350F carbs on a 400F... big bored?

ronnie

ronnie

Calm down and sail on
I'm in the process of boring my recently purchased 400f case for my 350f bike.. I have the old 350f carbs, I know they would have worked for the stock 400f engine with bigger jets. The question is will they work for a 400f that has been bored to 466cc? Or am I going to have to get the carbs bored out or should i just consider the possiblity of new carbs?
 
Correct!

I need to do the same for my 466 kit. Let me know what jetting you land on and where you are able to get the jets.
 
They are the same carb, but correct, the jetting will need changed. On my he.computer I have a pdf saved with some jetting suggestions for the 466 kit, I'll try to dig them up.

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You might want to look for a bigger rack of carbs. The stockers were marginal for 350cc, totally bodge for 400cc and for 466cc, nice if you spend your life below 5000 rpm.
I think the stockers can be bored out a little bit but not much.
I had a set of GS550 carbs for my CB350/4 and I was even going to get them bored out before installing them, but solved the problem when some guy bought the 350 from me at my asking price before I put the big carbs on.
It's been awhile and I'm hazy on the details of the swap, but I think the carb spacing on the GS550 rack was almost perfect for my 350...
Just my 2 cents.
Pat Cowan.
 
Neevo, I'll do my best when I get there.. I'm a good few months away from that stage. I'm just getting info so I'll know what to save up for next.

Kanticoy: If you could find that file, that would be much appreciated.. Even for my stock 350f it would be helpful.

Pat, that is what i was thinking. I heard the 350f carbs were the best for the 350f much less the 400f.. I had a inclination to get new carbs. And if i did keep the stocks and got them bored I would almost spend the same amount of money sending the off to get bored so I might have well just gotten new carbs that actually worked..

In due time we shall see..
 
pacomotorstuff said:
You might want to look for a bigger rack of carbs. The stockers were marginal for 350cc, totally bodge for 400cc and for 466cc, nice if you spend your life below 5000 rpm.
I think the stockers can be bored out a little bit but not much.
I had a set of GS550 carbs for my CB350/4 and I was even going to get them bored out before installing them, but solved the problem when some guy bought the 350 from me at my asking price before I put the big carbs on.
It's been awhile and I'm hazy on the details of the swap, but I think the carb spacing on the GS550 rack was almost perfect for my 350...
Just my 2 cents.
Pat Cowan.
Click to expand...

Anyone got the measurements for the GS carbs? Specifically the outlet spacing and carb outlet diameter.

GS carbs could be a suitable alternative to boring the originals out.
 
bottle neck in the sohc4s is the head.
spend the money to have the head ported and then buy CR26s
 
Re: Re: 350F carbs on a 400F... big bored?

surffly said:
bottle neck in the sohc4s is the head.
spend the money to have the head ported and then buy CR26s
Click to expand...

That's what I did. ;)

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Surfly, I was thinking about it... Might as well if I'm doing all the other stuff, right? How much are CR's usually run?


Kanticoy, do you remember how much it cost to port you head?
 
It was around $250 for the port job, the CR carbs are the killer. They retail for around $900. Rick Denoon does carb boring though, check his website, I want to say he charges around $200 for the work.

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$250 for port work? where?

join the sohc4 site and talk to mike in boston. he will get you squared away on what head work you will want and need.

$1000 in head work on a cb750 is good for more power then that money spent on alot of other stuff
 
I talked to Mike but found a better deal through a good friend. I'll talk to him about offering up the same price to you guys. And yes, he knows what he is doing, complete with flow jet work.

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Oh crap, 1000$... yikes thats way out of my price, especially if I still have to buy new valves, springs, etc... If you could get it done for 200 would be way way better.. Plus, the new carbs.. I feel like im working on a boat.. (Bring. Out. Another. Thousand)
 
well a grand is high and thats for valves, guides, springs and retainers.
But still it adds up fast.

making the head flow better will probably give better gains then the pistons.
Or just help make the most out of the parts

Motors are a package deal. no one thing will yield gains without work some place else
 
Yea, I realized that.. Maybe I'll just do the pistons and do the head work later on.. especially if I'm getting carbs. The head job can be done easier later on than the pistons. I'm pretty sure I saw somewhere you can remove the heads on these without removing the whole engine.. I could be wrong. I just want to get home and get this ball rolling!
 
Im not sure on the 350f
I pulled the motor on the one i built
On the 750 you can not pull the head
 
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