Topic: CB400F -- Things to Look For

[nomadwarmachine]

Hello, all -- longtime SOHC4 owner and wrencher looking to get a CB400F and wanted to know if there was anything "peculiar" to be looking for in these machines apart from the usual bearings, bushings, brakes litany that we all get into when we are looking to purchase. I've restored a couple of CB750s and a CB450K7 so I am pretty used to the CB platform, but I have not torn into the middleweight 4s before.  Googling around I found a lot of talk about loose camchains, a common problem with the twins, but this was the first I had heard of a camchain problem with the 4s.  I am curious if anybody on the board has actually thrown one.  I checked out the tightening mechanism and it looks like some Rube Goldberg contraption (why take a simple non-functional mechanism and complicate it?)   

If anybody has had any major problems with these engines, or has any advice on what to look for viz. the engine, please let me know.  Again, everything else looks like standard CB-ware to me.  Thanks everybody!

[Uncle Ernie]

Mr Machine,  things to look for which are basically the same for all SOHC4s except more so; the cam chain can be a buggared fast because very few owners paid attention to them until they made more noise than the engine itself.  The head gaskets seep soon.   The carbs get super *%#*d up real fast just sitting. The best thing you can do for them is make them write bad checks and turn them out in the rain. Spank them. They'll love you for it. Make them sit in a corner, and you'll be sorry.

[heffay]

uncie ern~ a toast!  to the 400f gods.   

[oldbiker]

I would suggest that almost all of this model can be taken care of BUT The exhaust system is expensive to replace and good chrome rear mudguards (fenders) are very hard to find.

[Gordon]

Uncle Ernie, you're making me miss my 400F! 

[Uncle Ernie]

Gordon, there are a few bikes that I've had and sold and had to have again. Time has taught me that there a some bikes I seem unable to live without; this is my 3rd and last CB400F. The only way it will leave this house is when my wife sells it to pay for my bonfire. I have new Honda needles/seats to install, and I'm sending my seat to Sargent. The hell with the head gaskets- at least the jugs won't rust. It's just too classic, too good looking, too much fun. The older I get, the more I like smaller bikes with more emphasis on handling than pure horsepower. 

[Barrett99]

Check the frame on the backside of the kickstand weld.  These frames have a tendency to develop a crack in that area.  If the bike seems to lean over farther on the side stand than it should that could be an indicator.  The first 400 I got after my 20 year hiatus had that problem and I've since learned that is somewhat common to the model.   I've also read on this forum that the upper triple tree is susceptible to cracking around the fork leg clamp
bolt.

[nomadwarmachine]

Excellent advice all around, thank you!  I will pay special attention to the triple trees and the frame.  I am looking at a couple of bikes this weekend, one with 12K miles and one with twice that.  Both are priced around $1500; I am thinking the lower-mileage model is the way to go, though my CB750K2 has 41K and is ready for another trip around the country, so there is no question of longevity when it comes to these SOHC/4 motors.  The prices seem to be reasonable, from what I have seen original equipment, non-concourse models sell for.  Something came up on Craigslist a few weeks ago for $750 but it looked like a beater, and I have had my fill of those.     Will let you know how it turns out!

[Tim2005]

Hiya, just a few other common things I'd suggest you check out... rust in seat base & front lower corners of fuel tank, mileometers which don't work, camchain tensioner adjusting bolt stripped or broken off (very common & a PITA), excessive smoking from breather when hot (top rings gone), broken kickstart lever, 6th gear gone, cracked sidepanels (esp. r/h), cracked front indicator mounting tube. Otherwise, they're a pretty strong little bike, they like to be serviced regularly (oil change, timing & camchain tension every 1500) & I like to think they need to be ridden hard! Keep the revs in the 6-8500 range & they're a lot of fun. 


Cheers

[jotor]

Check the frame on the backside of the kickstand weld.  These frames have a tendency to develop a crack in that area.

....and rust.  I've seen a few with the frame rail rusted completely out in that area.  Seems water gets in from above.  If they're good, I pour Rustoleum in there.