Hey all, I've recently installed a dyno jet kit on my 650. It is running great for the most part and definately has helped performance. I was out riding on the weekend and found that under load as in crawling through mud or pulling a trailer at about 1/4 throttle the engine stumbles or misses. It only happens at approx 1/4 throttle not slightly above or below. I'm thinking its the needle as it runs great otherwise. Just wondering if this has happened to anyone else and looking for some input before I start making changes. All my settings are at the dyno jet recommendations. 136F,140R, 5th notch on needles. I'm at about 2300'. Thanks in advance.

 

it sounds like your air/fuel screws to me

 

mine kinda does the same thing. i had the dealer to put mine in, they do a bunch so for 55$, i let him do it. as far as the miss, i guess I've kinda got used to mine, it don't bug me that much, it's just one little single burp, then hold on.

 

Thanks guys. I was thinking about messing with the air screws a little, just wanted some opinions before I start making changes. Carbs and I don't always get along to well. Thanks again

 

Tried turning the air/fuel screws out 1/4 turn to rich'n it but didn't help. That puts me at 3 1/4 turns out. Don't really want to go much further. Do you thinking another notch on the needle would help? I'm thinking maybe the 6th notch. Any thoughts. Thanks.

 

did you try turning them in to lean it out ?

 

Ya I tried anywhere from 2 turns to 3.5 and didn't help. Tried the 4th and 6th notch on the needles and it was much worse. On the Nyroc forum it sounds like this problem is quite common. Wish I new that before I put out the $65. I think I'll try puting the stock needles back in with the shims and see if that clears it up. Thanks for the help.

 

just so you know, from what I have been told is that the stock needles WILL NOT work with dynojet Jets. maybe you should try 1.5 then start bumping it up torward 2 turns out.

 

You were right there BFB. Stock needles don't like the Dynojets. For a small job this sure is taking up alot of time. Isn't that always the way. I messed around with the needles some more and settled on the 4th notch with air screw at 3 1/4. The poor performance I was getting earlier when I was trying different notches seems to have been caused by a plug going bad. I must have damaged it on my 50 th plug change. The miss is still there but not as pronounced as the other settings. I'm taking it to a tuning shop with a Dyno today so they can run some tests to get it dialed in as good as possible. Probably won't get it back for a couple of days but I'll let you know the outcome. Thanks again for the help.

 

mine went to the dyno doctor today also, should get it back tomorrow or thursday. there's a big hole in my heart and my garage right now lol