FZRSupport: the FZROnline Archive

Planning on using a stock 400 engine,K&N airbox filter and D&D slip-on. Will using the 600 carbs prove to be fruitless? Ive got a set of beautiful condition 600 carbs on my 400/600 and will be finally getting a 400 engine after many years this weekend. Im getting conflicting tid bits of info on using them. Ive read that other 400 racers used the 600 carbs,and just did a little re-jetting and all was good. A couple people have told me the 600 carbs are too big to use period. Who here has done it with good results? Any notes appreciated too

It will depend on the model of 600. The 3HE FZR600 used similar carbs to the 3EN 400 so once they're rejeted and tuned into the engine they should be fine. The 3HE airbox and filter are same as the 3en 400 too, your probably going to use the K+N filter that will fit inside the box .... it doesn't add any power but you can clean it which is nice.

The 600 4JH and 4TV (foxeye and Thundercat) use different carbs

3HE Carbs (see title )

It helps other people to read some background info sometimes

Perhaps it might be helpful for the guys with lost or defective 3EN Carbs if someone with that Carb-Conversion states which Jets are needed to run a 3HE Carb on a 3EN...i bet its not the same jetting as used in the Metal-Cap Carbs of a 3BF or first Generation 1WG, isn't it?
Because, otherwise it would perhaps be an option to put a Metal-Cap 3BF Carb (same jetting as in the 3FH, the California-Model with EXUP, as stated in the Service Manual for 3BF and 3FH) on a 3EN if that wil not result in a way to lean jetting for the 3EN...

Sorry, a bit newb to these bikes but are the 600 carbs Mikuni? I'm doing the same as OP, have a 600/400 that I want to put the 400 motor back in. Luckily it came with stock carbs but I may do some work to the engine before I put it back so maybe the Mikunis would work? The inlet diameter is definitely larger on the Mikunis than on the stock 400 carbs.

@asudef : Which 400 Model do you own(check the VIN)?
The 1st Generation 1WG and the 3BF / 3FH Models have the Mikunis with Metal Caps, the 3EN have got different to the 3BF/3FH/1st Generation 1WG the same Mikunis with plastic Caps as the 600s 3HE and 3HH have,but with quiet another jetting. The Metal Cap Mikunis have a diferent jetting than the plastic Cap Mikunis of the 3EN..i guess the 3TJ and 4DX 400s have just another Kind of Mikunis than all the other 400s and for these Models there also exist fitting Keihin FCR 33s instead of the original Mikunis
The only 400s Model where i'm not sure which Mikunis are used in is the 2nd Generation of 1WG aka 2TK....

@TomcatMJ: Its most definitely the 1WG model since I'm in the US. Only the carbs on the 600 motor have Mikuni stamped on them though. The 400 carbs I believe have black plastic caps and yes, I have been highly contemplating Keihins but for the street? I would like to bore out the motor for some torque but thats for another thread.

The US Models (3BF without EXUP and fo California 3FH with EXUP) have got the Metal Cap Carbs, i'm here in Germany but own 2,5 US FZR 400s..the ones with Plastic Caps are the Japanese 3EN (and perhaps 2TK) Models which also had been grey-imported to Europe and which VINs starts with 1WG (beside the "original" first Generation 1WG). Maybe a good idea to Check the VIN or the Motornumber to be sure which Carb to use...3BF and 3FH use (according to the Servicemanual) the same jetting which is definitely different from the ones of the other 400s with Plastic Cap Carbs. Parts for the Carbs are stil available from Mikuni (at least from Mikuni-Topham here in Germany, the official general Importer for Mikuni in Germany / Suisse / Austria)...