20 Most Recent 2008 Honda CB 750 - Page 3 Questions & Answers

possible water spry causing coils or spark plugs to arc to ground which will cause sluggish performance

firing order is 1 2 4 3 with 1 being on the left side of the bike

You will need to drain the carbs then remove the float bowls in order to clean the interior of each carb. Use spray carb cleaner and pay special attention to the float pin. Right now some trash is stopping one or more of the float pins from closing fully. This means gas flows into the carb(s) and the carb(s) have no way to stop the gas. The trash could be a bit of old rubber gasket, rust from the tank, a sliver of grass, or "cotton" from dandelions or trees. Those are the usual suspects. Please rate my answer. Thanks.

If it is grounded correctly then the coil must be bad.

one coil with the longer leads(I think goes on the left) and feeds cylnders 1&4, doesnt matter which
the other feeds 2&3, again doesnt matter which.
The coils fire on each stroke, compression and exhaust,

It sounds like bad coils to me. Coils should never arc from the coil wire, case or anywhere else. Please rate my answer. Thanks!

If you lost all electrics, it may be in the battery cables, check where it grounds to the frame and the engine, and check continuity of the cables themselves in case they have corroded or broken under the insulation.
.you said the main fuse is ok but does it have power to it? use a test light to check both side of fuse for power

It is probably the same chain. Look at your old chain. There will be a number stamped on some of the chain link side plates; 420 or the like. Match up the chain numbers to the new chain. You may need to replace sprockets. Look a them for wear.

It sounds like you are dealing with a bad spark plug cap. Unscrew the cap off of the end of the wire and check it with a voltage meter. It should read 5000 OHMS. If it is higher or lower replace the cap. If you purchase aftermarket NGK caps they will run about $5 each.

Do a compression test.

That sounds right to me. Once you have fitted the dyna coils, check the bike runs before fitting any electronic ignition. Many people are quick to throw away the points and condensors, but if you are not covering high milage every year is it really needed? If an electronic ignition fails, you are stuck. Points can be cleaned up and reset at the side of the road and are far cheaper to replace.

could be caused by a faulty or bad spark plug check the plugs for spoiling or none spark??

Taking a big breath here. Not knowing the maintenance of the motorcycle in question I'm going to assume (not a good thing to do) that the 750 starts and runs as it should through the idle and low speeds. If this is so then I would point you in the direction of the fuel filter and screen in the petcock/tank. What may be happening is the engine is being starved of gas at mid range where as enough fuel is entering the system at lower speeds.

If the filter(s) are clear or clean you may need to remove the carb(s) and clean out the high speed jets and reset the float heights. This is mostly labor as in time consuming. make sure the carb(s) are balanced and the slides are all opening and closing at the same time.

I haven't heard this "brake up" as you call it so if it's a lack of power stall hesitation and refuses to go over a certain point I'm thinking a fuel starve but, something else can be causing your greif and that is a break down in an ignition coil. Your bike is CDI ignition so if it's not the gas then the next thing is the coil(s)

Lastly because it's a four valve per cylinder design what could also be the problem is one of the exhaust valve springs in each cylinder my be weak or broken and allowing it to bounce or flutter.

Of course a trained ear could hear this at an idle or slightly blipping the throttle spitting or popping in the exhaust.

It could also be an intake valve and that can be seen in the carb throats and a gas wet air filter with gas laying in the air box.

Okay and the final thing is a worn cam chain with to much slack which has altered the valve timing and that's a bad thing, actually the valve problem isn't to good ether.

If one of the valve keepers drops off because the valve spring is week or broken that valve could drop into the cylinder and basically grenades the engine.

If the cam chain is loose it could break and personal experience I've had one break and it just cut the engine cylinders in half.

Your gas is the first thing I'd go after.

All Honda's make a rattle sound at idle. It goes away when you pull in the clutch lever or drive down the road. New or old , it is a normal sound for a Honda motorcycle. It did it when it was brand new and it will do it when it has 120,000 miles on it. Understand it, get used to it, any Honda rider will tell you there is no way to stop it . It is just a normal Honda sound.. Now go out and ride.

If you are talking about the ones that come from the very bottom of the carbs they usally go down behind the motor and point to the ground. These are drain hoses and you wnat to route them so if the carbs leak or you need to drain the carbs it wont get on a hot motor.

red hot black ground

what about it.

The rings or valve seals are letting the compressed fuel mix escape thereby pressurising the rest of the engine
The froth is old oil mixed with water - drain & flush engine

You have two coils with two wires each. If one plug wire is firing on a coil the other wire is also firing. Start by replacing your spark plug caps and your spark plugs . NGK makes plug caps for around $5 each. Spark plug caps unscrew off the end of the wire and should measure 5000 OHMs on a voltmeter. If they read higher or lower replace them. With any luck all spark plugs will now spark.

About the only thing I can think of on the rattle is a broken gear tooth or a cap nut from and OHC mount has come loose or has come off and followed the cam chain down into the gearbox. I would be leery about riding it until the problem is found. The last thing you need is to be sliding on the concrete in traffic after the rattle gets in the wrong place and locks ou the gearbox at 60 mph.