aussiechris

Thanks folks for all your replies, I am aware of the fire risks with welding magnesium but it seems to relate mainly to OA gas welding. The argon coverage from TIG welding mostly negates the problem. Fine shavings and dust are still a hazard. I agree that the main problem would be distortion. Given the amount of work involved in rebuilding the engine I think I'll play it safe and throw new cases at it. Looks like my dealer can source them ok. I think the main problem is that the rear bash plate rubber was worn through and, as Steve suggested, there has been contact between the bash plate and the mounting lug on the case. I need to replace these rubbers maybe every year. Chris.

I'm guessing this is going to get expensive... This is my beloved 2011 Raga 300. After the usual weekend practice and a thorough clean, I discovered both crankcase halves have broken around the lower rear engine mount. These are magnesium cases. I know there has been a reported issue of misaligned holes at this mount but I checked it about a year ago and it was perfect (no drilling necessary). Obviously this is what we have to expect to have a lightweight bike. Anyway, new magnesium cases appear to be unobtainable. I'd be happy to replace them with the standard aluminium ones hoping they might be stronger. The problem is that the local dealer appears to only have one half in stock and I thought they were sold as a matched pair. Looking at the Gas Gas Future thread, I'm guessing the factory won't be shipping any parts soon. So I might be testing my welding skills (I can weld aluminium but never tried magnesium).

The new pump looks good and I'll definitely get one. However, regardless of any claim to having two seals it still won't guarantee you won't get coolant in the transmission oil because there is no weep hole to the outside. Most water pumps (eg. Sherco, Montesa, virtually all cars and road bikes) have a weep hole between the two seals. If the coolant seal fails you'll see coolant leaking from the hole and it can never pressurize the oil seal. You can even keep riding if the leak is just a drip. With the Gas Gas setup, you don't know if anything is wrong until you get a transmission oil milkshake. It doesn't appear that this new pump changes that but I hope I'm wrong. Now all we need is a reliable thermo fan switch. Chris Brisbane Australia.

Forgot to mention - the part number is BT280232032. You didn't say where you are from but they cost about 20 pounds in the UK.

Yeah Kev, same description applies to the plastic cap - it should have a pressure relief valve and not vent until about 14 psi has built up in the radiator. It should not flow freely in both directions. My gasser has the plastic cap also. Sorry I don't have a picture of it. Chris.

Likewise the Pirelli (I think it is an M43) trials tyre. They are so rock hard you have to drop the pressure to about 1 psi and then they come off the rim. I think the IRC and Pirelli get used by the flat track guys a fair bit. The Dunlops are ok and pretty resistant to punctures but can be a pain to fit and remove. For a novice I'd suggest the X11 will do just fine.

It's not a thermostat but a pressure relief valve. The pressure is written on the cap but is usually about 14psi. So if yours is hollow and flows freely in both directions then it needs replacing. The system is pressurized to raise the boiling point of the coolant. The cap is also designed to allow air to be taken in if needed as the system cools. Normally there should be no coolant spitting out but you might get a bit on the first ride after filling the radiator. If any coolant comes out after that it's usually a fan problem (most commonly the thermo-switch). Just get a new cap anyway - they don't last forever. Chris Brisbane Australia.

I really like the X-Lites but they do get more punctures if you're riding sharp rocks. Mine generally have a few "dog turd" plugs hanging out of them but I will buy the same again. But there's nothing wrong with the X11 either. I think the weight difference is about 400 grams for a rear. Interestingly, the latest Gas Gas factory replicas are now being delivered with X11 tyres (they previously ran X-Lites). Chris Brisbane Australia.

Ok, thanks folks. Yeah, not much snow here at the moment, Breagh. It's been around 35 to 40°C most days but we're still riding. I'd just like to get the new bike before it becomes last years model. It looks like TwinShocked and I need to move closer to Europe! Chris.

Sorry Borus, I don't have any photos or videos at this point. Chris.

Just wondering if folks have been getting delivery of their 2015 bikes yet? Here in Australia we always have to wait for our new bikes but other brands like Gas Gas, JTG, and Sherco have been available for a couple of months now. My Montesa dealer ordered a dozen 4RTs ages ago and paid the factory a month back but they still haven't left Spain for the slow boat ride down under. What gives? The factory has complained that importers and dealers aren't selling enough bikes but it's starting to look like the factory is not that interested in making anything happen. Prospective Montesa customers are becoming frustrated and moving back to other brands. The 2016 bikes will be announced before this lot even get here. Chris Brisbane Australia.

Here in Australia we have a former Australian Champion riding one and he’s pretty darn impressive on it. He rides expert class on it and eats all but the biggest sections. He was kind enough to give me a test ride on it last weekend. I was quite impressed with the power but the bike takes some getting used to. As stated above, the clutch is just an on-off switch and best left alone. The regen braking is applied using a button on the left handle bar. Normally there is very little engine braking. Power delivery is smooth but you can’t get that instant zap that you can get with a petrol engine and a clutch. You need to use your body to get up the big stuff (but riding a 300 Gasser makes one lazy so I can’t do it). I must say the power is a lot smoother and more controllable than the little Oset electric bikes. As for endurance, the owner rides an all day trial (4 laps of 10 sections) and then does a few demos afterwards with about 15-20% power remaining so I think the advertised times are pretty conservative. Chris Brisbane Australia.

Yes, excellent tips there Steve. I made up a short (about 3" long) wire with a 6mm ring terminal one end and a male bullet connector on the other. Use white coloured wire if you can as it matches what it ultimately plugs into. The ring terminal is installed permanently on the coil mounting bolt with the other earth wires and then the wire just hides under the tank until needed. When the thermo switch gives out - just lift the tank (you'll be topping up coolant anyway) and unplug the thermo switch and plug your new bullet connector into the white wire female that you unplugged the thermo switch from. Up and running in a few minutes with the fan on all the time. I still prefer to run the proper switch to save wear on the fan but if it gives out in the middle of a trial (like mine did last time), I'm ready for it. Chris Brisbane Australia.

I agree with the above. You can also use compressed air (maximum 14 psi) down the filler neck while you ease the switch out of the radiator. I used plenty of rubber grease on the o-ring and housing last time and it came out a lot easier this time. I just wish someone would come up with a more reliable thermo switch. The last one only worked for six months. Chris Brisbane Australia.

This is probably not what you want to hear but... I have found that after installing a seal kit you need to fill the cavities in the caliper before reinstalling the pistons. Not easy to do but if you hold the caliper at a 45° angle (with the small fluid hole at the top), then pour in as much fluid at possible which will half fill the cavity, then holding that angle, push in the piston. Some fluid should shoot out the hole when you push the piston all the way home. Do this for each piston. That way, when it's all bolted together, at least the cavities behind the pistons are full of fluid and you can just bleed the bit of air that's near the banjo fitting. I also like to let the bike sit for a few days with the bars turned such that small bubbles can find their way back to the master cylinder. Then very carefully, just pull the brake lever in slightly just past the free play, and release. With the cover off you can sometimes see some small bubbles get released this way. Then the lever should be nice and firm. If the system is completely drained, I'll sometimes reverse bleed using a Mity-Vac tool. Good luck with it. Chris.

Hi Thomas, this is a bit late I know. I have a 2011 Raga with the Reiger shock. I find it's very easy to adjust. For the bottom adjustment, I just go in with a long screw driver (about 8 inch). It goes just below the swing arm and just above the left dog bone (that's with the bike supported on a stand). The top adjuster is easy using the special tool that should have come with the bike. Chris.

They are available as a separate part but a bit expensive (about $80 here in Australia). A decent welder can fix it cheaper. Chris.

Hey, nice job with the mig. Glad you got it sorted. And I'm happy you managed to squeeze in a pic of your 'wing! Mine is a 1995 model (250,000km on it now) and it came with tapered head bearings but had the same issue as the Ossa. Looks like we both ride the heaviest bike in world and the lightest bike!

Yes, on most bikes you can get to the edge of the bearing cone with one of those tools or a drift. But not on the Ossa. The genius who designed that part of the bike never considered how to change the bearing. I'm with OzThumper - welding is the go. Run a bead most of the way around the inside surface of the cone and wait for it tool cool. It should just drop out by itself. If not, you could weld a piece of rod or bar to it and yank it out. Bad design by Ossa (but the Honda Goldwing has the same problem and same solution). Chris.

Yeah, check that the wheel spacers are in the correct way round. One is longer than the other. One way to tell is if the brake disk is not central in the slot in the rear brake caliper. Chris.

Phil, Something else you might like to check. While the cylinder is removed, take a look at the plastic/nylon flywheel stuffers to see if there is visible heat damage. That sort of damage has nothing to do with cooling water. It is caused by a lack of lubrication causing the big end bearing to overheat. Some time back, I had to repair a 125cc Gas Gas moto-cross bike. My friend’s son had forgotten to put oil in the fuel. The piston didn’t seize but it destroyed the big-end bearing. The lad stopped riding when it didn’t seem to perform right. In this case, the plastic flywheel stuffers were melted and had turned brown in colour (they should normally be off-white) and the crank pin, rod, and bearing were toast. It may be a clue as to whether the new owner had failed to put oil in the petrol (you’ll obviously not get an honest answer to such a question). If run long enough it would cause the whole engine to overheat and boil dry. By the way, changing the idle mixture would not cause this damage. And 1.5 turns out is right for a Keihin but if it has a Dellorto then 3 turns out would be closer to the mark. You replaced the water pump a long time ago so it’s unlikely that was the initial cause of this event. If I understand correctly, the guy rode it the first day (probably on the original fuel), then took it out for a trail ride the next day. I’m guessing he re-fueled it at that point. It’s really easy to overlook adding the oil. Either that, or he crashed and the bike revved out for too long. Chris Brisbane Australia.

Hi Allen, You don't need to remove the adjusters, the caps unscrew as you'd expect. Remember to loosen the top triple clamp screws first. You will need to remove the large socket head bolts from the bottom of the fork legs (oil will drain out) to allow the spring cartridge to be withdrawn from the top. I can't remember the free length but you may find one or both springs broken. Mine had one broken spring a while back and the two pieces had wound together making it much shorter. Good luck with it. Chris.

I've seen this bike in real life and it looks even better than the photos. It's a work of art. Chris Brisbane Australia.

Apologies - I was thinking yours was a Raga for some reason. If it has the standard DelOrto carb then ignore my post above. Don't use any throttle on those. Chris.

Hi Chris, I have a 2011 300 Raga. After similar frustration to yours, I discovered that these bikes (with the Keihin carb) need throttle to start. From cold, pull the choke on and give it quarter to half throttle and it should start first kick. Same when hot except no choke. Sometimes I forget as my old Gasser was best with the throttle closed and then it won't start. Anyway, it costs you nothing to try. Chris Brisbane Australia.