srx or xt

[chippy]

Hi
  This is my first post on here,I am in the process of sorting a bike out ,for my friends widow.
   It is a srx400 frame from 1985,the engine is electric start(no kickstart) it has a water cooled barrel,the cylinder head appears the same as a srx600 without the decompressor bit.The no on the c/case is4su-005931 .Can anyone identify this for me?
  I am also having a bit of difficulty starting and keeping it running,I think the carbs could be gummed up.
 Are there any instructions on the net about these carbs?(I only own brits with amals)
 Will I need a gasket set before I strip the carb?
 All advice will be appreciated. Thanks chippy                     

[Steve H]

4SU I beleive is an SZR660 motor

[bullet350]

its the same carb set up (mostly) as xt600, xtz660, MZ skorpion. one big carb for normal running (the one with the throttle cable going to it) and one little carb thats not connected to the throttle. the little carb is operated by the 'suck' of the engine and opens when the engine revs are high(ish).
when left standing modern petrol taps can cause problems as many require a vaccum to open. check this first as its easier than taking the carbs apart.

350bullet

[mini-thumper]

If it has a vacuum fed fuel pump they can be difficult to start after being left standing, as my XTZ660 Tenere did. As yours does not have the Tenere tank, and the fuel is above the carb, there is little need for the pump and it can be removed. Fuel lines can by-pass the pump and connect direct to carb. There is a vacuum take-off on the carb manifold that needs blanking off, or connecting to a Scott-oiler (this same problem was mentioned by Steffan in a previous post).

If you need to remove the carbs, as I did recently on my SRX400, be warned its a tight fit. Losening the air box allows for a few extra cms, but I still found it difficult.

Good luck
BB

[chippy]

Thanks for the replies!
The carbs have K&N type filters,Are these instead of the airbox?The petrol taps sound a complicated set up! I have all brits in my shed,some drip fast and some drip slow!
 If I have understood this correctly ,I just remove the vacuum pipe and blank off the holes?
 While I have been messing with it it has been making strange sounds without the engine running,Is this the vacuum thing?
         Cheers chippy

[guest27]

Has the petrol been left for sometime in the carbs - modern fuel can go off and clog the carbs.  On the various lawnmowers that get used once a year whether the grass needs it or nto - I tend to let the float bowl drain out and let in fresh fuel - seems to help.  Ditton the couple of bikes that will start - now and again.

R

[bullet350]

apparently lawnmower specialists can supply an additive that stops the petrol going 'off'. don't know if it stops it turning to varnish in the carb, or if it stops it losing its ability to burn.

350bullet

[peterj]

The fuel tap has three positions - main (down), prime (horizontal) and reserve. The vacuum pipe switches on main and reserve. If you disconnect the vacuum tap only prime should flow, and this will run out the reserve as well. I've never needed any gaskets or seals when taking my srx carbs apart.

[trophydave]

apparently lawnmower specialists can supply an additive that stops the petrol going 'off'. don't know if it stops it turning to varnish in the carb, or if it stops it losing its ability to burn.

350bullet

Tis true.I use it in my very shiney VFR when it gets laid up over the winter.I am not sure if it actually works but I have never have problems with gummed up carbs(touches wood)Watch where you buy it from tho'.I have found a local stockist but he charges about three times what Mowerworld in Nottingham do.