www.zxrworld.co.uk

Hi All

I'm new to the forum so firstly I just want to say hi!

I need some advice about radiators. My L model ZXR400 is a track day bike only and is making a healthy 63BHP on the dyno at PDM racing in Bexhill. I would like to fit ram air to it as I'd like to try racing it and all the guys in the MRO paddock appear to be running an aftermarket ram air system of some sort.

My question is about the rad. Most of the racers appear to have cut a hole on the top of the rad to allow the ram air intake to come through to the airbox... but I'm somewhat scared to do this. My mechanical skills aren't too bad and I can twirl the spanners ok but I've never cut a rad before... what stops it leaking and going horribly wrong.

I've scoured ebay for a ready cut one... no luck and I've enquired about using an H model one (much smaller) but been advised that this makes the bike overheat? So my options are these..

1. Wait for one to come up secondhand
2. Use an H one anyway and hope it doesn't overheat
3. find someone who can successfully cut a rad for me and/or show me how it's done
4. stop worrying about ram air and just ride the thing a bit harder to make up for any power disadvantage...!

I'd be really glad of your advice guys, many thanks.

i assume you just cut the appropriate amount out with a hack saw and pliers, then fill the holes with a liberal dose of solder. i have not done it myself but this is one way of repairing them. i am sure someone will jump and tell us all a better way??

just so happens i have my rad off, so ive took a couple of pics for ya.

I very much doubt you'll find a second hand one. I was told how to do it by Dynotech, cut out the hole, sqeeze the tubes together (I put a bit of chemical metal down them first), then roll back a few times (before CM sets), then seal with araldite (again I used chemical metal).

I just sent the rad off my bike to be welded. Much more robust than using epoxy or solder. The only problem is you need to find a good ally welder who won't mind doing a small job like this. Of course I think most racers get by just fine with epoxy or chemical metal. Also, it's good to flip the brackets the other way round so they don't foul the air intake.

Thanks to all of you guys for your help and particualrly Simmo for taking pics, really appreciated.

I guess it's just a case of taking the plunge and getting the hacksaw out?

I might get a used one off ebay and cut that first incase it goes wrong, then I know I've still got a good one intact.

Someone mentioned Dynotech and I've geard good stuff about them do they have a website? and does anybody know how much of a power gain the ram air system gives? Is there one that's better than another..? I've seen 2 or 3 different ones on the market and there's two different ones on ebay at the moment.

Thanks again.

Dynotech don't have a website , tel number: 01256 881711

Ram air boxes I beleive will all give the same sort of performance gain, I had a standard airbox with forced air taken from the front of the fairing, when I fiyyed a BB box I only gained an hp, less than two, at the top end, but got about 4 bhp extra at midrange on their dyno. That was down to volume increase and more space about the bellmouths that allowed a smoother flow to them. The gain will only really happen above a certain speed which I beleive will be at at least 70mph so it is very difficult to measure the actuall gain on a dyno as forced air dynos normally don't have that sort of fan to give the effect of over 70mph. (things may have moved on more recently though ??) Saying that, I also wouldn't know what sort gain you would get by just fitting ramair over a standard airbox It would normally involve other engine tuning work as well

Thanks mate. At £200+ for the ram air box plus the rad work and set up it seems a lot of money and effort for a couple of horsepower. I suppose if you want to win then it's got to be done if everyone else is doing it, but at my level of ability I suspect it might be just as well to spend my money on good tyres and learning the lines? It would be nice to have though.. I'll have to see what Santa brings?? (apologies for mentioning Xmas in November by the way).

i don't suppose any one knows of any other model radiator that will fit a L model zxr? they do seem to be a bit thin on the ground...

AgentOrange wrote:Thanks mate. At £200+ for the ram air box plus the rad work and set up it seems a lot of money and effort for a couple of horsepower. I suppose if you want to win then it's got to be done if everyone else is doing it, but at my level of ability I suspect it might be just as well to spend my money on good tyres and learning the lines? It would be nice to have though.. I'll have to see what Santa brings?? (apologies for mentioning Xmas in November by the way).

Just to clarify, the extra (less than) 2bhp was compared to a standard airbox with a ram air modification. You may well see a lot more over a completely standard airbox. If you're handy, you could fairly easily modify a standard airbox, and use tubes to the front of the fairing to get air directly in; that would also save cutting a rad about.

As you say, every little bit helps, they all add up to possibly be quite a lot

But also, as a new racer, the first thing to get sorted is the suspension and handling, all the power in the world won't make 'you' any faster, if you then get into it, then start developing the engine. It's a very expensive old game

You can buy brand new ram air ready radiators.

Do a google on zxr400 race radiator. Looking at about £300 but any radiator repair place will mod yours as required for a lot less money.

done for ya

http://www.aaronradiator.co.uk/pages/motorcycle.html

Thanks chaps... Just got back from Birmingham where I went o see Joe Bonamassa, great gig... just logged on. I'll have a look at Aaron Radiators... although mine is fine at the moment they are prone to going rusty at the bottom, and a new race one might not be a bad idea when funds allow, and it could save a bit of hassle... £300 is a lot of money, but when your spending a similar amount on tyres for a couple of track days it doesn't seem like such bad value for money... decisions decisions... got to keep my feet on the ground though, and the advice about learning to race is good advice, thanks... I'm a track day veteran but I'm under no illusions that racing is another step up, and horsepower isn't going to win anything if I don't get my racecraft up to scratch!

The current 636/6rr radiators are similar in shape and size but the hose attachment is different. Those issues can be easily fixed as well and you can find them pretty cheap. Just picked one up on eBay for $50.00 shipped.