Jump to content

Lost acceleration and power band after rebuilding top end


G3mend

Recommended Posts

Hello all i just rebuilt my top end and went to 65mm pistons.  Im using stock carbs with 320 mains.  I have an open air box with KN air filter and a porting job.  When i bought the bike it screamed when it hit the power band.  Problem was it was jetted with 280 mains and i was running to lean and blew gasket and kept overheating.  At this point i decided to rebuild top end and go the next size up to 65mm.  Put everyhting back together and everything seemed good.  125 psi on each cylinder.  Broke it in using 15 minute heat cycles for a whole ank of gas never going above three quarter throttle.  After the break in, when i went to hit it (accelerate hard) and feel that notorious banshee acceleration it just want their.  Never really seemed to hit the power band.  While i rode i kept checking the temp of the head on each cylinder using a infrared thermometer.  The left cylinder seemed to top out at about 210" (fairly normal for hard riding i believe) and the right cylinder seemed to top out at about 175-180 degrees. 

 

It almost seems that the right cylinder isn't getting used to its full potential.  I swapped the ignition coils to see if the problem moved to the other cylinder but it did not.

 

Any help will be appreciated.  

 

PS i tried 320 and 330 mains and the same thing 

Link to comment
Share on other sites

Go through the carbs. Make sure they are in sync. Like surfjag said check the slides maby 1 or both are in backwards. Also 125psi for a ported banshee is very low. 125psi is stock. I would shoot for 150psi if your trying to run pump gas.

Negative, if there is port work on the exhaust it will lower comp. so if someone has a stock motor and ports it the compression will be lower if dome/head work isn't done.
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...