Topic: Mikuni carbs for a 460/4?

[fishhead]

The 26's can be told apart from the 28's by the thickness of where they mount to the carb holders (engine side).
 Right side top - 26mm
 Right side center - 28mm
 The 28's are noticably thinner than the 26's

Rudi's are 29mm smoothbores. They can be told apart from the 26-28's by the extra castings in the intake side bell (none of these shown in my pic are 29's- no extra castings in the intake side bell)

[turboguzzi]

Yes if they are from a Suzuki GS 750 they are 26mm Venturi . We use them to tune up a CB 400 f with 500ccm³ Powroll Big Bore Kit. It works but not without changing the Internal Parts like Needle / Jets etc.
Check in the Picture Galary cb400f.de about "Karsten Laue " and you can see the Result.....

do you have any pics info on those powroll pistons?

tnxs

TG

[Tel#277]

I assume the carb rubbers aint the original size with the Z900 carbs? - do the CB550 ones fit?

[turboguzzi]

I assume the carb rubbers aint the original size with the Z900 carbs? - do the CB550 ones fit?

I've used the stock 500/550 with the 26VM's, they work fine

[bwaller]

They work fine with the 28's too, (same carb inlet OD) although not if they're old and hard.

[rudi]

Hello from Germany.......
Answers to all your Questions : Yes I use different Intake Rubbers on the Cb 400 F Cyl. Head together with a Alloy Plate which I bolt on to the Head by using the Orig CB 400 F Thread Positions. I use Kawasaki Z 1000 A1/A2 Intake Rubbers with mold in Tubes for the connection of the Balancing Hoses.
The Carbs are Mikuni VM 29SS Rac. Carbs.
Photos from the 500ccm³ Powroll Pistons are not availabel. They are also sold out since a Long Time .
But dont worry , look over the Fence............
Have a look at at www.ooracing.com . They offer Pistons with 13 mm Gudgeon Pin and up to 60 mm .........The only wrong Thing is : They are 3,25 mm too short , look at the attached Photo.
The other Picture shows my 450 ccm³ Yoshimura Piston Kit which I upgradet with a low fricticion coating on the piston skirts .

[rudi]

Pictures...

[rudi]

pictures...

[turboguzzi]

Hello from Germany.......
Answers to all your Questions : Yes I use different Intake Rubbers on the Cb 400 F Cyl. Head together with a Alloy Plate which I bolt on to the Head by using the Orig CB 400 F Thread Positions. I use Kawasaki Z 1000 A1/A2 Intake Rubbers with mold in Tubes for the connection of the Balancing Hoses.
The Carbs are Mikuni VM 29SS Rac. Carbs.
Photos from the 500ccm³ Powroll Pistons are not availabel. They are also sold out since a Long Time .
But dont worry , look over the Fence............
Have a look at at www.ooracing.com . They offer Pistons with 13 mm Gudgeon Pin and up to 60 mm .........The only wrong Thing is : They are 3,25 mm too short , look at the attached Photo.
The other Picture shows my 450 ccm³ Yoshimura Piston Kit which I upgradet with a low fricticion coating on the piston skirts .

the powroll ones look good but are they 14 or 15 mm pin?

the ooracing ones looks familiar from so many other asian monkey-bike tuning shops. If you look hard enough youll find also 14 & 15 mm pins pistons. BUT, they will all have very low compression height. I accepted the challenge and shortened my block big time, had to find also some creative solutions to keep the cam chain tension (transplant of a CBR600 tensioner)

[Tel#277]

I've got the new "manifold" manufactured, and fitted Suzuki GS1000 vm28 carbs to the 460 motor,(though I'll need to do something with the cable mount as its too close to the Foale chassis rail).
As the chassis is that tight for size, removing the carbs for jetting changes is going to involve dropping the motor down/forward in the chassis, so any advice on jetting for them would be REALLY appreciated!

[specweld]

test run .
Tel contact Dave Roberts, Hartlepool.
dplatforma@aol.com
re honda

[specweld]

Hi tel,never done this before, hence the test run.
I have a 400/4 (bored to 500)
lightened ,balanced,polished crank
Robson rods (yes Robson not carillo)
web cam
gas flowed head
1mm oversize valves (inlet & exhaust)
26mm CR carbs
Dyna 2000 ign.
close ratio gearbox
TZ front end, AP brakes
TZ rear end, AP brakes
 etc. etc.
I have been playing about for years with cb400's. and if I can be of any help just get in touch, I'm only down the road from you in hartlepool.

I know 3 lads who run 500 hondas in CRMRC and they all use modern CR carbs.
Am not up to sending pics yet , but if you go to TTR400 site , click on SOME HOT 400'S , the first 3 pics are my honda (the yellow one),it's well worth browsing the rest of the site (loads of goodies, some in my bike) and kevin (who runs the site) is very knowledgable and helpful.

Dave

[Tim2005]

Tis good to see another 400 fan. Which Web Cam grind do you use & what's your opinion of it?

[specweld]

this particular engine is still running in so not sure how it will compare to others in the past. The cam is the softest of the 3 grinds,I think it was sent by mistake but the guy who did all the porting and valvework did some calculations and suggested it would work out better than the full race cam , he said he could get more or less the same flow figures but keep the power output further down the rev range.
(sounds good to me)

He has flowed several cb 500 heads with full race cams (inc. Col Stockdales engine) . we compared the results and the flow rates are almost identical .

Incidentally, the cheapest and most effective way to improve the carburation £ for £ is to bore them out and rejet them, plus you get the benefit of everything fits as it should. I have a set already set up and jetted,
you can try them on your bike if you want, an if happy you can just copy all the mods on to a standard set.