Ok, well after 5 years the problem is back.
The bike cuts out at high speed. That is over 70mph.
And it’s not fuel starvation, even though that’s what it feels like, as the carbs, breathers and fuel lines have all been cleaned.
Plus it still does it if I ride with the fuel cap open!
Any ideas?
Okay, then it is perhaps an air problem. Have You alredy checked the insulating mat at the bottom of the tank? Sometimes, it comes off, lies down on the air-intake and closes it. We already had this problem several times.
Thank you for your suggestion Sandro.
I will be taking it to my man to investigate asap.
Unfortunately this trip has been delayed as the battery, despite being on a drip-charger, has failed.
It did last for 3 years, I guess that is acceptable?
I got a new Yuasa battery today from Wemoto, ordered on 15th delivered on 17th, & all is well
but my man, Dave at Bol D’Or Motorcycles in Pulborough, excellent service, is having a check-up today,
I won’t be able to visit until next week.
I will let you, & the forum, know if your suggestion bears fruit. 🤞
So, I have had a look under the tank.
The foam mat had largely rotted away.
I guess it’s 20 years old now.
The crumbling remains, I scrapped off.
Checked there was nothing else blocking the air intake
& that the air filter was correctly sited. It is.
Then I took the bike out for a run &,
unsurprisingly given that I couldn’t find anything wrong,
The problem remains ☹️
There are two other things that might cause problems with the fuel supply.
First is the fuel pump. It is the same style like in my Honda NTV650 and a lot of other bikes. These pumps often have problems with the internal contacts.
There are often sparks leading to extended wear and reduced performance.
https://www.youtube.com/watch?v=lU0DT2FIKGY
Some pumps work "forever" and others give up quiet early (mine at 34.000 km).
Since there is a repair kit available for the BT1100 there is a possibility that also these pumps have sometimes problems.
https://yambits.co.uk/fuel_pumps_and_parts_for_yamaha_bt1100_bulldog.html
The second thing is the vacuum operated fuel tap. If there is a problem with the vacuum line or the tap itself fuel supply could be restricted.
There is no repair kit for the BT1100 tap but the XJ600 kit is supposed to fit:
http://cms.bulldog-bt1100.de/forum/viewtopic.php?f=2&t=12905&p=206444
https://yambits.co.uk/xj600n-fuel-tap-repair-kit-p-45147.html
Thank you for the suggestions.
I’ll look into these possibilities.
& let you know how I get on
Oh my word. That was quite a saga.
I’ll try to keep it brief but . . .
After receiving your advice I immediately ordered the repair kits from Yambits.
Very good prompt service, 3 day delivery time, £38.00 for both kits.
Took the bike to Dave at Bol D’Or Motorcycles (0044-1798 874949) who fitted the kit to the fuel pump.
Suffice to say, this didn’t work & I broke down a couple of hundred metres from his workshop.
Dave went online & found a trade only dealer selling complete new fuel pumps & fuel filters at a massively discounted price.
£36.00 for the both, that is less than half price!
So, next day delivery plus 1 hour for fitting & I set off again.
& I break down again!
This time I’d made it a few miles from his shop, so, I got Dave to pick me up in his van.
So, Dave is back in there trying to work out what was amiss.
He quickly found a wire & connector to the back of the underseat tray above the battery.
The connector was not fitting snuggly together (Bike is now 20 years old & has done 46000 miles).
Plus, the wire was being stretched when refitting the underseat tray.
So, after some cutting & re-siting of the wire plus judicious use of electrical tape to hold the connector together,
I am off again.
Finally we are there, bike now runs beautifully, it will hold a sustained high speed without choking,
like it was before.
The question, which sadly can never now be answered, is, had there ever been an issue with the fuel pump or filter?
or, had it always been the dodgy wire & connector?
Anyway, a happy ending.
I look forward to a summer of trouble free riding
Thank you, once again for your suggestions.
Hi Mark,
many thanks for your feedback! Good luck for summer!