Author Topic: 400F rebuild (Read 5860 times)

rz350ypvs · « **on:** April 20, 2009, 04:24:40 PM »

I'm new to the forum and I thought I'd start a rebuild thread for my '76 CB400F. I got it a few years ago, but I'm just starting to work on it now.

taymoor · « **Reply #1 on:** April 20, 2009, 07:46:22 PM »

how do the short cut headers w/o mufflers work in combination with the pods? better, worse, excessively loud? Also, did you have to rejet the carbs?

rz350ypvs · « **Reply #2 on:** April 20, 2009, 07:51:22 PM »

It's a lot rougher than it looks in the picture. I am going to strip it down to the frame and restore it. I am going to paint it red... I don't really like the yellow.

I'm working on the engine right now, I took the head off and there is cross hatching in the cylinders, so I'm thinking it was rebuilt and not run very much. I did start it before I took it apart and it ran decently, but I could hear some cam chain rattle.. at least i thought it was. I can't get the cylinder(s) off... anyone have any tips? I'll have some pics to post up later

rz350ypvs · « **Reply #3 on:** April 20, 2009, 07:54:19 PM »

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how do the short cut headers w/o mufflers work in combination with the pods? better, worse, excessively loud? Also, did you have to rejet the carbs?

That is how i got it. It is very loud and runs like crap with that setup. I'm not sure if it could be tuned to run better though.. I would think it would need at least some back pressure though.

DollarBill · « **Reply #4 on:** April 20, 2009, 08:12:49 PM »

Oh man I really want a 400f. It's the bike I was really looking for when I found my 750. One day I will have one..... Good luck with the rebuild!

Soundgarden rocks!

gregk · « **Reply #5 on:** April 21, 2009, 06:42:41 AM »

Looks like a good start. Lots of parts available on e-bay lately. Might want to find a rear brake stay and link rod.
You'll enjoy it!

greg

rz350ypvs · « **Reply #6 on:** April 21, 2009, 08:17:42 AM »

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Good luck with the rebuild!
Soundgarden rocks!

Thanks. Yes they do.

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Looks like a good start. Lots of parts available on e-bay lately. Might want to find a rear brake stay and link rod.
You'll enjoy it!

My dad has a '77, maybe I will just steal parts off it when hes not looking

We were on a ride and it was parked in front of a farm for sale. My dad also has a '73 CB750 that he bought new in '73.

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good luck getting the stock cam chain rattle out of there.

Is it near impossible to totally silence it? The sliders/tensioners that I removed actually looked pretty good.. but it still made noise. Thanks for the tips on removing the cylinder too.

kghost · « **Reply #7 on:** April 21, 2009, 08:20:26 AM »

Hey good luck and have fun.

I did one last year and love the little bike.

Industrial Rat400f Killer · « **Reply #8 on:** April 21, 2009, 08:57:12 AM »

Keep us posted and good luck.

rz350ypvs · « **Reply #9 on:** June 10, 2009, 06:50:14 PM »

I have been slowly working on the bike. I pulled the engine and took it all apart to paint it and replace the cam chain. I got my oil seal and gasket kit from Reproduction Decals. I ended up painting the engine with duplicolor engine enamel. I still need to finish assembly.

Joel · « **Reply #10 on:** June 10, 2009, 06:57:54 PM »

That's a great lookin' engine.

I've got a 400 as well but mine has yellowed, peeling clear coat and a layer of black paint on the cylinder fins from the previous owner.

I tightened my cam chain tensioner by pushing down on the plunger with a screwdriver. I think the springs on mine aren't doing the job anymore. Mine still has a rattle to it when running. I believe I was told that out of sync carburetors can give the engine a rattle sound as well. Also, be sure the tappet clearances are correct and that should help.

kghost · « **Reply #11 on:** June 10, 2009, 07:25:54 PM »

Engines looking clean.

YOu think about polishing those sidecovers?

DollarBill......your in Kville?

You can come down and sample mine

bigtuna · « **Reply #12 on:** June 10, 2009, 09:07:05 PM »

dude that effin engine is lookin awesome, carry on more pics please. thanks

rz350ypvs · « **Reply #13 on:** June 11, 2009, 11:58:44 AM »

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I tightened my cam chain tensioner by pushing down on the plunger with a screwdriver. I think the springs on mine aren't doing the job anymore. Mine still has a rattle to it when running. I believe I was told that out of sync carburetors can give the engine a rattle sound as well. Also, be sure the tappet clearances are correct and that should help.

Thanks for the tips. My dad has a '77 that has the rattle to it also.

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YOu think about polishing those sidecovers?

I did think about it. I have a 350F sprocket cover that I will probably polish and see how it looks on the motor ( I think it fits the 400). The little triangular piece that bolts on the clutch cover is polished. That alone may give it a little more contrast.

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dude that effin engine is lookin awesome, carry on more pics please. thanks

Thanks! I will definitely be posting more pics as I progress.

rz350ypvs · « **Reply #14 on:** June 16, 2010, 06:28:08 PM »

Very slow Progress...

Stormer · « **Reply #15 on:** June 17, 2010, 02:09:13 PM »

Nice bike and keep going my friend!
Very nice to see another 400F rescued and going back on the road.

rz350ypvs · « **Reply #16 on:** November 21, 2010, 09:09:02 AM »

^ Thanks.

Tank still needs clear.

gerryw · « **Reply #17 on:** November 23, 2010, 03:42:33 PM »

Looks great, keep the info (and pic's)coming

gerry (oshawa)

rz350ypvs · « **Reply #18 on:** December 04, 2010, 11:22:02 AM »

EkiF · « **Reply #19 on:** December 04, 2010, 01:37:44 PM »

You're close! Very nice job...
What exhaust you are going to use?

rz350ypvs · « **Reply #20 on:** December 05, 2010, 10:42:49 AM »

Thanks. My dad has a really nice stock exhaust from his '77 that he is donating to me. I will probably buy an aftermarket header/pipe for him.

supersports400 · « **Reply #21 on:** December 05, 2010, 11:38:44 AM »

Hi,

In despite of the fast looks of the CB400F, the RZ350 ypvs is a lot faster.
I have both, lucky me, a CB400f '75 and a RD350YPVS '89.

For the sound I like the CB400f @ 10000 rpm, the handling of both bikes differ a lot.

btw, the RZ (RD in Europe) is safer to ride because of it's front brake.

It's good that you're restoring the CB400f and put some money in it.
maybe you will never get the money back, put it will pay you back in pure pleasure,

Jensen

rz350ypvs · « **Reply #22 on:** December 22, 2010, 06:26:56 PM »

^ The RZ350 will destroy the 400F in every way.. My dad has a '77. My RZ can outrun my dad's CB750 pretty easily too. But, they are totally different bikes and I like them all.

Got a little more work done.

rz350ypvs · « **Reply #23 on:** December 31, 2010, 12:27:06 PM »

HalfFastMoto · « **Reply #24 on:** December 31, 2010, 12:32:32 PM »

Looking real nice. You're doing a great job!

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Author Topic: 400F rebuild (Read 5860 times)

taymoor

bigtuna