SXR Lites Class SXR Build for 2017

37

37

Precipitation Hardened
Location
Indy
chixwithtrix said:
I bought new needle and seat, spring and jets. Should come in next week and we shall see what happens.
Click to expand...
What is your jetting btw? Popoff PSI? Is popoff sync'd? Have the fuel pumps ever been rebuilt and if so, how recently?
 
chixwithtrix

chixwithtrix

Addicted
Location
Houston
37 said:
What is your jetting btw? Popoff PSI? Is popoff sync'd? Have the fuel pumps ever been rebuilt and if so, how recently?
Click to expand...

Stock. Everything is stock stock mfn stock hahaha. That is why I know it is lean, but am probably having other issues. Just rebuilt the fuel pump before the last race.
 
user_error

user_error

Location
seattle area, Wa
If it only does this issue when you turn left it is your fuel pump. Specifically, it is the tiny clear check valves mounted via rubber grommet in the pump body. These two clear discs have an ever so slight conical shape and if they wear out or are installed facing the wrong direction you will experience the leg turn bog syndrome. Combine this issue with some ppitential other issues like crusty/brittle fuel lines that are prone to not sealing properly, a clogged fuel selector, and testing new jetting specs and issues can be hard to pinpoint. On a race ski i would highly recommend running one single fuel line (use oem yamaha type fuel line) from the reserve pickup on the tank to the inlet on the carb. Put a rubber cap on the "on" pickup and maintain the return line in its standard position. Then I would recommend rebuilding the carbs and be extremely attentive to the direction of the conical check valve discs. Rejet to decent specs, lots of combos work very well, and then try some starts repeatedly to recreate a bog.
 
chixwithtrix

chixwithtrix

Addicted
Location
Houston
Well...the issue is when I turn right and has not really improved since I rebuilt the fuel pump.

Fuel selector has already been eliminated and I've replaced lines.
 
user_error

user_error

Location
seattle area, Wa
37 said:
Did you also change the check valves on the metering blocks?
Click to expand...

This is important, I have seen many people, myself included, become guilty of giving them a good visual look and determining that they are "good to go" and then skip on replacing them when rebuilding carbs.

I've also learned over some time that despite them LOOKING and SEEMING fine, their ability to seal against the fuel pump body weakens and will create fuel starvation issues like the ones you describe.
It might be worth cracking them open again and replacing them even if they they are relatively new? Pay extra close attention to the direction they are installed. Also make sure your plug wires are new/cut back. I've seen people swear they have carb issues and it ends up being a electrical thing
 
chixwithtrix

chixwithtrix

Addicted
Location
Houston
37 said:
Did you also change the check valves on the metering blocks?
Click to expand...
user_error said:
This is important, I have seen many people, myself included, become guilty of giving them a good visual look and determining that they are "good to go" and then skip on replacing them when rebuilding carbs.

I've also learned over some time that despite them LOOKING and SEEMING fine, their ability to seal against the fuel pump body weakens and will create fuel starvation issues like the ones you describe.
It might be worth cracking them open again and replacing them even if they they are relatively new? Pay extra close attention to the direction they are installed. Also make sure your plug wires are new/cut back. I've seen people swear they have carb issues and it ends up being a electrical thing
Click to expand...
Yes, I replaced everything in the fuel pump including the check valves. My little fingers hurt from that haha.

Tore down the carbs yesterday for new N/S and jets. All the stock stuff looked fine, no blockages. Just waiting on my T handles to come in and we'll see if it helped anything. If it doesn't help, then probably electrical. Maybe a weak stator...

a.jpg
 
37

37

Precipitation Hardened
Location
Indy
chixwithtrix said:
Yes, I replaced everything in the fuel pump including the check valves.
Click to expand...
...but what about the metering block check valve?

check.jpg

If this check valve is old, it will allow fuel from the diaphragm side to slam it open and pass through the metering block. This typically happens in left-hand turns on skis with diaphragm side out. Since your SXR carbs have the diaphragm side in, you'll experience a rich condition in right-hand turns. This could explain your right-hand bog.

(Edited because I was pulled away from my computer.)
 
Last edited:
chixwithtrix

chixwithtrix

Addicted
Location
Houston
Figured I'd update this thread for some closure.

Changed the jets, n/s and spring and it rode great for 30 seconds unti it wouldn't rev. I gave up, too hot in the garage to work in fixing it any more. Later found out it was most likely bad intake gaskets. That was after I sold it to a young racer and his father who drove to pick it up from another state. It went to a good home and I'm told it is fixed and riding fine now. They got it for a great deal!

Fast forward a few weeks to the present. I did what I said i'd never do....I raced a Superjet again. And liked it. Only with the rear sponsons can I ride it happily though hah.

Managed to take 2nd place overall in the lites class in my region! That was after missing the first whole race day and taking last in the second races when the SXR kept dying.

The finale in Oklahoma this weekend was super fun, even though I was out motored by pretty much everyone since my husband's superjet is stock-engined. Next stop is Havasu!
IMG_20170813_194651_136.jpg
 
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