Topic: cb400f engine mod question

[riktaboy]

I've searched all through the forums for anwsers with no luck...
So my first question for ANYBODY that might know would help the most if someone has the anwser..
I have a 400/4 big bore kit, 4x 53.5 mm pistons and rings 53.75mm.  What I need is the CLEANRANCE for the machine shop, so I can get these puppies in there.

Next does anybody have any info on or suggestions on aftermarket cams, I see alot of suggestions towards Megacycle cams, but I know there is also Web Cam and a yoshimura cam from KSM Enterprises..  Any suggestions in this territory would be greatly appreciated....

Any other engine mod suggestions would be great to read....

                                                                                                                 thank you in advance for any replies...

[ttr400]

Yoshimura piston to cyl clearances, Road 0.03-0.04, race 0.04-0.06 use stock ring gap. For a a mild motor with head work the best cam is the Road and track profile, the yoshimura from eaglescall is a new cam and not a re-ground cam like you get from Web or megacycle. For a race 400 with lots of work like mine I would go for a hotter cam.

Kevin

[ttr400]

Sorry I forgot to add that those clearances are in mm....Metric

[crazypj]

 I usually go with 0.0015" to 0.0025" depending on use 0.03mm is about 0.0013" and 0.06mm about 0.0026".
 0ne hundredth of mm is pretty close to four tenthousandths of inch (0.0003937")
I usually fit to within a tenthousandth or so.
PJ

[riktaboy]

So I guess a brand new cam would be better then a regrind?  With my size pistons it would bring it up to 466cc so the street cam from eagles call sounds like the way to go... 
Any suggestions on the head work or what to ask them for or should they already know where to go with it?

thanks for all the info so far, it has been very very helpful..............

[Bodi]

The original Yoshimura cams were regrinds, MC-Again either gets new blanks or has a supply of old cams to make their reproductions if they do an exact copy.
A regrind has 2 limitations on the finished profile; a hard limit in that you can't go any higher than the original cam profile and a soft limit where grinding deeper into the blank moves the tappet contact point off centre on the valve stem tip because the rocker angle changes.
If you could get blank cams you could grind for the same valve motion as a regrind cam - but with a higher base circle keeping the tappet contact patch centred on the valvestem.
I don't know if this is really a vital issue. Megacycle claims it is and they build up the lobes with hardwelding before grinding the new profile. Whether there's engineering wisdom or marketing BS behind this, I dunno.

[MRieck]

Skirt to wall is dependent on the pistons(s). Are they cast or forged. How deep are the valve pockets too?

[riktaboy]

don't really know if the are forged or anything like that, any way to tell?