HELP!!! port and polish problems 97cc DB motor

[williambriggs]

Need help I recently mildly port and polished my friends 97cc engine and when we got it running again the low end power and ruined and you can barely move. I adjusted the carb and checked the spark plug so the engine is running at the right AFRs but that only made it a little better. We noticed that once you get the bike up to speed and the RPMs up then it feels fine even faster then stock but how do I fix the dramatic loss in low end power.

I think it might be that the intake air isn't moving fast enough at low rpm because the ports are too big now. Let me
Let me know what you think or if you have been in a similar situation.

Please help! Any posting is appropriated. Thanks

 

[minikenny]

I think it might be that the intake air isn't moving fast enough at low rpm because the ports are too big now.

Bingo. You are 100% correct.

Now you know how much is too much. :laugh:

 

[neo71665]

And this is why you don't port without a flowbench.

I learnt this lesson years ago on a smallblock chevy.

 

[williambriggs]

Ok thanks for replying back fast I'm gonna do some work on it tomorrow and see if I can fix it. Let you know what happens

 

[Twid]

Are you going to add more material via jb weld?

 

[FirePowerMinis]

I find it hard to believe that there is enough material there to drastically hurt performance with a "mild P&P".
A willy-nilly hogging may hurt the very bottom. Maybe. Nicked seat, vacuum leak, plenty of other possibilities.

 

[williambriggs]

I find it hard to believe that there is enough material there to drastically hurt performance with a "mild P&P".
A willy-nilly hogging may hurt the very bottom. Maybe. Nicked seat, vacuum leak, plenty of other possibilities.

Yeah your right, but I just remembered that I port matched a carb spacer that was designed to speed the air flow by using the Venturi effect. I messed up the shape now I don't have the air flow I need at low rpm. I all I need to do is replace the spacer but I can only find them for sale in a kit with a carb and gaskets so I don't wanna buy the whole thing. If anyone has seen it for sale alone let me know. Thanks.