I just got back. Top speed did not change any, but my throttle response is now perfect. It gained a lot in the low speed, low to mid rpm stuff.

It really takes off. It does spinouts in high on asphault. But that seems to be wearing the tires a lot faster. Wheelies at the drop of a hat.

The muffler mod I did sounds awesome, but not loud. See this picture.

 

Hey guys. I just popped the airbox cover off and went for a quick tear. It ran way worse!!!! What's up with that? I threw the cover back on and it went like a raped snake!! I don't get it. A little help please?

 

You hafta rejet if you leave the cover off. You will get gobs of power from airbox mods, if properly jetted.

 

Thanks Nyroc. Carburetion is not my thing. Guess I'm gonna have to learn.

 

Yeah Kingmort, I just replaced the shop vac hose with a piece of S shaped radiator hose and got the exact same result at low and high speed(still slower at top speed)
So i have ordered a K&N filter with jet kit as it appears we are running lean.
Question NYROC, can the jets be installed without removing the carburetors?

 

So nyroc which jets are you running now? Are they right on or are they running a bit fat? One more question if I may. How many turns out are you running your air mixture screw at?
R.

 

I have the air screws turned to 3 turns. I am using 130 main jet in front and 134 in back. I changed to these jets since I modified my exhaust. Yeah, Prairiedust, the jet kit is installed w/o removing carbs. It is relatively easy, except for the jets being so tight.

My top speed is not as great as I think it should be, it does 62 fairly easy, 63 on a good day, and 66 down slight incline. These speeds are not diameter corrected for the 26" tires, compared to the 24.5" stockers. However, my low and midrange is incredible. I wheelie at the drop of a hat. I feel that my 650 should do better at high speed.

I am not sure if there is more speed locked up in the carb. One guy said he did 74 w/o the lid on. You guys are going slower with mods. I know you are lean if you slowed down.

My own experience with the top speed is confusing. I was getting 62 or 63 efore changing the belt, and it was really high rpm. When I changed the belt, I hit 62 or 63, but at a lower rpm. That is confusing to me. The camshaft can't do that. The cdi could be speed (not rpm limited) and if the carb was not jetted quite right I would get way different results. I don't know why it did not change at all.

I am just plain and simply cornfused about you guys that are slower with the airbox mods. Maybe we all gotta change our air jets? I use smaller air jets to richen up the high rpm at full throttle on a car with a Dellorto or a Weber carburetor, but these Keihin CV carbs are new to me still.

 

NYROC.
You could be experencing a slower top end speed due partialy to the fact that your old belt may have been streched. This may have made it ride higher on the primary clutch then your new belt, which would have given you a higher gear ratio. If this is the case you should have noticed a better bottom end and mid-range with the new belt.
I have not been a big fan on the ware patterens the belts have been leaving on the drive clutches to begin with. I personaly think the belts are incorectly sized for the clutch dimentions. I am hoping that when Gates makes a new belt for our machines that we will find new gained preformances.
R.

 

PrairieDust; what altitude are you at? I was considering doing the radiator hose thing to mine, but I don't really want to have to go through the trouble of re-jetting. I live in Vegas, and the elevation here is 2100 feet. I don't know if mine is running rich enough to install the hose or not with positive effects. How much speed did you loose? If it isn't very much, like only 2 or 3 mph off the max top speed, it might be worth the trade off if you gain more power in the low and mid range of the power curve. I know I would appreciate the low and mid range power gain more than absolute top end. I have had mine up to 67 mph one time just to see if it would do it. Otherwise, I could enjoy more acceleration if that is what you get by adding the hose. Does it pull harder than stock above 45 to 50 mph with the hose on it? It would be nice if it would boost the acceleration in that area which is were acceleration starts to drop off on the stock 650. What was your top speed after you installed the hose, and how did you determine that it improved low-end power?

 

Area51, I am pretty much sea level so I would say that you will notice a huge low to mid rpm gain and probably be right the money as far as fuel/air mixture at high rpm.
Go for it!!!