dombush

Hi With the backpressure of a blocked exhaust the unburnt oil in the silencer wadding can catch fire. This would tie in with the exhaust getting extreemly hot. Another symptom of this occuring is a muted exhaust note and a difficulty to tickover... needing constant revving and a very strained feeling. Suggest the the exhaust is dissasembled to identify which (if any) section is blocked. Dom

Hi Warby Beta Pinking is a funny thing casued by a number of issues. I'm just going to trot out some possible stuff that you can think about:- Pinking caused by:- ---Igintion timing too advanced (has it changed, easy to check) ---Poor grade fuel (ok, unlikely i know.. but if your worried you could use super unleaded) ---change in Squish clearance / compression (have you fitted a new cylinder/base gasket/piston?) ---Overheating-General (is the fan working?, blocked rad / damaged rad / low coolant) ---Overheating-poor pump performance (poor cooling flow causes hotspots on the cylinder head) ---Float height wrong (pilot jet is first to be exposed to air if wrong) ---Poor fuel flow (fuel filter blocked, fuel tap blocked, fuel needle valve blocked) ---Lean mixture (idle mixture screw incorrect, needle clip incorrect, lean jetting) ---air Leak (crank seals, inlet manifold seal, base gasket seal, carb rubber seal) Thats it i'm spent now... need a lie down!! Dom

Being a bit of a tinkerer i decided to replace my Dellorto PHBL 26 with a Keihin PWK 28 on my 06 250 pro. I'd read a number of existing posts and decided i wanted some of the advantages on offer. I thought i'd summarise the results as i found them. Why Compared to mates Sherco's and Beta's my pro has quite a strong pickup, great for wheelies but not as good on loose cambers or slippery climbs. The other major reason was lack of confidence in the tickover during tight turns or steep drops. I often clutched more than necessary to avoid a stall. I was guessing that an overall richness was part to blame. Lastly... it was a pig to start (however this was improved partly by reducing the dellorto float-tang height from 19mm to 16.5mm) Carb setup Carb was a PWK28 LH tickover and Airscrew model. Settings as reccommended by Kevin Hipwell of GasGas UK Main Jet 122, Pilot jet 45,Needle JJH- middle clip, Slide 3.5, Air Scew 1.5 turns out Other stuff GasGas Raga Reed block, flange, spacer, 3 gaskets,longer screws, flange rubber and 2 jubilee clips (reliably informed these parts arent strictly nesessary but provide a more proffesional "fit") Keihin specific throttle cable and angled cable entry for the carb top. Fitting Apart from awkward access to the reed valve flange screws its fairly straightforward procedure. Removal of the rear shock may be necessary if you havent got necessary tools to access these screws. Results Cold starting was a choke-second kick affair.. same as the Dellorto PHBL Hot starting could be achieved using any throttle opening. The Dellorto wanted no throttle:- hot or cold. The tickover rpm could be set slightly lower on the Keihin whilst remaining reliable/stable. Out riding, the snatchy pickup was gone, replaced with a much smoother linear initial power delivery. The bike was smoother/quieter and sounded slightly weaker. Higher up the rev range the bike was more comforatable and happier to rev out.. An unexpected bonus was significantly better fuel consumption, comfirming initial fueling thoughts. Conclusion Overall i think the bike is more forgiving and progressive for a novice like me. Would i do it again?? probably yes but its a bangs per buck thing... At

Thanks Graham hoped you would see the post and would be going. Dom

Hi i have found reference to this eastern centre trial on the ACU website, but need more details (directions, time etc??) is anyone going ?? Dom

Hoggy as you say it sounds like its a bit weak at pickup. I would:- adjust the idle screw slowly until the engine achieves the highest stable / consistent tickover. Turn the screw 1/4 of a turn richer to ensure that tickover is marginaly rich. See if this improves the overall pickup (if the ideal screw position is less than 1.5 turns or more than 4 turns from fully in, its likely that the pilot jet needs changing) If no improvement adjust the needle clip 1 slot down the needle (to raise the needle) see if this improves overall pickup re-adjust the ideal idle screw position as it is likely to have changed If no improvement (unlikely), try another slot further down the needle. However a change of 2 slots is quite a considerable change. After best pickup is achieved,find some open ground and move on to a plug chop at Wide Open Throttle. Try to hold wide open for at least 15-20 secs. Review the plug colour and adjust main jet as necessary sounds complicated written down.. its not Dom

Matt the best information i have found has been from Jim Snell's US based gasgas website. Information for pre 2002's (perhap non pro's?) here My link Infromation for post 2002 pro's here My link Hope this helps Dom

Hi Trials and motocross news old webite had some reviews of bikes. They tended to have reviews of the main manufacturers bikes every 2-3 years. Dom

Graham I take it that this is a recent thing (since the recent sub frame spruce up). Taking into acount the overlap in carb circuits, the area i would look at is the needle and the needle-jet. On high milage bikes like (diplomatic)ours, the needle taper can get worn especially if the needle doesnt naturally sit vertical in the slide. Often the difference between needle choices is 1-2 thou in parts of the taper. Therefore a flat on the needle or an ovalised needle jet could easily create this effect and is almost impossible to spot without a vernier. Is the blubbery performance accompanied by smokey running? Happy to lend my carb body to help confirm that its carb related. Dom

Hi fear not, that is almost certainly Lithium grease (or similar) put into the connector to waterproof it. It could be that there is too much causing a very bad connection.... but i doubt it. I think you are going to have to look elsewhere. Dom

Hi My view is it all depends on where they are going. Wheel bearings, swingarm etc... fine. Easy to replace, often fail due to contamination (not quality). Main bearings, little end, gearbox etc...no chance!!! Be aware that as well as basic quality there are different pre-load grades for some applications. Main bearings for instance are assembled to a different tolerance (C3) to cope with the rapid temperature rise / temperature differential across the bearing. Dom

Hi its unlikely that the idle mixture screw is connected with this issue, idle mixture affects mostly the lowest throttle openings. Sounds like its weak in the higher throttle opening ranges. Have listed my most likely guesses:- Fuel low or switched on?? (its been done) Blocked or missing main jet Incorrect Float height Incorrect needle clip position Blocked air filter missing air filter Does it get better or worse the warmer the bike gets? What is the effect of putting the choke on? Is the tickover erratic or reasonably stable? Is it better or worse when actualy riding the bike with some load? Dom

Hi has the engine been deliberatly "softened" by a previous owner. A list of possibles including some previous suggestions. Low compression:- --try a compression test ----someone fitted a head spacer (should be visible) ----someone fitted extra base gaskets ----Rings worn out (measure the ring end gap) ----scored or worn cylinder Other stuff --someone fitted a inlet tract spacer in front of the reed block --retarded ignition --Need to repack the exhaust (is it louder than others) --Bad jetting (does it smoke, not rev out or hesitate) --clogged air filter --crankshaft seals (irratic tickover, or smoking engine, or oil in the flywheel area) --Damaged reed petals (hard to start) regards Dom

Hi Drake I have been riding trials for a similar time as yourself, previously having ridden Enduro's until the knees clapped out. I came to a similar conclusion with my Enduro bike and my trials bike..... ----Is it working correctly,, jetting, suspension setup, brakes, clutch, tyres etc.... If not, sort those things out. ----Once it is working correctly, look honestly at your performance and understand how much the bike is the limiting factor. I can only speak for myself and say i've got a long way to go before the bike is the limiting factor. I know this because:- ----other riders are way ahead in results on much older (rattier) bikes (even 20 years older) ----I am aware that there's lots i'm not yet capable of. ----I want to stop dropping it too often before i make a bigger investment. However, some riders like to have the latest thing (nothing wrong with that), some are more/less capable with complicated maintenance, some are skilled enough that the bike is a limiting factor. Personally, I've got the bike A1 over the last months and will put a years trials under my belt. Then i might ask myself if i warrant a newer bike and if i dont.....i'll keep it. Regards Dom

Hi probably pointing out things you've already tried.... It sounds like it's running lean still, as if you partially unblocked the pilot, emulsion tube, incorrect float height or similar. When a carb gets really gummed (from keeping the fuel tap "on" and not using the bike for a few years) the varnish left can be hard to shift. Have a real close look at the orifices against a light source, often you can see its only partilally unblocked. I would look at the pilot jet, emulsion tube (if your bike has a removable one), main jet, float height and remove the idle mixture screw and give it a blast with a compressor. If its really bad, a long soak in carb cleaner or a trip to someone with an ultrasonic bath would do it. Hope you get it sorted. Dom

Just out of interest....did you wash / pressure wash it?????

Hi as you say piston slap in itself whilst not ideal, isnt a huge problem. Like everything else, there are degrees of slap and if its low key & goes away as the revs rise its probably ok. However, small end wear is a different matter. When the con-rod bearings (big end or little end) start to wear the free play allows the bearing to "hammer". This means that wear accelerates rapidly. Little end wear tends to be audible at all revs, piston slap only at low revs... but diagnosis isnt really possible by sight/sound. There really isnt a way of avoiding taking the barrel off and checking. If you've got the measuring tools to identify piston/bore clearance..great. If not, you can check for little end play and eliminate the more serious fault. Its important to check only for vertical movement, anything discernable by hand is probably wear that needs dealing with... also little end bearings are cheap!!

Thanks for the information slicks75

All having just replaced the fork seals on my 2007 i need to refill the oil and are looking for fill volumes. Searching the web i can find 2006 info... is 2007 the same?? also, there is some confusion about "refill after drain" volume and "from completely dry" volume. Getting to the point, does anyone have the correct 2007 oil volume information... or the air gap. Dom

Given that most M8 bolts take well over 60kg in double shear...I'd say the 2-off M20's fitted to your towbar should be ok!! Dom

Jon this is a question that comes up 3 or 4 times a month, have a look through any of the manufacturer specific forums or use the search function and there will be plenty of answers to your question. Be aware its a very subjective point!!! Dom

Jamie pretty much agree with Copemech on all points really. Issue 1 As you say fuel doesnt just sneak anywhere, it gets there because somethings wrong. Yes the ignition side crank seal is the obvious solution... however crank seals failing are usually associated with an uneven/high tickover due to the ensuing air leak. Also it is common to get an oily mess arount the flywheel / stator area. Getting neat fuel in there says something more dramatic is wrong. Are you sure its fuel (water sometimes gets in from pressure washing)also sometimes people spray lots of water dispersant in there (WD40 in tne UK). If it is fuel, its likely that the crankcase is flooding/has flooded... this could tie in with your "varnishy" looking carb. You dont say if the varnish is on the inside of the float bowl or the outside surfaces of the carb. If its in the floatbowl it could be that the bike has been stored for a long time with the fuel tap on. This leads to a constant cycle of fuel evaporation inside the carb leading to heavy deposits. This in turn could lead to the float valve sticking open and flooding engine. Normaly another sign of this is fuel leaking out of the carb overflow pipes. You dont say if the bike is generally running well or not?? Issue 2 Copemech's right.. fitting the rimband correctly takes time and patience but is very do-able. Liquid tyre sealant is a bodge best avoided or left until the last resort. Issue 3 if the green is varnish on the inside of the floatbowl???, you need remove all of the jets/float/choke/idle mixture screw and use carb cleaner to remove/dissolve the deposits and blow the carb out with an air-line. Pay special attention to the brass float valve seat and the float valve itself. These should be spotlessly clean and free of scoring, marks, deposits or pitting. If the bike has been flooding.. it could be wise to replace the two components. Look down the slow running and main jet to see that the orifice is exactly round indicating there is no deposit buildup inside the jet itself (this is also common where deposits are found) Issue 4 Sticking clutch plates is another sign of a bike being left to stand for a long time. Unless it happens regularly dont worry. Best not to put it into gear whilst giving it a fistfull sitting next to your new Ferrari!! Dom

My sons Beta Rev80 is in need of a new rear shock. I have heard that an early rev250 shock might fit. Does anyone know any more? Are any other bikes shocks the same length/eyelet size as a Rev250? Thanks Dom

Spike i can only speak for the trials / enduro clubs i've been a member of. Enduro is faster and typically has injuries, my club had 2 ambulances Insurance risk is higher as a result Laps are generally much longer (whilst at racing speeds) Level of damage to the land in winter is higher, meaning landowners tend to want paying, or repair work has to take place Noisier, meaning landowners have to worry about complaints / environmental inspection. Expensive timing kit is needed, more tape, stakes etc....for ??miles of track reasonably straightforward really

Caddabs like piston life, brake pads and as the previous poster says, there are so many variables that affect this. There are variables such as cleaning, lubrication, riding conditions and quality. I have had sand events kill a new chain in 4 events (enduro), and also had a chain last 2 years when only riding in the summer. However, there are a second variable... your view on what worn out is!! Personaly i take a relaxed view on this and tend to wait for the sprocket set to fully wear out as well, mainly because i've never really been adversely affected by letting it go for a while. The previous poster said pull the chain away from the sprocket and look for 1/4 of the height of the tooth to become visible... I use the same technique but allow a more relaxed 1/2 the height..Its a personal thing. My last comment is always buy a decent chain. People talk about chain stretch, but its really just wear (even if some of this is just bedding in). The better quality chains can significantly cut down the need for constant adjustment. Dom