80+ miles - enjoying an SP NT 1000 :-)

[mhsilverw]

Thought I'd wake the guzzi SP NT from it's slumber.
So after putting some air in tyres, as it was still sunny went for a splash of fuel, and a ride in some rare (sunny) end of Feb weather (UK).
An enjoyable canter round some unclassified, 'b' and smaller 2 lane 'a' roads. No repeat of it pretending to be a single after my tinkering with / replacing plug cap.  :)
Rode well, smooth around 3000rpm (and upwards), below that you know your tiding a twin, with big cc's, a bit lumpy.
What is recommended way of riding? Should I stay in top as guzzi seems to cope, albeit lumpier at lower revs or should I head for lower gears and keep engine in the 3000-5000 rev range?
Only irritant, a slight weep from l\h fuel tap. Dunno if replacement needed of they are rebuildable, like those on my MZ.
Still, 80+ enjoyable miles, and little traffic  :bike
Didn't seem to need much fuel, seems from last fill up about 60mpg!
Mark

[Chuck in Indiana]

should I head for lower gears and keep engine in the 3000-5000 rev range?

yep

[fotoguzzi]

3 to 6,000

[Bill Havins]

....below [3000] that you know your tiding a twin, with big cc's, a bit lumpy.....Should I stay in top as guzzi seems to cope, albeit lumpier at lower revs or should I head for lower gears and keep engine in the 3000-5000 rev range?
Only irritant, a slight weep from l\h fuel tap. Dunno if replacement needed of they are rebuildable, like those on my MZ....
Mark

Mark,

I don't know the history of your SP NT, but, to me, your comments make me wonder if it's time to rework the fueling system from (and including) the petcocks through the carburetors.  An SP NT should have a "lumpy" (as you call it) idle, but should immediately rev smoothly from idle on up.  My SPs (when correctly tuned) had no difficulty putt-ing about at revs as low as 2250 (in traffic, etc.).  Yes, the engine much prefers the 3000+ rev range, but can handle from about 2250 and up very satisfactorily.  At lower revs you "know it's a Guzzi," but it should be more of a "smile-maker" than "lumpy."

If it hasn't been done, consider pulling the petcocks and rebuilding them.  IIRC there is a crush washer where they seal to the tank, filters/screens around the inlets, and an o-ring that might want replacement.  Consider replacing the tubing to the carburetors, adding in-line fuel filters.  Clean and rebuild the carburetors, paying special attention to adjusting the float levels.

Once the above is done, carefully synch the carburetors and adjust the idle to 950 RPM (IIRC).  When you have done all of that you should have an engine that is "pure Guzzi" - "funky" idle and very useable torque from about 2250 on up.

Good luck and have fun!

Bill

[Triple Jim]

My experience is as Bill described.  Under light load, like going through a town at 35 mph, 2,000-2500 rpm is fine.  I'll downshift to get to 3,000-3,500 if I want to accelerate hard or go up a hill.  I agree that lack of carb sync is a contributor to feeling lumpy.  Low RPM vibration does become less noticeable if the carbs are correctly synched.

[Chuck in Indiana]

950 RPM (IIRC).

I've read here that 1050 is better. Too low an idle causes accelerated clutch splines wear. I always set them at 1100. Small blocks at 1200, although clutch splines have nothing to do with them.

[LowRyter]

don't lug your Guzzi

 :bike

[Bill Havins]

Chuck,

IMHO, an idle of 1100 RPM on an SP "just ain't right."   ;)  Perhaps I didn't own mine long enough to induce "clutch spline wear," or maybe the fellows I sold them to had to replace the clutches soon after they bought them.  I just don't know.  The "syncopation" of the idle of a carbureted Guzzi (at or about 950 RPM) really floats my boat.  I really miss that syncopation with my EV.

There is another issue that affects the SPs that many don't appreciate.  When the battery is slightly discharged the engine will idle just a little slower and will hesitate as it revs off of idle.  So if you have had the bike in the garage working on it over a period of several days (starting and stopping the engine, setting idle, balancing carburetors, and performing other tuning chores where the bike is not run on the street for long) the battery will slowly discharge just enough to slow the idle and make the transition from idle to higher RPMs hesitate.  This condition is easily misunderstood and leads to fruitless tuning that can take you further from your tuning goal.

I quickly learned to check the battery voltage after I had tuned my SPs.  Often a quick charge helped the bikes run like I thought they should.

Bill

[mhsilverw]

After some tweeking managed to cure fuel tap leaks and some minor adjustments.

Had to go for another ride  ;D, very gusty and windy in the fens, but my weight/mass was a match for the blowy conditions.

Improvement in running, and no leaky tap.  :)

And didn't lug it but a better balance and  less lumpy.

Think next job maybe some replacement fork seals  ::)

Mark