Exhaust mod = performance boost

[dzdaz]

It finally got warm enough(above 35) to have a nicer ride here today. Still wasn't getting very good top end so I did the exhaust baffle cut off mod. WOW! I got better performance all around, better power, about a 5 mph boost, and less bogging at wide open. It did bog a little but then pushed through it and actually started to pick up more speed. Didn't really notice it being much louder, just a bit deeper at lower speeds. Reading thru this site has really been helpful. Thanks to everyone. I'll definitly be doing some more modifications to my bike in the future. e.g. sprocket, plug/wire, better oil/gas, etc... Anyone know where I can get a gas cap that doesn't seep or are they all pretty much the same? Mine came with the 70cc kit I got from dacscommm.

 

[azvinnie]

glad to hear ya riding in better weather, as far as the caps for the gas tanks, some leak and some don't, we just got a kit from dax and the carb dosen't work. i lent him my spare carb and his bike fired up and stayed running. kind of crappy but wtf can you do.....anyway im building a trike and might have a spare cap that l can send ya when im done going through all my parts that l have............you taker ez dz

 

[Guest]

Are you returning the carb, or are you going to try to get it working first?
Set the needle clip in the middle. Make sure the carb is getting fuel....that the float is letting fuel in.

 

[azvinnie]

when i held the carb in my hand i felt alot of rattleing, l open the bottom of the carb and noticed the throttle hole pin wasen't even screwd in(part#47on grubes diag). the other prob was that the cilinder (with the needle) that goes into the carb was getting stuck in the carb. i switched it with a spare carb and it worked fine. thank god for spare parts!!!!!

 

[dzdaz]

I'm gonna keep the carb, and try that needle washer adjustment.

 

[mrsaxman99]

how much of the baffle did you cut out? I cut the ~6" tube that is connect to the end cap off, and got an increase in power, but it cuts out at higher rpm due to bad backpressure

 

[Guest]

It's not cutting out due to bad back pressure- it's cutting out because now it can run faster and is running out of fuel. put the next larger sized jet in and set your clip in the slide to the middle notch.

If you don't have access to a larger jet, then you CAN drill the main jet out. Find a drill bit that almost fits in it and turn it in with your fingers....then pull it straight out and some of the jet material will come with it. no more than that though. If you aren't confident in trying this, then buy a bigger jet....your dealer/seller may be able to help with this.

 

[gone_fishin]

'joe...it seems most of these chinese carbs have 4 slots on the needle.

most of them run best on slot 2 from top, (me: gutted muffler w/cap on, #2 slot, cut-out at top-end) are you saying try #3 slot for a bit more fuel? i have and it hasn't improved performance, but i've been considering boring the jet a tad. after your post, i'm confident it's worth doing.

i'm sure others agree with me when i say i appreciate your layman's info 8)

 

[Guest]

'joe...it seems most of these chinese carbs have 4 slots on the needle.

Well...go figure!
most of them run best on slot 2 from top, (me: gutted muffler w/cap on, #2 slot, cut-out at top-end) are you saying try #3 slot for a bit more fuel? Nope, the cutting out at the top end would be from the main jet being too small i have and it hasn't improved performance, but i've been considering boring the jet a tad. after your post, i'm confident it's worth doing. YES! Just don't OVER do it...just the tiniest amount of metal will be removed. Take your time and find the right drill bit and go slow, you don't want to break it off. In fact if it's too large sized of a bit, it will be difficult to start the process.
i'm sure others agree with me when i say i appreciate your layman's info 8) Thank you sir, it's absolutely no problem.

FYI the idle mixture screw adjust the idle mixture to about 1/4 throttle. The needle covers from 1/4 to about 3/4-7/8 throttle, the main jet is pretty much for WOT.

 

[mrsaxman99]

we (me and augidog) don't have idle mixture screws...along with most of the rest of us. We have an idle screw...that just sets the lowest the idle will go...has nothing to do with mixture.