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Is my carb upgrade logic sound?
Posted: Tue Sep 25, 2012 7:25 pm
by patthesoundguy
I'm going to upgrade the carb on my express because I put a 70cc kit on it and the stock carb is not cutting it. It going to get a new intake to match the carb. So here is my logic every one tell me if this makes sense... if my kit is 40% larger than stock then would a 40% upsize in carb make sense. So if the stock carb is 12mm then add 40% I get 16.8mm or round up to 17mm. My gut tells me a 19mm would be perfect but I have know Idea why. I need some guidance or I'm gonna go nuts trying to decide what to buy.
Re: Is my carb upgrade logic sound?
Posted: Tue Sep 25, 2012 7:33 pm
by abreen89
Go with the 19mm i put it on my 48mm bbk and worked great had great throttle response. If you get the 19mm from a hona aero 125 you can keep the bystarter set up as well
Re: Is my carb upgrade logic sound?
Posted: Tue Sep 25, 2012 7:48 pm
by patthesoundguy
abreen89 wrote:Go with the 19mm i put it on my 48mm bbk and worked great had great throttle response. If you get the 19mm from a hona aero 125 you can keep the bystarter set up as well
Thanks that's the kind of epearience I was looking for

19mm delorto phbg carb is going on the list. throttle response is what I'm looking for.
Re: Is my carb upgrade logic sound?
Posted: Tue Sep 25, 2012 9:22 pm
by abreen89
does the express have electric choke? if so go with something like this
http://www.ebay.com/itm/Honda-Scooter-N ... 9f&vxp=mtr
Re: Is my carb upgrade logic sound?
Posted: Wed Sep 26, 2012 10:27 am
by patthesoundguy
It has a manual cable choke. I ordered the delorto to match . The carb has replacable jets for the starter enrichment, idle pilot and main jet. I also ordered the racing float bowl with the drain plug that grants access to the main jet with out having to remove the carb or the bowl

that bike should work right with all of the goodies. It has 70cc kit on it now with boysen 2stage reeds stock carb with non removable main jet drillled. The bike works but its not breathing right through the tiny stock carb. There is the new intake, carb and filter assembly on the way.
Re: Is my carb upgrade logic sound?
Posted: Wed Sep 26, 2012 10:49 am
by LMH
Nice Im glad ya got to use the reeds I sent ya, a 19mm is the smallest Id use on the 70cc. I ended up taking off my Arechi 19mm for the OKO 24mm, but its was for top end more than throttle response.
Re: Is my carb upgrade logic sound?
Posted: Wed Sep 26, 2012 10:50 pm
by martynkim
abreen89 wrote:Go with the 19mm i put it on my 48mm bbk and worked great had great throttle response. If you get the 19mm from a hona aero 125 you can keep the bystarter set up as well
As I have done the BBK on the express 24 mm is the only way to go. That deltoro will hit just right then.
Re: Is my carb upgrade logic sound?
Posted: Thu Sep 27, 2012 12:25 am
by abreen89
martynkim wrote:abreen89 wrote:Go with the 19mm i put it on my 48mm bbk and worked great had great throttle response. If you get the 19mm from a hona aero 125 you can keep the bystarter set up as well
As I have done the BBK on the express 24 mm is the only way to go. That deltoro will hit just right then.
Listen to Marty he has the experience with the express but hey trying something different isnt out of line either. You never know what different carbs will do.
Re: Is my carb upgrade logic sound?
Posted: Sat Sep 29, 2012 1:18 pm
by DaylightDies
I ran a 19mm on a 70cc kit, was awesome! Alot more fuel consumption though

I think a 17.5mm might be better, and it seems eliteguy50 is trying to test that out.
Re: Is my carb upgrade logic sound?
Posted: Sat Sep 29, 2012 5:42 pm
by abreen89
DaylightDies wrote:I ran a 19mm on a 70cc kit, was awesome! Alot more fuel consumption though

I think a 17.5mm might be better, and it seems eliteguy50 is trying to test that out.
yea thats what im saying 19mm is good for up to 90cc. going any bigger would just be a waste of fuel

Re: Is my carb upgrade logic sound?
Posted: Fri Oct 05, 2012 10:46 pm
by patthesoundguy
Intake, carb and new air filter arrived yesterday. all I can say is wow

I'm so very glad I bought the trail tech CHT gauge, it makes setting up a new carb so much easier.
A plug chop or two and a larger pilot jet and I'm laughin
