OK gang, I am frustrated. I called DMC last week and they told me to use OEM Kawasaki jets and that they had changed thier recommendation to 138/142 jetting.

I ordered the jets and installed them a few hours ago. I put the air screws at 3-1/2 turns out like the said.

When I cranked it , it idles OK, but will not run past about half throttle. It is running real real rich. Popping and snorting and spitting when the main jets take over from the pilots.

I live in Louisiana so sea level jetting is perfect. I am pretty sure that I put everything back together correctly. I fiddled with the air screws to no avail realizing that these control idle to half throttle anyway where it runs fine.

I don't know what went wrong. If I don't get any help I think I will put the stock rear jet in tomorrow and see what happens. If it still runs like hell, I will just put the stock jets back in both. A note to consider is that I ran it about an hour or so with duals and stock jetting and the plugs were nice and black. Maybe I don't need the jets afterall.

Please let me know what you think and what you would recommend. Please also let me know if there is any mistake that I could have made reassembling the thing that could cause it to run rich.

Thanks in advance.

 

put the 135 and 140 main's back in and ride it for a few rides, see how it run's, you may be ok with the stock jet's all bikes are different.... the only way I have found to go by plug color is buy a brand new set and run them after the bike will start and idle without useing the choke, If you put new plugs in and start it cold with the choke you will black foul them and they will never completely burn off, put the stock's in, start it and let it run until it just start's to get warm not hot, put the new plug's in start it without the choke and ride for about 30 mins to an hour, all different throttle........ pull them out after ward and look at the tip, it should be tan to light brown, and the ceramic in the center of the plug that surround's the electrode should be very light tan, very little color is spot on jetting.......anything darker than light brown is rich..........87-89 octane gas will give the most accurate plug color also......

 

Danny,

Any ideas why mine is running so rich with the DMC recommended jetting?

 

I have no clue, some quad's are just richer by nature than other's......I was one of the first to Dyno-jet my Pra. 650 and had to go into it 4 times before it was right.....These companies give you a guideline, but absolute jetting depend's on the bike, run the stock jet's, make sure the air filter is cleaned and doesn't have TOO MUCH oil on it, as this will kill power, also before you take it apart again, ride it and when it start's to act up give it some choke if it get's worse your way rich, if it does this, crack open your air box lid a little and see if it get's better, if it does then you know letting more air in has leaned it, so you were rich alright, taking the airbox lid off I think will cause WAY too much air flow and it will run bad....you can try it, but I'm betting that the stock jet's will fix it..... also I think the stock airscrew setting's are 1 1/2 turn's 3 1/2 may be rich.........do this with the air screw's after you have rode it enough to get it warmed up, let it idle in neutral, and start turning the front screw CLOCKWISE until it idle's rough, STOP and then go COUNTERCLOCKWISE one full turn and stop....Do the other carb the same and your done with your air screw's........By the way I have junked my Dyno jet kit and have the Keihin jet's in it now and it's fine......

 

I already pulled the air filter out and it ran a little better but still would not really run past half throttle. Chocking it just kills it altogether. It is acting like it is richer than hell. As I mentioned, I rode it with stock jets and exhaust for an hour or so. It ran great. No backfiring or anything. I did notice with the stock jetting and exhaust that if I took the air filter out it started to pop as if it were too lean. That made me think that I was just rich enough with the stock air filter in.

 

Sound' like you already have it figured out, go back to the stock main's, but do the air screw's like I said and see haow it does after a ride or two, if it run's better than it does now, you know your on the right track, even if you do the plug's like i said and they end up darker than tan, If it run's ok leave it alone......enjoy it........

 

So why did you tell me earlier in the week not to "half ***" it by leaving the stock jets in. I thought I had to rejet to get the HP available to me by the free flowing exhaust.

I realize that every quad is slightly different, but this is really puzzling to me. Not to mention another 17 bucks down the toilet.

Anyway, thanks for your help. I guess I am learning if nothing else.

 

I dunno how much different the pipes are, but with my HMF Duals and stock airbox, I have 146/148 in mine and it is perfect. I have put it on the dyno to confirm it also.. Im not too far from you either.

 

I just went through this 2 days ago with my HMF duals. I had 145's and 148's in it. The exact same thing happened to me as is happening to you. I think the needle needs to be adjusted? I am no professional. What I recommend is to just go all the way with it. Block off the coolent lines, jet to 160/165 and cut holes in the air box. Also adjusting the needle position is very important.
This is what I had done to my V to get it running right. Otherwise, it would not get out of its own way...
Hope that helps.
-Max

 

Look Man, I didn't tell you not to half *** anything, this is the first time I've responded to your post ! Don't ask me anything anymore, UNDERSTAND!