feetupfun

Flat spots like that are usually because the pilot jet is partly or fully blocked. I will look up the standard size pilot when I get home to my workshop. My memory is saying #25

looks like pieces of a broken L section piston ring (should not be inside the primary drive casing)

maybe someone shortened the aluminium part of the barrell (where the base gasket goes) to achieve the right deck height with a different piston or conrod, but forgot to also shorten the liner. Unusual to have a tapered recess for the liner Very interesting problem you have there

Tubliss system if fitted has two valve stems

just thought of another possibility - maybe that rebore was done out-of-square

It is also possible that the crankshaft is not sitting in the middle of the engine, causing the conrod to rub when the cylinder is held square by tightening the cylinder bolts. I would also check that the crankshaft halves are not being squeezed inwards by incorrect shimming under the crank seal carriers.

You can get those orings from bearing shops I think that is the 525 model carby. It should be stamped 525 on the side of the body If it is 525 model Yamaha-Mikuni, the standard main jet is 240. I run 220 main at sea level and 200 main at 3000 feet ASL on that carby with a standard TY175 motor, reeds, air filter box and exhaust The standard pilot jet is usually fine at sea level and at 3000 feet, as is the standard needle clip position

To start with what carby is on it? There are two different design Yamaha-Mikuni carbies that came on TY175s and they have different jetting. A photo may be helpful with identification Yamaha TYs will work fine just by plugging the oil nozzle and running premix. Completely different concept to the TS185 You will need more oil in the premix than for your Beta because the TY is air-cooled. Once you can say what carby it is, then people can help you with jet sizes

They are two completely different processes, not usually done by the same company. The kickstart etc rechroming is called decorative chrome plating and is applied using electrolysis. Fork tubes are hard chromed, which is chrome metal applied (metal sprayed) at high temperature. Also fork tubes can be done semi-automatically while there is a lot of manual labour in doing decorative chrome work, especially replating something, hence why it is more expensive. That price for the decorative chroming does sound steep though from my experience

This is what the Aussie TY175JC looked like

in some countries they didn't sell a TY175 with this frame, but they did here and they were very popular

yes a standard steel TY175 tank should fit if the frame is unmodified

those lugs are normal on some frame models of the TY175 and TY125 Another difference on your bike to the more common TY175 frame style is the lack of a stand on the RH arm of the swingarm

I think I used something like 50-60 RPM and a tool steel tool I used a tool shaped for machining steel and it worked fine The brake material dust is probably abrasive (clean the lathe well) I mount the backing plate on a mandrel I also suggest that the drum surface should be machined smooth first

I thought this was a joke until jon v8's second post

I just read your question again. Do you have rules requiring a tube inside tubeless rim and tyre?

If I was choosing a new rim and money was not a consideration I would choose a tubeless rim purely because they are less hassle, make for a lighter wheel and there is a better variety of tyres to choose from. As for the tyre roll, yes I think a wider rim does help when you run IRC rears

I've got some 350 alpina drive-side flywheels but I suspect the postage would be pretty steep unless you also live in Australia

My M49 is the first of the M49 series (4900100) and my frame looks very much like your mystery frame, except your mystery frame has rear fuel tank mounts the same as a M27

A common failure on that bike To get that part off the engine, you will need to remove the clutch pressure plate (which is inside the RH engine cover)

Yes the Godden frame bike does feel front heavy compared with many other twinshocks, but it is easy to get used to and is then very enjoyable. I spread most of my competition riding on my favourite four twinshocks and find they are all lovely to ride if I spend a little while getting used to riding them before the trial (TY250A, heavily modified TY175, Godden Majesty 250 and KT250). My other twinshocks (OSSA MAR 250 Mk2, Sherpa T M49 and Cota 348) no matter how long I ride them for, they never seem to be as easy to ride as the favourite four

Yes that swingarm is one inch longer than a standard TY250 swingarm. It was one of the first things I measured when I got the frame kit.

Pretty sure the Series 1 Godden frames were yellow (not plated). My NOS series 1 Godden frame came bare steel. Here is a photo after I bead blasted the surface rust off and primed it (photo taken in 2006/2007) soon after I got the frame

Steve what fork tube offset dimension do you have in those zero angular offset clamps?

If you have a modified rear end, you can work out the spring rate by calculating the leverage ratio on the shocks. 1960s trials bikes like the M27 and series 1 M49 have a leverage ratio of about 1:1 and use 40 or 50 pound springs depending on rider weight. Work out the leverage ratio for a modified bike and multiply the original spring rate by that ratio to get the new spring rate. Leverage ratio = wheel axle travel / shock shaft travel or Leverage ratio = distance from swingarm pivot centre to wheel axle centre / distance from centre line of shock shaft to swingarm pivot centre measured at 90 degrees to shock shaft