Carbs and Airbox

I used the 4jh carbs. They fitted within the frame ok but were slightly closer to the frame at the right hand side. It didnt really pose as much of a problem though.
I managed to reuse the throttle cables from the 400 with the 600 carbs but i had to make a new mount as one of the cables mount up different. It would have been easier to get the throttle cables from a 600 though!

Both the cables on the 600 have adjustable ends unlike the 400.
Also you need to get the choke cable from the 600 as the 400s is not long enough. But fitting is straight forward.
It is a lot easier to fit pod filters on the carbs as others have but i wanted to keep the airbox. The 600 airbox is bigger than the 400. I have heard of people raising/modifying the tank to make them fit.
The 400 airbox will almost fit on the carbs so i decided to modify it to fit. This illiminated the tank being raised.
Firstly I dismantled the airbox. As the cylinders are longer on the 600, the carbs sit slightly higher and more forward than the 400. The airbox is modified by removing the rubber mounts and elongating the holes to make the box sit over the carbs.

The holes need to be elongated to the point that the breather pipe connector is clear of the carbs and the front mount will line up with its bolt hole.

As you can see in the picture above you are now left with a bit of a hole where the carbs originally mounted. I chose to patch this up with fibreglass(sorry no picture).I made sure the plastic was clean and ruffed up so the gf would key ok.
Around the carbs where the box now seats i used some soft rubber foam to make a sealing gasket/seat (can be seen in the above picture just).
With the gf set and neatly trimmed the box was reassembled and refitted.

I used a piece of soft rubber foam on top of the box to hold the box in place when the tank is fitted.

Since fitting the engine i havent had too many problems. The first was finding a good gearing. I decided to run a 520 chain and as the standard 400 runs a 15/45 gearing i decided to go for a 16 front. After my first trip to the track i realised it was wrong (for the track) as i wasn't getting 6th down the back straight. in fact it was only just getting 5th!
Eventually when i did my homework, converting the final gearing from the 600 i realised it converted to a 14/45. Time on the track with this gearing has proven itself.
Other problems i have had are non conversion related,such as a slipping clutch which was made worse by the wrong gearing! All sorted now though.
Handling wise there seems to be no problems with the extra wieght of the engine. No need for a respring as its only a few pies difference. I have how ever since done the r6 rear conversion and fitted sp forks. It can still carry corner speeds enough to go round the outside of r1s ,but has the bonus of keeping them at bay down the straights.
All in all its a wicked machine. Im doing one for the road now!

I hope this thread is helpfull if you are thinking of doing the conversion. Feel free to ask me any questions, if i can help i will.
Cheers Tim

fzrtim wrote:Carbs and Airbox
I managed to reuse the throttle cables from the 400 with the 600 carbs but i had to make a new mount as one of the cables mount up different. It would have been easier to get the throttle cables from a 600 though!

Both the cables on the 600 have adjustable ends unlike the 400.

The throttle cables from the 600 pose their own problems though! I first used the cables from the Foxeye donor and while they fitted the carbs, they were far too long. If they are tucked out of the way, then the throttle action is very stiff and horrible feeling and the slides will not close on their own. If they are positioned so that the action is smooth, they obscure the clocks, right across the 30-50mph markings...

I ended up using a single 400 cable and shortened the outer sheath to get the required length of inner exposed. This seems to be working at the moment, but I've only ridden her a couple of hunderd yards out by the garage!

The 600 cables do both have threads on the carb ends, but the return cable is only there for mounting purposes. The 'adjuster' always sits in the same place irrespective of where the lock nut is put, so it is just there to clamp the return cable into position.

Oh, by the way, the 600 Foxeye front wheel fits in perfectly including the EBC prolite discs that came with my 600...

Alex.

Hi, have any of you guys had your bikes on the dyno yet. Just wondering for comparison for my Thunderbike that I had to build in the 400 cases, using pod filters it has 88bhp and 41lbft of torgue. Just wondering what you get with an airbox?
Also have any of you had problems with wearing through your rad with the front wheel? Mine is currently full of radweld as the wheel keeps touching, but I have been racing it so i've been very hard on the brakes + using an r1 master cylinder

Hi Steve,

Just out of interest, what jets and carb settings are you using with the pod filters?
My hybrid has pods and it would be great to have a baseline setting before hitting the dyno!

Alex.

It was massive main jets I think it was 180's and I ended up using the needles out of an J or K model zxr750 due to the taper on them being about what was needed. Be warned it is a thursty beast, I ran out of petrol on the last lap of one race at brands cos I did't expect it to use that much. But it makes an awesome howl on the over run

... and you were competative with it too !!!
Kept up with the FZ750 Racer featured in PB mag a few months ago and that has an Ohlins front

Oh were you there evil?
Was hard work keeping up because it is way to heavy for the power it makes to meet the rags, also it needs more torque to match other bikes off the bends hence the 727cc plan

I spoke to you

I was with Cagiva in black leathers

Oh i remember now, man I've drank so much on my 6 weeks off i've forgotten what happend in my leave.
Out of interest how does cagiva fir on the 400, he's really tall?

http://www.holeshot-racing.co.uk/index.php?page=YZF600

Check the link out, see how much power can be extracted from a thunderkitty motor in a 400!