I installed a K&N and removed the lid and ordered the Dyno Jet kit (sucks, I hear now). Most jets are smaller than my stock main (158s ..what's the "s"?) BUT when i put the 160 main in and changed to the Dyno needle, it ran rich. I put the stock main in and it's still rich. What should I run?

I also removed the screen in the airbox. The Dyno instructions said that will increase airflow. It didn't say that the screen contained the nut that holds the airfiler in....I rigged up my airbox to hold it in anyway, but it was tough.

 

Dynojet kits work! The people telling you otherwise have no idea what they talk about. I dyno tune lots of raptor and other quads and the Dynojet kits work right the 1st time. Nothing else comes close.

Do what they tell you in the installation.

Yes the jets are smaller, but the needle will flow more fuel compared to the stock needle.

I say again. Follow the instructions to a T. Also try running it without the snorkel to see if it runs better.

 

He's right about everything except the easy to tune part, even when following the instructions it's a b*tch. Once you go past K&N filter and a full exhaust system the instructions are useless and barly work the first time anyways.

I agree they make good power gains and are designed well but they are not user friendly or ever provide you with enough jets(seems like they always skimp you! For the $ you pay you should get more than that!).

Also you're tuning these bikes on a dyno which is MUCH easier than guess and checking (which is what most people do). I had my rappy jetted with DJ needles on the dyno and it took them hours to get it smoothed out! The mods are extensive though...ran great after that!

 

Dynojet kits are stage 1 and stage 2. Stage 2 is not designed for cams, pistons and other mods. It will only cover exhaust systems and new air cleaners with the stock airbox. Different exhaust systems require different jetting and the kit is made to cater for 90% of them. You will always find one part that needs bigger jets than the kit supplies.

I also had to get bigger jets, because of the L&A adaptor, but it was never a product that Dynojet took into account.

The jets where cheap, so I have no complaints.

At least Dynojet comes with instructions. The GYT-R kits I have seen, comes with nothing but the parts. You have to try your own luck to get the jetting right.

I am also not sure what ratio you tuned the carb for. Most people run around 14.7:1.

 

Dyno jet kits work good. They just don't work good on YFZ450's The numbering system on DJ is different than stock jets.

 

type daddog jetting into your search engine. Go to the daddog jetting page. A lot of good advise there.

 

So the concensus is to follow the directions exactly, So I should put a dj140 main in, and leave the needle at the 5th from the top groove? (The directions also said to move up to dj160 if removing the screen in the airbox, which I did.)

Should I jet back down to the 140 (it is smaller than the stocker, even if the numbers aren't consistent, I can tell by looking at it) Or could I just leave the stock main in, and play with the needle position? It's in a pretty rich position now, how about taking it down a couple notches leaner? I know all of the basic concepts of jetting, I have a Banshee dialed in exactly where it needs to be. I never followed any instructions or even bought a jet kit with it (just bought jets).

Thanks

 

All quads are different...sea levels, weather, etc. I followed the dyno jet instructions to a tee and my yfz overheated. I called them and they could not tell me why or how the dyno jet numbers transferred into stock jet numbers. I got the ncvq needle with about 10 different jets and will rejet in a few days. GO TO THE DADDOG JETTING PAGE

 

Ok I'll look at the page. (Is it similar to Banshee jetting FAQ on Banshee HQ...I know that one by heart!)

 

I've never jetted a banshee, so I don't know if it's similar. I made a 26 page, a 6 page and a 4 page print out from daddogs jetting. I got my yfz at a 170 main, 48 pilot with the ncvq needle on #3, 2 turns on the screw. I'm going out today to run it and fine tune, but I think I'm really close. I ran a bit in front of the house yesterday and it ran like a raped ape. I'll opene it up later and let ya know how it went.