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Discussion Starter · #1 ·
At the beginning of last season I bought my wife an ultra spx. I only rode the thing a few times throught the season and the thing drove like a total dog, felt like it was only running on two cylinders even though all three were firing. Compression at the end of the season was 120psi. on all three.

Since then Ive talked to a few people who say they have owned one at one point or another and loved them and raved about how fast they were. I had to work to get mine above 70 on hardpack. Could this be a clutching issue? Any other ideas as to what to look at?
 

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my uncle had one and it was the exact same thing he couldnt even get around my 550 fan hahaha...i cant remember exactly but it was something with the coil and electronics...fixed it and the thing just about threw you offf
 

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have both clutchs inspected, springs tested or replaced.
carbs cleaned and synced.
chokes cleaned and synced.
by reading the plugs it should have giving you something, either one plug very black or all 3 very black.
verify jetting to your elevation.

them are some basic starting points.
 

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madcow said:
have both clutchs inspected, springs tested or replaced.
carbs cleaned and synced.
chokes cleaned and synced.
by reading the plugs it should have giving you something, either one plug very black or all 3 very black.
verify jetting to your elevation.

them are some basic starting points.
X2.....only heard of a couple with electronic trouble and it's usually voltage regulator.
 

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didn't see madcow's post when I submitted mine! listen to him, he's a wise man with a wealth of information! I've learned a ton from reading his past posts. thanks MC!
 

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Discussion Starter · #7 ·
The carbs were cleaned and jetting was checked for my location at the beginning of the season last year. The plugs always came out black, the few times that I did ride it I was always stopping to see if it had fouled a plug because of how sluggish it was.
 

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If the plugs are always black then thats your sign for being to rich. You want a nice cardboard color brown.Have the clutches been cleaned...ever? If you have dirty clutches that can hold you back from getting your rpms to the track. Are the lights nice and bright with no flicker in them? My voltage regulator is out on my XCR...way you can tell is the head light seem like they are barely on, brake like seems like it has a 1 sec hesitation, no matter how high the engine is reving.
 

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Should also think about temperatures. lets say 20 degrees or above with the 390 mains, that are probally in it, it will run rich. may have to step it down. Just a thought.
 

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this may seem crazy but make sure all 3 carbs are opening. Years ago I blasting across an field and lost power. I thought I burned down. After checking it over really close in the field we decided to limp to the next town. While considering our plans I decided to check that the carbs were opening and 1 was not. I drove 100 miles home like that and could still hit 75 mph but what a dog.
 

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bigwedgies said:
black plugs show a problem.
gonna sound dumb but is the vent going to the airbox from the carbs?
What? There is a vent hose that goes from the carbs to the air box but I dont see that being the problem. Also Better to have black plugs = rich then have white plugs = lean.
 

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KRSS144 said:
bigwedgies said:
black plugs show a problem.
gonna sound dumb but is the vent going to the airbox from the carbs?
What? There is a vent hose that goes from the carbs to the air box but I dont see that being the problem. Also Better to have black plugs = rich then have white plugs = lean.
Carb venting is a huge deal. That is the entire principle behind the tempa flow.
 

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if the vent lines are cracked or unhooked on sleds that have them going to the air box you will run very rich.

if the chokes are stuck it will run very rich. very common on the old round 38's to have a choke plunger stick open. or someone set the chokes to tight where they are always on a little bit.

sync of the carbs can make a sled run badly but you usually see a difference in plug color from one to another cylinder. not always though.

bad clutch springs or someone makeing there own clutch kit and messing it up can make a sled run real bad real easy. if you cant get to wide open rpms it will load the engine and make it look like an over fuel problem. i have seen broken or bad primary springs do this.

if it was my sled i would do

1. remove choke plungers to verify they are free and set them. at the same time i would air check needle and seat, double check jetting on the needle and pilot jets as well as main for your area.

while you are doing that you can make note of vent lines.
if that didnt fix it then i would look at the secondary spring and helix to see whats in there compared to stock, and probably remove primary spring and replace it.
 

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Discussion Starter · #15 ·
Thaks for all the suggestions guys. I guess I'm not familiar with the vent tubes going to the air box, I dont recall ever seeing anything like that. What/where do I need to look?
 

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jbshocks said:
KRSS144 said:
bigwedgies said:
black plugs show a problem.
gonna sound dumb but is the vent going to the airbox from the carbs?
What? There is a vent hose that goes from the carbs to the air box but I dont see that being the problem. Also Better to have black plugs = rich then have white plugs = lean.
Carb venting is a huge deal. That is the entire principle behind the tempa flow.
Didnt know it had a tempa-flow???? So let me ask you this...when taking off/out the airbox to install a K&N airfilter for each carb where do you hook up the vent lines then?
 

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28sstony said:
Thaks for all the suggestions guys. I guess I'm not familiar with the vent tubes going to the air box, I dont recall ever seeing anything like that. What/where do I need to look?
In order to clean the carbs like you stated, you would have had to pull the 3 tubes from the air box,because the air box would have to come out in order to get at carbs. Does the sled even have an air box?
 

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X2 on the choke plungers. They had my Ultra running like crap 2 years ago. Add some preload to your plungers, not the lever. By doing that you can force the plungers to seal the choke tube harder. The plungers have little rubber pads on them that dry out and won't seal worth a turd over time. If adding preload fixes the problem, order up some new plungers, they won't last very much longer.

Here are your carb vents to the airbox:
 

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There's is something to be said about a CLEAN engine compartment.^^^^NICE!!!
 

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ultrawillie said:
There's is something to be said about a CLEAN engine compartment.^^^^NICE!!!
Thats what women are for. Teach them to polish chrome and clean the sled engine bay correctly and then you can jam to John Cash or David Allen Coe while supervising her. Thats the Ol School way that im sure Willie wouldnt get away with!hahahahaha....whats up brother, and Im in complete agreement with checking carb vent hoses and making sure all carbs are throughly clean and synced and chokes are correctly adjusted.
 
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