Originally Posted by threepot
Hi guys,can you throw some light on this?,recently bought 96 Tiger. Bike was cutting out after about 3 miles..traced that to blocked carb inlet filter. But now it runs poorly at low revs..hesitant,but clears when i open throttle to accelerate.Not sure if this was before clearing filter,didnt ride it far b4 buying..mistake!New plugs fitted. Noticed it has k&n air filter and std silencers.Have recently cleaned carbs,checked float heights,checked pilot screws..seems to be flat spot under hard acceleration now? Thanks
Here's what I'd do -
Check the colour of the plugs, this usually gives a good indication of what's going on. Black & sooty means too rich, white means too lean. Black and oily is an ignition problem. They should all look roughly the same colour. If not then the odd one out is the problem cylinder/carb.
Check the carb rubbers and complete primary airbox for leaks, when the PO installed the K&N he or she could have put it back together badly, maybe put some silicone in the joint (there's only one). Oh and make sure both of those hoses underneath are connected too, the breather hose and the overflow hose.
Pull the carbs out again and change the tiny 3mm O-Rings in the idle screw holes, they should also have a metal washer that sits between them and the spring. If it's not there, buy new ones. Set the screws to 2.5 turns out.
EDIT - another thing to watch out for is a second rubber or washer stuck in the idle screw holes, make sure they are empty before re-assembly in the order - O-Ring, metal washer, spring, idle screw. You can also stretch the springs a little to give them more strength, and lubricate the thread to avoid serious problems in the future!!
Change the O-Rings under the throttle slides , they're cheap as chips but can cause big problems.
Clean the idle jets thouroughly, and make sure you can see through them and that the holes are clear. Use a piece of brass wire to clear any blockages.
Check the throttle slides for correct operation, they should rise and fall easily and smoothly. If there's resistance - something's wrong. Maybe not relevant in your case as they are high speed related, not idle, but while you're in there you might as well.
Check the choke plungers for correct and free operation, are they closing properly? Pull the springs a bit to make them a bit longer, this gives them more "closing strength" I've found. And lubricate the shafts.
Check the idle air inlet jets at the rear of the carb - they are the ones in the RHS hole that are removable, the LHS holes are emulsion tube air inlet jets and are fixed but should also obviously be clear.
Look at the throttle butterflies to see if anything is awry. They should all look the same, apart from that I can't describe any known problem. You might look for odd staining on the wall of the carb, that could indicate an air leak from around the throttle shaft.
Balance the carbs. She aint gonna run too well if the carbs aren't balanced. You'll either have to have your own tool for this or take it to a garage. If you're going to buy your own I recommend the Morgan Carbtune Pro, it's cheap and works really well.
You said you checked the float height, not sure how you did it, but this is how I do it. Remove the float bowls and rotate the carbs so that the floats move from the open (sitting low in the float bowl) to closed position (sitting high up in the carb body). Do it a few times and when you see that they reach the closed position (you'll see them stop moving as the carbs continue to rotate, should be at about the 60° point), stop rotating - the floats have a line along their mid section, that should form a parallel line with the base of the carb.
As long as they look near enough parallel, you're good to go. Again, they're not going to affect the idle performance, so I shouldn't worry too much.
The only thing that's going to cost you money is the O-Rings (cheap as), and the balance tool if you don't have one (a bit expensive, around the 60 - 70 euro mark).
Here's everything I have that's carb related -
Apart from that I have no more ideas
Hope it works out