Topic: rev limiting issues

[friscochop849]

Been lurking around quite a bit on the site for past couple years but now I'm banging my head against a wall here. So for starters I have a 74 750 cases bored to 849 kit 78 f2 head with cycle x super flow Valves and heavy porting job on head. Cx-2 cam mikuni rs34 with k&n pods for them. Power arc ignition and ngk iridium plugs. Got the carbs 90% dialed in but can't get the motor to go over 7k rpm it acts like its hitting a rev limiter and when I wot the motor just chokes but if you ease in it fires all the way to 7k I have changed the maps on ignition and the heavier the advance curve the higher the motor revs up with the heaviest advance curve on it the bike rev limits at 8k now. I'm stumped and need some advice on this one guy's.

[lucky]

It is running lean.

Why don't you tell us how it is set up.
What intake system.
What exhaust system.
Main jet size.
Slide needle clip position.
Idle jet size.
Mixture screw adjustment.


I would bet if you give this bike quick throttle when warmed up, it wants to stall, bog, or just quit.

If you pull the choke out when it is running is the throttle response better?
It bet it would be.

[friscochop849]

Well it's got the stock carb rubbers on mikuni rs34 flatslides main jets are 120 idle jets are 17.5 don't know needle position and it has hot rod carpy 4 into 1 without a baffle. And your exactly right it does bog on hard throttle application but it doeant seem lean exhaust temps at the head are in the high 200s low 300s across the board.

[brandEn]

welcome to the forum

You should read the last half of this thread
http://forums.sohc4.net/index.php?topic=113293.200
He has a very similar setup as you ans has RS34's. He mentions his jetting and carb specs.

another good thread
http://forums.sohc4.net/index.php?topic=122398.0

another
http://forums.sohc4.net/index.php?topic=85462.0

Hope this helps!

[scottly]

it fires all the way to 7k I have changed the maps on ignition and the heavier the advance curve the higher the motor revs up with the heaviest advance curve on it the bike rev limits at 8k now. I'm stumped and need some advice on this one guy's.

Your initial advance setting may be retarded.