Topic: CB400f big bore kit on Ebay?

[jessezm]

Does anyone know anything about the maker or seller of this kit, and whether it would pass muster for a street bike?   

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=130367595209

I'm in the middle of a cafe build and wasn't planning any major motor work, but I already have a gasket set and this seems like a pretty cheap upgrade...  Plus my top end could probably use a freshen-up anyhow.  I only rode the bike once before tear-down and it pulled strong but flattened completely at 60mph, though I think that was the front brake dragging (I had to unsieze it to test ride through the neighborhood...), or carbs.  On inspection, there is quite a bit of build-up in the exhaust ports, and the owner says he never had the bike over 8000rpm, so that makes some sense.  Also, there is lots of cam chain noise at idle, and I'm not sure yet of the tensioner is good or not (owner never adjusted cam chain, and bike has 5,800 original miles).  So I guess what I'm saying is, Should I rebuild the top end, or just leave it alone for now?

[Bodi]

The kit looks OK to me.
Be aware that this kit means you will need a rare and expensive special head gasket to open the top end again: you should do a full valve job, I would recommend guides be replaced (and use eight with seals, stock has seals only on intake). This will hopefully avoid a head removal real soon.
I recommend (strongly!) that you have the barrel section and head machined true flat as part of the job. The 400F is notorious for oil leaks at the oil gallery risers on each end of the barrels/head joint. Having the parts flat really helps avoid this frustrating leak and the head gasket eating repair attempts. Also, take great care with the oil orifice restrictor seals and use a bit of sealant around them.
This kit works best with a mildish cam upgrade for the street, webcam or a few others will supply this.
You will need to rejet as well, so do as much other "stuff" as you can at once - header/muffler and intake changes like pods or a revamped filter box (to use more available air filters). The rejetting process is a time consuming and boring process, do it as few times as possible!
These kits usually sell around $500.00 so don't expect the current price is realistic, there are a bunch of 400F owners waiting for the snipefest near closing time. And you just pointed this auction out to a lot of them (err.. us). Check out pricing for retail kits so you don't bid more than this would cost you elsewhere.

[jessezm]

Cool, thanks for the advice!  Now I'm really wondering if I want to spend another 800-1000 on the bike or wait a year or two.  Plus that's a really good point about the gasket...  But on the other had, I'd hate to have done all this great body and chassis work and have the engine performing like snot...  I do have K&N pods and no airbox, a new assortment of jets, plus I've changed to electronic ignition and dyna coils, plus a MAC muffler, which I may further modify (it sure is ugly!).  Decisions, decisions...

[jessezm]

Well, I did end up purchasing the big-bore kit for just $110 (figured hey, it's worth at least that...).

Here's what I decided:  I'm going to stick with the motor I've got at the moment in order to get my project on the road (besides, it may run just fine).  However, I just bought a set of heads with 8k miles off Ebay for $20 (sorry to whoever I outbid at the last second...), and now I'm in the market for a used cylinder for a decent price as well.  So I'm going to take my time and rebuild a second top end the right way, which I'll bolt on when ready.

This way I can take my time cleaning up this second set of heads, do a valve job, and bore the cylinders while I send the cam out to Web or megacycle or somebody.  Hell, maybe I'll try to pick up an extra rack of carbs and send em out to Rick Denoon for boring as well!  I figure I can safely leave the bottom end alone.

Does this sound like a decent plan?  Hopefully the cam chain tensioner is still working, as there was a lot of cam noise at idle when I started the bike up that once.

[hosspowerinc]

Did you get the piston kit yet? Ive sent the seller a few questions but wondered what luck you had and if you installed them yet.

[jessezm]

The kit does seem to be very good quality, and it is installed now.  Only problem with the install is that the boring takes off all of the taper at the bottom of the cylinder, and fitting the pistons in was a major challenge.  I broke a ring on my first try, but I think that's more from this being the first time I've ever put a top-end back together. 

I'm waiting on my tank and seat still and haven't dome the wiring yet so unfortunately the true test is yet to come.  Truthfully, even though I've also installed a Webcam as well, I probably won't realize a huge benefit until the bike breathes a little better.  But I cannot bring myself to replace the stock headers, which is the limiting factor.  If I ever do, I will have my carbs bored by Rick Denoon as well and then I expect I will notice a real difference.

[MRieck]

The kit does seem to be very good quality, and it is installed now.  Only problem with the install is that the boring takes off all of the taper at the bottom of the cylinder, and fitting the pistons in was a major challenge.  I broke a ring on my first try, but I think that's more from this being the first time I've ever put a top-end back together. 

I'm waiting on my tank and seat still and haven't dome the wiring yet so unfortunately the true test is yet to come.  Truthfully, even though I've also installed a Webcam as well, I probably won't realize a huge benefit until the bike breathes a little better.  But I cannot bring myself to replace the stock headers, which is the limiting factor.  If I ever do, I will have my carbs bored by Rick Denoon as well and then I expect I will notice a real difference.

The machinist can cut a chamfer. They usually do.

[jessezm]

There ain't much left to cut into after taking 3.5mm from each sleeve...  But it would have been nice.  Now that I've got the "feel" for doing the install I think I could do it again much more smoothly, even without the chamfered bores.

[hosspowerinc]

If you dont mind me asking, who did you have do the machine work and what was the cost?

[jessezm]

Bob Hamilton of Golden Age motorcyles out of Virginia did the work.  He is a 15 year Honda mechanic and has all the tooling in his home machine shop for the work.  I highly, highly recommend him.  Because this kit takes multiple passes with the boring machine, he may charge a little extra, but i got a great deal.  If you are interested, send me your email address and I can send you pictures of the finished work.  Here's the info:


For $140, this is what I provide.

 1)  Ship me your CB400F cylinders.
     Hamilton Systems, Inc.
23336 Rogerdale PL
Sterling,  VA  20166
703-447-1989
bob.hamilton@asg.com

2)  I will media clean your cylinders, exterior fins included.
3)  I will dress your gasket surfaces for a good seal.
4)  I will bore your cylinders with a Kwik-Way FWS Boring Machine.
5)  I will hone your cylinders with a proper cross hatch and finish.
6)  I will clean/debur the surface followed by a coat of lube to prevent rust.
7)  I will bill you and provide status as to how the bore job went.
  I will ship your cylinders back to you with your new Big Bore Kit ready to install.

Also, optionally, there are 3 separate types of coatings that can be applied to your pistons for longer life, smoother running and better performance:

1) Dry Film Lubricant (DFL), is a lubricating fill applied to the skirt of the piston that reduces friction, inhibits galling and seizing and in some instances can aid in dispersing heat.  They are slippery and provide an extremely low coefficient of friction, which provides added protection during high engine temperatures and other extreme conditions.

2) Thermal Barrier Coating (TBC) is a ceramic based coating applied to the crown of the piston that insulates the piston and rings against damaging heat transfer, keeping more of the heat inside the combustion chamber.  It also provides a more even distribution of combustion, which not only increases efficiency and power, it eliminates hot spots that can lead to pre-ignition and detonation

3) Oil Shedding Coating is applied to the underside of the piston allowing oil that is splashed onto the piston to shed rapidly. The longer oil clings to a hot surface the hotter the oil and the part becomes. By shedding the oil more quickly, this helps eliminate hot oil from blocking the cooler oil from contacting the hot surface. cooler oil will be splashed over the surface more frequently.

The pistons are media cleaned first to assure a good bonding surface (ring grooves are covered).  After the coatings are applied, the pistons are baked at specific temperatures and times.

The normal cost is $10 per coating per piston.  But I'm running a special for 4 cylinder bikes:  $100 for all 3 coatings on all 4 pistons.  $70 for 2 of the coatings on all 4 pistons.  Or the standard price of $40 for one coating on all 4 pistons.

Here is my website address:   http://www.goldenagemotorcycles.com/

Thanks!

Bob Hamilton