dombush

Jimmie i used one on my 2006 250. It had 2 good effects and 2 small side effects:- Good The flywheel significantly reduced the tendency of the bike to stall when travelling slowly down hill or negotiating tight turns on tickover "in section". This in turn allowed me to utilise this to trust the bike and keep the overall speed down. I'm quite small & light and i found the flywheel smoothed out my poor throttle control. Bad If "firing" the bike up a big hill in 2nd / 3rd the flywheel can affect the bikes ability to slow down at the top. This is just a get used to it thing. The steering can "push" a bit in mud or poor grip when rolling the throttle off. Overall it works for me, mostly because it helps with my hamfisted throttle control. Dom

No need for more explanation, Steve has it. Damping in one fork leg, spring preload in the other. Floating disk compensates for a number of possible braking misalignments. Done

Lewis seals are around £5 each. The good news is that they can be replaced without removing the engine and splitting the crankcases. The bad news is you need a couple of special tools and you could make a make some expensive mistakes if your not experienced at this. Special tools are:- Clutch holding tool £75ish Flywheel puller £13ish Seal driver (i just find something that suits) So, if your good with this sort of engine work (bodywork off, drain fluids, brake lever off, clutch cover off, clutch off, crank pinion off etc.) great. If not, i'm not sure how much a local shop might charge. Probably not much more than the cost of the tools. Dom

Hi Dont worry the screws arent left hand thread. If they are standard they'll be a button head screw that takes a reasonably small allen key. As you are aware the danger is rounding off the hex socket in the fastener. I suggest the following as a procedure. Get a friend to help you Find a centre punch and small hammer. Ensure that the centre punch point is defined but not overly sharp. One person applies a reasonable torque with the allen key The second person takes the punch and heavily taps the fastener head in the correct direction. Try to apply the punch to the outer part of the fastener head (more torque is applied). The combination of the two forces will shift it if it can be shifted. If the above fails there are two other techniques but they get more drastic. Get a jewlers gas torch (tiny flame) and heat the fastener head to try to use expansion to break the seized surfaces. The fastener needs to reach 200-250 degrees but NOT cherry red. Grind the head off the screws to remove the master cyl. Heating the "sticking out" portion of the screw is now easy and some mole grips or a vice can be used to turn the screw shaft. Dom

Hi assuming that we are talking about performance rather than bling (i hope so), bit of a boring but practical response:- Flatslide carb (Keihin or Dellorto VHST) Jetting spot on. New piston rings. Set the squish (piston to cyl head) to a performance oriented value. Decent rear shock (ohlins, TRP etc.) Shock spring to suit your weight. Clutch basket replaced if worn Dom

Dan Firstly, its normal for a bike to lose power when it overheats. This is normally due to pre-ignition or worst case a partial seizure. Both issues are initialy minor but will turn terminal very quickly. A couple of questions:- The most obvious one is... was the fan running when it was boiling over? Were you travelling quite slowly (using it in sections for instance) when it boiled over? If the fan isnt working then the engine will most certainly overheat. This would be expected. My 07 125 will start its fan after 15-20 minutes use "in section" in the winter. Halve that time in the summer. If the fan wasnt running during the overheat then the most likely issue is a failed thermostatic switch or failed fan motor. Disconnect the fan from the thermostatic switch and wire the fan directly to a 12v battery to understand if the unit is faulty If the fan works, Unclip the thermostatic switch from its housing and withdraw. Rewire the thermostatic switch to a 12v battery and dunk the sensor end it into a cup boiling water. If the fan doesnt start after 30 secs then the thermostatic switch is the likely cause. My particular bike had a switch fitted to allow a rider to switch the fan on manually, this and your example are common mods for bikes that are used on road trials. It isnt beyond the realm of possibility that the thermostatic switch wasnt rewired correctly after trying to correct your modification. If the fan was working during the overheat there are a different set of possible causes. Let us know the outcome of the above first. As far as manuals are concerned, there is a "combined manual" due to the engines being very similar despite capacity differences. Look here http://www.sherco.com/EN/service_manuals.html under 2009 and download the "All 2 strokes trials models maintenance manual". I think this is the best information around. There are some other more detailed documents for specific procedures / issues. Dom

Zero I guess that i'm saying that you need to check the "sag" on the shock to confirm its knackered. I attach a couple of links that deal with measuring sag to determine condition and another with a suggestion on where to get another spring. http://www.trialscentral.com/forums/topic/42958-gas-gas-suspension/page__hl__suspension http://www.trialscentral.com/forums/topic/37579-problems-with-sag-settings/page__hl__suspension Dom

Hi the oil / damping condition of the shock does not affect the "sag" of the bike when staticly loaded. The sag is a function of the spring / spring preload itself. Springs "relax" over time and they are also rated for different rider weights. The issue you describe is likely to be attributable to one of these issues. Do a search on suspension sag or suspension setup to identify if your "sag" is correct. Dom

+1 on Paul W's advice just start again and check the basics while its apart. I could be something deeply complex, but most problems are issues with the basics. This way, you can move onto the next level of complexity knowing you double checked the fundementals. Dom

Ben there's milky and milky.... given the Sherco has no oil viewing window, where are you looking to see the milky oil? A small amount of water in the oil will not harm anything in the short term, so i suggest keep riding the bike for an hour or so and see:- Does it get worse.. in the extreme it will go a cream colour Does the cooling system water level go down? Have you been power washing the bike since you refilled the oil? Have you got a long small pipe fitted to the gearbox breather? If there is a leak the coolant level should go down and the oil should get worse. If it gets worse after power washing, consider how water could have got into the gearbox... there are a few ways. Do that and come back to us. Dom If it doesnt go down and the oil doesnt get worse, run it for a bit longer then drain and refill with fresh oil.

Hi flooding in the manner you describe (assuming the leakage is coming out of the overflow pipes) is likely to be float height or needle valve related. Float height is simple to fix. A search on this will get you the correct height setting See this link..http://www.ducatimec...llorto_3_2.html except i believe the correct dimension is 18.5mm. Needle valve issues are normally related to a poor valve seat. This can be seen visualy as marks on the tapered area. see part 9 on this diagram http://www.dellorto....arts/PHBH_l.pdf Worth dismantling the carb, blowing it all through with an air line to ensure there's no dirt hanging around in the inlet pipe. The rear brake being poor could be a number of things, just a few ideas:- oil contaminated pads / disc-----should be able to see this if you remove the pads air in the brake lines (sponginess)-----Brake pedal doesnt stop solidly (lots of travel and gradual power) very very old brake fluid----- very dark brown colour, pump new fluid through by bleeding continuously. perished brake lines ----- difficult to tell... effectively they bulge instead of transmitting pressure to the pistons seized pistons-----take the pads out and operate the brake, see if the pistons move freely . are they easy to push back into the caliper?. If not...seized master cyl piston seals poor condition---- spongey pedal, takes a few pedal strokes to work The fan might not kick in for quite some time in this winter weather. Try this:- There may be nothing wrong at all. The radiator hoses will be pretty hot before the fan wants to kick in. Also the motor will likely be pinging / detonating if overheating. Run the bike under load for some time (10-15 mins). Then operate at very low speed such that the radiator isnt cooling the engine. The fan should kick in after 5 mins or so. you can short out the thermostatic switch to see if the fanworks at all if the fan works but it isnt being switched on it could be the thermostatic switch. lots to think about... do the simple checks first. Dom

Hi Mikey Dont disagree with anything written so far... some other things worth talking about. When trying other bikes dont make the mistake i made, looking for impressive sharp response and power (wheelies, hopping). Trials at the novice level is about planning, accuracy, subtleness, control (rider skill). Pick the bike that allows you to achieve this. I am regularly beaten (!!) by guys on older bikes, so after you have decided the type of bike you want, buy on condition as the main factor. Spares are expensive!! I run a 2006 250 Gas Gas that was immaculate, i ended up calming it down a bit to smooth the response. I have since ridden Beta's and Sherco's and can genuinley say that i could compete on any of them. They all have their strengths. Lastly, "bling bits" rarely make a huge difference (shock, carb excepted). Basics like setup, tyres, brakes, pegs, grips etc..do!! Dom

Hi When i started riding trials (ex-enduro) i mistakenly felt "impressed" by sharp power and minimal damping (wheelies, hopping etc.) As time, experience and initialy lots of poor results passed... i realised that minute control of the bike was the key to good results. Since that time, i have seen the light and made some mods to a standard bike. Got the carburation correct so its not blubbery or snatchy, especialy during transition from idle to low revs. I fitted a Keihin carb which i found more "tunable" and precice than the Dellorto originally fitted. Fitted a flywheel weight to help reduce stalling as well as reduce sharp pickup, helping grip and stability. Slow action throttle. Gearing to reflect real competition use rather than road use Fitted new tyres Adjusted and fettled the clutch to give a really gradual bite Got all the controls, pedals, throttle freeplay, handlebar position etc. exactly right. All these things help and i really feel at home on the bike. 90% of all sections for novices aren't hopping, wheelies etc., they are basic control exercises. Glad you're on the right path earlier than i was. Dom

Hi Diesel the way i look at it is... I'm competing in a sport where the ability to find grip in the most sketchy circumstances is 1/2 the battle. therefore i go for the best tyres i can afford. Of course different people have different motivations / opinions.. As it happens the survey reflects my thoughts. Dom

Matt so, yes you can over-oil a filter but it would have to be quite extreme to have any significant impact. The correct amount of filter oil is when the filter has total coverage (no dry patches) but when scrunched in one hand no oil drips. Be careful not to wring (twist) the filter as this stresses the glued joints and can cause rips. Most people i know wet the filter in a number of evenly spaced (10-20) places an then place into sandwich bag and scrunch several times to distribute the oil. Lastly the filter is removed from the bag and scrunched to allow excess to drip off. Dom

ShercoBen Ok, the water pump seals are an easy fix, probably 30-45 mins if you know what your doing. Also the parts are less than 10 pounds (so long as the water pump shaft is ok). Like Copemech says, difficult to say who's at fault, probably best to just get it done. Dom

Ben your correct that white or milky (emulsified) oil is likely to be water in the oil. it could be that the inner water pump seal has failed. couple of questions to rule out other causes:- When you replaced the piston, did you remove the clutch cover or drain/replace the gearbox oil? Have you seen water leaking from the small tell-tale hole located on the underside of the water pump housing? Have you unexpectedly needed to top-up the cooling system water level? Dom

A few ideas based on things i would like to receive (are you listening kids). A nice pair of trials gloves. A nice trials specific tyre pressure gauge One of the "sevice kits" that are advertised for specific bikes (various oils etc.) Some S3 (or similar) clutch / brake lever span and bite point adjusters i feel a bit like Bruce Forsyth on the generation game.... a cuddly toy, a toaster... Dom

Hi There can be a number of causes for the symptoms you describe. However, lets start with the most likely. Be careful with the plug looking oily after 20 mins running with the choke on, this is a reasonable situation given that the choke would cause excessively rich running after 1-2 minutes. The previous post dealt with the potential for a blocked jet. This is entirely feasible but just one of a number of causes. For oil to be pushed out of the gearbox breather this means that the gearbox is being pressurised from the crankcase. The most likely reason for this is a damaged crank seal on the clutch side. To check this is the cause, get a glass of water and with the engine running, submerge the breather tube into the water. If the tube either blows out a continuous stream of air or starts sucking up fluid then its likely that the crankcase seal has failed. A very slow bubbling ( a few bubbles in a minute) could just be air expansion due to warming of the gearbox. This is not necessarily a problem This seal can be replaced without removing the engine, but does require some knowledge and tools to do so. Remove the kickstart and Rear brake pedal Drain coolant and remove the water pump housing Drain the gearbox oil. Remove the clutch cover (preserving the gasket) remove the clutch pressure plate and plates Hold the clutch basket with a special tool to allow the crank pinion nut to be loosened. Hold the clutch hub with a special tool to allow the clutch hub nut to be loosened. Remove the clutch components then remove the crank pinion and woodruff key The seal can then be removed with a sharp hook or other tool that wont gouge the aluminium crankcase or the main bearing that sits behind the seal. The new seal can then be fitted.carefully after greasing the lip-seals and the taper on the crank. Care must be taken to ensure the seal is inserted perfectly square and flush . Of course, if the breather doesnt bubble, and it isnt a blocked jet either.... we'll think some more. Dom

Keep going, the answer is in there somewhere Dom

So, a few widespread ideas to mull over Idle fueling or transition ports blocked, these are the tiny drillings in the main throttle bore on the reed valve side of the throttle slide. (not the idle jet) Idle air bleed blocked (one of the ports on the bellmouth of the carb) Jets / idle mixture screw blocked. Remove everything from the carb and spray through with carb cleaner then blow through with an airline. idle Jet not screwed in properly or even missing (sorry) Leaking or poorly sealed choke plunger (choke operates only at small throttle openings) Broken reed valve petal (this can affect starting ability also) and result in spitting back through the carb. Ignition timing too advanced. Do the basic marks line up? Whiskered plug (unlikely, as this is normaly intermittent running / very hard to start) Float height wrong (fuel level too high / low). something wrong during re-assembly of the crankcases causing binding. (crank binding, crank pinion to clutch ring gear, clutch bearing etc.) My suggestion here is to take the plug out and rotate the crank with the flywheel.. does it feel free? Is it running very rich on idle, meaning it would normaly tick over but cant due to mixture? There's nothing blocking the exhaust / inlet from your rebuild (rag / exhaust bung etc.)? If you wind the tickover speed screw out, can you discern when the slide stops stopping on the screw and hits on the base of the carb? Point being... is it hitting the screw? Air leaks.... many causes although normally causing high or variable tickover. Can usualy be identified by weak running or by inability to hold steady revs at no load (not in gear) Dom

Questions:- When you hold it ticking over manualy, does it tick over freely and without labour? Does it pick up from low revs quickly or does it hesitate ? Dom

Excellent S35 pilot arrived last night and immediately fitted and tested in the garage. Immediately ran better and wasnt too weak when snapping the throttle open from tickover. I found that the ideal fuel screw position is sensitive on the VHST. Need to test it under load though, somewhere other than the garage!! Trouble with looking so closely at the bike for a long time is you notice other things like a slight drip from the water pump tell-tale and the gearbox breather pushing a bit of oil out when the bike is tipped over. No rest for the wicked!!

This happened to me once on a CR500, one of the most frightening experiences of my life. As has been said above there are two main sources of such problems.... The cable itself and the slide sticking in the carb. Copemech has covered the slide sticking subject. Also caused by poor / missing air filter. A list of the possible cable related checks might be:- Throttle housing too far up the handlebars leading causing jamming against the handlebar end and the grip. Freyed inner cable at the twistgrip housing end. This can be found by removing the snap-cap on the Domino twist-grip housing. ANY freying here is bad. Also check that this area is free of dirt / excess grease and that the cable "drum" rotates freely. Damaged / poorly seated outer throttle cable entry into the twistgrip housing. This area should be held "in line" by a strong rubber boot when handlebars are turned. Any rocking of the cable outer here is bad. Similar issue at the carb end of the outer cable. Where the outer cable joins the "swan neck" of the carb there should be a rubber boot to stop water getting in at this joint. Check that it isnt easy for the cable outer to slip out of the "swan neck". This could easily be caused by poor cable routing or if the swan neck has been oriented poorly when the carb is refitted. Check the routing of the cable with the rear mudguard and tank off. The cable should take a reasonably straight path and not be over constrained on its route. Check for areas of the cable that have worn through the outer plastic sheath to the steel reinforcement below. This is bad. Lastly, remove the slide from the carb removing the 2 screws holding the slide cap on. Withdraw the slide and look at the cable inner and return spring. Spring in good condition?? , ANY cable freying here is bad. Hope you find it... confidence is everything for young riders (and older ones!!)

Chris i guess there could be a number of mechanical reasons which require a process of elimination to find. clearly some of the previously mentioned suggestions are worth investigating. I would start by determining "whats changed" and work through it logically. Less likely but worth checking is that you havent got a cyl head leak due to compression. I say unlikely because a leak here might also coincide with a cooling system issue. When this has happened to me it manifested itself as a high pitch squeek, occuring at the same frequency as the engine revs. Using the kickstart, turn the engine over slowly but firmly and listen to see if the high pitch noise is related to compression. look around the entire cyl head / spacer / barrel joint for obvious oil residue Check to see if you are losing coolant either at the same joint or from the radiator overflow hose. see if the frequency of the noise coincides with engine revs. just a thought. Dom