Motorcycle Repair: 1984 Honda Magna Vf700 bogging Problem, spark plug wires, 1984 honda magna

Question
Hi Bill,

I have a 1984 Honda Magna, 700cc that "boggs down" when it hits 6000rpm or higher, or at load.  

So far I have rebuilt the carb (remove and reinstall 4x times looking for problems in the carb), sync the carb, install new jets, check the floats, install new fuel filter, new plugs... Even had a master car mechanic that is pretty good at troubleshooting motorcycle (he has a magna also), had the mechanic scoped on a computer reading the KV and says no problem with any cylinders or spark.  I even took the carb completely out and had the mechanic personally look at each float bowls, checking the jets and float gap and sync the carb for me.  I ask the mechanic could it be the spark plug wires, bad ground, ignition coil and he said the KV check on the scope indicates no problems.  I ask him if loss of vacuum would cause the problem and he said no.  Mechanic told me he couldn't find any other problems.  

The bike fires up instantly and idles like a kitten at 1000rpm.  Accelerates with no problem up to 5000rpm.  Then it hesitates, bogs, no power once it hits 6000rpm.  This problem began when I put to much concentrate fuel injector cleaner in the tank trying to clean out the carbs.  Again, carbs seems to running like brand new now after I rebuild it.  

Any advice would be greatly appreciated.

Bruce

Answer
Bruce, check out this link first...
http://users.rcn.com/kochc/moto/spark/ig_repair.html

You have focused on the carbs, and it would appear that they should be in fine condition. Excess use of fuel cleaners can damage other parts in the system...
Petcock... The rubber gasket inside the petcock may have melted with the fuel conditioner, causing starvation at higher rpms.
Fuel filter.. replace if in doubt.
Fuel pump, fuel cut relays should be checked for function and flow.
Check the fuel tank venting system to see if there is a reason to cause a fuel flow restriction at higher speeds.

http://www.powersportspro.com/partsfish/ to see online microfiche illustrations of your bike.

Bill Silver