Bofeng Carb Boring.

[Jayraye39]

I found a way to bore out the bofeng Carb That does not effect the first 3/4 of throttle response, air/fuel ratio, and will give you a 3mph gain when held wide open..

This mod might not work if your motor is not ported, port matched, and case matched.

Take the stock intake tube bore out the top and bottom opening with a drill bit. the top to 16mm and the bottom match the size to the jug intake port.

Then take the carb turn it upside down and again use a drill bit to start shaving away 1mm of the roof of the throat. make shure to go back and forth slidings through the opening and the exit of the carb. I used and 8mm drill bit.

When your done it should look like a half egg shape at the top all the way through the carb.

Since we did not touch the side walls of the carb or change the shape of the lower 3/4 of the carb bore. We do not lose the venture effect. Their will be very little change in the throttle response and air fuel mixture. If your bike is jetted correctly it will run rich when at WOT.

Once at WOT you will have 1mm of extra air being mixed with the rich fuel to even out the power curve once again.. very liitle tuning required after doing this. All I had to do to fix the idle and overall performance of this mod was to simply sharpen the tip of my carb needle.. this mod will not work if you dont bore out the alum. intake tube to accept the larger itake of air/fuel.

when i ran after the mod my bike topped out at 47 mph when my previouse runs hit a wall at 44mph. when at WOT. If you cant get the slide to uncover the opening all the way. just cut 2 coils off the slide spring then stretch it out a hair. Your welcome and enjoy.

 

[GW's Motorized]

I see you dimpled th intake tube, does that even do anything with this small of an engine?

 

[Jayraye39]

I see you dimpled th intake tube, does that even do anything with this small of an engine?

I personally didnt think it would. but in an atempt to get this bike to 50mph. Im attempting anything. I do not have a test to support my opions oon this but the answer is YES. I feel more pep on the acceleration and a defined crispness the how the throttle responds. I ended up dimpling the entire track from top to bottom a few months back

 

[GW's Motorized]

I was toying with the idea of modding my old carb and intake just like this, but I haven't had much time between swapping carbs and going on a long road trip so I decided not to start on anything because I'd probably forget about it

 

[Jayraye39]

well if you attempt it in the future dont bore the entire opening bigger cause it will mess up the geometry of the entire carb and it will then be trash. ive attempted boreing 3 carbs and this is the only way I found worked and kept the functionality of the carb the same

 

[ImpulseRocket]

Basically a minor cathedral port. The reason it doesn't mess with the low speed is because the airflow is unaltered on the bottom. No change in intake velocity has occurred across the jet, so it will work the same. You just opened up the top of the throttle sweep a teeny bit to gain extra cross section at wot.

You could likely widen it to the same width as the standard venturi up top. Keihin did the same with the PZ venturi design, and for the same reason. Better total airflow with no adverse effects on low throttle fueling

 

[WillitBoost]

Can confirm, 8mm end mill, raised the roof of the BoFeng by 1.4mm, increased max rpm and HP. All round a great cheap mod! Still gets a bit rich up top but so much better than stock.

BT100 V1, Custom hydroformed expansion chamber.

 

[Jayraye39]

Thats awsome. I knew it would work. Have one member on hear which I blocked but he always is giving me crap because I never do the actual math with my mods. Instead I gather tons of info and combine that with common logic to take an educated guess on some of the parts or mods on my bike. then I report by posting my personal findings. This member said flat out "your mods arnt helpful" guessing never helps anybody". I told him i like to think outside of the box and my entire bike is an educated guess. the only way to find new mods is test ones theory or educated guess. thanks for running it on the dyno buddy. made my day

 

[WillitBoost]

Your logic is sound, and made complete sense to me so was worth trying. I can see his thinking in that if it's not proven, it's just a theory but in this case, I couldn't think of a reason not to try it - aside from potentially trashing a $5-10 carb.

What you've done I would never have even thought of doing, very creative! I've posted your mod in a few FB groups and hopefully it'll become a bit more of a mainstream free mod. I'll show it on my next youtube video too.

Nice work Jayraye39!

 

[GW's Motorized]

Your logic is sound, and made complete sense to me so was worth trying. I can see his thinking in that if it's not proven, it's just a theory but in this case, I couldn't think of a reason not to try it - aside from potentially trashing a $5-10 carb.

What you've done I would never have even thought of doing, very creative! I've posted your mod in a few FB groups and hopefully it'll become a bit more of a mainstream free mod. I'll show it on my next youtube video too.

Nice work Jayrae39!

You should check out some of his other mods. He's pretty good with the free moddi g type