I have an interesting problem with a 1984 Suzuki Katana 750. It won’t rev over 5000 and if you hold the throttle more than half open it splutters and loses all power. This is how we received the bike and we don’t know its previous history or what might have been done to it.
- Idle is good
- It has good power up to 5000 rev’s.
- Starts easily
- Doesn’t blow smoke
- I think it has correct carb’s.
- Constant Velocity BS 32SS Mikuni.
- The main’s are 117.5.
- Raising or lowering the needle has little effect. They are currently set to the middle position but I have tried top and bottom positions.
- I have tried the air screws in multiple position with little effect from half a turn out to 3 turns out, they all have the “O” ring fitted.
- I have tried raising and lowering the float level with little effect. It possibly seems a bit better if the level is higher.
- Carb’s seem clean inside with no evidence of varish or died fuel. I have sprayed CRC carby cleaner down all orifices.
- I can see the diaphram piston lift about half way on each of the carb’s but no further. They move freely and can be lifted by hand but don’t open further when the throttle is twisted.
- The diaphram’s look to be in good condition and seat properly.
- The butterflies fully open with the throttle.
- It has pod filters rather than the original air box.
- Timing light shows that advance moves about 10 degree’s when I rev it. Does anyone know if it should get more advance?
- Spark seems fine on all cyclinders.
- I have tried another coil.
- Pulse generators are approx. 400 ohms.
- If I put my hand over each carby inlet in turn (without pod filter) I get plently of fuel on it. So main jets are passing plenty of fuel.
- Extra earth’s have been connected to coils to ensure they are ok.
- Power is good at coils and igniter (12.7 volts)
-
Any idea’s would be appreciated.
- Idle is good
- It has good power up to 5000 rev’s.
- Starts easily
- Doesn’t blow smoke
- I think it has correct carb’s.
- Constant Velocity BS 32SS Mikuni.
- The main’s are 117.5.
- Raising or lowering the needle has little effect. They are currently set to the middle position but I have tried top and bottom positions.
- I have tried the air screws in multiple position with little effect from half a turn out to 3 turns out, they all have the “O” ring fitted.
- I have tried raising and lowering the float level with little effect. It possibly seems a bit better if the level is higher.
- Carb’s seem clean inside with no evidence of varish or died fuel. I have sprayed CRC carby cleaner down all orifices.
- I can see the diaphram piston lift about half way on each of the carb’s but no further. They move freely and can be lifted by hand but don’t open further when the throttle is twisted.
- The diaphram’s look to be in good condition and seat properly.
- The butterflies fully open with the throttle.
- It has pod filters rather than the original air box.
- Timing light shows that advance moves about 10 degree’s when I rev it. Does anyone know if it should get more advance?
- Spark seems fine on all cyclinders.
- I have tried another coil.
- Pulse generators are approx. 400 ohms.
- If I put my hand over each carby inlet in turn (without pod filter) I get plently of fuel on it. So main jets are passing plenty of fuel.
- Extra earth’s have been connected to coils to ensure they are ok.
- Power is good at coils and igniter (12.7 volts)
-
Any idea’s would be appreciated.
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