Gravity fed carb, fit a pump?
Discussion
Would this work with the aforementioned pump John?
https://www.ebay.co.uk/itm/Universal-Adjustable-Gu...
Or still too much pressure?
https://www.ebay.co.uk/itm/Universal-Adjustable-Gu...
Or still too much pressure?
This type of gravity system worked well on motorbikes for years, I think under bonnet heat combined with poor flow is the problem here, extra heat when climbing hills (causing vapour bubbles) combined with extra fuel demand.
Two stroke mixture is quite viscous, so I'd ditch the funny little filter in the tank and use one of these where the return pipe is fitted to the carb supply pipe instead.
https://www.ebay.co.uk/itm/183113979336
I would also try to route the fuel lines away from heat as much as is possible.
ETA Not sure the separator includes a filter, so an inline filter may be required as well.
Two stroke mixture is quite viscous, so I'd ditch the funny little filter in the tank and use one of these where the return pipe is fitted to the carb supply pipe instead.
https://www.ebay.co.uk/itm/183113979336
I would also try to route the fuel lines away from heat as much as is possible.
ETA Not sure the separator includes a filter, so an inline filter may be required as well.
Edited by oakdale on Sunday 6th June 13:16
oakdale said:
This type of gravity system worked well on motorbikes for years, I think under bonnet heat combined with poor flow is the problem here, extra heat when climbing hills (causing vapour bubbles) combined with extra fuel demand.
Two stroke mixture is quite viscous, so I'd ditch the funny little filter in the tank and use one of these where the return pipe is fitted to the carb supply pipe instead.
https://www.ebay.co.uk/itm/183113979336
I would also try to route the fuel lines away from heat as much as is possible.
ETA Not sure the separator includes a filter, so an inline filter may be required as well.
Can't easily ditch the in tank filter, it's integral with the fuel tap. There is an inline filter too that I put in. The return pipe is already teed off the carb supply.Two stroke mixture is quite viscous, so I'd ditch the funny little filter in the tank and use one of these where the return pipe is fitted to the carb supply pipe instead.
https://www.ebay.co.uk/itm/183113979336
I would also try to route the fuel lines away from heat as much as is possible.
ETA Not sure the separator includes a filter, so an inline filter may be required as well.
Edited by oakdale on Sunday 6th June 13:16
Tyre Smoke said:
Can't easily ditch the in tank filter, it's integral with the fuel tap. There is an inline filter too that I put in. The return pipe is already teed off the carb supply.
Can't you just remove the tap and cut the filter off?I realise the return pipe is on the supply pipe, that's why I suggested putting the vapour trap there.
If the return is for degassing the fuel which I think it will be, its orientation will be important, the return to the tank should be at the highest point.
Tyre Smoke said:
Why though, it's not restricted at all?
It's just that in the picture I saw of one it looks a bit small and restrictive and you've got another filter in the system anyway, but as you've seen it you will be a better position to judge. Also I'd got the impression you had a fuel flow problem. 
You shouldn't need a pump. Trabitha was designed and developed (haha) to run without one on petrol not much better than paraffin and whatever oil could be scrounged or stolen, while enduring basic (if any) maintenance of the butter-knife-and-mallet school.
All you have done in recommisioning is replace new for old on like-for-like basis and I'm confident you haven't b
ksed the mixture or timing so she ought to be happy, and she mostly is it seems.
But clearly there is a starvation problem. I still suspect a breather problem.
If you do decide on a pump the scuttllebut among A series Spridgeteers is the Facet solid state pump is okay. It's available down to 2.5psi.
Hardi is another fave but a bit on the spendy side.
But you shouldn't need one. It wouldn't fix the problem, only hide it.
All you have done in recommisioning is replace new for old on like-for-like basis and I'm confident you haven't b
ksed the mixture or timing so she ought to be happy, and she mostly is it seems. But clearly there is a starvation problem. I still suspect a breather problem.
If you do decide on a pump the scuttllebut among A series Spridgeteers is the Facet solid state pump is okay. It's available down to 2.5psi.
Hardi is another fave but a bit on the spendy side.
But you shouldn't need one. It wouldn't fix the problem, only hide it.
I'd also remove the inline fuel filter you have fitted as there will be a pressure drop through that as well, even more so if its not vertical as it will trap some air too.
The fuel you'll be putting in now will be much more free from contaminates than Sergey filled up with in the Eastern block in the 70's, I wouldn't bother.
The fuel you'll be putting in now will be much more free from contaminates than Sergey filled up with in the Eastern block in the 70's, I wouldn't bother.
Good point Ambleton. The East German handbook states that it must ONLY be run on good quality petrol of MINIMUM 88ron premixed with MINERAL two stroke oil.
She must think she's died and gone to heaven running on Tesco 95ron and two stroke oil from a garden machinery place (still mineral, but low ash and easy mix).
She must think she's died and gone to heaven running on Tesco 95ron and two stroke oil from a garden machinery place (still mineral, but low ash and easy mix).
Tyre Smoke said:
Would this work with the aforementioned pump John?
https://www.ebay.co.uk/itm/Universal-Adjustable-Gu...
Or still too much pressure?
TS,https://www.ebay.co.uk/itm/Universal-Adjustable-Gu...
Or still too much pressure?
You can read as well as I, TS, that this PRv can be adjusted between 1 and 5psi - 27 to 140 inches. If that bit of Chinese cr%p was reliable - I've found the opposite with other Chinese PRVs, which were badly designed and made.
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