Topic: Too much power

[camelman]

Well, my 400f literally has too much power for the stock clutch.  I bored it out to 466 and had Rick Denoon bore the carbs out for me.  Once I hit 7k, the clutch slips.  I checked the clutch spring lengths and the clutch discs.  The springs are much longer than the service limit by a couple tenths of an inch, and the clutch discs are much thicker than the service limit by 0.07" or so.  What can I do to get more grip out of the clutch?  I really don't want to install stiffer springs since the clutch is annoying to pull already.

I was thinking about some spacers underneath the springs, but other ideas, or info on how thick the spacers should be, is appreciated.

By the way, if I had the stock front sprocket on the bike instead of the extra two tooth one I had laying around, then this thing would definitely lift the front wheel in first gear just with engine power!

Thanks,
Camelman

[MoMo]

Camelman,  are the steel discs nice and clean and flat? Did you deglaze them is what I'm asking?  Are the fiber ones original?  Even if they are within service limits they could be hard and consequently slipping.  New fiber plates are still available from Honda, for a mere 12 each ...Larry

[camelman]

Larry,

Good point.  I imagine they are original.  The steel plates looked clean and unglazed (probably from the clutch slipping and cleaning them off).  Is it common for the clutches to go bad with age?  This is for a buddy of mine, and he is fine with paying for it, so $12 each sounds good to me.  ;-)

Camelman

[MoMo]

Camelman,

I have resurrected at least 7 CB400 fours in the past 3 years and none had a clutch problem, actually I never even pulled the clutch on any of the bikes even though all had been sitting for years. None slipped but none were 466 either.  www.mrcycles.com has the plates for 11 each but I would try taking the clutch apart and sanding every plate with fine emery paper glued to a flat surface.  In the past I salvaged a few clutch packs. I had a thick piece of tempered glass to which I glued a sheet of fine emery paper and then worked the plates in a circular manner. I have a new set of fiber plates and an entire extra clutch pack if you need anything....Larry

[dave500]

if you have a little hand held sandblaster do the steels with it,ive used white washed silica sand on them and it improves bite and smooths the take up.

[jessezm]

camelman--
  I've had slippage on my 466-kitted 400f as well.  Usually it's when I'm hard on the throttle headed uphill.   The bike only has 6000 total miles on it so I imagine the clutch is original.  I also am getting some hard shifting when the bike heats up now, too, so I was suspecting warped clutch plates or slightly grooved basket.  I have yet to take things apart though.  I'll be following to see what works for you.  I feel stupid for asking, but since I haven't seen it said here yet, do you have the clutch properly adjusted and the motor and the handlebars?

[jessezm]

And a little off topic, but can you tell me your experience with the carb-boring?  are you using pods or stock filter?  are your head pipes stock or aftermarket?  stock cam, or different?   Thanks!

[camelman]

It is starting to look like stiffer springs or possibly a Barnett clutch.  I was hoping not to have to do that, but I definitely got the whole thing adjusted correctly, so I need to find a way to hold the power now.

I'm running stock everything except for a Dyna ignition, 466 kit and the bored carbs.  I have not ridden a 466 without bored carbs, but this sucker is fast! Carb tuning has not been bad, although it is sluggish below 3k rpm and it has a dead spot about 1/8 throttle.  I think that is just tuning issues though because I don't have those problems when it is cold.  I've settled with stock everything except for 90 mains.  The low end issues just appear to be too much fuel through the mixture screw.

camelman

[754]

Blasting the plate should help. Also look at the edges, should be one rounded and one sharper..from stampimg..orient all the same way.
 Get springs and Barnetts plates.. yeah it wont be as smooth as stock, but after building a hotrod motor, you may as well be able to reap all the new power..
 If you want stock behavior..leave it stock..

[camelman]

Okay, my first trial will be with cleaning everything up and sanding or blasting as recommended.  I will also put in a washer beneath the springs.  If that does not work, then I'll try a barnett clutch, or stiffer springs.

[ttr400]

I suspect that your clutch plates are worn. one thing I do if using old steel plates is beadblast them. Yes the oem plates with Barnet springs works well.
I also use the barnet plates,fibre's and springs in some motors, It's a bit grabby but works well.
One other thing is the std Honda clutch can handle more HP than you could ever make.
What sprocket sizes are you running?

I have found this quote from Pops Yoshimura to be right on the money.

Gearing: when fitting the 458cc kit many customers raise the overall gearing, don't! Honda have overgeared the stock CB400F to prevent owners over-revving on freeways,autobahns etc, and the stock motor will rarely better 10K rpm in top gear under normal operating conditions. With the 458cc kit, ported head, cam etc peak power is developed at 11-11500 rpm and the engine cannot achieve these revs on the high stock gear. So we reccommend fitting a gearbox sprocket with a one tooth less than stock: this also gives improved acceleration right up to maximum speed whilst making sixth gear more usable.

Kevin

[camelman]

Kevin, that's the kind of practical knowledge I'm looking for. I have an 18 tooth front and the stock tooth rear sprocket. I have a Barnett dealer in town who can get me the springs. Should I get new Honda discs too?  I'd prefer not to have a grabby clutch since this will see in town use.

The 18 tooth front is just a stand in for right now. How many teeth do you recommend?

[754]

Do you have a hot cam? If you do you will find your most comfortable power in the mid to uppper revs.
 With a motor like that I find I can accelerate quicker by grabbing some revs and slipping the clutch in some cases, rather than gear down I am talking say at 20mph in 2nd gear)..
same thing off  the line.
 I slip the clutch a lot, never had stock plates hold up doing that..

[ttr400]

Stock CB400F gearing is 17-38 I would use a 16T front. this motor will rev around 500 rpm more than stock in top gear. The 400's like to be revved so acceleration will be great with the 466 kit, and you will still be able to pull higher the stock top speed.
If the steels are usable (not warped) bead blast them and re-use with OEM fibre's and barnett springs. should be good.

Kevin

[camelman]

Thanks for the info!  Is sandblasting acceptable, or do I need to use bead media?

Camelman

[dave500]

i use white washed silica sand from the local garden supply yard,its used in plastering etc,two bucks gets me a 20 litre paint bucket full.