will this help?

GoldenMotor.com

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
22
0
memphis Tn
No. The stock carb is going to limit airflow. Adding a bigger hose does not make the faucet flow more water so to speak.
You want a performance boost?
Add a tuned pipe.
 

rustycase

Gutter Rider
May 26, 2011
2,746
5
0
Left coast
Exactly what the maniac said!

IF you DO pull your intake manifold off your engine, it will probably reveal surface mis-matching and gasket restriction of the intake tract and frequently slag from original casting.
Attention to these situations will be of more benefit than a larger diameter tube.
Best
rc

... with any increase in power there is always some sort of trade-off.
a tuned pipe is the easiest way to get more power... usually at upper mid-range to top rpm... but you will lose bottom end torque. You must decide how you wish to ride the motor assisted bicycle.
 
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2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Another example of someone selling something and calling it "High Performance" in hopes of people buying it because of the name. It is a marketing ploy, along with words like 'speed', 'high output' and my favorite, 'billet'.

As Maniac said, you can only push so much through a given space at a given pressure. Enlarging the intake manifold diameter will not increase the carburetor venturi area.

Tom
 

rogergendron1

New Member
Sep 18, 2013
882
2
0
42
woburn ma
an 18mm ID intake manifold will only help flow if your carbs venturi is 18mm also !

if you have a 15mm carb a 18mm manifold will still only flow as much as a 15mm carb !

however if you run the mikuni vm18 and you have a 15mm intake than your restricted by 3mm ! then the 18mm intake will match your carbs venturi diamiter and flow correctly.

i run a 16mm carn and a 16.25mm intake it preforms verrry well ! i used to have the stock shorty intake and it was only 13mm ID my carb venturi was 16mm it was restricted by 3mm ! you could hold the throttle open with the motor off and the filter removed and looking into the venturi you could see the stock shorty intake manifold protruding into the carbs venturi boar 1.5mm a full 360 degrees. by swapping out to a longer and larger boar intake that is propperly matched to my carb i gained higher rpms and the motor revs up MUTCH quicker ! there was a small but noticable over all power increase as well, on the down side i lost fuel milage lol
 
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