Author Topic: How to tell the difference between a 350F and 400F head?  (Read 728 times)

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Offline magconpres

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How to tell the difference between a 350F and 400F head?
« on: April 26, 2010, 10:00:32 PM »
I have a head that I think is for a 400F, but could be for a 340F.  No numbers stamped on it.
How can I tell the difference?
1975 CB400F, stock,  on the road
1975 CB400F, ran when I parked it. Cafe Racer bound
1986 TLR200 commuter and trail bike when with the kids...90MPG!
1986 TLR200, Vintage Trials build up coming
1986 TLR200, Not sure what to do with this one...Vintage Trials Super Moto?
2004 GasGas 300EC...my enduro racer
2004 Sherco 290...Trials bike
2004 CRF70... Son's ride
2006 PW50 ... Daughter's ride
1982 XL500R (04 XR250 front end)...my DS bike.

Offline MaaseyRacer

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Re: How to tell the difference between a 350F and 400F head?
« Reply #1 on: April 27, 2010, 10:11:32 AM »
On the front it should be stamped 408cc or 347cc.
1961 CB72
1961 CB77
1962 CB77
1962 CB77
1965 CB160
1970 Triumph Bonneville
1972 Honda CB450
1975 Norton Commando

Offline ttr400

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Re: How to tell the difference between a 350F and 400F head?
« Reply #2 on: April 27, 2010, 10:28:43 AM »
CB400F has 4 full fins up to the spark plug hole, 350F has 3. 350F has vertical fins at the front. 350F has a extra fixing at the back of the head to bolt to the block, M6 screw. 400F does not have any.

Bore size is only on the block not the cyl head.

Kevin
CB400F- 492 Yoshi Racer.
Cb400F- 466 Yoshi Cafe.
CR750 D Mann Replica.
VFR750R- RC30 - 1988.
www.ttr400.com

Offline magconpres

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Re: How to tell the difference between a 350F and 400F head?
« Reply #3 on: April 27, 2010, 09:34:29 PM »
Thanks.
So the head I got is a CB400, but the carb insulators bolted to aren't for a CB400.  They are very shallow and domed instead of looking like tubes.  I'llpost a pic later and see if anyone can identify them.
1975 CB400F, stock,  on the road
1975 CB400F, ran when I parked it. Cafe Racer bound
1986 TLR200 commuter and trail bike when with the kids...90MPG!
1986 TLR200, Vintage Trials build up coming
1986 TLR200, Not sure what to do with this one...Vintage Trials Super Moto?
2004 GasGas 300EC...my enduro racer
2004 Sherco 290...Trials bike
2004 CRF70... Son's ride
2006 PW50 ... Daughter's ride
1982 XL500R (04 XR250 front end)...my DS bike.

Offline Kevin400F

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Re: How to tell the difference between a 350F and 400F head?
« Reply #4 on: April 28, 2010, 03:22:18 AM »
The "shallow, domed" carb insulator description sounds like you might still have the base of OEM insulator but the rubber tube has disbonded and come off.

Offline magconpres

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Re: How to tell the difference between a 350F and 400F head?
« Reply #5 on: April 29, 2010, 07:53:02 AM »
Kevin,
You're probably right.  I didn't realize the insulators where constructed from two pieces.
I'll post a pic once I get batteries for my camera.
1975 CB400F, stock,  on the road
1975 CB400F, ran when I parked it. Cafe Racer bound
1986 TLR200 commuter and trail bike when with the kids...90MPG!
1986 TLR200, Vintage Trials build up coming
1986 TLR200, Not sure what to do with this one...Vintage Trials Super Moto?
2004 GasGas 300EC...my enduro racer
2004 Sherco 290...Trials bike
2004 CRF70... Son's ride
2006 PW50 ... Daughter's ride
1982 XL500R (04 XR250 front end)...my DS bike.