neo

Hi All, Just a bit of an update. I found the seal on the RH (oil) side had a hairline crack in the outer lip. And found that the seal on the LH (gen side) had a very swallow v-grove inside...as if both inner and outer lips had worn out....So I think I was experiencing problems from both sides. Both new rings and both new seals are operational. Finished putting her back together late last night and rode her on the driveway (because it was a bit dark to venture onto the rocks ) ...Once the engine had warmed up she was running like sh** ...far too rich and would not idle. Carb setting were 48 pilot, 120 main, JJH needle, Clip in the top position....been like that for 8 months or so. Fresh start this morning and changed the setting to Clav's settings....well as close as I could get....35 pilot, 114 main, JJH needle, Clip in the middle position. Ran better but now running very leak and hunting....And at this point I was starting to get worried .....Swapped the 35 for a 39 and bingo! all has came good......Not sure if my 35 was a bit blocked but she's now running good with an airmix screw 3/4 turns out, so I'll probably leave it there for now. A ride on the rocks reveled a softer/smoother low speed move off and a more consistently controllable level of power higher up too. So I'm happy so far.......It's all really looking good but the real test is after a days riding. Best of balance. Neo

It's funny how all comes clear when you look at the other side....the barrel side that is The old gasket shows a good fit on the barrel (apologies for not aligning the gasket precisely). New seals arrive tomorrow.. Best of balance. Neo

Just checked the 2005 parts book....M037 is the part number for both the 290 and the 250. .....The difference for the 2006 onwards, must be in the thickness. And the M037 carries through all the way to 2009 for the 250. Although 3 other thicknesses are now available.....All of them with different part numbers to the 290 ones....I think all this is making my head spin Best of balance. Neo

Hi trialsnutterman, Gasket for my 250 is M037 ...which is what I ordered....but I can see what you're saying now. The coverage is wrong....but I know the 290 uses the same crank case as the 250. So I can't understand how the gasket could be wrong. Anyone know how to tell the difference between a M037 and a M681 gasket? Thanks Stork...I'll be sure to check all you say. :-) Hi Tony, I was looking at it in the sunlight today....definitely Black......Hmmm..maybe we're looking at a bad/incorrect batch from Sherco Viton Seals on order. Best of balance. Neo

Maybe more to the point....what do GasGas use now and is it adaptable?? Best of balance. Neo

Good work Cope. I guess the problem is decals? Best of balance. Neo

Ok Gents....here's the update.... After some fuss I managed to get that main pinion off (without a puller and without marking anything). The seal came out dead easily using a "Seal Hook" (which I made myself some months back). I saw this tool on an old motorbike article and it works a treat. It a hook but it also curves around the shaft (hard to see this curve in the photo below) when it pushed past the seal lip. Even the old seal is barely marked..... Having said this the came out so easily I wonder if it was tight enough to seal against the case in the first place. .....And this old seal does not appear to be a Viton seal because it's black....I'll make sure I replace these with Viton (brown) seals. And if you look into the crank shaft you can clearly see that similar tarnishing and traces of oil on the side of that main bearing. There's no traces of movement in the main bearing on that side....but I guess it was well oiled Measured the amount of old oil, with precision, but it only came to only 350ml .....I think this problem could have been an even bigger problem in the future You know what gents....I'm getting really excited....this is starting to look like we've found the problem Also, if anyone wants the number on that water pump shaft bearing it's .."BC+ SKF HK 0808 GERMANY" Best of balance. Neo

No that was my son's 125 I did...this 250 has never been split.....And Id like to keep it that way if possible I'm running 98 with Synthetic 80:1 I didn't measure the coolant when it came out....but I know there was a lot in the bucket and it was a clean fluorescent green...Identical to what went in and it's been in there about 6 months now. All water ways are also very clean inside. But I'm going to try and measure the oil when it comes out....to me that RH seal is now a very strong possibility...so I'll change both this week. I also remember some time back changing the oil and and finding it odd that only 370ml's came out. I only discovered that by chance, when I pored the old oil into an empty oil bottle. Can I do any harm spraying carb cleaner in and around the top of that crank area?.....I know I can dry most of it out with the high volume warm air blower I have. Best of balance. Neo

The old gasket is identical to the new one bought from Sherco. You guys might be onto something here. As I noticed, on dis-assembly, that the two front bolts were not as tight as the two back bolts... What else could I have been burning but premix?....that's all that's in the tank and the carb, air-filter and air box are all dead clean.??? Good idea...yep I do that. New rings both have a ring gap of 20 thou. I'm not keen on splitting the case at this time. But I reckon I can do the main seals without doing that. so might try that next....If I mess up I just have to split the case anyway I suppose Many thanks gents. Best of balance. Neo

Hi all and thanks Cope. I'm must say that due to my current situation, as the purse strings get tighter and tighter, these "nutter" tactics will become more and more common for me. From my prospective I just gotta keep riding and if I kill myself on that BIG ROCK in the process.....well at last I'll be doing what I enjoy most. I'll also add that I'm no fool.....and compared to riding MX "Bent bar Trials" is a calculated risk I'm prepared to take. Best of balance. Neo

Hi all, Lifted the barrel off of my engine today. I

Has anyone found a suitable replacement thermostat for the Sherco? I can't believe the money Sherco charge for this device.....looks like it comes out of a dishwasher to me. And there might be an even better/slimmer one waiting to be discovered Best of balance. Neo

I would guess that the poor voltage regulation (compared to a computer power supply) would be the reason the fan died so quickly....assuming you didn't do the "cup of water" test You could introduce extra components to stop this next time but to be honest it wouldn't be worth the hassle. Best of balance. Neo

Hi All, I mildly bent my bars a few weeks ago and place an order for some new ones...which I recently got. I've always been one to change my bars when I've bent them. But I was told (some time back) that you can straighten them if it's just a small bend and if you do it the right way...with a good amount of heat. I've never wanted to do this because I visualized big burn patches on my bars, which I didn't fancy. But last weekend I thought I had nothing to loose and gave it a go.... I was amazed how easy it was and how the anodizes finish (on my Sherco bars) was hardly tarnished. The hardest thing was knowing which direction they needed to bent back. So now that I have a spare new set to hand I thought it would be a good time to use these and make an alignment jig. So next time this will be even easier....but I don't know where to start. Has anyone done this before?....any ideas on how it could be done? Best of balance. Neo PS...I if you choose to do the same thing you do so at your own risk....For a competitive rider I don't think it's worth the risk. Correctly or Incorrectly straighten bars can fracture and break....so if in doubt DON'T DO IT!!!

Hey Cope....I'm sorry to let you down on that ....It just been a combination of many things, these past few months, that's got in the way. I'm deep in study during the week so don't touch the bikes weekdays. And we're praying for rain at the moment....if this dream comes true this weekend I might have time to whip the 24mm off of the 125 and try it on the 250......I'll use the jets/setting out of the PWK 28 to get it going. Best of balance. Neo

I experienced the same with our 125 (Sherco's are awesome ) ....and I hope I'll see the same again when I open up my 250 Best of balance. Neo

While on this subject....has anyone managed to change the bushes on an 06 or an 07 (adjustable) shock? Best of balance. Neo

OK...I've place an order for new rings....and will do the seals (if need be) after that. But with all this in mind, I once read (I think it was you Cope that said this) that too much 2T oil will actually aid the piston ring seal....would this apply to a hot engine too?....Would raising the level of oil in my tank go some way to proving this theory? If so, I run 80:1 synthetic now ...what should I raise it too? Best of balance. Neo

Why's it gone so bloody quiet???? I've found previous posts, about GG releasing a fourstroke, in this forum dating back to 2005!!.....Come on GasGas .....Sherco are releasing their 2010 soon ....do something, say something or loose out on a ton of business Best of balance. Neo

Hi clav....the fact that you'd changed the rings before suddenly came to me while I was riding today.....so you've been through two sets of rings in 6 months?? ....but why didn't it fix the hunting problem the first time?? Another thing I'm confused about is why would I have good (high) compression if I have worn rings?? Also, just speculating... some time back I did a post stating that my bike to needs a rev-up (clean out) each first ride of the day....Maybe....If I have a problem with a main seal and it's on the water pump side, maybe it's sucking in a small amount of gearbox oil while the bike is cooling down (at the end of my riding day)....leaving this oil in the crank case for the next time I ride.?? Peter, I'm thinking I might do what you suggest but do both seals...and what the hell.....I'll fit a new set of rings at the same time. Best of balance. Neo

Ok, I'm gonna give the pump-up test another go too...But one thing that concerns me is when I set it at 2-3PSI, when I check the pressure (with a digital low pressure tyre gauge), I'll lose quite a bit of that pressure each time But at least I can re-check for the soapy bubbles at that low pressure....I'm also going to carefully use heat around on the flywheel side of the case. clav, are you saying that now you've done the top end you don't have the problem anymore? Peter, yep I guess I gonna do them seals one way or the other Best of balance. Neo

Yes I know what you mean Peter, It's not the money....it's the learning, the diagnosis, the discovery and the proving that make it feel like winning to me And after all this time I don't really wont the problem to just suddenly disappear without knowing why .....with 100% confidence. And I love working on Trials bikes.....(hate working on cars )....and I love discussing this stuff with those that know Hope you know what I mean? Best of balance. Neo PS...Thanks Stork and Cope....I'll come back to you after I've done some damage to my lungs or my wallet .....already found an Inlet pressure gauge ....only had it 25 years...still brand new!!!

Hi Tony, Thanks for the information on this. Interest how these are C4 rather than C3 ....is this something to do with the fact they grease filled? Best of balance. Neo

Ok Gents, I've decided I need to "Suck" on this problem But how do I create a vacuum in the cylinder and how would I hold it there and measure it? And how could see that air is going in through the seal? Would this be called a "Leak Up test" Best of balance. Neo

Hey Tony, You know the SKF website and the Sherco parts book are enough to drive you around twist I assume the bearing you got are rubber sealed both sides?.....because that part number "2RS1" are sealed on only one side And the "ETN9" is different bearing altogether And the only bearing SKF do that seals on both side is the "2Z"....... Can anyone shead some light on this? Best of balance. Neo