mattylad

Look at the mijossi.com website for more details on Rayer mods. I have a test from the time in french if you PM me I'll send a copy. maybe even got it from this site Also on the site leboncoin there is a full rayer including swing arm for 1100 euro not too far from you. I have seen the ad and thought it way too expensive for what it is. i would go up to 250, 300 Euro.

I would use a heavier grade oil such as 20W40 which was recommended as standard. I think it is 164cc The Yam has a problem with topping out if much lighter oil is used.

There are two possible ways to go on this one. As Woody has said you can take weight off the flywheel and the engine will pick up faster. The standard Yam porting is very conservative, the squish gap is way too wide and the 22mm carb and reed block are good for low end power. The airbox is also restrictive. With a standard engine I would, cut back the airbox lid and drill other holes to allow air in. Use the thinest air filter I could find. Open up the reed stops. The squish gap needs to be reduced to 0.9mm and barrel lapped to cylinder, for example my 175 had a squish gap of 2.15mm as standard! The rear tailbox needs replacing with a WES or similar. Or more radically you could port your barrel and retain the standard flywheel weight along with the above mods. The theory is to have a high powered engine calmed down by a heavier flywheel with more inertia. this is better for finding grip or at the top of bigger steps. This is effectively the route taken by the 200 fantic which was very succesful after the Yam. For the porting a good starting point is to raise the four transfer ports by just 1mm. also widen the smaller rear transfer port as much as possible without overlapping the end of the rings. I allow 3mm from the piston pin to port vertical side. Finally I also add the reed cage and airbox boot from a TY 250 with a 5mm reed spacer and use a NEW!!! DT175 24mm carb or OKO 24mm flatslide. Most old carbs are worn out and need replacing. This needs about 3mm removing from each vertical side of the reed entry on the cylinder. Finally I then take a load of aluminium from the roof of the inlet side to allow much more gas to flow directly up the boost port. The exhaust port remains standard. I also use a DT175 piston as this has larger windows in the rear for improved gas entry. You can go even more radical on the boost port and rear transfers so that they open earlier but try the first mod first. I have a bike that both lugs reasonably well down to low rpm and then will really rev out almost like a modern 125. It needs to be ridden more like a small bore modern bike on and off the clutch. Happily the clutch will stand the abuse. It is great fun to ride on easier events.

Not a reflection on the rebuild but this has got to be in the running for the most ugly bike ever built. Eye catching does not describe the bile green colour. Thanks for sharing/

I also think you are missing the fact that even back in the 60's and 70's. The efforts Sammy Miller put in to his Ariel were at the forefront of technology of the time. Where I grew up the Bultacos ridden by Dave Thorpe were a lot better than the standard offerings (so was the rider!!!). The factory Suzuki of Nigel Birkett, Yamahas of Mick Andrews were both mega trick and so I asssume were the bikes from other manufacturers. Remember often very small changes in geometry, riding position, suspension set-up, caburation or engine porting can have some pretty dramatic effects both positive or negative depending upon the rider. What suits one rider may not suit another. It true that a good rider will beat a poor rider no matter how much cash the bad rider has thrown at his machine. Equal riders will often set bikes up in different ways to suit their morphology and riding style so what is acceptable? Remember modifications keep people employed and cash comes into the sport, riders keep riding and events keep getting put on. A pristine rebuild of a standard bike would not get ridden as its value would need to be preserved (and they are just not as much fun). The avaliability of new spares means they will get ridden as they can be rebuilt. Just get out and enjoy riding. It is you against the course, the results are only a comparison of how you have ridden on the day compared to others. In any event human nature being what it is we will always have those who bend, stretch or totally break the rules! Which poor scruiteneer will have the knowledge to pass FAIR judgement on what is acceptable and then have the task of turning someone away. If riders themselves were sufficiently honest most bikes would be in the "specials" class anyway. Conclusion, anything but the most basic set of rules are pointless and may the deepest pockets or well stuffed wallet win!

You could also put the entire system on the BBQ or a fire and heat it to burn out the gunk!

If you read french look at Mijossi.com which has an article to improve performance of a TY125 which also includes shortening the rear exhaust perforated tube or even better using the centre core from a TY250 which is significantly larger.

The DTMX uses different crankcases. The centres of the studs are different where it bolts to the cylinder. Be careful before you buy. Why not buy a TY175 cylinder on ebay uk, much cheaper than in France!!! Also look on the Mijossi.com site there is an article to improve power from a TY 125.

I'm going on holiday to Tenerife in mid february, anyone out there have a contact for clubs or riding schools etc. Many thanks

I spoke with Mick andrews a while ago and in his opinion reeds are not necessary. Although if you talk with Keith Horsman you get a different story. I have a few ex-works engines and they came with about half a dozen flywheels of different weights so that may be one way to go. Theres actually not much wrong with a well set-up standard engine in my opinion, it all depends what you are riding against. Here we have a pre 1978 class so youre not up against a Fantic for example. rex caunt sells some lighter clutch springs which help greatly.

Message for Andy T Did you make up the airbox from scratch or is it a modified version? Any help would be most welcome as your airbox looks about the most stylish i have seen in a long while. Cheers

I only grease part of the taper, the quality of the fit is too good (yam quality) You are probably correct about not greasing but you have problems getting the thing off again if you don't so the choice is yours. If it does fly off under load you have a long walk back but at least it is well contained. Ive been running mine for a year now in this condition without problems.

I also had one that was well and truely stuck, tapping, penetrating oil. swinging on the end of a torque wrench, nothing would shift it. Resorted to the "hot spanner", put on puller and heated the the magnto taper. It got b****y hot but sprung off with quite a bang! Luckily I caught it before it hit the floor. This is not the first time it has happened on a Yam so I lightly copper grease part of the taper to aid removal in future.

Lee, Thanks for your answer, indeed there is a C on the piston which was made for Fantic by Galardini (spelling) as both names are cast on the inside. At least I know it is a standard piston and not mucked about. Matt

I have stripped down the top end of a Fantic 245. If I buy new piston rings are they all one size? The barrel has C stamped into the top fin I assume this is the clearence code. The bore looks very clean without any marks so should be OK. The reed windows in the piston are just two small holes (approx 10 to 12mm) with a single hole high up just below the rings is this normal? What is the thickness of standard base gasket as the one I removed is very thick approx 1 mm. What is the method to ignition time the engine? Spark will kill a horse! What are the standard carb settings as mine has a Dellorto 55 slide, 98 main and 40 pilot jet. Any useful mods that can be done on these engines.

The lad lives up in Cockermouth, West Cumbria.

My nephew is mad keen on trials and is looking for his first bike. What would you recommend??

Bit serious this, at 47 I'm still glad to be breathing!!! As long as you can ride the rest is immaterial. Obviously fine dining and good wines has done nothing to harm my performance (if only). I admire your resolve.

"Incidentally if somebody turned up on one of the extremely rare Cheney monoshock cantelever Ossas they should ride as a monoshock also. A previous post mentioned "Evolution" well that bike is a perfect example of "Evolution" a converted monoshock is NOT." Given that the Cheney/Horsman/Ossa UK bikes were built in 1974 to 1979 or there abouts they are most certainly twinshock period. I can assure you that the rear cantilever suspension is no where near as sophisticated as a Yam mono so why would you peanalise them? They are more a historical quirk than a real threat to the winners podium.

The same Mr AC seems to make a habit of changing sections. We spent a couple of years in planning sections for a world round and on the day before you would not believe how many rocks were moved as the section was "too difficult", funnily enough AR and TB had already passeds the sections as fit for purpose!

Still think there is place for an "Evolution" class. All the modified bikes running against each other whilst the real twinshocks can play together.

Save a lot of time and mess and buy a WES tailpipe which is repackable. The middle box will almost certainly be blocked as well and this involves cutting and welding. Well worth the effort though!

New spokes can be bought try Nigel Birkett or JK Hirst.

Barnett make Kevlar clutch plates for the TLR which are the bees knees.

The reason the case breaks is that the clutch arm puts a trmendous pressure on the casing. If the bolts holding the case, especially the one behind the sproket the flex will break the alloy case. And yes they all can be welded and most are.