Well i've got my bike (1988 fzr 400 3en1) running reliably ... ish and i've started looking onwards to next winter when i will go about making it horribly unreliable again
The list in my head so far is:
Race can
Break piston strip and clean
Head gas flow
Degree cams
Reshape valves
Skim head
Advance ignition
Jetting

Now to the questions:
1. I understand that the entire front end off the 600 is a direct swap? Are they better as standard and is it worth swapping them or would it be better to just upgrade the internals in the standard 400 forks?
and while on suspension are there any common swaps for the rear shock? Obviously aftermarket shocks are available but tend to come with a rather hefty price tag as well!

2. Are there any common parts or usable parts that are interchangeable between the 600/other bikes and the 400, like cams, carbs, valves, flywheels etc.?

3. Are there any options in terms of changing the EXUP valve opening time, and are there any advantages in doing so? I spent the last 6 months or so doing a lot of work on an Aprilia RS 125 and you could use the SP model RAVE controller to make the RAVE valve open 800rpm sooner which completely smoothed out the power curve, Getting rid of a huge jump when it opened as normal at 8200RPM.

As i say this is only the beginnings of a plan at current so any suggestions are more than welcome,
Thanks in advance,
Geo

For a 3EN1 ...

Look for a front end, a YZF750 is supposed to be quite light, look for the later style with adjustable forks. They'll blue spot calipers too.
Rear end, I'm not sure the R6 shock conversion is going to work with the swingarm sooo I'd look at the 17" rear wheel conversion. If you have a 120/70 front then you can run a 160 /55 (?) rear but only if the engine can pull them.
The engine .... if you want some quick usable power increase fit a 600 engine, best to use the 3HE because you know it fits the frame but have a look at the 4JH if it still has the holes to match your frame rails.

Just depends on the budget really.

As far as shocks go, I did some research and several will fit straight in but you'll need to alter the dog bones.

Those that fit, as best as I can remember, are:

ZX6R P6-P8
CBR600 RR3-RR6
R6 5SL

and a couple of others.

I did put a post up about it a while ago if you care to search for it....

Evilchicken0 wrote:For a 3EN1 ...

Look for a front end, a YZF750 is supposed to be quite light, look for the later style with adjustable forks. They'll blue spot calipers too.
Rear end, I'm not sure the R6 shock conversion is going to work with the swingarm sooo I'd look at the 17" rear wheel conversion. If you have a 120/70 front then you can run a 160 /55 (?) rear but only if the engine can pull them.
The engine .... if you want some quick usable power increase fit a 600 engine, best to use the 3HE because you know it fits the frame but have a look at the 4JH if it still has the holes to match your frame rails.

Just depends on the budget really.

Thanks for that, Will keep an eye on the bay for a YZF being broken then, do you know if the forks are a direct fit into the standard yokes or is it the whole front end that needs swapping?

I was already looking at a 17" wheel conversion so that is a distinct possibility, will see what comes up in the way of parts over the next few months.

Was really looking at keeping the 400 motor to be honest, Its not so much a quest for more power as a bit of fun over the winter to state my tinkering habit! Shoving a 600 in is no fun at all, and gets rid of all braging rights when you show up bigger bikes!

thunderace wrote:As far as shocks go, I did some research and several will fit straight in but you'll need to alter the dog bones.

Those that fit, as best as I can remember, are:

ZX6R P6-P8
CBR600 RR3-RR6
R6 5SL

and a couple of others.

I did put a post up about it a while ago if you care to search for it....

Thats brilliant thanks for that, will have a root through and see if i can't find the thread about it

Ta' very much!
Geo

You'd need the whole front end of the YZF, but there's not much point if you keep the 400 because then it becomes more about corner speed and handling and the wider wheel / tyre (front and rear) will slow the steering down. Keep the tyres skinny and quick handling.

So, if it's more about fun - Go for a later FZR600 3HE forks with the 298mm disks - check they're the 38mm forks so they'll fit you yokes, your wheel shoud fit but you'll need some disks, fit the bluespot calipers. Then fit new springs oil and seals - vary the oil level and spacers (that should keep you busy).