So I jetted my bike tonight, And it seems to be running fine. This is the first time ever touching a carb. It only took my 3 1/2 hour's, But I did also install ims tank so that added alittle more time I do have some questions.

Right now im running DJ124, 3rd groove on the needle, And the mixture screw around 3 turns out, With a stock exhaust, stock air filter till my Uni air filter shows up hopefully tomorrow, Snorkel removed, And air injection system is also removed.

Im wanting to know if a KDX200 snorkel would be a better idea then it being removed? Also would drilling the the first baffle out of the stock exhaust help any? The only thing i've noticed is I still needs a little throttle to start when hot. I did only get to ride for 15 mins, Because it's been raining all day. So im hoping to ride some more tomorrow to see how it does on a longer ride.

Thanks for any help

 

My guess is you are running rich right now. Opening up the exhaust should make it a bit more lean. Putting in the KDX snorkle will make it a bit richer than no snorkle. I'd think you could have your air/fuel screw in much more than 3 at this point. I also thought it was the second clip position that was about right for a bike a bit more opened up than yours.

But, every bike is a bit different!

Oh, and, more importantly: I'm no jetting expert by any means! Hopefully, one of those will come along soon and help you out more than I can.

 

I went by the dynojet stage 2 instructions, Because it's my first time jetting anything It seems to be running fine other then needing just a tiny bit of throttle when starting hot. Im hoping that it doesn't rain tomorrow so I can take it out for a longer ride.

When I first started it after getting it all back toghther, It only needed the choke for 10-15 sec then it was good to go. Way better then when it was stock. I had to let it warm up for at least 5 mins even on a 90f day, And it would still drop on it's face until it was fully warmed up. I think ill take a drill to the stock exhaust unless someone has something against it.

 

Wait until your uni filter is installed, Stage two is for a performance exhaust though. Read the stage one instructions and look at the differences and if you feel changes are necessary go in that direction. Follow the instructions that came with the kit for best results though. I've installed many kits over the years and Dynojets are usually very close to perfect if you do it right.

 

When I first picked up my 2006 a year ago, it was all stock. I was ready to drill the baffle after reading lots of posts. Then I started finding some saying it didn't really do much at all. And worse it ruins the spark arrester. If you don't need a spark arrester (all city driving), then give it a try but don't expect much. But if you ride public land, I wouldn't suggest it. I put on a used HMF can found on ebay for $120.

DavidR has done the best mods to the stock muffler that I've found, but I think his work deleted the spark arrester. Search around and you should find his thread.

BTW, I have DJ 124 main, clip 2nd down, stock #35 pilot, and drilled the enrichment jet (choke) to 0.018". Mix screw about 2 turns out (Kouba screw...easily adjusted). Also lid off, twin air filter, smog delete, power bomb header, HMF slip on can. I was going to move clip to 3rd, although it was there at one time and I think 2nd down is a little better for me. But next time in the carb I hopefully will be doing a big bore kit. I have to give a little throttle to start hot also, and it doesn't bother me. Before kitting, it was choke nearly all the time.

 

Welcome aboard, HiLuckyB.

You are going to hear lots of differing opinions about jetting, air box, exhaust, etc. The trick is to find out what works best on your bike.

For proper running, a high intake velocity is important. The faster you can make the air rush into the engine, the more efficiency (power) you will have. I think the factory has pretty well optimized the intake tract for this. Increase the size (KDX snorkel, remove air box lid, etc.) then intake velocity must decrease.

Along with decreased velocity which takes away some of the ram effect of the air flow, turbulence is created which affects jetting in an unpredictable manner.

Without a dyno, it takes a little more work to get the jetting right, but can be done. Low speed and mid range will have to be done by feel and driveability. The main jet can be tested by high speed, full throttle acceleration runs.

It is more difficult to "feel" a rich running bike than a lean running one without lots of experience. For the low speed and mid range circuits, I find it easiest to jet down until the bike runs too lean and the go back up a step.

IMO, there are really just two breathing restrictions on the bike. First is the muffler. Second is the valve area. Since the snorkel area is already much larger than the intake valve area, there is no gain by making the snorkel larger. (The KDX, being a two stroke does not have this issue).

So, I would suggest making one change at a time and test. If the change is better, go another step until it gets worse, then go back to the previous setting. You will need to do this for the pilot circuit, mid range (needle) and main jet.

BTW, it is normal to have to open the throttle slightly with a warm engine.

Good luck.

Ron

 

I don't know if it is normal, but I also have to crack the throttle to start the warm engine. It is pretty irritating. I don't have to push on the accelerator pedal of my trucks to start them. Surely this can be fixed?

Comparing intake or exhaust valve area to any other area to try and find the weakest link is flawed I think. For one thing, the valves are open momentarily while the other openings are open full time. Might be better to compare the carb throat to the snorkel throat. Both of which are smaller than the exhaust which is intermittently passing pulses of hot air at a much high flow rate than the intake.

 

Taking a wild guess here... but I bet your truck is fuel injected. Your bike is carbureted. Those of us old enough to remember carbureted vehicles will attest that pumping it before starting (or choking it, before automatic chokes were standard equipment) was standard procedure. Carb'd sleds are the same way... in fact, some people don't know how to start a flooded sled. They'll wait for 30 mins or so, instead of just cracking the throttle wide open and pulling it over. Sounds perfectly normal to me to have to give it a little throttle to get it started - especially if you have messed with the jetting (i.e. made it richer).

 

Yeah, but our old carbed vehicles usually always had an accelerator pump built into the carb, so when you pumped that pedal, you actually pumped fuel into the intake to aid starting...or accidentally flood the engine sometimes. The reason our motorcycles without an accelerator pump respond to cracking the throttle when starting hot is because the given jetting and/or the design of the carb responds better to the increased air for the air/fuel mixture. This is a bit how a "hot start circuit" works on some bikes that are equipped with it. A hot engine generally needs more air and less fuel, because fuel atomization is usually more efficient at higher temps. I'm sure I'm missing some of the science and particulars here in my description, but that's about all I know about the hot start process.

 

Keep in mind that the air enters the engine under atmospheric pressure and the exhaust leaves under much more pressure.

Ron