feetupfun

You should listen to this person

With NGK plugs, the lower the number, the hotter the tip of the centre electrode operates at. If you are going to ride your Scorpa at sustained high power output, you should use a cool plug ie an 8 or 9 - to prevent the electrode tip from geting too hot. The problems with getting the tip too hot are: The tip disappears fast The tip radiates heat to a localised region of the piston crown and may cause it to soften and develop a hole When the tip glows, the fuel mixture can be ignitied by the glowing metal rather than the spark, so the timing of ignition is no longer being controlled.

Sounds normal to me. How about you post a photo of yours?

The rear Shinko tyre in the photo has a different aspect ratio (lower profile) to Michelin/Dunlop/IRC - looks more like MITAS Lower profile = probably inferior to the name brand tyres on logs, rocks etc but probably OK for Dirt Track racing I already wasted my money trying a MITAS so I'm not going to be the bunny

I seem to recall that the Cota 123 had a 20" front wheel so I'm not surprised that the Whitehawk 80 also had 20". I'm not saying anyone still makes a 20"tyre though. Everyone I know with a Cota 123 fits a 21"rim so they can get tyres for them.

Don't use hypoid oil in or near any wet clutch system as it causes the clutch to slip

This is the best picture I have for the frame on my M198. The steering head detail will be the same as what your M199A should be like. I will take some bare frame pictures on the weekend if no-one else has before then Regards David

Treat the tapered section of the fork tubes with phosphoric acid following the instructions on the bottle. It may be called rust converter where you live. That will cause all corrosion activity of the steel to stop, and create a protective layer on the steel. The process must be complete before assembling (to avoid damaging the aluminium top clamp with the acid) Assemble the taper dry and clean (no grease).

I don't know what prices are like in NZ, but it would sell in a flash at the buy-it-now price in OZ

The PDF on John Canes website will probably show this in better detail but here it is as a JPG

http://www.tytrials.co.uk/trailandtrialsuk...ific-Parts.html Open the above then click on "Majesty Article page 2" It is a PDF file so you will need a PDF reader

Here is what that original model TY175 Majesty looked like http://www.tytrials.co.uk/sitefiles/tytria...Article%202.pdf

There was another 175 Majesty type other than the two you mention. The first Majesty type had a modified Yamaha frame and looks very much like the one in the eBay photo. The frame mods were limited to the top shock mount being moved.

Paul, A current model Mikuni VM26 is nothing like the standard carby that came on twinshock Yamahas. Yes you can get new Mikunis to work on TY250 twinshocks, but don't expect to be able to buy jetting the same as what was in the TY250 Yamaha-Mikuni carby, and don't expect the needle jet, needle or throttle slide to be able to be transferred from the original carby to a current model VM26, they are dimensionally quite different. Parts for the original TY250 carbies are available. David

You might be interested in this thread http://www.trialscentral.com/forums/index....=ty175+big+bore Regards David Lahey

Ok here are the measurements for some Bultaco barrels from my shed. There were a few more that I had forgotten about. All are 71/72mm bores. All are distances from the top end of the sleeve Stamping, Exhaust top/bottom, transfer top/bottom, inlet top/bottom 27, 37/60,46/60,64/85 107, 32/60,46/60,65/91 and had finger ports 157, 38/60,45/60,63/83 86, 34/61,47/61,67/91 and had finger ports no stamping but is from my M198 and appears unmolested, 40/61,47/61,65/85 Yes I know that a M157 is not supposed to be a 250 but I'm just reporting what I saw Regards David

I can measure the exhaust and transfer port heights of a couple of Bultaco trials barrels, but am not offering to work out the timing from that nor am I offering to assemble anything to get the inlet timing The barrels I can measure at present are M198 (1977 238cc trials) and M27 (1967 250cc trials)

I believe that fuel-injected (Japanese and US brands) two stroke outboard motors are quite popular

The white with red stripe was also sold in Europe. We (Australia) got the pale blue one.

Cooktown is a great place for riding a trials bike, but is a long way from the closest trials competitions. There are trials riders in Cairns which is only a few hours drive and there is a group who ride trials bikes together and who ran one trial in 2009 in Townsville, which is about 8 hours drive from Cooktown. The major trials centres are in the South East corner of the state near Brisbane and near Gladstone on the Central Qld coast. Gladstone would be about 17 hours drive from Cooktown and Brisbane about 25 hours drive from Cooktown. You will find that long-distance dirtbike touring is very popular in the North end of Queensland and there are also very good MX and Pony Express events in the area.

If you are changing the angle at the headstock you will probably be limited in how far you can reduce the rake by the wheel or guard hitting the frame or exhaust header when the forks are compressed. If you are making big changes to the rake it might be a good idea to see what the trail will end up at before you get too carried away.

The diamond pattern looks like the pattern that would be made if the washer was gripped in the jaws of a bench vise

Some 1980s KX footpegs fit straight on but don't ask me which KX models. I just extended my standard KT pegs

Rickman did make frames for Montesa running gear and motors but I have only seen Rickman/Montesa enduro bikes not Rickman/Montesa trials bikes

If you want the standard KT bars they are available as replicas made in New Zealand (Fred and Debs KT Parts). My thing is to have 1970 bikes set up as they were at the time for comparison purposes so I use the replica bars on my KT (and on my OSSA MAR) and standard footpeg positions.