1991 DR 650 sounds like it will start, but does not...
 

Hi

I got this bike for a very fair price, but the kink is that it wont start.

When you kick it (kick only) it will give a pop or a series of pops but never more than that. The combustion sounds nice, no wierd sounds and if I increase the idle the pops will also come more frequently - when the bike decides to give them!

I have have tried to give it some brake cleaner in the fuelfilter (to check if it was gas starvation) and that did pretty much nothing.

I checked the valve clerance and it was ok.

If I dont use the decompression lever, then the bike is very difficult to kick so I think that there is compression.

The previous owner said that he started it after a long winter break and he rode round the block and it just died (wouldent react to the throttle) and since then he could not start it.

The carb has been cleaned and appears to be in good working order. The idle jet is a "50", the stock is a "45". The bike has an aftermarket exhaust which restricts alot less so I suspect that is why.

When I got it the pilot screw was backed out 8 and 1/4 turns and I have read elsewhere that standart is around 2 and 1/2 turns. But adjustments to the pilot screw seem to have no apparent effect on the starting difficulties.

Any ideas? Cracked piston? Rusty valves?

Just go down the line: Spark, fuel, compression, timing, vacuum leaks.

Take the spark plug out, plug it back into the spark plug wire and ground it to the frame. Kick start it and see if you've got a nice bright blue spark. How does the plug look? Sometimes replacing even a decent-looking plug will fix your problems.

Does the spark plug smell strongly of fuel after kicking it a few times? You said the bike sat for the winter. Does the tank have fuel? Is the petcock on and flowing? Is the fuel any good or is it old? Carb passages clear? Try using starter fluid instead of brake fluid straight into the intake (no filter) and see if that works.

Put your finger on the compression hole (or have somebody else do it) and then kick the bike. Finger should get blown off. Better yet, plug in a compression tester and get a number.

Check the timing.

Check the connections from the airbox to the carb to the head. Make sure all the boots are tight and snug, no leaks.

Even if everything is ok mechanically there is a technique to kickstarting large singles. I don't know about the specific requirements of a DR600 but for my XR600 Honda if you don't follow the routine (given in the handbook) you can be kicking for a while (to say the least).

Briefly it consists of - fuel on, hold decompressor in and kick three times to draw fuel through carb. choke on, decompressor in and turn engine to just past TDC with kickstart, (ignition on), make sure throttle is shut and do long swinging kick.

If it doesn't start repeat the last bit. If it still doesn't start then (ign off) fuel off, open throttle wide, decompressor in and kick over three times to clear out excess fuel. Then start again.

In addition, if the bike hasn't been started for a week or so drain and refill the carb float bowl otherwise, even using the technique above, it'll never go