Author Topic: Hi from WA, CB400F rebuild  (Read 2081 times)

Offline AndyPerthWA

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Hi from WA, CB400F rebuild
« on: March 09, 2022, 12:05:54 PM »
Hi everyone, I have just rebuilt my 400-Four which I purchased in Sydney in 1983. She has been across the Nullabor Plain 3 times and now resides in Perth, Western Australia.
having trouble setting up rebuilt carbs, they are leaking out the overflows.
Cheers
Andy

Offline K2-K6

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Re: Hi from WA, CB400F rebuild
« Reply #1 on: March 09, 2022, 12:16:04 PM »
Welcome to the forum, posh garage there  ;D

The carbs can take quite a bit of detailed careful work to get them comfortably working certainly.

Bike looks really good.

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #2 on: March 09, 2022, 12:40:37 PM »
Thanks K2-K6, it's frustrating trying to get her running well without overflowing fuel, I've had the carbs on and off about 20 times!

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Hi from WA, CB400F rebuild
« Reply #3 on: March 09, 2022, 01:06:05 PM »
Welcome to the forum. We have a few 400/4 owners in Perth hopefully one will pop up soon and say Hi.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline K2-K6

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Re: Hi from WA, CB400F rebuild
« Reply #4 on: March 09, 2022, 02:08:57 PM »
Thanks K2-K6, it's frustrating trying to get her running well without overflowing fuel, I've had the carbs on and off about 20 times!

Have you tried polishing the inlet valve seats of the float valve shutoff?  Something like a bbq wood skewer with t-cut (just a gentle abrasive polish) to make sure of competent sealing surface may assist reliable close off.

Either twizzle it with your hands or spin slowly in a drill to give the tapered seat a clean and smooth surface.

Drives you nuts when they keep letting fuel out doesn't it. Seems so simple but fundamental to running well.

Offline philward

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Re: Hi from WA, CB400F rebuild
« Reply #5 on: March 09, 2022, 09:02:17 PM »
Welcome to the forum. Hope you get the overflowing sorted. Plus 1 on K2-K6's suggestion.
Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Honda CB350K0 (1969)
Kawasaki ZZR1100D3 (1995)
Kawasaki ZZR250 (1990) Project (Going on eBay ASAP)

Offline Laverda Dave

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Re: Hi from WA, CB400F rebuild
« Reply #6 on: March 10, 2022, 09:24:07 AM »
Welcome to the 400/4 forum :). As anybody will tell you, the yellow ones were the fastest!
I agree with Nigel about the carbs, they are a real pain to set up to avoid leaks. I have found along with many others on the forum that it is best to use the old brassware if you can and cleaned in an ultrasonic bath along with the rest of the carb parts. I have used Keyster carb kits twice and could not stop the leaks so reused the originals and hey presto, no more leaks.
Did you bench sinc the carbs before putting the carb bank back on the bike, worthwhile doing and saves a whole lot of aggro if you do.
Type in 'carbs' to the search box and you'll get a few links to threads all mentioning the same subject.
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #7 on: March 10, 2022, 10:08:13 AM »
Welcome to the forum. We have a few 400/4 owners in Perth hopefully one will pop up soon and say Hi.
Thanks for the welcome Nurse Julie, I will view your posts.

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #8 on: March 10, 2022, 10:10:52 AM »
Welcome to the 400/4 forum :). As anybody will tell you, the yellow ones were the fastest!
I agree with Nigel about the carbs, they are a real pain to set up to avoid leaks. I have found along with many others on the forum that it is best to use the old brassware if you can and cleaned in an ultrasonic bath along with the rest of the carb parts. I have used Keyster carb kits twice and could not stop the leaks so reused the originals and hey presto, no more leaks.
Did you bench sinc the carbs before putting the carb bank back on the bike, worthwhile doing and saves a whole lot of aggro if you do.
Type in 'carbs' to the search box and you'll get a few links to threads all mentioning the same subject.
Thanks for the welcome Laverda Dave, yellow is great though mine was red originally and spent most of its life black!
Thanks for the advice, I may reinstall the original jets but they are terribly gummed up

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #9 on: March 10, 2022, 10:11:52 AM »
Thanks K2-K6, it's frustrating trying to get her running well without overflowing fuel, I've had the carbs on and off about 20 times!

Have you tried polishing the inlet valve seats of the float valve shutoff?  Something like a bbq wood skewer with t-cut (just a gentle abrasive polish) to make sure of competent sealing surface may assist reliable close off.

Either twizzle it with your hands or spin slowly in a drill to give the tapered seat a clean and smooth surface.

Thanks K2-K6, I'll give that a go next time the carbs are off!

Drives you nuts when they keep letting fuel out doesn't it. Seems so simple but fundamental to running well.

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #10 on: March 10, 2022, 10:12:51 AM »
Welcome to the forum. Hope you get the overflowing sorted. Plus 1 on K2-K6's suggestion.
Thanks for the welcome Phil, and the recommendation

Offline McCabe-Thiele (Ted)

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Re: Hi from WA, CB400F rebuild
« Reply #11 on: March 10, 2022, 10:18:34 AM »

Thanks for the welcome Laverda Dave, yellow is great though mine was red originally and spent most of its life black!
Thanks for the advice, I may reinstall the original jets but they are terribly gummed up
[/quote]

I have found that overnight soaking in petrol & acetone make good solvents on carb parts.
Honda CB500 K1 (new pit dug out ready)
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #12 on: March 10, 2022, 12:09:56 PM »
Thanks Ted, I'll give them a soak and try to clean them up!

Offline Laverda Dave

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Re: Hi from WA, CB400F rebuild
« Reply #13 on: March 10, 2022, 12:17:03 PM »
It wasn't so much the jets but the fuel cut off valve that gives the problems of leaking carbs. The new valves don't appear to seal properly hence Nigel's comment about using T-cut. I tried it but it didn't work so I cleaned up the old valves and it cured it.
Float height is also critical.
1976 Honda 400/4
1977 Rickman Honda CR750
1999 Honda VFR 800FX
1955 750 Dresda Triton
1978 Moto Morini 350 Sport
1978 Honda CB400/4 'Rat' bike
1982 Laverda 120 Jota

Offline AndyPerthWA

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Re: Hi from WA, CB400F rebuild
« Reply #14 on: March 10, 2022, 09:21:00 PM »
Thanks Dave, I’ll soak all the old brassware in petrol or acetone and try to scrub them back into shape

 

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