Honda-SOHC

SOHC.co.uk Forums => CB750 => Topic started by: SumpMagnet on July 29, 2018, 11:53:03 AM

Title: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 29, 2018, 11:53:03 AM
My project bike is on the way, but I know it has not got an airbox and had some grotty pod filters which will not be left in place. They don;t look fit to filter air let alone dirt .... but the question is...what's the best route to go.

Originality says airbox, but I have had a brief trawl on E-Bay and not seen any F2 items for sale. Obviously, I would need a set of carb-box rubbers too as well as an element. Are these crafted from rocking horse poop...or just one of those thigns that come up if you look long enough?

She is going to get a light cafe racer makeover, so I could go for pod filters again, but I have had issues with these things in the past. Admittedly it was with CV carbs, which do not mix well with pod filters unless you like an overly rich midrange and lots of popping on the over-run...as well as wet running issues. I understand slide carbs are a bit easier to setup ass they are less reliant on intake pressure to work right. That was with old school K&Ns before the foam 'Ramair' type came out as well. Either way....I won't be looking at the cheap Chinese unbranded ones.

I also have no idea if the jetting is stock...but will be looking at the matter when I pull the carbs apart for a thorough clean and check. Somewhere in the shed lurks an old set of vacuum gauges too, which will need fresh pipes but should work.

Title: Re: 750F2 ...airbox...or pod filters
Post by: sye on July 29, 2018, 12:11:20 PM
http://www.yamiya750.com/index.php?main_page=index&cPath=246_251_182_82

UK Supplier here:

https://lpmreplicaparts.com/honda/CB750K0/airbox.html
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 29, 2018, 12:31:39 PM
That fits an F2?

Saw it but as it only listed Ks I moved on. So much to learn!
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 12:58:17 PM
I have a later air filter box.
I can dig it out and post some pics if your interested

Mick
Title: Re: 750F2 ...airbox...or pod filters
Post by: Nurse Julie on July 29, 2018, 01:21:41 PM
That fits an F2?

Saw it but as it only listed Ks I moved on. So much to learn!
Maybe Sye got his links muddled up, it doesn't fit an F
Title: Re: 750F2 ...airbox...or pod filters
Post by: sye on July 29, 2018, 02:02:34 PM
That fits an F2?

Saw it but as it only listed Ks I moved on. So much to learn!
Maybe Sye got his links muddled up, it doesn't fit an F

Oops, soz, somehow an F2 became a K2  :o
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 29, 2018, 06:06:11 PM
Mick...that would be great.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 06:49:16 PM
Here you go there are a few scratches but nothing visible when on the bike.
Its not distorted like most the crap on eBay and has all its internals minus the filter itself.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 06:58:40 PM
Here you go there are a few scratches but nothing visible when on the bike.
Its not distorted like most the crap on eBay and has all its internals minus the filter itself.


Is that F1 or F2 box Mick ? Can't remember what they looked like  ;)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:02:35 PM
I thought they were the same.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:08:06 PM
I thought they were the same.

One is a 405 and one is a 392. Maybe another member can confirm  ;)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:11:34 PM
How do I know what's what
mine just has HM 750 F-F on it.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:13:54 PM
How do I know what's what
mine just has HM 750 F-F on it.

Me thinks Haynes 66 has a F2 in bits at the moment, he should be able to confirm  ;)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:21:55 PM
Just found the remains of an early box as well if any ones interested no markings stamped on it and no brackets or bolts 
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:26:38 PM
How early Mick ?


Look what i found after 4 years of searching  ;)


 
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:30:05 PM
Its of my April built 71 k1 its a bit distorted but it does go together with a fight

That was a good find were did you get it?
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:32:06 PM
Its of my April built 71 k1 its a bit distorted but it does go together with a fight

That was a good find were did you get it?

I thought you said early  ;D ;D

A Honda dealer that retired and sold off all is NOS stock  ;D ;D
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:33:47 PM
OK not that early but looks the same if you paint it  :P
Almost if you squint a lot and get punched in one eye
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:37:27 PM
K1 box
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:42:36 PM
Looks the same as a K2 to K6 Box

Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:45:35 PM
It does. Good to see I taught you something  ;D ;D
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 07:52:24 PM
It does. Good to see I taught you something  ;D ;D

You taught me what ? That if you don't fit new O rings, your valve caps will leak  ;D ;D ;D
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 07:56:13 PM
They were new as you found out a certain well known supplier sells the wrong size.
I just didn't think I would have to measure new O rings  ::)
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 29, 2018, 09:53:52 PM
Mick...what would it take to pursuade you to part with that airbox :)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 10:09:46 PM
I presume the later box?
How does £20+postage sound
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 10:16:57 PM
I presume the later box?
How does £20+postage sound

I will take it  ;D ;D ;D Only joking  ;)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 10:18:18 PM
I know its cheep init  ;)
You can have the other one if you like Graham
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 10:21:02 PM
I know its cheep init  ;)
You can have the other one if you like Graham

Have a load of boxes here Mick, cheers for the offer.
I paid twice that, for that impossible to find air filter  :(
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 10:24:38 PM
I can believe that I just paid £35 for a genuine oil filter on my new van just to keep the warranty going  >:(
Then the garage wanted £425 just to change the oil  :o
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on July 29, 2018, 10:45:14 PM
I can believe that I just paid £35 for a genuine oil filter on my new van just to keep the warranty going  >:(
Then the garage wanted £425 just to change the oil  :o

Yep, that is unreal. Was in a bike main dealers and noticed that the price was £140 for a oil change and the labour charge to fit a chain and sprocket kit was £250  :o
Title: Re: 750F2 ...airbox...or pod filters
Post by: Green1 on July 29, 2018, 10:56:15 PM
That is taking the piss some what.
I didn't get the van serviced at the main dealers in the end. As long as a VAT registered garage do the work it keeps its warranty going. My brother did it for £100 the only problem is he had to stamp the book with a Kwikfit stamp.
So I have no chance of being able to sell it now  ;D ;D ;D   
Title: Re: 750F2 ...airbox...or pod filters
Post by: Greebo on July 30, 2018, 10:45:09 AM
My project bike is on the way, but I know it has not got an airbox and had some grotty pod filters which will not be left in place. They don;t look fit to filter air let alone dirt .... but the question is...what's the best route to go.

Originality says airbox, but I have had a brief trawl on E-Bay and not seen any F2 items for sale. Obviously, I would need a set of carb-box rubbers too as well as an element. Are these crafted from rocking horse poop...or just one of those thigns that come up if you look long enough?

She is going to get a light cafe racer makeover, so I could go for pod filters again, but I have had issues with these things in the past. Admittedly it was with CV carbs, which do not mix well with pod filters unless you like an overly rich midrange and lots of popping on the over-run...as well as wet running issues. I understand slide carbs are a bit easier to setup ass they are less reliant on intake pressure to work right. That was with old school K&Ns before the foam 'Ramair' type came out as well. Either way....I won't be looking at the cheap Chinese unbranded ones.

I also have no idea if the jetting is stock...but will be looking at the matter when I pull the carbs apart for a thorough clean and check. Somewhere in the shed lurks an old set of vacuum gauges too, which will need fresh pipes but should work.

If you going café racer style & sorting the internals of the carbs & perhaps upping the jet size, then forget Pod Filters & definately the Stock Airbox...
I have been through all this with my K6 & to get it running well with no missing or flat spots I tried velocity stack & bingo it worked perfect, it now runs like a gold watch....
Although the bike ran reasonable with the K&N Pods it had some missing & baulking at certain Revs which is not good enough. heres the link for the v-stacks & they are a damn site cheaper than the K&N's

https://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-carburetor-parts-polished-aluminum-honda-cb750-velocity-stacks-full-taper-sd-ecb750-pft.html
 
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 30, 2018, 10:54:17 AM
Mick....you got a deal. Drop me a message with the details and I can give you the address etc. Many thanks!

Those bellmouths Look tasty...but I want some kind of filtration. I want to be able to use the bike as everyday transport and I would just worry about grit and dirt getting in.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Greebo on July 30, 2018, 11:08:20 AM
The V-stacks have a mess gauze, but I guess you will have to see how it goes [trial & error] with the airbox or pods which ever you decide on
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 30, 2018, 09:56:22 PM
well..I am going to give the airbox a spin first....but nothing is set in stone.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Greebo on July 31, 2018, 04:51:12 PM
well..I am going to give the airbox a spin first....but nothing is set in stone.

Go for it, but I have to say the Aesthetics of the stock air-box is not very Café Racer.... :o
Title: Re: 750F2 ...airbox...or pod filters
Post by: SumpMagnet on July 31, 2018, 05:02:59 PM
I know what you mean...but in reality...if I do go the bellmouth route, I would still want an airbox at home in case I ever chose to put it back to stock.
Title: Re: 750F2 ...airbox...or pod filters
Post by: Greebo on August 01, 2018, 09:55:29 AM
I know what you mean...but in reality...if I do go the bellmouth route, I would still want an airbox at home in case I ever chose to put it back to stock.

Good luck with it mate...keep us all posted on the results... 8)
Title: Re: 750F2 ...airbox...or pod filters
Post by: Trigger on August 01, 2018, 02:41:10 PM
Why's it listed as a KW4 if it's an early filter?

Depends on how early ! 30 years old. The bike was only in production for a few years and no one copied the air filter, so OEM part only that has not been available for 20 years  ;) Never used on any other model and the model was only sold in 3 counties  :o 
 
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