Help with flat side tuning

[nlovien]

23 hours ago, Portaz13 said:

Cables are not yet connected however where they were holding throttle shut on either the carbie or the throttle did lower the revs. Can the return spring be adjusted? 

should be, have a close look at the spring on the shaft  - you'll see a choice of pegs on the alloy casting for the spring end loop to fit over

[Portaz13]

Great thank you,  I will have a look again 

[maxwin]

18mm Float heights?  I have the brown squarish floats and I thought the float height was 14-15mm.

[Portaz13]

These are black,  info in could find said 17mm . I left it alone thinking if the float height is a lower number being measured upside down then That  would mean more fuel.  Am I on right track with that? 

Edited January 16, 2018 by Portaz13

[maxwin]

You have the black round ones I guess, less float height means more fuel in the float chamber.

I like to set them up on a bench and measure what fuel comes out of each and adjust accordingly

[Portaz13]

They are not round I will take a pic,  how do you go about setting on bench with your method?  

[Portaz13]

OK so now it idles and runs pretty good,  pulls hard just needs a few on road pump adjustments but every time I gave it a bit of throttle when I stopped the idle was high. I adjusted it 5 or 6 times,  it came back to 1500 now probs with idle screw. So I'm thinking it it possible that idle screw is moving when I'm on the throttle?  I can see how it would even run with probably a total number of 6 turns or so 

[nlovien]

i'd be checking that when idle the throttle cam is 100% sure closing against the idle  stop - not hanging on the cable

also - my previous comment ref: ilde screws was misleading - on these carbs the idle adjustment screws are kinda like a mini throttle - they are not mixture adjustment screws like on some other carbs - they adjust how much of the mixture goes in -- sooo if your say at 3/4 turn adjustment close it down further - say down to 1/4 turn only - ok it will not idle, so now open the throttle cam via the main idle adjustment screw = basically your changing the relationship between idle jet and throttle cam - see if this helps - and try it the other way i.e. more idle adjustment screw / less throttle cam but always ensuring the cam does stop against the - stop

another thing to check - if you've got filters fitted make sure nothing is blocking the idle air jets at the mouth of a carb venturi

edit: just had a play with this - if you find you've got a stumble just as you pick up throttle then you've wound the idle screws in too far - on my AFR gauge it idles nice at almost bang on 14 but if you then open the throttle it goes to 20+ = open the idle screws up

 

Edited January 17, 2018 by nlovien
had a play

[Portaz13]

Thanks for reply,  no filters fitted just trumpets.  It idles fine now and very minimal hesitation now it simply the main idle screw that needs constant adjusting while riding I haven't touched the pilots since I put carbs back on. They are at 3/4 ish  each 

[Portaz13]

6 hours ago, nlovien said:

i'd be checking that when idle the throttle cam is 100% sure closing against the idle  stop - not hanging on the cable

also - my previous comment ref: ilde screws was misleading - on these carbs the idle adjustment screws are kinda like a mini throttle - they are not mixture adjustment screws like on some other carbs - they adjust how much of the mixture goes in -- sooo if your say at 3/4 turn adjustment close it down further - say down to 1/4 turn only - ok it will not idle, so now open the throttle cam via the main idle adjustment screw = basically your changing the relationship between idle jet and throttle cam - see if this helps - and try it the other way i.e. more idle adjustment screw / less throttle cam but always ensuring the cam does stop against the - stop

another thing to check - if you've got filters fitted make sure nothing is blocking the idle air jets at the mouth of a carb venturi

edit: just had a play with this - if you find you've got a stumble just as you pick up throttle then you've wound the idle screws in too far - on my AFR gauge it idles nice at almost bang on 14 but if you then open the throttle it goes to 20+ = open the idle screws up

 

I will pull the tank off again and check the Cam is returning OK,  I just can't see why I would need to continually adjust idle. Regardless though definitely making progress 

[Portaz13]

Well got it sorted so far,  main idle screw was coming loose so fixed that and adjusted pump a bit more and she runs well,  went for first decent ride 

[banoffee]

Happy days 

[nlovien]

brilliant  - its a love hate thing that is a key reason why we torture ourselves with these bloomin bike things - we hate them when they don't work, but we love them all the more when we manage to sort it - Robert Pirsig's buddy with the BMW doesn't know what he's missing 

[KATANAMANGLER]

Good stuff.

[Portaz13]

Thank you so much guys for all the help.  It made the difference for sure.  BTW settings were for future reference 

Clip 3 on needle 

3/4 turn out for mixture screws

Don't have any jet sizing but maybe it may help someone