chewy Posted January 29, 2011 Report Share Posted January 29, 2011 I am finding my 2011 250 Sherco quite frustrating to ride, Having been through the white gunge in the carb episode(s), the cold weather running and retarding it to calm it down and keep it running in a forward direction, slow action throttle it seems (is it possible to say this?)too responsive.Admittedly I'm getting on and can't move or react as quick as I used to but the motor stalls easily and wants to go or stop and it's not easy to find that bit in between whwere the grip is. Discussing this with a long time riding mate (between us we have 70 years of competition experience) we are thinking it may be good to lower both primary and secondary compressions normal method is spacer after the reed block and head spacer or thicker base gaskets. Has anybody else been down this "road" with these bikes, I can't retard it any more as any more wouldn't be healthy for the motor. I can't get 40 years younger, I can't change bike for at least a 12 months probably by then it will be loose enough to forgive me a bit more frequently. Quote Link to comment Share on other sites More sharing options...
perce Posted January 29, 2011 Report Share Posted January 29, 2011 I'd try dropping a tooth on the front sprocket. I have previously used a reed block spacer to slow up a 250 gasser. Quote Link to comment Share on other sites More sharing options...
timp Posted January 29, 2011 Report Share Posted January 29, 2011 Hi, I have a 2010 250 and am the wrong side of 50!!. I like the bike to be really soft so possibly how you want it. I have, 1 slow acting throttle 2 downgeared about 1 tooth on the front 3 retarded about 2mm 4 Keihin carb 5 wheel back as far as possible If yours has the dellorto flatside I would borrow a keihin (I could even sell you one as I have one spare) and try that before fitting spacers etc. The keihin will really soften it off at the bottom end where you feel for grip. Also get the wheel back as far as possible. If downgearing by 1 on the front it will perhaps move it back enough. You can have a go on mine but I think you are a fair distance from me. Quote Link to comment Share on other sites More sharing options...
copemech Posted January 29, 2011 Report Share Posted January 29, 2011 (edited) They are a performance oriented machine as set from factory it seems. Last 250 I rode in '10 seemed fine out the box for me, but I been stuck on the 2.9's mostly, as all that is available here for the most part. My '05 250 was fine after a bit of settling, and still a fav. The 250 was often referred to as a "quicker" bike by many, but my impression on this is simply the fact it has a bit less low end grunt than a 2.9(272), so to make biger power you got to take into the revs a bit more. Not being a big fellow, at what I think translates to your 11.5-12 stone, the things move me just fine and then some. Not as good a lazyman bike as a 2.9 on pure grunt or for a heavier rider. I'm not sure if you stated it somewhere, but does this bike have the VHST 28 on it?(i don't like 28's, elliptical excess, will toutch on this later) Where is the timing currently? Having had to try and adjust these things to my taste for years now, and trying to help others do the same, yet taste varies and none the same. I am not really sure the inlet spacer makes a lot of difference. A had one on my '05 250 though. Nor base gaskets for that matter. I run the Boyeseen reeds, seem more progressive, to a point. I think the old 26 PHBL may be better if set well, I am still on the 24 OKO and is butter smooth. The 26 would be the ref, based upon Neo's testing on the 250. I ride a lot in second gear. I use the clutch to apply smooth power and find grip, reguardless of rpm or gearing. This requires a re-think of your riding style. Add a good working clutch.(mods) I run with 2 springs out of the clutch for light operation as not to tyre my power finger. In a way, i wish they had a bit more flywheel weight, but this is not an old TY yam in a Scorpa, thus it is me left to deal with my own limitations, and prefs. I gotta learn the bike! And feddle with it! If there were a perfect bike, then everyone would have it! Edited January 30, 2011 by copemech Quote Link to comment Share on other sites More sharing options...
rlracer Posted January 30, 2011 Report Share Posted January 30, 2011 I have a 2010 and a 2011 2.9 sherco. Tried a one tooth smaller counter for 5 minutes and took it off, didn't like it. Changing to a black throttle should slow it down plenty. The new motor runs really well ! Gobs of traction for me. It does fall a little short in the turning department but that will be fixed next week. Quote Link to comment Share on other sites More sharing options...
ormplus Posted January 30, 2011 Report Share Posted January 30, 2011 fit the maximum of base gaskets , makes a big differance. Quote Link to comment Share on other sites More sharing options...
copemech Posted January 31, 2011 Report Share Posted January 31, 2011 fit the maximum of base gaskets , makes a big differance. Ormplus could well be right here, although this is one teknique I have personally stayed away from over time due to the fact that it is more labor intensive, and less easily reversed. The Max number is 3, btw, and if my measures are roughly correct, the standard gaskets are 0.25mm thick each, allowing a change of .5 mm. I recently did a somewhat quick refresh of my '07 2.9 with a cleaning and inspection and a fresh ring set. It came from factory with ond standard gasket plus one 0.05mm shim gasket. Having the chance to experiment a bit, I just went back with 2 standard gaskets, so it is in the middle here. Difficult to determine here due to fresh rings, but yet as things have seated in a bit over a few riding sessions, I am really unsure I can tell much difference at this point, and may still recomend doing external mods as the Boyeseens first. Cheap mod, and easily changed if needed. I think if I had to summize things in my personal taste, I do not mind riding a fairly quick and powerful modern bike, I simply like it a bit more controlable and progressive, and find little need for more, only less power, if anything. I still like the quicker throttle tube, yet with a smooth bike. Quote Link to comment Share on other sites More sharing options...
copemech Posted January 31, 2011 Report Share Posted January 31, 2011 Carbs and sizes, The ellipse! Ironically, these bikes all came with a 26mm Dellorto PHBL for years, in 125,250,272 range. Same for some other brands. It is a versitle carb, and runs well in most applications if well jetted. I am not going to get into theories of volumetric efficiencies here, but it still remains a big carb like the 28mm Kiehin will flow more mix, and deliver more power if the motor can take it. This carb does seem a more precise metering device, delivering smooth power down low, yet still lots of it. Problem here it simple fact it is a larger bore carb! Thus, for a given mm of tug on the slide movement, you get a bigger "HOLE"(ellipse)as the thing opens up!!!!!! So for a 1mm movement on things, on a set idle opening, the larger carb simply reacts more by allowing more air in as there is a bigger bore...... This same effect applies throughout the range till the ultimate flow rates are reached, and limiting total power based upon flow. All this basically translates into two factors it seems. The Kiehin seems a better mixing device, and the smaller the carb, the better progression. As Kiehin does not seem to produce it's carb in the smaller versions, the OKO copy seems the only available option throughout the range of sizes depending upon what you want. The OKO is also CHEAP! By comparison, and if I ad my wishes, I would likely be on with the OKO 26, on a 250, rather than choking down the 272cc bike with a 24mm, yet at the same time, I cannot really tell any top end loss from the 26 Dell, must suppose it just flows a bit better, which is not hard to imagine if you take a look at the inlets! Quote Link to comment Share on other sites More sharing options...
neo Posted January 31, 2011 Report Share Posted January 31, 2011 I rode a 2010 250 just yesterday and it was creamy smooth and very progressive....in our currently hot climate. Base gasket (according to Splat Shop) for the 2011 is 0.4mm but 1.0mm for the 2010 ... this might be telling us something?? My well tuned 2006 250 was producing more power with my OKO26....but only any good if you like it like that...thankfully (at my "soon to be" wrong side of 50) I do!! Chewy, your an experience rider so I'd lay odds that you're still looking at small fault on your bike somewhere. Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
chewy Posted January 31, 2011 Author Report Share Posted January 31, 2011 Thanks to all for the sensible (and sensitive there's no fool like an old fool!) comments As Neo says It is really no critiscm of the bike it's simply making it work better for me. I will check out carb specs (it was new in October). My overiding problem at the moment is getting a tyre with any flex in it to stay on the rim (I have yet to finish an event with this bike using my hitherto favoured IRC rear), Ran it last week on the original Michelin and came up with these finding grip issues, the Michelin hhignlighted the motor /feel issue. (for me the Michelin in our typical going gives far less feel and practically no warning of impending going backwards feeling!) Without a consistent "grip datum/reference" I'll be floundering about trying to ghet the motor to suit me so today the first job is to "confront " my dealer with it's either the tyre you sold me or the rim you sold me or it's a bit of both ( it will have to be a rhetorical question which is why I've been trying to gather info/data on what and how to measure wheel/tyre relationship) but I'm rapidly losing faith just before doing that I 'll whip the tyre off again and measure the circumfrence of the "seating for the tyre" as this is what i can also measure easily on the tyres;... why does one have to go through all this crap is another question that keeps coming to mind. Timp I'm sure we've spoken since stopping riding the SSDT I.ve been observing the last 10 years (we're the tent people as most riders refer to us! just 'cause we take a tent to keep out of the weather, not cause were gypos or anything like that) so this year I'll make a point of speaking. Thanks to all ; the info won't be wasted. Quote Link to comment Share on other sites More sharing options...
copemech Posted February 1, 2011 Report Share Posted February 1, 2011 Not having run the IRC, Icannot comment on them, although seems to me the South UK guys riding in the nud seem to swear by them. I just throw on a Dunlap, and seems I can run them as low as needed without probs. Other thing I was going to point out was after installing the 24 OKO and taking the bike to some limits on the big mountain hills in TN, I kicked the timing back up a bit, to about a -2mm rotation on the plate, as it just seemed a bit lacking under load, and a bit too slow. An entirely different perspective on the running as compared to flatland running, when you gotta pull hundreds of yards of long hills at mid throttle. Had to adjust the main jet quite a bit. So current setting, smaller carb, better progression, still good power and relatively quick response. Still has a "kicker" in the mid revs when needed whick I think has to do with the dual stage reeds. Onse again, I could do with a bit heavier flywheel I think, but this is another issue! Quote Link to comment Share on other sites More sharing options...
neo Posted February 1, 2011 Report Share Posted February 1, 2011 It does fall a little short in the turning department but that will be fixed next week. How? IRC's... I love'm .... but I'm still waiting to read the alleged news about the company going under??? Best of balance. Neo Quote Link to comment Share on other sites More sharing options...
timp Posted February 1, 2011 Report Share Posted February 1, 2011 Timp I'm sure we've spoken since stopping riding the SSDT I.ve been observing the last 10 years (we're the tent people as most riders refer to us! just 'cause we take a tent to keep out of the weather, not cause were gypos or anything like that) so this year I'll make a point of speaking. Thanks to all ; the info won't be wasted. Not sure we will have a word this year. I didn't get in! Quote Link to comment Share on other sites More sharing options...
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