peterb

Hi chaser, for the time being, you can knock out the LHS bush and replace it with a new one, it is a shouldered type DU teflon lined bush generally available from good bearing shops, probably only a few pound in the UK. Should never have been supplied in the first instance. If you don't want to head down the milling track, which is the best option as then you can use a decent sized 6004 bearing like what should have been used originally, you can have someone turn up a sleeve to take up the difference between the two new kit bearings, I can't remember the size but they were a smaller OD than a 6004, and the bearing housing, shorten the aluminium bearing separator sleeve (the sleeve in between the left and right bearings) to the appropriate length, then fit everything together packing the new bearings with waterproof grease. I did get a GG year 2000 rear wheel to fit as a spare, but this was a lot of mucking around with spacers, sleeves and getting the longitudinal distance correct for the sprocket and disc. I don't think a Pro wheel would fit, might do, best to try one first, but the Pro axle is a smaller diameter than the Ossa, and the Ossa has a very tight tolerance for the caliper distance away from the swinging arm, different to a GG. Best bet is to get the hub milled out and then it's all done proper like. Bye, Peter B.

Hi chaser, there was a kit made available for the 2011 first release Ossa's, that comprised of two ball bearing's and a sleeve to take up the difference between the bearing housing and the OD of the new bearings. Both bearings and sleeve were for the chain drive side, to replace the teflon bush there. Before these became available, we modified our Ossa's to take a single 6004 bearing. The wheels were centralised on a mill table and the housing milled out to accept the 6004 bearing. This might be the way to go should the kits no longer be available. Bye, Peter B.

Thanks bondy and Larry, that was very quick. Bye, Peter B.

Hi bondy, Do you have the inlet skirt height dimension for a 325 M199. From where is the measurement made, the top of the piston ring that is flush with the crown? Would you have access to the port timing details in relation to degrees before/after top dead centre? I ask this as someone has modified the ports with a die grinder. Bye, Peter B.

If you can get a Mahle piston, that would be great. A GG piston has the piston ring pegs in the "wrong" location for use on the Bultaco. In Motion would be able to help with a piston. Bye, Peter B.

It's very saddening to read the news, Martin was a great trials rider and an ambassador for the sport. I will always remember him for being a true Yorkshireman and for getting a brilliant clean on one of the harder sections at the Wye Valley in 1977, bouncing off almost every rock on the way up the gully. PeterB.

The JTX270 came with a 122 main jet as standard. These were always too rich. We used to run these with a 118 and some with a 115, try both. Standard needle was a D36, tend to be a bit lean at low revs, a D34 works very well. Bye, PeterB.

Check to see if the clutch hose runs up over the frame tube directly in front of the top of the radiator, between the two outer frame tubes. You can also cable tie the hose to the square section piece of frame at the headstock, though you shouldn't need to. Also, check if you have the correct plastic piece in the right spot, there are "right" and "left" plastic pieces, the photo at the beginning of this thread shows the plastic piece correctly, the clutch hose routing is shown correctly also. Bye, PeterB.

Generally, the thermostats have their temperature range stamped on, eg: 71/66 that is, at 71C the switch contact is made and at 66C the contact "drops out" such that the fan would turn on at 71C, then keep going until the water temp reduced to 66C. You can check the thermoswitch out by immersing the switch into a cup of water with a thermometer, that you can use for a stirrer, then add hot and cold water to check the operating range. Best to stay with the standard range thermoswitch. Bye, Peter B.

If the metal lip is a bearing seal, it should not face the inner crankcase. In the older motors, the crank bearings were open to the crankcases to allow oil mist to lube the bearings. There would have been an oil seal fitted to the outer side of the bearing, with it's spring side facing toward the inner crank case. You could always prise off the metal "dust" seal if it is in the way. Bye, Peter B.

After you try the correct plug, NGK BPR5ES and it is still getting wet, check the carburettor jets. I haven't got the correct sizes here but remember the main jet to be around 108, pilot 33, needle type D36. Check the float arms are parallel with the main body when touching the needle valve. Clean out all of the carb passage ways. You need to have a look at the clutch plates, the older motors had a problem with the fibre discs, where the fibres would detatch from the plates whenever the gearbox would take in water, like drowning the motor or having the water pump leak coolant into the gearbox. The water created a problem with the adhesive used on the fibre plates. You can still get new plates from Sureflex if needed. If this is not the problem for the clutch not disengaging properly from cold, then let us know. The motor jumping into gear is caused by a weak gear selector return spring, have a look on a parts drawing, follow the right side of the gear selector shaft, at the end there is a selector mechanism with an indent roller, the roller is held in place on the selector cam via a spring, these did tend to reduce in spring tension over time, if you can't find any I have them. Bye, Peter B.

Looks like they are then! You might be able to source from your local Honda shop although the bikes were not imported into the UK as far as I know. If you need a Honda parts list, I can send you one on email. Bye, Peter B.

Hmmmm, well the water pump shaft on the GG is rotating at crankshaft speed up to 7,000 rpm, water/coolant is a non lubricating medium so that with the spring force of the lip of the seal pressing onto the shaft, wear will eventually occur, through a combination of high rotational speed, friction of the seal against the shaft and the non lubricating qualities of the water/ethylene glycol mix. The Viton seal usually wears as can be seen by the loss of it's sharp edge. Bye, Peter B.

I found that the plastic sensor holder has sharp edges on the two small holes where the rubber holding/guiding pegs slide into. The rubber tends to bind up on the sharp edges. Remove the sharp edges a little, with a twist drill bit held in your hand, then fit the sensor unit as above, use a bit of spit on the rubber guides and pull on the rubbers a little with pliers while fitting. They usually go in ok with a bit of a fiddle. Bye, Peter B.

From discussions with the factory, the bankrupt Jotagas company in Alcaniz was bought 2 years ago by the current owners, with the agreement to continue operations under the JGAS Racing name. It is therefore business as usual. In my opinion, the original Jotagas business has finally come through the Spanish judicial system and has been declared bankrupt. This does not affect the day to day business of JGAS Racing, which is continuing to produce bikes. I hope this clarifys the situation. Bye, PeterB.

Ossa made the 15 degree butterfly for the 125 motor to obtain a power increase over the standard 125 motor fitted with a 5 degree disc. The theory behind the 15 degree disc is that this allows more air flow at low revs, and therefore can acept a relative increase in fuel. This required a new map specific for the motor size and the 15 degree butterfly. I was told the 125 with 15 degree disc had a similar spread of power to the Beta 125. The 15 degree disc was made using a mandrel, say a 25 dia round bar with the top machined at 15 degrees, drilled and tapped to accept the blank brass disc, then turned down to size on a lathe. I was told they worked well on the bigger motors too. Bye, PeterB.

Reggies idea above would be the easiest option, but if you want to remove the nipple, you can try heating up the caliper a little, then attempt to remove the nipple. Pretty sure it is an M6 x 1.0 thread. If it snaps, they usually neck off flush with the caliper body, you can very carefully drill the remains out, following the same angle as the thread, with a 5mm dia drill bit. Then you can recover the thread with an M6 x 1 tap. Done this a few times over the years and turned out ok, just need to be careful when drilling. The nipple has a taper at the end which seals off against a taper inside the caliper, be careful not to damage the caliper taper seating area. You can buy stainless steel nipples from an auto brake shop, all sorts of different lengths and types, best to take the caliper in to check them out. Bye, PeterB.

I am sorry to hear about Colin. I remember him from riding trials in the East Yorks area in the 70's, he used to organise events for the Eboracum club, including the very popular Colonial Trial, held in the winter months. He was always a happy bloke with a ready answer, a real enthusiast. My condolonces to his family. PeterB.

Hi Huski, The piece you have found could well be one of the two rods that are used in the selector mechanism. The "rods" are sprung agains the selector pawls to engage the rotary movement one way, then another. I'll try to paste a photo of the parts here. Not able to paste the image. If you wanted, you can PM me with your email and I can send you the parts drawing related to this. I don't think the video for the "oil filter" is quite correct. Yes lots of the metal shavings do get trapped there, between the belleville spring and pressure plate, same on GG and Ossa's, but this happens due to the particles getting flung out due to centrifigual force and getting trapped rather than there being a specific oil filter mechanism. Bye, PeterB.

Probably best to stick with a Sherco designated piston kit. Years back, with the early Sherco's, the gudgeon pin centre line in the vertical plane, was different to the GG piston, I don't know if the same holds true to date. And as mentioned earlier, there is a noted difference between the centre line of the gudgeon pin and the piston crown, between the GG and Sherco pistons. Bye, Peter B.

These cylinders are made by S3. The bore is electroplated with nickel silicon carbide, then honed with a diamond hone to achieve the desired piston/bore clearence. Are you replacing the piston as a matter of course, or do you consider there is some wear, is there piston slap? It is quite normal for a well looked after trials bike to go for at least 10 years on the same piston (and rings), not like a motocross bike. If your piston is an A and there is no piston slap (rattle) then replace with an A. If you have considerable noise from the top end, you can use a B piston in the A cylinder. There are only minute fractions of a mm difference between the A and B in the lower piston skirt diameters. I have done this in the past with success. No need to hone the cylinder unless you need to clear light surface damage. Bye, Peter B.

Hi Roger, Post a photo of your bike, real Kiwi ingenuity. Bye, PeterB.

I've always used an ATF rated to Dexron III, since at least 1992 in all my GG bikes, nothing flash, but changed often say 20 - 30 hours use, earlier with new bikes. A synthetic is not necessary. 600ml is fine with the older motors. I found that using a multigrade oil creates extra clutch drag, stay with the ATF. I tend to be a bit old fashioned and like to know I have oil in the fuel, so I ran with 50:1 fuel/oil ratio on the GG's. Always used a mineral oil. Never had any oiling problems. Bye, Peter B.

I've used a pre-mix of 50:1 for 20 years on GG. Use an ATF rated to Dexron III for the gearbox, 600 ml is fine. Bye, Peter.

Hi Ian, More info on the type of noise would help, knocking, whirring, grinding, scraping, tapping, top end, bottom end or gearbox. What seems sort of rough? Could be many things. There is only a nut on the LHS of the crankshaft that tightens up on the flywheel, if this is loose, the flywheel tends to shear the woodruff key rather quickly, as it spins on the shaft. So, not likely to be that. Has the motor/gearbox taken in water at some stage? Main bearings may have failed. Does the gearbox oil look milky? Is the clutch grinding on the outer casing? What model year is the bike. More info would help to diagnose. Bye, PeterB.