Triumph twin Strombergs...

[greyV8pete]

Re: Triumph twin Strombergs...

Most carbs that I have worked on had a fibre washer between the needle valve body and the carb. Maybe the supplier forgot to fit it which would be about par for their bodge level. Mechanical pumps usually have a thick (used to be asbestos) gasket between the pump and the block as a heat shield. I have been told that reducing the thickness of that will raise the fuel pressure due to increased cam lever stroke. Personally I would think that the spring undr the diaphragm would control the pressure and the gasket/ lever stroke would just affect the total flow per pulse. However both worth a check. Peter.

[David]

Re: Triumph twin Strombergs...

Thanks David & Peter,

I will go for a regulator once I have the carbs working again, or as a last try before binning them!

The needle valves have a brass washer between them and the casting, presumably that works better than fibre when being constantly immersed in fuel.

Will report back after the next attempt Tuesday evening.

[b_caswell]

Re: Triumph twin Strombergs...

Most Strombergs have an alloy washer under the float valve some service kits supply more than one thickness.

David, before refitting the float bowl clean off the remains of the old gasket and then smear some grease on the new one to stop it sticking.

Best of luck

[David]

Re: Triumph twin Strombergs...

Most Strombergs have an alloy washer under the float valve some service kits supply more than one thickness.

David, before refitting the float bowl clean off the remains of the old gasket and then smear some grease on the new one to stop it sticking.

Best of luck

Thanks Ben, you mean grease the float bowl gasket, or the needle valve seating?

[greyV8pete]

Re: Triumph twin Strombergs...

On my classic I was told to soak the gasket in water for a few hours. It makes it swell up a bit and gives an excellent seal. In that case following Ben's suggestion lightly grease the top edge of the float chamber body (rather than a damp gasket) to make subsequent removal easy. Peter.

[b_caswell]

Re: Triumph twin Strombergs...

Yes grease the float bowl gasket or Peters method sounds interesting.

[David]

Re: Triumph twin Strombergs...

Yes grease the float bowl gasket or Peters method sounds interesting.

Sounds like a good idea as I've spent half an hour a time picking old (new) gasket off both 'new' carbs when sorting out the needle valves.

[David]

Re: Triumph twin Strombergs...

Right, three start ups with mixture, timing and idle all tweaked each time and it's now starting easily, ticking over nicely and settling back to an idle when revved hard.

Still seems to be running a bit weak on fuel using the old lift the dash pot 1/32 trick but having richened the carbs up a full half turn of the needle (only 2 turns to play with) I'll leave it until I've done some road tests.

No fuel leaks... touch wood, metal, plastic and an other superstitious thing I can find...

You never know I may actually have it ready for Kop Hill Climb weekend after this one, which was it's last proper outing, a full year mostly off the road!

David.

[philcoyle]

Re: Triumph twin Strombergs...

Thank goodness for that , we can all sleep at night now, are you drawing in too much air from the rocker cover breather pipe? just a thought.
But well done for persevering.

[greyV8pete]

Re: Triumph twin Strombergs...

................................Seems you guys are partly on the right track it seems that later GT6's had reducers on the breather inlet on the carbs to counter some starting issues...................................

Looking back to post #66; To save further expense I would be tempted to get some bar that just fits inside the hose from the rocker cover and try drilling a gradually larger hole in it to get the air restricting for optimum running / starting with the carb jet adjuster nuts set at mid travel (or at whatever setting is recommended as a basic setting for these carbs). Peter.

[b_caswell]

Re: Triumph twin Strombergs...

Well done Don't forget that when the engine bay gets quite warm the air density will reduce thus enriching the mixture.

[David]

Re: Triumph twin Strombergs...

Looking back to post #66; To save further expense I would be tempted to get some bar that just fits inside the hose from the rocker cover and try drilling a gradually larger hole in it to get the air restricting for optimum running / starting with the carb jet adjuster nuts set at mid travel (or at whatever setting is recommended as a basic setting for these carbs). Peter.

I just found this on Canley Classics web site, I have the restrictors so will fit them, hopefully, according to 'people that know' these were used to improve idling, which is something I'm struggling with.

plate_a12.jpg

[greyV8pete]

Re: Triumph twin Strombergs...

I just found this on Canley Classics web site, I have the restrictors so will fit them, hopefully, according to 'people that know' these were used to improve idling, which is something I'm struggling with.

[ATTACH]7908[/ATTACH]

Good news! Keep chipping away. You are nearly there. Peter.

[David]

Re: Triumph twin Strombergs...

Well that was a good day. Restrictors in place, can't see them in the linked below video. I 'think' they have made it easier to get a good idle but jury still out on that.

Running OK now, still two issues to fix over the winter;

- Choke mechanism on the side of the carb is weeping a very small amount of fuel, doesn't drip, just slightly wet to the touch.
- Front carb (same as above) needle is very stiff to turn so I will take the top apart and see what's going on.

I will test drive tomorrow, video below, running with choke.

https://youtu.be/vDh0Ec5Afgg

So hopefully that's it... just need to put the air filters back on.

Don't buy carbs from [PM me for supplier name prior to buying] unless you want to rebuild them yourself to get them running!

David.

[David]

Re: Triumph twin Strombergs...

This is never ending... after a run out in the heat yesterday temperature was up to 3/4 on the gauge, so I have the electric fan on.

Took it out again to day, forgot to turn the fan on and the car overheated after a couple of miles and spat the coolant out. Luckily I was metres away from a friends place of work so I turned in and have left it there. I have only ever used the electric fan when in traffic.

I'll go back this evening, fill it up and hopeful drive home OK, fan on!

But, the question is why is it suddenly running this hot, timing looks OK, plugs are greyish brown, maybe a tad lean? Would the new breather setup cause it to run lean. Maybe I'll try blocking that off by joining the carb breather pipes and venting the rocker box to atmosphere and see if that helps.

I'm getting close to putting the 'For Sale' sign on it...

[UPDATE] - Red hot engine, stone cold radiator = thermostat dead... luckily a local Vitesse owner had one his garage and was kind enough to drop it off to me so I'll pop that in tomorrow.