To tune, or not to tune?

jeffersonchristopher · Post by **jeffersonchristopher** » 01:30 pm Nov 12 2015

Alright lads? Hope everyone is well?

Here's today's question then...

I can't bore a 1990 kdx 200 out can I? So I want to tune it instead.

Work would include fitting an fmf fatty, vforce carbon reeds, upgraded ignition coil, iridium plug, re pack the stock muffler, and finally, take it up to bdk Race engineering to have the carb rebuilt and be jetted.

For the money it will cost to have that done...

IS IT WORTH IT??

Cheers!

Chris.

Post by **Julien D** » 02:27 pm Nov 12 2015

Yes, but.. are you talking about a vforce reed block, or just the carbon fiber reeds? If so, I'd skip those and get the boyesen 607 2 stage power reeds. I'd also recommend RB Designs for modding the carb.

cornishwrecker220 · Post by **cornishwrecker220** » 02:36 pm Nov 12 2015

Speed is just a question of money.......

How fast do you want to go !

jeffersonchristopher · Post by **jeffersonchristopher** » 04:47 pm Nov 12 2015

The whole reed block was what I had in mind.
Do you think the boyesen reeds are just as good?

RB designs are in the states? I'm in the UK so it would cost over the odds in shipping?

A friend of mine said it is all pointless if I'm not going to big bore the cylinder...
I'd like to think that statement is incorrect.

Thanks for your replies.

KDXrider1989 · Post by **KDXrider1989** » 05:42 pm Nov 12 2015

I have the boyesen 607 reeds and they made a good difference. I also have an FMF pipe, that alone will probably be one of the best things you can do to this bike, really wakes it up as the stock unit is very restrictive. definitely get your carb rejetted. after those two and jetting the carb, itll be a completely different bike. you can do a big bore on these motors, but it rids of the powervalves. I cant remember the thread completely, but its all for torque and no top end, and without the powervalves I think it was more abrupt power delivery. IMO these bikes are best on a stock bore, you start boring them out and you run into problems. the RB head and carb mods are also good, though I didnt do them on my KDX

Post by **Julien D** » 06:07 pm Nov 12 2015

jeffersonchristopher wrote:The whole reed block was what I had in mind.
Do you think the boyesen reeds are just as good?

RB designs are in the states? I'm in the UK so it would cost over the odds in shipping?

A friend of mine said it is all pointless if I'm not going to big bore the cylinder...
I'd like to think that statement is incorrect.

Thanks for your replies.

The boyesen reeds aren't going to be quite as good as a vforce 3, but they are so good that price for performance makes it hard to justify the aftermarket reed block. RB designs is great, but if you're in the UK and have a local outfit you can use, that's probably going to be more reasonable dollar for dollar. Your friends statement is incorrect. The difference between a stock KDX and a slightly modded and well tuned KDX is considerable. The pipe and jetting alone makes a huge difference.

Dekon · Post by **Dekon** » 07:55 pm Nov 12 2015

Jetting really wakes the bike up.

jeffersonchristopher · Post by **jeffersonchristopher** » 04:58 am Nov 13 2015

Thanks for the replies lads! I think it's fairly obvious what I'm going to do then!

Watch this space...

Chris.

bultaco4ever · Post by **bultaco4ever** » 10:33 am Nov 16 2015

May I jump in here and ask a question? I have Boyesen reeds in my 200 now. They look a little worn. I have three petals on top and three on the bottom. The 607 reeds look like they have two larger petals on each side. Will they fit on the block that I currently have?

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