sxr 700 gas consumption

[smurf]

Bought a 2000 sxr 700 last season with 2500 miles on it. We also own another 2000 sxr 700 with 15,000 miles. The big difference between the 2 is the gas consumption. The one we bought with 2500 miles on it only gets 9 milese to the gallon compared to the other which gets 16. It also has a flat spot at 35 mph that you have to throttle thru which may or may not be related to each other.

We have been through many things during the season. Clutching, carburators, needle settings, etc. - nothing improved. Wondering if maybe the fuel pump could be causing somthing here. Isn't dropping gas or fluid anywhere. Not sure how it could be burning so much gas. Sled runs great otherwise. Seems to be set up the same as the other one we have. Why the difference????

Any help would really be appreciated

 

[daman]

Is the motor healthy,did you do a compression or leak down test on it,
how's jetting, stock???

what kinda R's are you seeing from dead pin to WOT?

and to the site

 

[yamaholic22]

Weak stators can cause behavior similar to this, not exactly sure why. But seen it happen on vipers, never on an sxr. And as Daman said how is the engine condition such as compression and leak down? Are the floats set correctly in the carbs? Clutches clean and operate smoothly?

 

[smurf]

Thanks for the response. Clutch had heavy hitters in it when I bought it and I replaced it with stock - no improvement. Clutching runs smooth. Compression test was right on. Jetting is at stock settings. Floats look right. It's really been puzzling to myself and other sledding friends. Answer is there somewhere though.

How does one check the condition of the stators? What does anyone think about a possible connection to the fuel pump? Could the flat spot at 35 mph have something to do with the gas consumption?

Thanks,

 

[snoden700viper]

I'm going to take a stab at this one. We had 98 XTC 700 triple that went from 14 MPG down to 8-9 MPG just like yours. We replaced the fuel pump, oil pump, checked compression, checked stator and still nothing changed. Cleaned carbs over and over, adjusted floats, checked reeds, replaced fuel lines and still it keeped us scratching our heads. After a long conversation with a local mechanic he convinced me to change the needle and seat in the carb. Well he was right! The owner of the sled (my brother) admitted he didn't clean the carbs after each season but did clean them prior to the start of each season.....TOO LATE! We changed the needle and seat and what a difference, fuel milage went back to 14 MPG and the sled ran much better. A 2000 model year with 2500 miles is great but thats also a sled that has sat around alot with very little maitenence too. Hope this helps ya out and good luck.

Snoden

 

[smurf]

Great response. On the surface sure makes sense. We did have the needles out and they looked good and were set to the correct settings. Things looked clean, but I suppose there still may be a problem with them that I didn't notice - I'm not really an expert.

If I would change the needle and seat in the off season, any way to check if it made a difference. Can't stand the thought of having to wait until snow to really check it out. Guess that's dealing with Wisconsin weather for us snowmobilers!

Thanks for the toughts.

 

[crewchief47]

Could the flat spot at 35 mph have something to do with the gas consumption?

Thanks,

You said you replaced the clutch weights when you got it but is it possible that a primary/secondary bushing is going bad and causing your flat spot and poor mileage? The float needle and seat is an interesting thought. I would think you would be able to smell the excess gas being pushed through the system, hmmmmmm.....

 

[snoden700viper]

Smurff...I suppose you could ride it around the yard for a hundy plus miles....lol. Not sure the wife and neighbors would like it a whole lot. Seriously though I have no clue if their's a way to check it out. In regards to the needle it won't show any signs of wear or their might be a problem. It's in the seat where the problem is, it builds up with varnish creating the problem.

Crewchief has a good point with the gas fumes. I did not ride the sled so I don't have that answer for you. Now if it's just pushing alot of unburned fuel thru the exhaust I'm not sure the rider would pick up the smell of fuel at speeds either. I've had fuel line leaks under the hood and could pick that smell up rather easy because it's contained under the hood and flowing right back at you....hmmmmm!

One other note was how rich it ran...which should be obvious. Plugs were black as coal.

Snoden

 

[smurf]

At this point, I will probably check the needles and clean the carbs again. I will also check the primary/secondary bushing. As far as the gas consumption, there is zero gas smell anywhere. I really doubt that the unburned fuel is going out the exhaust, but cant' rule it out totally. I have rode sleds for over 25 years - can't locate any unusual smell under the hood nor out the exhaust.

And Snooden, wife really wouldn't have any problem with running around the yard with the sled - we both are already tired of the grass cutting thing!

Unless someone has something to add - I will get around to messing with it over the next couple of weeks. I'll post if anything new develops.

Thank for the help

Smurf

 

[pro116]

those non pv motors all have a little flast spot.I thing snoden is right.
Move the clip one spot leaner in cleans up the mid range on those sleds.