Author Topic: cb400 increse cc (Read 4924 times)

corser85 · « **on:** November 10, 2012, 01:06:12 AM »

hy folks, after the last race of the season i want to increse the prestation of my little 400, the idea is to rebuild the engine to 500cc using the piston from the honda xl or cb500
I know that the con rod of the 400 ins't good because have 13mm piston pin, what can i use?
anyone have make these work?

Bodi · « **Reply #1 on:** November 10, 2012, 11:55:21 AM »

The easiest is to use a 458/466 kit. These are available from a few sources. Mostly you find the 466 kit, it was originally a rebore size for the Yoshimura/OMT 458 kits but usually folks went straight to 466.
To go any bigger you have to resleeve.
The 466 kit alone makes a definite difference in power. With a cam and bored or CR carbs the difference is amazing.
What mods are allowed in your race class though?

turboguzzi · « **Reply #2 on:** November 11, 2012, 02:58:47 AM »

ciao corser

what is the diameter of the crankpin bearing in the 400? maybe you can use rods form other bikes....

classic bike tuner · « **Reply #3 on:** November 11, 2012, 03:18:03 AM »

u can use yamaha xj 550 rods [4U8] these have 15mm ppin butt are to wide [20mm]
can easely be machined to 16mm
bigend same as 400 need to modify bearing shell slot
and use the kvo bigend bolts
rods can be found on ebay
center to center distance is 1mm longer thats no propblem only more compression
olso for 500 cc you need new liners you can use cb 500 liners and use a xl/cl 125 piston [56,5mm bore]
olso need to widen the cranccase for bigger liners

gerrit

classic bike tuner · « **Reply #4 on:** November 11, 2012, 03:25:36 AM »

xj 550 rods
http://www.ebay.com/itm/Yamaha-XJ550-XJ-550-2257-Connecting-Rods-/110898393927?hash=item19d20f3347&item=110898393927&pt=Motorcycles_Parts_Accessories&vxp=mtr

http://www.ebay.com/itm/1980-Yamaha-XJ550-Seca-30-DAY-WARRANTY-Engine-Piston-Connecting-Rods-/200700613434?hash=item2ebab0533a&item=200700613434&pt=Motorcycles_Parts_Accessories&vxp=mtr

and much more

corser85 · « **Reply #5 on:** November 11, 2012, 08:44:23 AM »

for Bodi: i can increse the displacement to the limit of the 500cc class,and my idea is to reach these limit, i must only save che original engine design.

for turboguzzi: i'm not sure about the diameter of crankpin bearing.

i've read in the forum about a work on a 500f whit the con rod from the suzuki gsxr 1000, but i dont know if i can put these on the crankshaft of my 400f, however the idea of the xj500 rod is intresting

turboguzzi · « **Reply #6 on:** November 11, 2012, 12:33:11 PM »

trust gerrit

Howell · « **Reply #7 on:** November 12, 2012, 01:16:18 PM »

Gerrit working on one of the Honda's

turboguzzi · « **Reply #8 on:** November 13, 2012, 10:31:44 AM »

anybody knows what crankpin diameter do these 400/4's have?

classic bike tuner · « **Reply #9 on:** November 13, 2012, 01:43:52 PM »

cranckpin 350/400 about 32mm 500/550/650 = 35mm

gerrit

Chris Tyler · « **Reply #10 on:** November 13, 2012, 02:36:07 PM »

Hi Gerrit

Thank you for the information. What do you do for a head gasket?
Thanks Chris

classic bike tuner · « **Reply #11 on:** November 14, 2012, 03:50:27 AM »

head gasket use std one and replace the steel rings for cb 500 one's

cut the gasket with a metal cutter to the size of the 500 rings
first remove the 500 rings from a [old] gasket

dont now were to buy 57mm bore head gaskets for cb 400

gerrit

Chris Tyler · « **Reply #12 on:** November 17, 2012, 02:32:49 PM »

Hi Gerrit

Would you mind running through a few options?
ie easiest way to up performance from standard.
Rods?
Pistons? I believe the cut outs in XL pistons are not in the same place.
Would you not turn down the liners if fitting 500 liners rather than opening up the cases?
Cams?
valve mods?
porting?
opening up standard carbs ie 26mm bore.
I have no knowledge of these engines but will be stripping 2 engines very soon. I am not after being at the front just looking for a better ride a bit more go & reliability.

Thanks Chris

corser85 · « **Reply #13 on:** May 12, 2013, 03:35:14 AM »

i return to write in these discussion because the work on the bike continue.
however since the championship has started, and the time to spend on the bike is so short, the first race i've run with the normal 400cc engine, but now i have to rebuild this engine that will become in the future the n°2, the idea is to stay in the 400 displacement, but with some little modification: head, carb, cams and electronics ignition
I'v found a modified head , i'm not sure that is good but i want try it, and i want to try to put the 26 keihin carb from a 500, the diameter of the manifolds in fact is 26mm.
I think that with a rubber extension between the original manifold and the carbs i can insert it, but i remember that if i increase the distance between carbs and the head change something but i forget what... someone remember what?

corser85 · « **Reply #14 on:** May 12, 2013, 03:37:04 AM »

http://i992.photobucket.com/albums/af44/bentonracing/P9230011.jpg

a job as Bill/BentON as you see

specweld · « **Reply #15 on:** May 12, 2013, 05:38:38 AM »

Chris, re. head gasket,you can cut one from copper sheet ,
quite time consuming but it can be used over and over again, just aneal it every time you rebuild.
copper can be high pressure water cut , there may be someone near you who can supply, the first one is the expensive one because you are paying for the programme but after that they are relatively cheap.
A few years ago I had them laser cut from aluminium, cost for1 £80... cost for 5 £100.

copper is better , its stonger.

turboguzzi · « **Reply #16 on:** May 12, 2013, 01:55:58 PM »

You been to Varano and didnt come to say hello? after all our message exchanges? shame on you....

corser85 · « **Reply #17 on:** May 13, 2013, 04:58:12 AM »

no turboguzzi i talk about the first race of trinacria's trophy, the sicilian championship!

turboguzzi · « **Reply #18 on:** May 13, 2013, 05:55:15 AM »

ok, perdonato

if you are coming to adria this weekend , look for 999....

corser85 · « **Reply #19 on:** May 13, 2013, 12:17:22 PM »

i cant, but if you whant ,next week, we want see some photos

turboguzzi · « **Reply #20 on:** May 13, 2013, 02:32:22 PM »

Quote from: corser85 on May 13, 2013, 12:17:22 PM

i cant, but if you whant ,next week, we want see some photos

in the meantime, this is form varano

http://forums.sohc4.net/index.php?topic=83871.msg1368946#msg1368946

Rick4004 · « **Reply #21 on:** June 13, 2013, 10:13:14 AM »

Hi Gerrit

Did you use the 550 bearing shells, or switch in 400F shells?
If you used the 550 shells, did you plug the oil jet holes?
If you used the 400F shells, did the rods require any resizing of the big ends?

Thanks

Rick

classic bike tuner · « **Reply #22 on:** June 14, 2013, 02:13:50 AM »

use the 400 shells than automatic the hole is plugged
meabe need new slot for shell
biggend side of rods need to be narrowed from 20 to 16mm wide crank is standard

Quote from: Rick4004 on June 13, 2013, 10:13:14 AM

Hi Gerrit

Did you use the 550 bearing shells, or switch in 400F shells?
If you used the 550 shells, did you plug the oil jet holes?
If you used the 400F shells, did the rods require any resizing of the big ends?

Thanks

Rick

Rick4004 · « **Reply #23 on:** June 14, 2013, 09:40:19 AM »

Thanks Gerritt

I am thinking of getting a batch of these done as follows;

Narrowed/surface ground to 400F specs
Small end bushed to 13mm for use with standard aftermarket 458cc kits
Big end notched for use with standard 400F shells.

If I do a batch of 16-20, maybe I can get a bit of a volume discount on the machine work.

If anyone is interested in a set, let me know.

Rick Denoon
www.denoonsp.com

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Author Topic: cb400 increse cc (Read 4924 times)