Triumph TR 250 1971

[dynamic]

Does anyone own or have experience of the above bike as I have just bought one, it starts fine and runs very smoothly at low revs when accelerating 15mph + the motor seems to die and not respond to throttle position
 when I shut off and come down to under 15 mph it all feels normal ? could I have an electrical breakdown or short maybe  ?

[iansoady]

Could be almost anything but for a start I'd be looking at blocked main jet. Failing that, seized auto advance. Then the world is your oyster.

[Rex]

An electrical breakdown/short  would happen at any road speed.
As ever, the bike needs a good going-over using a workshop manual, but given the symptoms I would suspect that the carb needs a really good clean and inspection followed by the various ignition components.

[Grunt]

Going down the worlds your oyster route I’d be checking fuel flow, i.e. blocked filters, air hole in the tank cap big enough not to create a vaccuum. There’s a saying about electrical faults being fuel faults and fuel faults being electrical, or was it rear wheel problems being front wheel problems, can’t remember now.

[dynamic]

Thank you all for your input just got the bike on Saturday so I was very inpatient to go out and ride
 logically I should have at least given it a once over however I will now check through all systems and report what I discover    watch this space...………………..
PS this will also include RTFM  !

[Mark M]

If you are new to the bike, do you know how the choke works? Usually on the right handlebar it is a lever and for normal running (ie, engine warmed up and at normal road speed,) it needs to be open, that is, with the lever pulled towards you, so that the cable is tight and under tension. This is the reverse of most (all?) Japanese bikes. It catches a lot of people out!
REgards, Mark

[dynamic]

thanks for the input Mark there is no choke fitted , the carb is a very new looking (shiny) Wassel I have removed it and blown it through very thoroughly all is very new looking inside and no debris was found
I checked the points gap (using dial gauge) and the setting was spot on points opening at 38* BTDC and a gap of 15 thou. at highest cam point
I started to check the electrics starting with battery pos. to main loom and could not get a reading
  from pos. to neg. via the battery which has a fuse inline on the pos.
 side still no reading from pos .earth to the battery neg. terminal nothing I could see the fuse strip was intact however when I took the fuse out of its holder it just disintegrated in my hand although it seemed brand new
so a new fuse fitted and it started with no hesitation
I have yet to try the bike on the road so I will post my findings.

[Mark M]

I hope that's it, fingers crossed you have beginner's luck!
REgards, Mark

[Oggers]

I' m with Ian. Check main jet first. You need to remove it, blow it through, and ensure the hole is absolutely clear, not just clean the carb or spray the innards with cleaner. Also check float isn't sticking, float needle is not sticking, and float height is correct.

Afetr than - then yes air leaks  - nip up all flanges/gasket interfaces - check all hoses, and for any fuel filter blockage. Pull the fuel line off the tank and see if petrol flows correctly - could be full of gunge inside...... as could the fuel lines themselves.

[iansoady]

Given the fuse issue the bike probably started on the alternator output (which is good news). I do wonder whether you have the battery correctly connected?

But as everyone has said, it's best to give it a through check over. It won't take more than an hour or so and you'll get more familiar with what's what.

[mini-me]

Get shot of it asap is my grumpy advice, I knew them when they were new, probably one of the worst bikes to leave any British  bike factory.

 guarantee claim after guarantee claim, fragile, badly designed, assembled by a work force that hated them.

Sorry I'll amend that, to 'the worst bike'  after the 500cc version

It will have been through dozens of previous hamfisted destructive owners; dismantle half the bike to change a 20p spring, then some fool always put the cam followers in the wrong way round, stripped threads galore..........

[dynamic]

I have just fitted a new condenser and had a quick blast up the road and my "dying engine problem" has just disappeared
before my condenser arrived I did change the fuel pipes and have a healthy flow from each tap
I have a pos. earth on the bike same as my T100, so one less item to check ?
as for get rid now at the moment I am looking forward to a longer ride weather permitting or just get some "full wets" if anyone knows of any 19/18 inch hoops available in the Criccieth area ( part used will be fine )

thank you all for your input many many more stupid question to follow …………………………..