Graham Howard Posted February 17, 2002 Share Posted February 17, 2002 I have just rebuilt my 1700 x flow, which apart from forged pistons with 10.5:1 cr is in in fairly standard spec. The previous owner of this engine upgraded it from a 1600, but I have noticed that it still has 30 mm chokes fitted. When it is run in I intend to go for a rolling road session to get it properly set up. All the information I have indicates I should be running 32 mm chokes. In the period before the rr sesion I want to make sure I am running safe jetting. The current set up is: main jet 120 Air corrector 165 Emulsion Tube F16 Idle 50F9 Choke 30 mm From Dave Andrews web site the indication is that I would need to go to 130 main jets. Can anybody tell me what jetting they are running on their 1700 x-flow so that I can be in the right ball park if I fit 32 mm chokes. Thanks Graham Link to comment Share on other sites More sharing options...
Big Brother Posted February 17, 2002 Share Posted February 17, 2002 Graham, My Seven was a 1600 and was upgraded to 1700cc Supersprint spec (234 cam) prior to me buying it. I had to change a shed load of bits to finish the job. 32mm chokes were on the list. I am looking at the receipt for the rolling road session afterwards and it needed the following: F16 Tubes 130 Mains 155 Airs Idle 50F9 Hope this helps Steve www.Se7en-Up.co.uk id=limegreen> Edited by - steve motts on 17 Feb 2002 21:38:52 Link to comment Share on other sites More sharing options...
Graham Howard Posted February 18, 2002 Author Share Posted February 18, 2002 Thanks Steve, a great help. Now I will go and order the bits Graham Link to comment Share on other sites More sharing options...
Roger King Posted February 18, 2002 Share Posted February 18, 2002 A Supersprint with forged pistons (I am assuming that this is what you now have, rather than a completely standard engine) will benefit from 34mm chokes. Your current jetting is for a standard Supersprint, but you have chokes that are 30mm instead of 32mm. You are therefore likely to be running rich at the bottom end at the moment. Supersprints tend to be jetted too weak at higher revs, so you may find you are about right here. Try this:- Choke 34mm Main 130 ET F16 Air 140 Idle 50F9 Pump 35 Bear in mind that the main jetting is determined more by choke size than engine type, so if you run a smaller choke, lots of other things will need to change from the above suggestions. Link to comment Share on other sites More sharing options...
def843t Posted February 19, 2002 Share Posted February 19, 2002 Another question for Roger. What do you recommend for 1800 x/flow on 45,s with 244 cam. Thanks in advance Brendan Link to comment Share on other sites More sharing options...
def843t Posted February 19, 2002 Share Posted February 19, 2002 Another question for Roger. What do you recommend for 1800 x/flow on 45,s with 244 cam. Thanks in advance Brendan Link to comment Share on other sites More sharing options...
Roger King Posted February 20, 2002 Share Posted February 20, 2002 As a starting point only:- choke 36mm Main 145 Air 155 ET F16 Idle 60F8 Pump 35 Plus probably progression hole mods, but try it first. Link to comment Share on other sites More sharing options...
Graham Howard Posted February 21, 2002 Author Share Posted February 21, 2002 Thanks Roger I have ordered some 34 mm chokes. I will be contacting you to arrange a rolling road session in the next few weeks. Graham Howard Link to comment Share on other sites More sharing options...
cdg Posted February 21, 2002 Share Posted February 21, 2002 On a flow bench, you'll find the 34mm choke flows virtually no more air than a 32. Just ask David Vizard or Dave Walker! At lower rpm they perform slightly worse. Chris. Link to comment Share on other sites More sharing options...
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