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2005 RX1 MCX rear mount

silver rocket said:
Did you check your fuel pressure regulator. Hook up à pressure gauge to your fuel line. I have mine set at 3 psi at idle. Take it for a spin and watch your fuel pressure, it should always be higher than your boost pressure by at least 5 psi.
Click to expand...
You should also check you float height and make sure your float bowls are not leaking when boosting. The float height should be set 11 to 15 mm. Also check you fuel vent line for any obstruction. I think your problem is fuel related. I checked the MCX instructions and at 8 psi you should run 130 main jets.
 

Sea level to 1500 feet.

I ran 127.5 mains.
Set Floats to 14 mm.
4 psi fuel pressure at idle.

Was still rich.
 
You did the right thing. Loved my boosted Rx1 but fuel injection is the way to go. I'm running a 2014 Arctic Cat Crosstour boosted with 4 stage and anti-lag with méthanol injection.Over 300 H.P on pump gas. Love it.
 
I finally got to play with this again.
I tried wight the choke on and no better performance. Maybe a little more sluggish throughout. I checked the numbers for the TPS versus the manual and they are within spec. I didn't check for positioning tho, Just the sensor itself.
Next I picked up a fuel pressure gauge and checked it at idle. It was set to 7.5 psi. I dialed it back to 3psi and took it for a rip. The gauge stays about 3 until it boosts then it maxed out at 10, not really a gradual increase. Very similar to the engine RPM I would say. I really don't want to pull those carbs again but guess I will have to and re check the float height. One thing I did notice compared to other carbs I had worked on is these needles didn't seem like they had any "spring" in them. The spring that makes the float stop from rising. So that made it difficult to get a good reading on the float height since i had to hold it where it stopped flow to take reading. Is this something I should be concerned about?
Very weird hanging of the idle if I turn the screw to get RPM up to 1500 as well. If I touch the throttle after I turn up the idle, it will hang at 3-4k RPM. I actually have to turn idle screw back down to 1200 or so where that noisy clutch engages. That's why I was questioning the TPS but don't see how it would affect this on a non fuel injected unit. Bt then again what's the point of the TPS in this application, what does it control?.
Sorry bout the long post.... Anyone wanna buy a RX1. Haha good deal
Oh and ken I didn't get a a/f meter. Since it is running ok under boost and that's where you say it melts pistons, Im gonna try to trouble shoot without and read plugs to check if it's gettin too hot. If that's an absolute to have to tune these things guess I'll have to bite the bullet and get one. Please advise.
 
IMHO AF guage is an absolute necessity. You need to see where you are for AFR's at various RPM's & load.
You will be taking those carbs off over & over without.
RX 1's like to run rich so virtually impossible to tune by plugs.
Not sure you are setting those floats right. Did you look up the procedure?
Dave at Hurricane has springs or can tell you which Holtzman to get and can likely help you out.You pretty much are going to need AFR info to talk to him I would think. [As said above I think it is green sprin]
Are your caps leaking at all?
Change the mains yet?
 
X2 on the AFR gauge AEM makes a great wide band for about 170-180.$
It was suggested to me by many of the knowledgeable talents on this site
once the AFR gauge is installed it tells you what your engine is doing and if you are in danger.
also billet caps from STM, BOV, holtzman carb spings -All these parts are mandatory and relatively cheap
Only then can you start tuning.
Good advise on the fuel regulator as well ... I think mine is going south as I have your problem but at WOT
and all things point to my FPR.
 
Ok, I'll pick up an AEM, there are a couple options for range. Will the digital 11-17 be good? Also, are there site sponsors for the billet caps and springs?
Thanks guys
 
Personally I wouldn't bother with the billet caps. I've been running the stock ones for years by sanding a slight bit off the bottoms where the screw holes are so it will squeeze the centers down tighter. I've run up to 24pounds of boost this way. After I finally broke down and put a wide band on it I found where it was rich and where it was lean and ended changing out a bad fpr. I now use an Aeromotive boost referenceing regulator and it works great. I run it at 4.5 pounds and it's a 1:1 rising rate so it adds 1 pound of fuel pressure for every pound of boost. As for melting pistons if they 're too lean in midrange it will eat them up too . Just not as fast as WFO.
 
This is the AFR gauge that I got http://www.ebay.com/itm/NGK-NTK-966...Parts_Accessories&hash=item20f5f9e80b&vxp=mtr and Once I dialed it in It showed me that fuel pressure regulator that I got from one of the Canadian turbo builders took a sh!t so I put a Aeromotive 13301 regulator on it and problems started going away. As far as the carb spring and billet caps I still run the stock caps with the outside of each cap slightly sanded down on the bottoms under the screw holes so it puts more squeeze in the center of the cap and doesn't leak under boost. I'm using the stock carb springs with one coil removed so the slides come up easier under boost. I'd like to help you out on jetting but I'm running my own homebuilt system and it's happy at 155 mains ans 17 pilots and I ride at 7-9 thousand feet.


Ken........
 
Wow thanks for the great info guys. I was suspecting the FPR, but almost eliminated it. Now if I could find one close to me today, or should I go with something aftermarket like others are running? I'd like to get out today since we got a good dump of snow
 
Hey ken, looking at your post you mention the aero motive 13301 regulator. I found one of them today and the sales guys said it was controlled by vacuum. Does the regulator in the turbo setup get its regulation from pressure from the intercooler? Sorry for the noob questions but I don't want to buy something that won't work. Thanks again
 
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