new sherco

[chewy]

Just bought new Sherco ST250 delighted with it so far but have never had a Sherco before, everything works fine exept for its propensity to stall, I noticed that when it does this it tries to run backwards so I have retarded the ignition by about 4 deg. it seems better (on the drive) and runs much smoother, question/concern is that it may run a bit hotter,has anybody found same problem and cure? A mate said only use 98 octane fuel, bottom gear seems high compared to 6 speeders which sort of highlights any bottom end sputtering issues, As I say I think I have sorted it now but have no chance to try it in anger untill next wekend any pointers appreciated.

[ormplus]

your bike is under warranty , dont mess about with it . take it back to your dealer or you will loose your warranty.maybe needing a bigger pilot , as for fuel it will run perfectly fine on pump unleaded. we us it in all our bikes, even doing scottish championships.

[baldilocks]

my 07 290 was exactly the same when new and I did what you have done, made the power delivery nicer and didnt stall as easy. Personally I think they are too far advanced out of the box. Yes it runs a little hotter but mine went round the ssdt like that and didnt overheat once so I wouldnt worry too much.

[chewy]

thats the response I was hoping for thanks Baldilocks. Any other little "foibles"/fixes would be well recieved.

[rockyrider]

Congrats on your new purchase,Chris. Now you're one of us Sherco nuts. Hope you enjoy the bike trouble free. Over here we,(I) run run aviation fuel, supposed to be over 100 octane, mine does no pinking.

[copemech]

Cool! New Bikey!

Well, I can only speak in general terms reguarding the new bikes, as I do not have one and have not ridden a 250 since last March/April timeframe, on the '10 model. Have not owned a 2.5 since '05.

As they have changed the engine castings on the '11 model, I am not even sure if the look the same on the stator side? Did you find your factory "tic" mark on the plate? Was it aligned with a ref mark or a casting web?

Seems typacally, the Sherco's do come with the timing set for optimum performance, and a bit on the edge, and I have always changed mine, usually out of neccessity on the 2.9's.

Having done the basic math, I can tell you in simple terms that 1mm of distance on the outer diameter of the stator roughly equates to 1 degree of timing change, and from my experimentation I set the limit at about 6mm before bad things start to happen. So you should be somewhere in the mid yet at about 4mm. A change of 1mm will tell no difference, takes about 2 to make any noticable change in performance. My happy spot now is 3! Bike is still quicker than me!

Jetting and fuels seem to differ a bit accross the pond, yet the intake tracts on the new ones differ as well and I am not sure just how much this effects things with the dellorto.

Again, I always had to change things. My '07 came with a 30 pilot and would not lift the front wheel off idle it was soo weak. Last setting was at 38 before I changed to the Oko.

I just think they run better if you get the jet up into a more workable range of the fuel screw at about a "lean best idle" of about 2.0-2.5 turns out on the fuel screw, and yet without making them a bit lumpy at 1/16 (crack) of the throttle, as at that point you have gone a bit too far, so maybe try a 35-36 range I would think.

I set the idle to get a good idle when in gear, not too high, but not too low. My 2.9 will chug up the drive at the house in second with no throttle without stalling. I find little reason yours should not do the same.

I recommend the BP5EVX platinum ,non resistor plug if you can get them, scarce over here.

Seems proven you can take this plug a bit wider to .7mm range, as I still have the same one in since I got the '07, seems to give just a bit better (cleaner) pull off the bottom under heavy load. I would not go that gap with the resistor type irridium plug, yet the probably work ok at the .6 setting.

You will just have to play a bit with the tunings, keep us posted!

Now you can take this of the Gasser threads!

Edited October 24, 2010 by copemech

[chewy]

Thanks guys all you said rings true , there was no marking re stator plate position, I moved as copemech said c.2mm on periphery and it did make some difference so I went another 2 degrees, immediatly the notor ran smoother ( essential for me and the going around here) I was able to refine carburation better as well, all I need to do now is try it in "anger". regards runnimg at tickover ; it's a bit subjective regarding speed of tickover, After 40 years of trials competion and countless bikes my (dare I say forte) is finding grip off the bottom end for that I need motor to stay alive at lowest possible revs, As it was it would just "go out" (stop with a kick;..a backfire not really but back wheel trying to reverse as it stopped) .. you had to keep throttle open to keep moving which made un neccesary challenges in sections even using clutch. I can stall it now but it doesn't kick like it was. Elsewise the bike is well sorted , it steers well, even I can hop both ends with reasonable predictability, brakes perfect,clutch actation is sweet ; first bike I have had for many years to have a sweet clutch out of the box, very serviceable, I have made a mudflap to protect rear suspension links a bit, I dont think the back mudguard is as good as it could be for actually keepimng mud away (It came with the non homolugated rear mudguard with no rear light and holes where you "sit") I assume they are there for good reason (to let some heat away from exhaust maybe) pointless in the conditions we frequently have as the mud off your ass will get pushed in/through. Motor is really tight at moment with no annoying mechanical rattles, I moved the engine mapping switch to behind front light ( I leave it on soft at all times anyway), I have an interest in footpegs but standard cast & machined ally ones are nice with a prpoer bush setup rather than a spacer to mount the spring. Swinging arm is really narrow/really nice, I havn't messed with fully adjustable suspension setup as it it god for me (this may have been due to Steve Saunders doing the PDI?). It occurs to me that other new owners of new models should report on thier bikes.

Thanks again for the reassurance guys.