can someone explain this endcap to me? it looks like the exhaust has no where to go? am i just a moron? ive never seen something like this before

 

I used to think that way, but I was wrong. If you make a modification and it wants a leaner jet, does that mean it's getting less fuel? NO! Brake Specific Fuel Consumption can go up, while jetting goes down if the velocity of the intake charge pulls more fuel after the modifications. Continuous testing and design improvements are changing all the time, so make sure you have dyno tested, up do date and accurate information on the exhaust system you run.

don't trust plug readings on a DS650. If you can read them accurately, you are alot better than me! The dual plug system and the fact the ignition fires every revolution (not just compression stroke) keeps the plugs white and clean - you have to be really rich to get color on them - or at least that's been my experience.
222

 

I agree with 222

Understand. . . the higher the flow (in this case velocity through your carb) the lower the atmospheric pressure is inside your carb.

Since you put a bigger exhaust / open end-cap you have decreased restriction in the exhaust thus increasing flow of air in your engine and through your carb. . .

So. . . now you have higher velocity through your carb.

So, with reduced pressure in the body of the carb and constant (relatively) pressure on the fuel, your carb is essentially sucking harder on the straw and drawing more fuel into its thirsty self (Yum Yum. . . engine likey fuel).

So, you sometimes actually have to go to a smaller jet (straw) to get proper jetting.

This is the same information engineers use to design wings for airplanes and keeps these planes in the air. Off topic but, wings are shaped to get a faster air flow over the top of the wing to create a differential pressure causing lift (and that's all I know about airplanes!)

 

I thought we were talking about jets not planes

 

Very well said.
...and, you just explained why the metering rod on a Lectron looks like it does!
222

 

[img]i/expressions/face-icon-small-confused.gif[/img] If you say so [img]i/expressions/face-icon-small-confused.gif[/img] [img]i/expressions/face-icon-small-confused.gif[/img] [img]i/expressions/face-icon-small-confused.gif[/img]

I'ld like to run one of those on my Bike to see how it does vs. the FCR's but, I can't justify the $$ just to try something out. I know the FCR's can do the job and I really wonder at the 4500' ASL elevation I usually run at, if the FCR's aren't a better carb. I know the only way to tell this is to get one and try it but, my focu$ is NOT on spending more money right now. So, for now I guess I'll have to settle for being a little slower.

I've actually got a set of dual Lectron 41's I should send you to re-work for gas. They've been set-up for Alky and nave a few parts missiing. I just don't have the time to get them fixed up.

I've actually got an extra tranny and some other parts that I hear you guys may be interested in as cores to speed up your turn-a-round to customers too. One of these days when I have some time I'll have to get with you. . .

 

well...it does make some sense to what you guys are saying...maybe ill throw in my stock 165 with the yoshi and see how it goes...afterall it only takes like 2 min to change the jet.

 

Well i just got back from taking out the 173.5 main and putting in the stock 165 main, and was very surprised to see my top end was better...hmmm. Pretty sure you guys were right on this one...against the wind up hill on the highway i pulled my rev limiter and thats 80mph as before with the big jet i was having to tuck down with no wind and a super long stretch to pull it.....think i lost a tiny bit of mid tho......................I will test her out a little later tonight to really see if it made that much difference, there were to many factors this time with all the wind out there.

 

Well, mid is controlled by needle clip position and top by jet size right? Maybe you just need to go a little richer on the needle.

 

Yeah it sucks being broke.When i get rich[img]i/expressions/face-icon-small-wink.gif[/img][maybe in my afterlife] i'm going to buy my wife a quad to.Well i'll say it for her[img]i/expressions/face-icon-small-happy.gif[/img]