MX FCR Project (Monster 750).

[koko64]

With a mildly ported M750 with Termis, open modified air box, FCR39's, FBF hi comp pistons we are running a 52-60 pilot jet, 155 main jets,  needle on posn 3 or 4 & slow air jet screw 1-11/2 turns out there's a range of tuning to allow for fuel density variations, etc and level of porting. This local 750 has mild porting and stock cams and valves. 

Your local tuners will be more precise with jetting.

[Von Eisen]

Thanks, I have a good selection of jets, will set them up similar (52-60 pilot jet, 155 main) and go from there ... Ive become even more enthusiastic after seeing your progress 

[koko64]

If your fuel has Ethanol you may go richer on the needle, will be interesting to see. E fuel is only a minority option here.

At least the slant body carbs will fit without a fight I have picked up another fat MX 39 and are looking for another slant bodied dirt carb for two complete pairs. That should give a set each for myself and a customer who is also keen to have a choke on his carbs.

[koko64]

If your carbs came with slow air jet screws and not the regular fixed jets then that gives you a lot of leeway to adjust out little glitches in the lower throttle range.

[Von Eisen]

 Good to know, as they do have the adjustable slow air jet screws  seems plenty of leeway for dialing in with these carbs ... Im up in sunny Qld, so I guess were running the same ethanol contents koko.

  As you previously stated, the banked Ducati FCR are rather costly down here in Oz (working with the ever deprecating AUD) if the graft is successful, this is a cheaper option.

[koko64]

E free is good. Forgot you were local. Running 98 with hi comp pistons? The bike I work on runs 98 fuel with stock ignition and no pinging.

[Von Eisen]

Yes 98, ignition is stock, apart from a set of ExactFit coils, Ive never had any pinging probs either

[koko64]

Picked up another slant bodied FCR39 with choke off ebay. I'll use those ol' slant body carbs and save the fancy MX's for a customer with a modded motor. The MX version are fast action with the aggressive throttle cam.  This 750 is for pillion and scrambler/wet weather duties, so I best go for the softer version.
My machinist buddy is probably flat out in the workshop during self quarantine. I'll give him a call and maybe drop off some supplies.

[koko64]

s-l300 (2) (1) by Tony Kokonis, on Flickr

[koko64]

20200326_155556 by Tony Kokonis, on Flickr

Modified rear manifold. The lower lug on the cable bracket may need to be cut off, maybe. Of course business has slowed, so now is the time for projects. As we head into winter I'll do the carb swap.

[koko64]

20200326_162005 by Tony Kokonis, on Flickr
An oem FCRMX carb with the cast in one bellmouth filled with titanium epoxy weld. This will let me port the inside lip due to the lack of a removable velocity stack.

[Von Eisen]

20200326_155556 by Tony Kokonis, on Flickr

Modified rear manifold. The lower lug on the cable bracket may need to be cut off, maybe. Of course business has slowed, so now is the time for projects. As we head into winter I'll do the carb swap.

The manifolds looking good, straight shooter  ... 

[koko64]

If we go to stage 3 lockdown, I'll have time to take the 750 off the road to do this.

[Von Eisen]

Don't think that is far off, hope my cable shows before then 

[koko64]

Yeah, you need everything for the stage 3 lock down project. The other carb arrives Tue.