The saga continues!
 

I have now replaced the relays, rectifier, starter button and neutral switch. The bike is now giving a nice healthy spark, but will only run for about 3 minutes. Stripped and cleaned the carbs yesterday, not had a chance to try it today, but will try and get a look tommorow.

We also checked for sticky valves, and all appears to be ok. Have rigged up an alternative fuel supply, and put an HT tester on the plug so we can check if the spark is staying strong. Hopefully this will give us conclusive proof of whether or not the engine is losing it's spark while running. There was dirt in the carbs, but nothing too excessive, may have been enough to clog the jets though. Also using fresh fuel to try it out.


Fingers crossed!

Pete

Here is something else to try. My XT600 3AJ was sluttering at high revs. Felt like fuel problem, so cleaned out the carb. Found red fluff in float valve filter, turned out to be the paper from the inline filter had broken up. It also slightly clogged up the fuel pump. Not sure if you use inline fuel filters, but it might be worth checking the fuel pump for muck, tends to get neglected.

Thanks for that, somethin else to check out at the weekend.

Pete

When you cleaned the carbs did you check the small filter under the float needle held in place by the philips screw.
This can get blocked causing fuel starvation and engine to stop but engine will restart once fuel passes through the blocked filter.

No, didnt check that, another job for Saturday.

Thanks for that.

Pete

The XT still has a strong spark, but still not runnin right.

We tried some easy start in the carbs, fired instantly and ran for a good 5 minutes, before cutting out. Fired again instantly with another whiff of the evil stuff, and ran again, but cut out. Third time, it backfired and blew the carbs off again.

Cant find any mention in the manual of this wee filter in the carb, so haven't managed to check it yet. Could it be a mix up with some of the hoses on the carb? Getting a good strong regular blue spark, so I think all the electrical demons are gone.

Any ideas?

Pete

To find the float valve filter, remove float bowl, remove float and valve. You will find filter underneath where the valve sat, its rather small wire gauze, I think there might be a philips screw holding it in place. Hope this helps.

Had a look in my clymer XT600 manual page 239
note no.10
Remove the screw securing the fuel valve seat and remove the fuel valve seat

You will find the filter here.

Good luck

Thanks for that guys, I'll have a look ASAP

Pete

Ok I just got the carb off at the weekend and there was flakes of paint in the wee filter behind the jet. Next stage is to bybass the fuel pump, but didnt get the chance to try it. The bike was sparking away good style right up till it stopped. If it runs, we'll blow out the pump with the airline and stick inline filters into the feeds from the tank, or just run it without the pump.

Hopefully this will put an end to this bloody infuriating story.

Pete

Lets hope you have found the cause.

Well Ive now removed the fuel pump, put fresh fuel in the tank, and it's still the same. I still have a good healthy spark, and there is fuel getting to the carbs. But the bloody thing wont run for more than a couple of minutes.

The carbs were stripped, cleaned and blown out with an airline.

Am I missing something totally obvious, or is the obvious thing to sell it and cut my losses?

Pete

Spark + fuel = explosion, every time!
 

Pete,
I know how you feel (reasons x many in my posts of recent past!).

Could you have an airlock forming in your fuel tank after running the engine for a few minutes - mine certainly gets a lack of atmos pressure in there and I loosen the cap occasionally; there is always a hiss of air going into there.

Might be worth reading back over earlier threads about running problems for the XT/TT - this has helped me a lot to get new angles on a problem.

Alternatively or as well as, review what has changed - what has caused this to start now? Summarise and recap the issues in this thread - I have found that over time I have lost sight of the obvious!! :rolleyes2:

I hope this helps, if only a bit!

Dave

starting probs.
 

try taking the coil off and sanding the frame behind to bare metal.spray on some wd40 and rebuild.this helped my tt600r.also set all carb to factory settings.ie.float,idle air screw etc.my bike runs and starts great at 3.25 turns out.also set auto decomp cable.i can now start my bike 1/2 kicks hot or cold.:thumbup1:

XT v's TTR
 

Ade,
Pete has an XT which may not have the same carb (or decomp cable, esp if it has a starter motor) - but what do I know!

For the record, when I had my carb out recently I checked the idle screw and it is at 2.5 turns out from fully in - it works for me, so I have left it there (another thing that I have fiddled with in the past couple of months). The old spark plug is a healthly colour at this setting.

Dave