possible coil problem

[905teg]

My bike runs perfect until it warms up, after about 7mins of riding the bike starts to run like crap and starts running on 2-3clyinders. Sometimes it goes back to all 4 cylinders and most times it will just stall when i come to a stop.

I sent my bike out to have the carbs cleaned and synced, they added an inline flilter and kreem lined the tank.

I get the bike back and its still doing the exact same thing. I inspect the bike and find one of the wires from the right coil loose. The slot/housing where the wire attaches into the coil is broken off, the wire is still connected to the screw but its loose and exposed.

I picked up a new set of coils from a gsxr 750 88-91. I installed the coils and now my bike wont start at all. I tested each plug and each has spark.

Any thoughts?

[Chris H]

Regarding the coil change if you fit the old coil do you get the old symptoms or is it a none runner no matter wot?. And if you get it running again them look at possible air leaks due to expansion, also valveclearences.

[905teg]

I reinstalled the left one and still no start.

I'm going to remove the plugs a start the bike to see if any gas comes out, as well as drain the carb bowls.

If I still can't start the bike, i'm stumped.

I have spark, fuel and compression should be fine because it ran perfect before it cut out.

[905teg]

I drained the carb bowls, they all had fuel in them.

I rechecked for spark, all cylinders have spark.

i tried bump starting, i get nothing.

question: Does it matter which cylinder the Ht wires go to from each coil? (ex. left coil  to 1-4 or 4-1 and right coil 2-3 or 3-2) I tried both ways, still nothing.

[Wudy]

Think it does matter yes mate.

Left: 1&4
Right: 2&3

Can't give any more help as to why it's not starting though, sorry!

[905teg]

Ok I think I fixed it!!

First thing I did was spray quick start into the air box, fired right up. Let it idle for 1-15mins, idled normal. Took it for a ride and the same thing started happening, the bike lost power and was running on 2-3 cylinders. Died once I came to a stop and did not restart.

Took the bike apart and checked the vacuum line, it was working fine. I removed the fuel line with fuel filter that connected to the carbs and ran it to a jerry can. I left the vacuum line connected and started the bike, no fuel coming out. I turned off the bike and switched the petcock to prime, still no gas. So I removed the fuel filter and started it up again, this time a smooth flow of gas came out. Turned off the bike and switched the petcock to prime and fuel came out.

Put everything back together without the fuel filter and the bike runs better than ever. I guess there is not enough vaccum pressure to pull gas through the fuel filter. When I put my finger over the vacuum line it has very light suction.

Side note: I tested the resistance on the 88' GSXR 750 coils and they are 3.5ohms, so they work fine on out bandits. They are bigger coils and mount with only one grounding point.

I hope I can ride trouble free for the rest of the season.

[97af]

I read all of the posts and said "its the fuel filter" to myself. Been there,done that. I dont think its the vacuum that is the problem, It is the height relation of the petcock to the gas inlet of the carbs that is the problem. There just isnt enough pressure for the fuel to go through a restrictive fuel filter....which really sucks. You probably wont have any dirt gremlins in the "oh so tiny" pilots now that the tank is clean.