dombush

Pat there will be a number of engineering establishments that will BZP (bright zinc plate) fasteners, a quick look in your local yellow pages should do it. You will normaly have to wait for them to get a batch together...However..... a word of warning. Fasteners used under high stress (anything chassis/engine related that has a stress raiser.. e.g. a head of a bolt) can suffer from a condition called "embrittlement" after plating operations. Quality plated fasteners you purchase will have gone through a process of "de-embrittlement" after plating. This is basicaly a very high temperature (400-600 deg) normalisation after plating (usually lasting around 24 hours). Without this we have experienced the heads of screws snapping off like carrots. For lower stress applications (fasteners for plastics, other non critical areas) i wouldnt worry. The good news was i got very profficient at drilling out bolts!!! Dom

Gaz the effects of overheating on a multicylinder engine and a single cylinder are very different. It is highly unlikely that the cyclinder head is warped needing skimming on a single cylider engine. It could be the o-ring, but have you noticed loss of water?? You can also normaly see the marks caused by the leakage on the head, or as damaged/flattened o-ring. Before you go the cyl head leakage route, but i would look at the following... cooling fan, water pump, blocked / damaged radiator, ignition timing first. Dom

I agree that 75ml is adequate, you can run more but..... lets not start that old argument again. Litle end bearings normaly outlast the piston, changing them as a precaution while the engine is apart. However i have had one fail suddenly. Little end wear is normaly audible aunder all engine loads... but is easy to spot as slight vertical play once apart. Piston slap (excessive piston to bore clearance)comes on slowly at first, accelerating as the wear increases. This is normaly noticable under no load situations (tickover). Piston to bore clearance really needs a bore gauge / micrometer to judge properly. As far as getting at the barrel nuts, most of us grind the ring of a ring spanner down to fit. Dom

efi64 you can assume that the Beta 80 is the same size as a full size Trials bike (and not much lighter either). My son is 4.5 stone, 10 years old and small in stature and spent most of the first trial on the floor. However after this he grew in confidence always standing up etc. etc. Now i'd say that after maybee 10 hours on the bike its no worries... even on heavy cambers / climbs etc. I guess the point is that its not just a size issue, its also confidence, clutch control, throttle control. Happy to measure his height for comparison if it helps. Dom

I found myself strangely distracted by the photo, studying it for hours...... then i worked it out, they're 80/20 mix, rubber backed, barley twist, blue floor tiles... very rare...

Bezerk obviously diagnosis at this distance its just guesses... however, here's a few. At a basic level, bogging when the bike heats up spells rich mixture.. but.... Have you had the plug out immediately post bog (to see if its rich or lean) Does it smoke heavily when its bogging (rich..carb float issues, does fuel leak out of the overflows)? have you tried applying choke mid bog (if its weak, this will perk it up at low revs, if its already rich this will kill it completely) Have you tried removing the fuel cap just in case the tank breather is blocked. how far do you ride before it bogs (if its +5 mins it might be overheating.. ign timing) Does the exhaust note sound strangled or muted (clogged exhaust... overheating) have a look at the ignition timing marks.. are they correct It could be a dodgy plug/coil electrics but this doesnt sound likely given the description. Generally these work or they dont. So, some ideas there... good luck Dom

Hi Asaf This document from Jim Snell's excellent "Trialspartsusa" website should give you the information you are looking for. Link to gasgas jetting specs Dom

Most 2 stroke engines have had reeds since the late 1970's early 1980's. Although i cant comment on your particular model, i would be very surprised if it hasn't.

Hi you dont say how old your bike is? or if the problem is a sudden one or has developed over time / getting worse? engine knock under load likely to be 1 of 2 causes:- Pre-ignition (pinking) under heavy load Piston Rattle (however this is mostly heard under no-load at idle) Its worth looking at the pre-ignition side of things before launching into a top-end rebuild Ignition timing... has it moved or been moved coked up plug, wrong plug, coked piston or blocked/coked exhaust overheating due to low water, damaged water pump, faulty fan, leaking cyl head joint etc. overheating due to running weak, blocked jet/s, check the plug colour, clean the carb, blast with compressed air Air leak somewhere at the inlet... usualy indicated by poor idling / slow to return to idle damaged reeds (difficult to start?) Another thing to check before top end rebuild is the cranking compression. I dont know the healthy compression for your bike, but i suspect it will be 150 - 200psi. This is really easy to do, and a good trick for checking ring wear is to put a little (1-2ml) neat 2 stroke oil down the plug hole and re-check. If the compression goes up enourmously (it is normal for it to go up 10-15%) its likely rings. If none of this is conclusive.. its barrel off time Good luck

had a root around....found this on Jim Snells excellent trialpartsUSA website It sums up some of the details discussed. My link hope this helps Dom

Hi couple of answers:- It doesnt matter which way up the gasket goes if it is a straight paper gasket Always check that the tranfer ports line up with the gasket cut outs when dropped over the crankcase studs. this can determine the way that the gasket is fitted. I have never applied lubricant to gaskets because it makes them stick when you take it apart next time. Some people put RTV silicone on them but i wouldnt. The reason that there are 4 gaskets is to achieve the correct piston to Cyl head clearance (squish), this is required to deal with production tolerances look at the gasgas manual to see what the squish clearance for your model is There are a couple of ways to measure squish, the one i use is squashing some soft solder. I assemble the barrel/piston/head and insert some 2mm solder through the spark plug hole, then turn the motor over on the kickstart. You then pull the solder out and measure the "squished" solder. typical squish clearances are between 1.0 and 2.0mm. A number of factors determine this but generally larger engines have bigger squish clearances if all this is double dutch, you are probably best just measuring the gasket you took off and getting the same again. The danger of getting it wrong is probably not great, the worst being you change the characteristics of the engines power (too abrupt or the reverse) Dom

I was in the same boat, just 8 weeks ahead of you. I raced enduro for a number of years. I got lots of advice at the time and here is the stuff i think was relevant. I'm 10.5 stone and a 250 is easily enough for me despite my yearning for something bigger. Despite rumours, all the manufacturers have small issues... I would have considered anything from the main names (Sherco, Scorpa, GasGas or Beta). I spoke to a few of the manufacturers and although they were all helpful, the Lampikns shine out on customer service (Beta). OEM spares are very expensive compared to the mass produced bikes...Therefore condition is everything, buy as new as you can afford. As a beginner its going to be a while before the bike is the limiting factor so dont think you have to have the latest Whiz Bang. Like MX the square edge on the tyres is important, although it is more common to turn the tyre 180 deg. Dont worry if the bike isnt road registered, not many trials require this. I used the coating on the forks, condition of the pegs, header pipe, rubbing on the frame, state of the disks/chain/sprockets/tyres to tell me how it had been looked after.

All an earlier post discussed some mods to a Beta rev 80, i wondered if anyone had some more detail on these. [*]Modification to the front pipe [*]what should i set the squish thickness to? [*]opening the airbox inlet apertures [*]fitting a rear shock from another Beta [*]what weight fork oil do people use? lastly, what is the average piston life?? or do you just replace when it shows piston slap.

40 year old Enduro rider who's knees cried "ENOUGH" also wanted to involve my son, cant think of a better way. My mate said i was taking up "golf for motorcycle racers" anyway, first trial this weekend for us (Gulp) Dom

The guys are right. Its a classic basics thing. If you haven't altered anything (carb, ignition timing,or anything else major) then:- Fuel, good fuel? unleaded can deteriorate in months. Buy a can of easy-start and spray down the carb before kicking, this is so volatile that it will enable a start under very poor conditions. Can you smell strong fuel from exhaust when youve kicked it over a few times on choke? If not, check fuel supply, and progress to the carb. Ignition, sparking with the plug out?, clean, dry plug? Test the plug on something else (lawnmower, another bike), plugs can break down under compression. Compression, usual resistance under kicking? Try a compression tester and make sure its above 100PSI (most engines will start with a minimum of 100PSI). with these 3 basics the majority of engines will start and run badly even with minor faults (broken reeds, worn rings, crank seals gone, poor ignition timing etc.) Dom

Good thing its hard to get it stuck..... You'd never push it out!!

To cut a long story short, things have moved on a bit since the 1930's to 1980's when bores werent always round, rings were cast iron, pistons were softer and most importantly oils left significant deposits on bores and cylinder heads. The one point that isnt considered in the SAE article is speed of break in in competition engines(achieving a good compression quickly). Its important for a trials bike to seal well at low RPM, so quickly matching the ring shape to the barrel is very important. The article is based on road based applications where longetivity of components / performance is the main consideration. A hone will provide a surface that will initialy wear components faster but will provide the seal within a much shorter time. This is why many manufacturers reccomend non synthetic oils during the first ??? thousand miles as they actually provide some controlled initial wear to get the seal established. However, i'm tempted to say that you are probably worrying unnecesarily (get it honed). There would be far more wear caused by too rich a mixture or by dirt getting past your air filter. Getting the basics right is more important. Personaly i would be more concerned with the correct piston to bore clearance, port chamfering, ring gap and squish clearance. Dom

As an experienced enduro rider who's knees have failed. im looking to try trials. I have around