tony283

Alan, As Mike said the correct plug for this model is B7ES and for your TY175 it should be the B9ES. With regard to the fuel these machines were originally running on 20:1 (ish)using fairly low grade leaded. Currently any good oil with premium pump fuel is acceptable at 40:1 and like any 2 Stroke of the period you can expect plug fouling once in a while as David suggests. Our modern day fuel does not much care for oil and will need to be changed about every 2 months if you are still using the same mix from a can as it will leave a tacky varnish like resin on piston, rings, reeds, carb slide and in the petcock. I always carry a spare plug on EVERY outing as I have done since I started in 1962 ! I doubt you could ever overheat the Ty250A motor and when I had the FIRST one imported to the UK for the 1974 SSDT the Yamaha mechanics advised dropping the choke on the long road sections and ride through the burble and spits. These bikes would do over 80 mph on the public highway !!! not bad with 4lbs in the rear. Tony

Full report and pictures of Round 1 of the 2010 Ahrma Trials Championship on 13 Feb now up on my "blog". just hit the Blog caption to view. Day 2 will be up in 3 days time. Tony

There are many ways to remove wheel bearings but by far the easiest is to use the right tool. Have a look at my blog and locate the article "How to .. Wheel Bearings" published in Feb 2008 and it will give you a detailed guide with lots of reference pictures to help along the way. Tony

Squid, You don't say whether its the normally welded flat nut on the inside on the bracket or the bolt is just spinning and not moving in or out? In my experience the nuts don't normally break away from the weld and its more likely that someone has cross threaded the bolts at an angle when replacing the shield. If this is the case remove the "good" 3 bolts then use the shield itself as a pressure lever as you unscrew the offending bolt. Tony

ATF is as good as anything in the Yam. Tony

Tis the season opener! If I can ever get out of this snow and get to Arizona then we have Rounds 1&2 of the Ahrma Trials Championship this coming weekend, 13/14 Feb. There will also be a Beginners Trials School all day Friday, cost $30.00. For the MX men you can ride both events as the sections WILL stay open until you are finished. For those wanting a sneaky preview then look at my "Blog" under "24" which will give you an idea of the 12 sections for each day. Tony

Paul, On all my Yams I use 150cc per leg of a good SAE 10 fork oil. Tony

Paul, Not sure where you are located but in the US Bob Ginder does a complete jetted carb, Domino throttle and cable kit for $160 at www.bjracing.com and also the reed kit with extra spacers for another $40. I usually get my carbs from him and its just bolt on and go unless you need to alter jetting for high altitude. Tony

The standard plug is the NGK B7ES for all the 250's and the B9ES for the 175. Most people seem to run with too wide a gap! Tony

We spoke ! before the system went pear shaped..... and I see your other question has not been relisted re; reeds....... as I said if you buy a WM26 for trials application maybe a 2.5 slide is ideal and with the new reeds come down one size on the main and then test. I'm assuming you are familiar with how to achieve max perf from carburation, if not ask and we can go through it. Tony

Squid, Getting to be quite the mechanic!! All replies contain all the info you are looking for. Buy a Domino throttle, fast or slow (white or black barrel) a universal throttle cable and an auto blanking rubber for the side of the carb. Remove the forward cover plate to get at the oil pump and remove cable from unit then the whole pump. Blank off the cable inlet in the case with a simple nut and bolt. Seal the rubber where the oil lines enter with silicone. You can run in this configuration with just the bare shaft coming through the clutch case as it has it's own oil seals. However most of us remove the case and then remove the oil pump drive shaft. Now you need to make, or buy a cover where the oil pump use to be. What I have always used is the piece of alloy from behind the bracket on the chainguard as these often get bent into the shock. Hammer it flat, cut to shape and drill, seal with the good old blue silicone and the job is done. Bear in mind you will need two short bolts as the pump bolts will be too long. Run the sytem on 40:1 with a good 90+ octane but remember in these days fuel is such a poor quality it goes off after a couple of months with a very noticeable lack of power with the 125. Tony

Well as always a good question, see my blog under "What does it cost" and it will give you a feel for where you willl be going. Tony

John, It doesn't have a "cage", its all part of the filter element. Tony

Squid, I'm assuming you have sparks, or know how to quick test? Lay the plug on the fins of the head and hand crank the engine, should be a rich blue spark. Make sure you have the correct plug and the gap is 22thou, or somewhere close. Not sure what your starting technique is but with the baby carb, zero throttle movement and full choke. As it starts to warm up remove the choke. If it won't start then normally the choke system is plugged so open the choke and blow c.air through the angled pipe. If it will only run on the choke then the pilot will be blocked again! Can sometimes take 2 or 3 cleanings to get all the muck out of the carb even though you think you have it all! Tony

For those that read the "Testing the Pachyderm" article you might like to get a look at the real rhing..... the New JPS edition of the SWM Jumbo. Its on my "Blog" under "Extreme Makeover The Reveal" and has a load of pictures of the beastie in it's new livery. Either hit the blog button or go to www.blackcatvintagetrials.com Happy Christmas to all Tony

Squid, Another common problem with an old carb! .....and one that hasn't had much attention, DO NOT USE THE BLADE OF A SCREWDRIVER to pry apart! Using a soft hammer or the plastic end of the screwdriver you were thinking of using as a pry bar gently tap around the bowl and the two parts will come undone. Assuming you have already removed the slide, cable etc once apart you will also need to blow through all orifices when you have it relatively clean. Make sure to clean the pilot jet and choke system. When you look through the pilot jet it will look like there is a "S" in it but that is supposed to be there!........ and never ever use any silicone anywhere near a carb. Tony

As you are new to the mechanics "bit" take the carb off the bike and then remove the float bowl. Check the inside of the bowl for any gummy (red) deposits and clean out well. If the deposits are white like calcium clean them off too. Push the little rod out that holds the float mechanism and the float valve will drop in your hand. It is about 3/8" and is usually a triangular rod with a pin head on the lower end and a sharp point on the top end to close the valve as the level fills. Any roughness or deposit on this end will not close the valve and the fuel WILL overflow. A light sanding of the top of this rod will normally fix it. Tony

The 525 just refers to the TY175, 434 for the TY250A's and 493 for the later models. The next set of numbers either on the headstock or engine will give you the year of manufacture. Tony

Alan, The fork position is standard for the TY175 whereas the 250 fit flush. The pegs and hangers look standard but a SM set are even better. Tony

.....and now a little Christmas fun! Having just rebuilt a Jumbo for a friend it was taken on a test ride. Full report and pictures are on my "Blog" www.blackcatvintagetrials. com or just hit the Blog button. There are all the other articles on the rebuild from scrap to showroom. Happy Christmas Tony

Had all those problems on my 1960 Don Morley Bullet. Sent it to Dave Lindley (number and address available from Hitchcocks) You will need the extractor tool from Hitchcocks, the only model reference on the top is on the green badge "Lucas Racing Mag"...... when you get it off it will say HR1 on the underside, Dave has all the parts and should cost about 200 quid with the new platinum points (mine had 1 plat, 1 tungsten!)....... remember these mags won't run on the new HT leads either, needs the old copper core. All the stories on my blog under "Prince of Darkness" and "Dim & Dimmer" Good luck. Tony

Woody, I'm currently rebuilding a Jumbo which has had all the same problems with the plastic. After several attempts at restoration I finally decided to redo the colour scheme for the entire bike. The tank has now been resprayed and looks good. The whole saga of this machine is being published on my "blog" in 4 parts. The first two are up and entitled "UGLY BETTY" and "BEAUTY & THE BEAST" you might find them amusing and be able to share any tips in the future. Tony

Yes, any item up to model year 1974 may be used. Tony

1974 was the first year they were sold in the UK, I know I had the first one! Yes they were very competitive back then and still are in Vintage competitions. Most parts are readily available and they were very well made and seldom have any problems. Tony

For those following the saga of "old men on old trials bikes" 3 days of Vintage trials reports and pictures are up on my "blog" and pictures from Buckeye, Milliken, Turkey Rock, Cotopaxi and Casper can all be seen on www.trialsphoto.com Tony