: 1978, hondamatic, cb750a replacing the stock box????
« Reply #1 on: December 20, 2008, 03:09:15 pm »
oops, sorry. this may have not been the right place to ask this? tips/tricks

Offline raymond10078

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Re: 1978, hondamatic, cb750a replacing the stock box????
« Reply #2 on: February 24, 2011, 10:23:39 am »
Hello!  I am a fello Hondamatic owner.

I have not made the change you are speaking of, and I won't (at least, not until I swap out the carbs for a CV set).

Having monitored/search the forums here - a relatively consistent message emerges: going to individual pod filters creates a new set of problems.  I recall a lot of posts that tell the horror stories of the misbehaving carbs, causing the owner to eventually ditch his brand new filters back to the stock air box, which then eliminated the problems being experienced.

So, in summary, my two cents is leave it installed.

If you still choose to experiment (remove your air box and install pod filters), then I'd say that you'll have to jet up.  No, oiling the filters (which is required of cotton filters by the way) won't allow you to run stock jets.  I suspect that the guy that you know, may be working on even older Hondas, that were jetted rich from the factory.  Your (and my) 78 were jetted comparatively leaner - meaning that when you switch to pods, you'll be too lean (except maybe if you live/ride in Denver).

Lastly, from my own personal experience, I can get the air box in/out pretty quick and easy.  I've found that if you remove the bottom half and the filter separately, then remove the top half, it comes out much easier.  Trying to pull out the entire box (which I did the first time) was a big pain in the backside.
1978 CB750A (upgrading very, very slowly)

Past bikes - Honda: SL350, CX650C, CB900C, CB1000C, CM450A; Kawasaki: several 1972 750 H2's; Suzuki: TC90J.

Bikes I want: CX650ED, a mid-sized japanese V-twin with ABS.

Offline popslady

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Re: 1978, hondamatic, cb750a replacing the stock box????
« Reply #3 on: March 06, 2011, 12:04:55 pm »
I drag race HONDAMATIC 400-450-750  and use CV CARBS on all those bikes, for the 1978 CB750A a set of Mukini,s  CV carbs from a 1981 kawasaki LTD 1000 with Sudco adapters to the 750 manifold  W/120- 135 MAIN Jet and a  2 into 1 twin pipes open header.