sherpa325

It definitely looks like a !99A frame. The stamping of numbers on the frames can be pretty random, but after the numbers there is a horizontal stroke and then the A, the same as the engine. It could be faint and hidden by the undercoat and paint.

The PHBH is a larger version of the PHBL. The PHBL is a small body carb used on trials bikes to save space, with a maximum bore size of 26mm whereas the PHBH goes from 26mm to 30mm and I think your cota would be a 26mm. I wouldn't think there would be any gain going from 26 PHBH to a 26 PHBL. The Keihin is a Flatslide 28mm and will give you more topend power if that is what you are chasing and they are pretty much standard on most newer bikes, but there is nothing wrong with a Dellorto.

All front wheels from 1972 [M91 M92] are the same. The magnetos for the 250 and 350 will both fit but the 350 is a fair bit heavier. The exhausts are very similar and can be made to fit if you are handy with an oxy torch and your rear muffler is what is called a 'clubfoot'.

The couple of books I have at home say the first Sherpa T was based on the Millers modified Sherpa N. It's hard to find any information on the Sherpa N or the Matador, so it is difficult to work out what differences there are in those two models.

As these model bikes are really scarce here in Australia, I was always under the impression that the first Sherpa T was derived from the Sherpa N but it also appears that the Matador has a very similar model number M4 vs M4-1. I was wondering whether they both shared the same frame with some minor variations, brackets etc. If anyone could shed some light it would be greatly appreciated. Thanks Greg

Try a new condenser, notorious for giving a spark when turned over by hand but break down under load

I'm pretty sure there were two 'clips' that held the wiring in place. One was mounted on the taillight and guided the wires to the side and the other one was on the guard mounting bolt. There was also a hole a head of the mounting bolt with a rubber grommet for the wires to exit.

Thanks for that!

Talking to a couple of mates and we have no idea what the horizontal 'flat surface' on the engine case is there for. It's not on the earlier round case models, any ideas??

Mine started to increase in length and then I realised, after some research, that the fuel I was using had ethanol in it, although it wasn't advertised. I started to used ethanol free fuel and surprisingly it went back to its original dimensions.

You can get a 9 tooth front sprocket, not sure whether yours would have a 10 or 11 as standard. As I said before there is not one modification that that will magically make the bike super easy to ride. These bikes are meant to be ridden on the clutch all the time and riders that are new to this style really do struggle to adapt. You have to learn to cover the clutch with one finger at all times, in other words you never ride the bike without your finger on the clutch. As soon as you start to get out of control you pull the clutch in and moderate the power going to the back wheel, it does take some time to adapt, but once you do you'll feel much more comfortable.

There is no one modification that will make the bike easier/tamer to ride. They all make an improvement to ride ability. I would start with the cheapest and easiest, slow throttle, gear it down one on the countershaft. Low compression head makes it easier to start and less drama with fuel, larger base gasket is also a cheap mod and the flywheel weight also helps. A mate of mine who was having difficulty in transitioning from a 325 Bultaco to a 250 gasgas and having to get used to using the clutch eventually did the mods and the bike was so easy to ride, very predictable and still plenty of top end for the sections he was riding.

Yes the two stroke 250 [tyz engine]

All of the mods have an effect, I personally like the low compression head as it has the added advantage of making it easier to start and less sensitive to fuel.

It's not to hard to dumb down a 250 gasgas. A mate of mine had the same predicament and basically tamed his gasgas by gearing it down, flywheel weight, low compression head, slow throttle and eventually a thicker base gasket. The bike is so easy to ride and still has enough power to ride decent sections. It's also very easy to start and obviously still has great brakes and suspension and is 30kgs lighter than a twinshock. The other late model bike that is easier to ride is the Yamaha engined Scorpa. They are a great bike with a very easy motor to live with. Twinshocks require a decent level of mechanical ability to get them to perform, generally speaking the brakes are average as is the clutch and suspension and you can spend a lot of money on them if you are not careful.

I personally think too many things can go wrong if you you farm the job out to an inexperienced company. InMotion have a great reputation and are easy to deal with even though I'm on the other side of the world

600cc of gearbox oil in the gearbox and 300cc of ATF in the clutch will work fine.

I have seen split markers dislodged when the bike was no where near the marker. One happened when the bike hit the rock so hard the marker fell off and the bike was a good meter from the marker, the rider was Fujigas. I have seen another one dislodged by sprayed debris, mud and small rocks, and the bike again was a fair distance from the marker. Many times the marker is removed by an earlier rider and the observer places the marker back as best they can with the marker just sitting there without any adhesive or fastening at all.

I think you need more throttle.

When my son was riding at a very high level and I was maintaining his bikes I kept reducing the oil ratio until the bike stopped blowing smoke at full throttle. We found that about 80:1 was the cutoff point for blowing smoke. Every time we pulled the engines down they were in great condition with plenty of oil visible on the crank. In all my years of working on two strokes, including air cooled twin shocks, I have never seen engine damage like yours, very strange.

I'm not a fan of the lanyard, but they are compulsory for competition here. A few of my mates have wired a kill switch as well as the lanyard, not hard to do. The magnets don't wear out and are trouble free and as I don't like the strap around my wrist I attach the cord to my glove and I don't use the cord when practicing

I put the heaviest gearbox oil I can find in the gearbox 600cc. The reason is that there is a breather above the countershaft sprocket and if you put the bike on its side the lighter oils spill out pretty quickly. In the clutch case 300cc of ATF if you aren't going to play with the clutch when riding. If you are running fibre clutch plates and plan on slipping the clutch then any of the light gearbox oils like ELF, GRO etc will work. In the engine we are running 60:1 of any of the new synthetic oils. Cheers Greg

Has anyone tried DP clutch plates and if so how do they compare to Surflex. I have tried the Kevlar and find them too sharp for my liking. Any feedback would be appreciated.

I always use the S3 ones on all my bikes including twinshocks and using genuine Keihin carburetors and have had zero problems on any bikes and I am very fussy.

Why would they cause issues, I have them on my bikes with no dramas