tony283

OTF, small world! I was stationed at RAF Finningley when mine arrived from Brian Leask (Husky) as Yamaha didn't have an official importer at that time, they built it up out of its crate coming up the M1.I think I went to that event you mention when all 3 of us were riding and I remember a nasty little section in a deep mud filled bomb hole with a grassy bank exit. I was at the back of the near 200 entry using the obscure ACU rule which allowed members of the armed forces to sign up on the day even if it was an Open to Center event. I casually asked the Observer what "it" was riding like and got the reply "All 5's apart from TWO cleans...... and they are riding the same bike as YOU!!" The bike rocketted out of that hole to my surprize and didn't touch the grassy bank either and I DID make the THIRD clean of the day. So at that trial 3 of us on the Yams had a 5 point advantage over the entire entry. Tony

Back to the question originally asked. I had the FIRST TY250A in the UK which was flown in from Japan as I had an entry in the 1974 SSDT. The TY250A was very well built and was the first true trials bike to come complete with lights. Two other TY's were in the 74 SSDT, myself, Peter Oakley and that "man" Mick who was riding something very special!! The TY250A was the first trials bike with a reed valve system and this made it a ferocious little beast compared to Monts and Bults of the same period. The brakes were excellent although the footrest position, as we now know, was too high and too far forward. A lot of people did not like Yamaha's first entry to the trials world as we just were not used to the "snap". My SSDT bike completed the event in perfect condition save for the bash plate which was fiberglass and all the eyelets came loose but other than that everything else was good on what was then an 1100 mile ride round Scotland. For 75 and 76 I rode the 250MAR around Scotland and I would say at the time it was the perfect clubman's bike. Big comfy seat, virtually unbreakable engine, and the ability to find grip in just about all sections when others were failing, especially at very low revs. Betor forks were good and the footrest position was closer to what we now strive for on a vintage bike. Weaknesses were of course the brakes, or lack of if wet, and cheap Spanish steel used on the rear axle.... I changed 2 in Scotland! Braking action was better using a decompressor and engine braking rather than relying on the worthless front brake. With the later Yamahas, the A was only made in 74, the porting was changed which made the motor much softer off the bottom than the snappy crocodile behaviour of the A model. I still ride my TY Superglitz model with the A motor, rearset pegs, Magical shocks and a flatsside OKO to go with the Ossa style through the frame big bore WES system. Eng sprocket comes down to 12T and this deals with the modern section of round the corner into 18-24" step. After all these years it would be interesting to ride an Ossa that has had the reed valve system fitted. Tony

Torben, Good luck with the rebuild ! I did one for someone back in 2009 and you might find some of the info, including pitfalls, useful. Go to the "blog" and hit 2009, then Nov, this will give you all the articles starting at "Ugly Betty", then Dec 2009 for "The Reveal" ... "Testing the Pacyderm" and then in 2010 find August for the actual testing and you will see some pictures of the kickstart case saver that stops punching the hole in the case. You will also see the "never undo gotcha bolt!!!" About 2 hours worth of reading but you might find it helpful. Tony

deal with the simple things first, most likely a blocked Pilot jet Tony

You will be able to read the size on the main jet as it is easy enough to read. The Pilot will need to be unscrewed with a small flat blade screwdriver and also where the needle clip is will give us info on the set up, likewise the slide may also be marked numbers from 1.5 to 3 Tony

Well of course you never did tell us what the jet sizes were in the carbs ? Tony

Did you try Bob at BJ Racing? he will custom build them for you and you won't have to pay import duty (springs) from the UK. Tony

Not a lot of info to work on. First we need to know what "new" carb you fitted and what the jetting is. Is the auto lube still connected? or are you running premix ? I'll assume the new carb is a Mikuni VM26 which is ideal for these bikes. The plug should be NGK B7ES set to 22thou. Point gap at 15thou and the TY has fixed stator timing unless it has been altered. If you have a Mikuni VM26 it needs a 150-160 main jet and about a 35 pilot jet. I'll also assume you have an in-line fuel filter ? If as you suspect its the carb causing the problems a good blow out with compressed air should solve most problems. First blow through the choke/enrichment circuit by depressing the choke lever and applying air. You can see through the main jet and see daylight. The pilot jet to the rear of the main can also be seen through when clean even though there is a "S" shaped wire in it. Normally if it won't start its the choke circuit blocked, if it runs on choke but falters and dies when the choke is taken off its a blocked pilot jet. When running and warm you can adjust the Airscrew for best pick up starting around 1.5 turn from fully in. Check your carb and jettings and let us know Tony

I'm currently using them on my TY250A Superglitz. I tried them on my Majesty mounts but have since switched back to the standard mounts where I feel they provide a better action. I also have the Magical fork springs fitted. Value for money ?? time will tell! Perhaps the better shock in the US is the Falcon which you can have custom made by BJ Racing. Tony

Airscrew and Idle Screw. Two completely different screws with two entirely different functions. The Idle Screw gently raises the slide in the carb body when screwed in allowing more fuel/air to be let into the engine thereby increasing RPM. The Airscrew on a Mikuni is located to the rear of the carb body and allows air to combine with fuel which gives instant pick up from idle when set correctly. If you slam the throttle wide open from idle and pick up is not instant, or the engine dies then this circuit is either not cleaned/partially blocked or incorrectly set. When the carb has been cleaned correctly, pilot jet and circuit blown through, located to the rear of the main jet down a rabbit hole, (no poking around with wires please) Start as you have been doing, adjust idle or tickover screw for about 800-1000 rpm with the idle screw. Now turn Airscrew 1.5 turns out from full in. Now adjust the airscrew in 1/4 turns until you achieve the fastest tickover....... if you are not around the 1.5 to 1,75 turns then you need to change the pilot jet. With experience you will be able to skip this step by just opening the throttle quickly and getting the desired results with minor screw adjustments. With all this done lower the rpm with the idle screw to your desired tickover if thats what you want. Tony

This seems to be going down the "red herring" road ! ...and equally the "little knowledge dangerous route" Lets get back to the basics that the panel of real experts have been advising and that so far have not been followed. First lets establish that all is well on the electrical side which means following their advise re contacts and earthing....... and disconnect that kill switch which the bike never had when new! You say you have fitted a new plug ? Presumably the correct type ? Plugs of course come not only for our trials applications but a host of others. A new plug invariably comes with a huge gap ! This needs to be reset to 70's era gaps which is 22THOU. I trust the points gap has been correctly set at 15THOU. Common problems with wiring are where others have mentioned where the cabling gets hot and brittle. Also have a look at the plug lead by removing the cap, and check the wiring is not rusty ? .....if so cut back a little to new bright wiring. You say you have a Mikuni fitted, what model and when ? Ideal Mikuni for this application is a VM26 with about 155 main jet and 35 pilot. Set needle clip to middle groove, airscrew at around 1.75 turns out. Basic info for carburation, Main jet controls flat out performance. Needle and clip control mid range performance. Pilot jet controls pick up off idle. If you decide to keep the current carb check the jetting numbers and keep us informed. Good luck and Happy Christmas Tony

Usually a quick and satisfying fix. First check your "new" cable. Some new OEM cables have a tight spot where the wire runs through the steel tube at the bottom, might need to be bent slightly to give a smoother run. The TY brake plates get a crud build up in the actuating pivot, combination of mud and old grease. Remove and clean. Also clean the contact point on that cam and also the shoes where they touch the cam. Tony

On a VM26 try 35-40 pilot and 290 Main. Yes, not a misprint 290 Main. Tony

A lot of hard work has gone into getting the BLM permit for this one but the final rounds of the ITSA Mtn West Championship are NOW ON for Oct 20/21 at Roswell NM. Tony

Standard settings for a VM26 on a TY250 should be 150-160 main and 30-40 pilot, with airscrew about 1.75 out. Tony

You can do virtually anything with the original frame, its just the Otter frame they do not like! Currently all the "other" after market frames are seemingly acceptable within the Premier divisions and of course nobody would bat an eyelid at a 2012 Dick Mann frame. You can use the Otter frame in Classic if thats any help. Tony

For whatever reason the actual Otter Frame is NOT allowed in Premier Class and can only be used in Classic. No reasons were ever given ! Parts up to 1974 may be used on Premier machines but strangely no mention of NEW frames from Nevada and made in Colorado that grace many Premier Heavyweights. For eligibility your best bet is to contact Matt at Speed & Sport........ or join ITSA Tony

For those coming to Casper next weekend there is a preview of some of the terrain in today's "Blog" article; "Where the Deer and the Antelope play" Hope to see you all there Tony

Full report and pictures from Round 5 now up on the "blog" and on Facebook http://www.facebook.com/#!/MountainWestVintageTrialsAssociationItsa Tony

Last 2 sections to be set today. From reports looks like a good number of riders coming and some new faces for the beginners line. Fun sections for all lines, and some hazards you may not have seen before! Don't miss it. Tony

Full reports of the 2 day on the rock are up on my "blog" .... with pictures ...... more news on the Dolres event coming soon Tony

The Standard is a 13T but for modern day trials a 12T will be better. Yes, if you have a full coverage side cover. There is a key tab that must be flattened before undoing the nut which should not be too tight. Tony

ITSA Mountain West Rounds 5 & 6 Aug 11/12 Day 1 Sign up 0800 Cozy Comfort RV Park, Dolores Co on Highway 145 0900 Leave CC for Dolores High School and form up for Escalante Days Parade riding your trials Bike down Central Ave 1000 Trial Starts at Cemetary, 3 loops of 12 sections 1800 Awards in Cozy Shade Garden, Pot Luck cookout, bring something to share Day 2 Sign up 0900 1000 Trial starts at Town Dump, 3 loops of 12 sections 1400 Awards ALL CLASSES, VINTAGE & MODERN including BEGINNER TONY

you might like to read my "blog" on all the modificationsI have recently made to my original SM Trials Cub Tony

Well we did it, 50 sections, 8000' of ribbon and judging by the smiles everyone (subject to class) enjoyed it apart from 15A (Sat) and 16C (Sun) and not forgetting the Rattler that was checking 13E Sunday !! If you liked the format yes, or no, lets hear some comments before our next double header at Turkey Rock CO on Jul 28/29 Tony