Odd fuel restrictor dual 38s

[yamanube]

Pulled my carbs off today and found a 140 main jammed in the return line. The slave carb plate appears to still have the stock restrictor orifice, cant figure out why it is there.
Would this cause any adverse effects? It would seem to me that since the stock orifice is smaller than the 140 jet, it wouldn't have any effect. Is this accurate?

 

[Jr.]

I would think you are correct? But the question is, what else did they try to do if the stuffed a return jet in it??
I would pull the carbs all the way down and look for evidence of additional tampering?

 

[yamanube]

I would think you are correct? But the question is, what else did they try to do if the stuffed a return jet in it??
I would pull the carbs all the way down and look for evidence of additional tampering?

My thoughts exactly, I have not found anything else out of the ordinary but the ski does run strange (prompted the carb removal) very lazy down low.

 

[Jr.]

What jets are in it?? Any upgrades?

 

[yamanube]

What jets are in it?? Any upgrades?

135/72.5 stock NS and springs unknown popoff. Limited B, ADA head, mystery ported 61x cylinder that has a 1mm spacer under it and decked top, stock stroke.

 

[Jr.]

Use 137.5 M H adj 1.25 turn out 75 P L adj 1 turn out 1.5 N/s 115 gr spring
As a starting point. Thats what I use for my port spec. You should be fairly close?

 

[yamanube]

It doesn't seem to have any lean hesitation, just seems to build RPM real slow unless you keep it up in the midrange, on plane. Recovering from a jump or nose stab is garbage until it seems to clear out and run.

 

[yamanube]

This is the questionable engine setup. Have been too lazy to do much tinkering and am leaning towards just building something from scratch.

http://www.x-h2o.com/index.php?threads/mystery-engine-cylinder-spacer-porting.192692/

 

[Jr.]

Sounds like your chasing a ghost? In this case, its best to start at square one and check everything?
Who knows where the advise came to build it? The issues are probably compounded!
Good Luck!

 

[Storbeck]

Seems like the spacer probably means raised ports with lots of timing, which would make sense to be lazy down low, no?

 

[yamanube]

Seems like the spacer probably means raised ports with lots of timing, which would make sense to be lazy down low, no?

This was my thoughts, I was really hoping I would find a sweet spot and make it hum and really enjoy it but I just dont know if it's there. I have even swapped in my zeeltronic setup with limited improvement.

 

[joelake]

Pulled my carbs off today and found a 140 main jammed in the return line. The slave carb plate appears to still have the stock restrictor orifice, cant figure out why it is there.
Would this cause any adverse effects? It would seem to me that since the stock orifice is smaller than the 140 jet, it wouldn't have any effect. Is this accurate?

A few years ago I purchased a gpr1200 for the wife. I went through the carbs and followed a tech thread on pwc today for removing the accelerator pump to stop mid throttle seizure. Long story short, to equalize the fuel pressure across all 3 carbs, the return restrictors on the number 1 and 2 carbs were drilled out, and a M5 thread tapped in number 3, with a 150 (?) Main jet threaded in. This was supposed to keep them all fed and equal, instead of carbs 2 and 3 having to scavenge off the restricted return from number 1...... Number 1 had the only fuel pump. Sounds like this was attempted by who ever did your carbs. Why? Dunno.

 

[Pro-pulsion]

I was just looking at your engine thread, my thoughts are that it could be as simple as they milled the head, or at least "a" head too much, in a panic to get the squish clearance back so the pistons wouldn't smash the head, they added the base shim. But it was only barely enough to do the job, so to prevent any over temps in the squish band and melting the piston edges down, they added the restrictor thinking it will increase fuel pressure in the carbs forcing more fuel into the system which in turn will help in cooling the pistons. I have seen some pretty wonky things done before. It seems that they do something first before doing their homework, then start reading and throw every trick in the book at it whether it is applicable or not to try and bubble gum it together then sell it off. The intake porting to me looked questionable too, as though they just let loose with a compact 90* air drill. There is a lot of inconsistency in the transfer walls where they went too deep in spots. I could be way off which is certainly not unheard of, but it's the best I can come up with right now You might want to get a measurement of the squish just to see if it is on the ragged edge. It would certainly explain the gutless bottom end when the exhaust port is raised by the base plate. That will really narrow your peak power band window but also isolate it for being a top end machine only.

 

[yamanube]

It has an ADA head on it, which I have yet to remove, but looking at the edge where the cylinder meets the headhsell I can say with 91% certainty, they milled the cylinder.

 

[Yami-Rider]

Restricting the return line will raise fuel pressure, thus richen your whole tune. I run a restrictor on my xs motor in then return line, but the carb return is drilled out.

 

[yamanube]

Restricting the return line will raise fuel pressure, thus richen your whole tune. I run a restrictor on my xs motor in then return line, but the carb return is drilled out.

I understand the reasoning behind it, my question was more will the 140 jet do anything being downstream and larger than the factory return orifice.

 

[Yami-Rider]

Oh gotcha. Being that big, wouldnt think it would have much effect.