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
I acquired one from Hawaii a few years ago and had it shipped to AZ. The story and pictures of the rebuild are on my "Blog" under "Just For Her". Brenda rides it round the loop while on her photo duties.
Built mainly for trail riding rather than serious trials it had a few differences and came with flashers, the stand went back on the left side like the 250A, smaller engine and carb but just like the TY175 to look at.
..... and in answer to the opening question I think you would be better off fitting a 175 barrel and piston and of course the bigger carb.
Just finished 5 Vintage Trials events, 2 Days at Cotopaxi followed by a 3 Day event at Casper last weekend. Full report and pictures of Cotopaxi Day 1 on my "blog"
You will remember that since AHRMA and the AMA could not reach any agreement AHRMA is on a go it alone basis. The organisers of the Woodstock event are an AMA club and therefore are not allowed to run an Ahrma event. The reason for Sandia getting the CNX is not quite as described on the AHRMA website as I have attended ALL the Sandia trials and seen a steady increase in numbers! It was actually the husband and wife team who had done all the donkey work over the years saying No More!
The "rival" organisation who also ran the Wittman event, the same weekend as Buckeye, has taken it over and despite there being an alternate venue in Bull Hollow Utah and volunteers to set up both disciplines, Ahrma decided not to engage in a "double header" on the same weekend.
However you can see the last few events have all had good turnouts with Chehalis at over 100 and the 2 day at Cotopaxi recording 40+ entries and several more in the Twinshock and Support Classes.
Having followed this thread from start to finish it would appear there are many strong views, some of which have not been thoroughly thought through. Trials are trials no matter what set of rules are in force, the skill factor required to negotiate hazards has not changed through the years, currently some hazards are beyond the scope of both the clubman and National Champion.
Consider this, who is buying the latest factory machine and why ? Surely it is not on the results of the WTC? No, it is the percieved chance of "if I had one of those I could do better!"
The only way to go IMHO, is Non Stop, where perhaps a newbie can envisage that , just maybe he can get into a fun sport without risking life and limb.
Full considerations to both sides are explored on my blog in THE STOP NOSTOP NONSENSE
Getting back to the original topic, and we all know these threads wander about, I'm trying to find a few shots of our flight on the last Lanc PA474 when we flew over the reservoirs around the back of Sheffield to honor the last few survivors of the Dams Raid by 617Squadron. I need to look back in my log book to see the exact date but in all my years on BBMF it was a truly fantastic experience to come over all 3 Dam walls at height you would not believe, and then fly on to RAF Marham where 617 was based and meet up with those heros whose exploits remain forever as part of Britain's heritage.
For those that enjoy the Lancaster saga I was lucky enough to spend 8 years on the Battle of Britain Flight at RAF Coningsby. A story to touch the heart is on my "blog" called
"A TALE OF TWO CITIES".
To fly on the last Lancaster (PA 474) for 8 years was a very rare honor and has many happy memories.
Squadron Leader Tony Down RAF (Rtd) BBMF 1983-1990
The frame number with 493 would indicate the later models around 78/79 as you say. The 434 engine number is from a TY250A model from 74. The engines are only slightly different with the 434 having the recessed fins on the barrel and the wider engine cases. The 493 engine has full width fins, slightly different porting and the slimmer mag side cases.
There are (were) 3 wires coming from the stator onwards. The Black wire is the live wire and when I re-wire Yams, for competition use only, I put a splitter just before the top coil and and a single extra wire up to the kill switch. All single wire switches ground out through the frame/handlebars when the switch is depressed. You may find when you re-wire that the first 10 inches or so of the original wiring coming out of the flywheel case are brittle and if so should be replaced with new wires as this will save a lot of problems.
The stand mount for the TY250A machine is on the frame whereas on all later models the stand mount is on the swinging arm on the right side. The stand length is also different.
Drain off the current oil and use an ATF. Run for about 30-60 mins periodically running with the clutch lever against the bars. As the oil soaks in it will free off and should then be fine. A very common problem with old clutches and old oils.
As I said a very common problem especially with current fuels so check that pilot jet, when cleaned you can see through it save for the "S" inside the jet. Yams will run quite happily on full choke, and indeed it was the practice to drop the choke on the long road sections of the SSDT and ride through the burbles until you got to high speed. When you fit the new inlet gasket do NOT use any sealant! or you will have BIG BIG trouble!!! Remember the 2T motor relies on crankcase compression and if the seals were gone you won't have very much making it very hard to start. While waiting for the new gasket you can run it, even if the old one is split or broken and it should run fine.
It sounds like a classic "Blocked" Pilot jet! If you have just fitted a new tank etc it is quite likely the pilot jet will be blocked. A good blow through with compressed air.
The 428 and 53 tooth is standard for the year along with a 13 tooth engine sprocket. Depending on your area and type of trials riding a 12 tooth engine sprocket might be an improvement and is what I fit on ALL my trials Yamahas.
Full report of the AHRMA Trial at Milliken is now up on my web www.blackcatvintagetrials.com This weekend is a double header at Turkey Rock, Howard Colorado.
Depending on what models you acquired then the oil inlet from the posilube system is different. On the TY250A (1974) with frame No 434- the oil system went directly into the base of the cyclinder on the right side. Onthe later Ty's, frame No 494- it went into the side of the carb on the right side. If you are keeping the original carbs, strip and clean! If not and for great performance fit prejetted Mikuni VM26 carbs using 150-155 main and 30-35 pilot jets. With regard to manuals you can find them on ebay and both the Parts and Repair books work well. The parts manual shows everything and is a good source of info for ordering.
Let us not forget Mick who might be able to hang onto the bars now after his surgery. I'm sure he will be pretty determined as it is the Silver Jubilee.
As for Lingo 75........ when the cry goes out "All Trials Riders that can't TAP DANCE are QUEER" you will be able to recognize the non dancers and avoid them like the plague!
More often than not on an older machine the clutch will have dried out causing the cork to stick to the steel. Try draining the box and refill with ATF. Ride the bike while continually exercising the clutch. As the oil warms and the engine heats up it will penetrate and suddenly free off. Can sometimes take up to 1 hour of running.
Ahrma Vintage Trials Casper Wy
in USA Trials Reviews & Previews
Posted · Edited by tony283
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