Honda-SOHC

Ah! OK...  I'm working/hoping to get adequate performance from the OEM but am wanting alternatives in case I can't get sufficient performance. 

FWIW, my CB400 is going to be my normal rider, not a weekend or "special event" bike.  Therefore, as much as I would like to retain the OEM gear/appearance, It's less important than being able to STOP.

The not-returning-to-idle seems to have been caused by the high-idle stop being out of adjustment!  The manual calls for .012"/.3mm clearance and there was none. It was holding the throttle slightly open which got worse as the engine heated up.  I adjusted the clearance per the Honda specs and, once the engine was good and warm - which takes more time than I would have thought - I adjusted the idle stop screw to 1200 RPM.  From that point on the engine returned to that RPM when the twist grip was returned to the idle position.  But the idle is a bit rough and the engine still bogs when opening the throttle quickly. 

further re the bog - I haven't found any info in the Honda service manual or a Clymers that mentions changing the position of the needle to adjust the mixture in the range the needle controls.  I'm NOT saying there isn't any info, just that I haven't found it.  I'd think that raising the needle might reduce/eliminate the bog.   Any thoughts/experience re this?

I'm definitely going to pull the carbs/check/adjust everything out but we're going out of town on Tuesday for a week so that will wait until we return. 

Thanks guys for offers to assist: I really appreciate it!

 I did a bit of checking this morning.  The timing per strobe is dead on and the advance mechanism is working correctly.  I futzed around a bit with the airscrews/idle speed adjustment and managed to make a bit of improvement.  It didn't hang up at high RPM when revved up/back to idle but since it was raining I didn't care to go out to see how it acted on the road.  If it's dry tomorrow I'll do that and, if no change, pull the tank/examine the various linkage/cable settings/adjustments.  I'll check the valve clearances as well.

Again, thanks!

My new to me CB400 does the "won't return to idle" thing.  I noticed this the first time I rode it.  It will idle OK after starting/warmed up but when out riding, it will hang at 2500+ RPM.  Blipping the throttle doesn't help.  I have found extensive posts here re that issue so I'm going work my way through the suggestions/opinions.

 I had a Norton Commando that did the same thing and it turned out the mechanical advance weights were sticking in the advanced position when the throttle was reduced to the idle position.  So I'll check it with a strobe light and verify that the weights are functioning properly.

I don't know if the carbs were worked on previously.  There are receipts and mechanic's notes for an engine rebuild but no mention of carbs and no parts receipts for carb parts.  So I need to at least check them for proper linkage adjustment, etc.  Also will check sync though when it is idling at 1200 RPM after start up, it runs smoothly so I'm thinking the sync is reasonably close.  Popping the throttle open when running down the road at say, 3000 RPM will result in a major bog; opening the throttle less aggressively it pulls well.  I should go through the carbs I guess but if I can sort out the not-returning-to idle with external adjustments, I'll delay that..

Also noted a seep from the oil pan gasket.  I checked and all bolts were all adequately/evenly tight so seems like a new gasket is in order. 

A problem I have for mechanic work is that our bikes and car are in an apartment building multi-car garage.  So there is no workbench or electricity and everything I do has to be contained within the parking slot which also contains our MiniCooper and two other motorcycles.  Obviously, things like the carbs can be removed and worked on indoors but much care has to be taken with any operation that might end up with oil or fuel being spilled on the community garage floor.  Replacing that oil pan gasket might be tricky under the circumstances...

Just got back from checking things out and then going for a quick ride.  Brake caliper works properly - piston moves in/out smoothly, fixed-pad swingarm was correctly adjusted, I hadn't looked but turns out the brake lines are new and the pads appear to be as well.  Don't know what brand they are.

Interestingly, the brakes seemed to improve a bit after some repeated heavy braking from around 85 MPH (indicated).  After doing that, they seemed to react a LITTLE bit better.  Or maybe I'm already getting used to them.    Definitely a fun bike to ride and I was pleasantly  surprised with the engine response as the tach passes 6k RPM, heading for red line!   

Hi all!  A few days ago I acquired a '76 CB400 four, took it out for my first ride.  Fun little bike...except for the front brake which I found totally inadequate. 

Subsequently I found this site and read all the posts I could find, seeing much re the "wooden" feel and generally mediocre stopping power.   On my bike the lever is firm, no sponginess.  It just doesn't apply any real stopping power, regardless of how much  pressure I apply on the lever.  The bike has 13,276 miles and is in excellent, well serviced condition with a lot of receipts for work done, to include replacing the cam chain tensioner as well as other engine "freshening."  The only modification to the bike from stock is an electronic ignition.

I contacted a well-known vintage Honda spares supplier, asking them for recommendations to improve the brake.  I was surprised that rather than trying to sell me a new rotor, new lines, new master cylinder, etc), the response was, "New pads may help but the brakes on a CB400F were never great." 

The front brake feels pretty much the same as the stock front brake did on my '73 Norton Commando - maybe even a bit worse - before I replaced the OEM master cylinder with a Brembo from Colorado Norton Works.  That, a set of braided SS lines, and some more aggressive pads in the OEM caliper transformed that brake.  It is now acts and feels like modern brakes.  Of course the down side is that the master cylinder does not look anything like the OEM version.

My general thought is to go down a similar path though from searching and the suppliers response, it doesn't sound like anything is going to make the sort of transformation I am looking for.

So...I'm wondering if anyone has done something similar (different master cylinder) or found some tricks/tweaks/mods to the OEM front brake that I have not managed to find via the search function.  Also, what are the most aggressive brake pads for street riding, including aggressive riding on narrow, twisty roads?  I don't care about rotor wear.  If I had to replace a rotor every 10,000 miles to get good brakes, that's fine.

Thanks!