XT Tenere 3AJ Running issues
 

Please could I pick some brains. I'll try to give all the details.
My '89 3AJ as been faultless for over 10 years but this weekend has had some issues.
A full tank of fuel and after around 50miles I settle into a little duel carriageway riding. 50-60mph seems fine but getting closer to 70 to overtake or wind back the throttle for a hill and it starts to miss a little until I back it off a bit.
longer into the journey it seems to get worse. I can pull over and just about keep the revs going as not to cut out and after around 30 seconds it will happily tick over and I can set off again, sometimes it cuts out all together. then just left for a minute it will fire back up and run again.
It seems like riding A and B roads are fine but long drawn out duel carriage way/motorway riding causes this.
Last year during lockdown I serviced the bike, tank was already clean inside, new fuel lines and inline filters and checked the fuel pump (it looked fine inside)
I took the inline filters off for my return journey this weekend thinking they could have been causing some fuel starvation but didn't seem to change anything
Any ideas from you guys would be greatly appreciated

It could be the secondary carb not opening properly, it's the RH side & has the dome on top, there is a diaphragm inside & it could have perished.

https://images.wemoto.com/full/CARBU...M/10064220.jpg

It could also be your float needle valve filter is blocked, have your checked that?

http://www.partsnmore.com/images/parts/480/48-1572.jpg

It may be an electrical issue, we will talk about that later.

Mezo.

Just to add to the list, this does sound like classic symptoms of fuel starvation so it's worth making sure that there aren't bits of rust floating around in the bottom of the tank getting stuck in the fuel line, or if the bikes been left standing a while then ethanol snot can cause this sort of thing too.

some checks are easier


disconnect rubber boot and check with your finger that CV carb slide can move freely


for fuel starvation check - close tap, remove drain screw from carb bowl, open tap, fuel should stream out the carb bowl drain pretty freely...


like mezo said, it could be ignition power coil on its way out, so check the two items above first

Blocked tank breather? High fuel requirement causes a vacuum that the breather can't cope with, reducing fuel flow. Lower revs and enough air can enter to let the fuel flow and get back to atmospheric pressure.
Happens a lot on older TTR locking tank caps (not later ones with a breather pipe)

Thanks mossproof, I did think of this as it seemed to get worse on both occasions as I was getting into the journey and fuel was dropping in the tank so I released the petrol cap as it started to happen and for a few miles after but sadly no difference

Thanks turbofurball, I had the time last year to go through the bike and the tank was spotless, the diaphragm in the pump was clear and I replaced fuel pipes and filters

Thanks for your input everyone. Sadly I've not had the chance to get the bike out of the garage since I've returned home. I can't remember if I filled up with E10 before my ride Cornwall-Surrey but it was E10 coming home (not sure if this could have made a problem)
But will be filling up with E5 now I've found some and will take for a long ride and see if the problem is still there before looking deeper into it.
Thank you again for your help, I will report back

I don't think E10 would cause an immediate problem - my (albeit rough) understanding is that it tends to 'gum-up' older engines over time.

Not sure what year your 3AJ is but I checked my 1992 3TB on the UK Government's E10 checker website, and its modern enough to be unaffected by it apparently.

Ed

Yeah, if you're parking the bike for months at a time the E10 leaves snot in the carb, but shouldn't cause problems if you're using it regularly-ish. I've managed 6 months without problems before, but always had to clean everything after a year of sitting with E10.

Best thing is to just open it up and have a poke around for something not looking right (or get someone else to if in doubt)

I finally got chance to look at the bike today. The inlet manifolds have become un bonded, the rubber and the ally totally separated. I'm surprised it ran as well as it did.
Replacement manifolds on Ebay were a lot cheaper than I expected. I've not ordered any yet, just wondered if these are cheap and nasty manifolds or if it's just the price they are now. I'm sure years ago they were more like £60/£80

Dont buy china cheap shit! They cant handle heat, rubber cracks after 1year...