Running out of ideas.

jas328sport · Post by **jas328sport** » Wed Jun 13, 2018 2:50 pm

Has anyone got any more ideas on what I can try to solve the low rev cutting out that I am still getting after about 15mins of riding.
So far I have replaced plugs and coils, inlet rubbers, toobs and cleaned all jets, fuel and air filters and have removed all of the connectors under the tank and sprayed them with contact cleaner. Carbs have also been balanced.
I am convinced it isn't down to valve clearances as it still starts instantly however hot it is. In fact I am not so sure it is even heat related anymore as when balancing the carbs yesterday it got hot enough for the fan to cut in several times and yet it still didn't miss a beat, after I had put it back together I left it running until it was hot before going out on it and it still didn't play up for the first 15mins. When it is playing up the idle is bouncing around and the top end is really noisy where it isn't firing properly but if I just leave it idling then it seems to sort itself out, it only ever plays up when it is being ridden. It isn't spluttering, it is literally cutting out on low revs and small throttle openings, if you try and pull away gently then it is like a bucking bronco until you give it more throttle although for the first 15mins of riding it behaves perfectly.
Anyone got anymore ideas of what I can try next, are there any other electrical components that could cause this issue. [/list]

redapple · Post by **redapple** » Wed Jun 13, 2018 4:06 pm

air leak maybe soapy water time?

but I had a similar problem and I ended up cleaning my fuel pump and my fuel lines also cleaned out my tank and the petcock. There was a huge amount of crap in my one

jas328sport · Post by **jas328sport** » Wed Jun 13, 2018 4:20 pm

redapple wrote:air leak maybe soapy water time?

but I had a similar problem and I ended up cleaning my fuel pump and my fuel lines also cleaned out my tank and the petcock. There was a huge amount of crap in my one

Apart from the inlets, where else could there be an air leak.
I haven't touched the fuel pump, is that easy to clean out. It definitely isn't anything to do with the pet cock as my twisty bit has snapped so I can't turn off the fuel, when I remove the tank and the pipe from the fuel filter then petrol flows really well, a bit too well as it always make a mess while I struggle to block the pipe.

Tipper2 · Post by **Tipper2** » Wed Jun 13, 2018 5:54 pm

Is there any popping or backfiring when it's not running properly?

Tipper2 · Post by **Tipper2** » Wed Jun 13, 2018 6:03 pm

And have you checked the carb diaphragms for holes?

Just thinking out load here as it looks like you've done the obvious things.

Just rembered my mates exup was randomly running like a bag of shite years ago when I had my first one so we spent a day swapping one thing at a time from mine to his.

Turned out to be the end-can!

redapple · Post by **redapple** » Wed Jun 13, 2018 6:17 pm

I had the same problem with the pet cock
https://www.ebay.co.uk/itm/8mm-Quick-Re ... Swe2FZ1kXT

This should solve that problem.

disconnect the pump from the carb and put the end in a jar then turn the bike on should see petrol flowing into the jar at a decent rate, if doesn't then your pump might be knackered. Also have a look at the points for the pump might have tarnish on it.

http://www.exup1000.co.uk/phpBB2/viewto ... highlight=

jas328sport · Post by **jas328sport** » Wed Jun 13, 2018 6:30 pm

Absolutely no popping or backfiring.
Diaphragms have been checked and all looked good.
Will test the fuel pump flow and check all of the hoses again.

jas328sport · Post by **jas328sport** » Wed Jun 13, 2018 6:51 pm

Thinking about it I suppose if it were ignition related then I guess it would be backfiring.
Just another thought but how is the tank vented as maybe there is a vacuum being created when being ridden and at low revs it is not able to pull enough fuel, then when you stop, after a while it is able to catch up again, i suppose the same could be said of the fuel pump as well.

Teego · Post by **Teego** » Wed Jun 13, 2018 7:09 pm

jas328sport wrote:Thinking about it I suppose if it were ignition related then I guess it would be backfiring.
Just another thought but how is the tank vented as maybe there is a vacuum being created when being ridden and at low revs it is not able to pull enough fuel, then when you stop, after a while it is able to catch up again, i suppose the same could be said of the fuel pump as well.

IIRC when you lift the seat off you see a vent tube coming from the back of the tank. The rubber tube exits between the motor and swingarm which is a pretty cruddy area. Possible tube blockage or a kink somewhere along the line.
Anyway, costs nothing but your patience to check.
Good luck.

jas328sport · Post by **jas328sport** » Wed Jun 13, 2018 7:45 pm

Teego wrote:
IIRC when you lift the seat off you see a vent tube coming from the back of the tank. The rubber tube exits between the motor and swingarm which is a pretty cruddy area. Possible tube blockage or a kink somewhere along the line.
Anyway, costs nothing but your patience to check.
Good luck.

I didn't realise that was the only way it was vented, I removed the pipe and that is totally clear when I blow down it, I then undid the tank cap and it took a decent blow down the actual tank outlet before I felt it clear and could then hear the air hissing inside the tank so there was definitely a slight blockage there. I suppose an easy way to rule it out would be to ride it until it starts to play up and then undo the filler cap and see if it improves.

Teego · Post by **Teego** » Wed Jun 13, 2018 8:05 pm

jas328sport wrote:
Teego wrote:
IIRC when you lift the seat off you see a vent tube coming from the back of the tank. The rubber tube exits between the motor and swingarm which is a pretty cruddy area. Possible tube blockage or a kink somewhere along the line.
Anyway, costs nothing but your patience to check.
Good luck.
I didn't realise that was the only way it was vented, I removed the pipe and that is totally clear when I blow down it, I then undid the tank cap and it took a decent blow down the actual tank outlet before I felt it clear and could then hear the air hissing inside the tank so there was definitely a slight blockage there. I suppose an easy way to rule it out would be to ride it until it starts to play up and then undo the filler cap and see if it improves.

Yup.

Tipper2 · Post by **Tipper2** » Wed Jun 13, 2018 10:28 pm

Sounds like we're making progress which is good!

Tipper2 · Post by **Tipper2** » Wed Jun 13, 2018 10:33 pm

Blocked tank vent would cause bigger problems at high revs due to greater displacement but well worth a look at.

oldskoolexup · Post by **oldskoolexup** » Fri Jun 15, 2018 9:04 am

Have you tried temp replacement of "Digital Ignitor" (cdi/ecu) box?

jas328sport · Post by **jas328sport** » Fri Jun 15, 2018 1:50 pm

oldskoolexup wrote:Have you tried temp replacement of "Digital Ignitor" (cdi/ecu) box?

I take it that is the next link in the ignition side of things. I would certainly be happy to try another one if somebody has a spare going cheap or even better one that I could borrow just to rule it out.