Back Firing/Surging At Speed(60mph/100kmh+)
 

Trying to sort out the above problem with my 94 XT600E (34000 km) has seen me trawl all 114 pages of ideas and advice on this site (with a special mention for Aukeboss) as well as a German site and others.
I have come up with a list of possibilities(and cited cures) that may help others to avoid the trawling.
The list is not exhaustive(but will be exhausting for my mechanic) and may be erroneous in that some of it is third hand and may suffer through translation problems.
While I have tried to group them into particular areas they are recorded just as I read them and are in no particular logical order.

None of this is my advice.

Feel free to correct or add to the list.
Proper names of parts wouldn't hurt.

AIR
*Clean/replace air filter-wash 3 times with petrol(while another guy prefers Prepsol Engine Degreaser), dry, oil lightly with engine oil or air filter oil.
*Airbox and Air Intake System blockage
*Air snorkel to CPI blockage
*Air Box-wire mesh gauze supporting air filter corroded

FUEL
*Take off tank, remove tap, make sure filters on tap clean
*Clogged petcock
*Petrol cap breather blocked..vacuum in tank
*Fuel line too close to cylinder leading to fuel vaporisation
*Strainer on reserve blocked
*In line filter/s blocked
*Check flow from tank
*Ethanol and Float Level in Carburettor problem..get additive/new needle.

CARBURETTOR
*Obstruction above needle-clogged white screen above needle valve-discard and replace with in line filters
*Reset Carb settings to standard
*Clean Carb-small filter blocked-remove float, undo Phillips screw, pull out brass bit that float/needle sits in-discard replace with in line filters
*Cracked manifold rubbers..Carb seating rubber(same thing?)..get many mentions as the culprit...idle engine spray manifold/carb connection with carb cleaner or water-if engine note changes then seal is cracked/perished..don't overtighten hose clips on rubbers
*Diaphragm on second carb damaged
*Pilot air screw in base of primary carb(?)
*Synchronisation of second(RH) carb-valve in mixture channel to cylinder head should NOT start opening at 5mm lift of primary slide but at 7mm. Adjust by putting 7mm drill bit under slide LH carb and adjust screw until butterfly valve just opens
*Check vacuum operated slide of second (RH) carb-does it move easily and return to rest position after opening?

ENGINE
*Top piston ring worn
*Cam shaft not correctly alligned

ELECTRICAL
*Pick up Coil breaking down when engine is hot
*Bad connection at ECU
*Plug damaged or incorrect gap
*Kickstand safety switch fault
*Weak signal to spark plug
*Coil faulty
*Bad connection in CDI to ignition switch wire
*Spark arrestor wire mesh in 'inner silencer' clogged
*Loose wire that connects to a 'black box' (that regulates timing of spark?) under the panel above the rear wheel

Thanks for your effort. Quick referral lists like this are always handy and save having to do the trawl that you have just done. I hope that you get your surge sorted.
:thumbup1:

The stock airfilter is a dry paper type, you cant clean it like a foamfilter, snd it shouldn't be oiled.

Only way to "clean" it, is to use compressed air. and/or tap it to get dirt/sand out.

I did have once upon a time a similar problem...

There is a relay on the outside of the battery BOX (on the LHS).
Mine got loose and broke the outer casing and when it vibrated sometimes it would touch the frame or engine and would make my bike surge and backfire!

It is attached to the battery box with a rubber band!
It should be right next to the solenoid!



Vando :cool4:

I have seen printed on some original paper type Toyota van air filters the cleaning instructions. It states to wash the filter with water and detergent(after blowing it out with compressed air if you have it) then rinse and dry.
Obviously the drying will take a day or so(speaking from experience), so normally this wouldn't be a very practical idea. But if you have little money or short arms and deep pockets, and don't mind your bike parked-up for a day or 2 this could be an option.
Bob