Mickey,

Sounds like you are well on your way. It took me a while to get the jetting lined out but maybe you will have an easier time. Just don't get mad and give up, I almost did a couple of times, it will help when you get it lined out. Keep us posted on how it turns out.

 

UPDATE:
Just took it for a quick ride up the street with the swiss cheese lid installed. Its still jetted with the stock jets and I plan to install bigger jets and adjust the needles soon. I just wanted to see what would happen with this modded lid.

Well, it popped thru the carbs upon start up (indicating a lean condition...so I need to adjust the needles), but that stopped once it was warm. Upon driving it, it didn't cut out or make popping sounds, but it was noticeably sluggish compared to the old set-up (stock lid). On a positive note, it was still strong enuf to pull a big wheelie upon take-off. It sounded louder overall and kinda strange whenever I hammered the throttle. I'm quite sure its too lean now with the stock size jetting, so I'll go ahead and try 2 sizes richer to see how that does (along with adjust to the needles). Wish me luck...I'll try to keep everyone posted once.

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

With 9 one inch holes I expect you will be up near the 160's in your jetting before it is right. With my mods and 3 1" holes in the lid, I'm at 148-150.

 

NovaKaw650,
Thanx for the recommendation...that sounds like a good guess b/c I've had about 3 other people on the various atv forums tell me the same jetting recommendation. Whenever I think I ***FINALLY*** understand how this jetting stuff works, then I do a different mod and discover that I still have a lot to learn about jetting!

FYI: I live at 100' above sea level with 95 to 100 degree weather right now (very humid too). Maybe its my low altitude or year round warm temps, but for whatever reason I have noticed over the years that other folks with similar mods as me usually report having much bigger jet sizes than me??? For example, I used to have DAJ's installed along with some common mods (Nyroc pipe, Napa hose and Twin Air filter, stock V-force cams, Dyna cdi)...with those mods installed, DAJ instructions (plus the owner of DAJs) recommended keeping the stock size main jets...however, it ran WAY too rich at stock jetting and I ended up running 3 sizes BELOW stock jetting to make it work good with the DAJs. While I no longer have DAJs, but I'm still guessing that my proper jetting will be less than what other folks with similar mods have...but that's only a guess and I could be wrong. I'll try 145/148 first and see how that runs...if its too lean, then I'll go buy some bigger jets and try again.

Thanx again for your advice!

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

I have a Twin Peaks that is big bored with ported heads and fundy cams. The stock air box in practically any configuration didn't even come close to supplying enough air. I ended up with so many holes in the lid that it may as well be taken off. If it wasn't used to mount a Boondocker manifold I would have thrown it away. We ride a lot of deep mud so I was worried about mud in the airbox. This may sound hokey but I split an inner tube and made a bonnet that fit around the outside of the airbox and made a pretty decent shroud to deflect the flying mud and water. After riding in a very muddy rodeo the filter was still pretty clean. My only other suggestion is to use a very well maintained and oiled k&n in the event that some mud and water does make it's way into the airbox. Hope this helps

 

I have found some new info since this thread was started. I have a friend who has a DS650 he says it has a very similar carb set up, meaning both have vacume actuated slides. He says a trick the DS guys have been using for a while is when they completely remove their airboxes and put filters directly on the carbs the cut a couple of loops out of the needle or slid spring what ever you call it. This is suppost to weaken the spring thereby letting it open faster with less vaccume pressure needed. I haven't tried it but he said it was VERY common and when you really think about it it makes sence.

 

Fastfatboy,
Wow...what a great suggestion. I never would have thought about doing that. It just so happens that I have 2 extra (used) diaphram springs and may experiment with your idea. Thanx for the tips!

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

Take 3/4 of an inch off the overall length of the springs. If you pilot and needle circuits can deliver enough fuel, you will see a noticable difference in throttle response from a standing start.

 

NovaKaw,
Thanx for the advice. Do you think shortening the springs will require add'l carb adjustments like adding or removing a shim from the stock needles/adjusting the idle mix screws richer/leaner OR does this mod work fine without the need to adjust the carbs?

Happy trails...[img]i/expressions/face-icon-small-smile.gif[/img]

 

If you have a shim or two under the needle and the pilots opened up 3 - 3 1/2 turns, you should be good.