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Re: Basket Cases

Posted: Thu Nov 24, 2011 11:13 pm
by Greg Harding
Hi Everyone,

Graham, Pursang you say, they were already on Steve's bike, we were not sure but the tip to tip dimensions were close to what I wanted. And yes the brakes were far from the only thing that is good on your blue beauty!

JC1, you are getting quite a collection of bikes and like me, don't seem fussy about which bikes. Fixing old bikes is character building and you can learn a lot as you go, it seems there is always something to test you!

Thought I would share a before and after shots of Steves M49, he is painting his tank and seat base, so is using mine in the interim. Apparently it belonged to a wild sort of character who raced flat track on it a long time ago.

Re: Basket Cases

Posted: Tue Nov 29, 2011 5:55 pm
by Geoff Lewis
Hi All, Have finally got a TY 250 C (I think) and would like to know what improvements are worthwhile during the rebuild.( THe bike is essentially dissasemled) For example , is there any engine improvement using the WES silencer system from Millers? I am certainly not a stickler for originality. It needs rebore and is on original bore at he moment. One of the engines I got with this stuff has a strange barrel and head with a huge reed block. Any idea what it could be? I will be using the bike only on the odd occasion and for practise in C+ type sections.
Regards Geoff

Re: Basket Cases

Posted: Tue Nov 29, 2011 9:19 pm
by Greg Harding
Hi Everyone,

Holy flower powered kombi vans with square barrels and physcadelic concentric flatslides! Geoff, have you been having some sort of bad trips?------------ Welcome to the 70's man!

The "C" model in my opinion is the first of the good ones as they sorted the swingarm out and ditched the surfboard under the seat. Any chance of getting junior to post some photos for everyone to see? What parts if any are missing as I do have some spares? The extra barrell, is it square or round, perhaps it is off a DT?


Re: Basket Cases

Posted: Tue Nov 29, 2011 9:23 pm
by David Lahey
A standard TY250C motor is a forgiving, reliable and powerful motor with an extremely wide RPM range but they do have very pronounced flywheel effect to the point that the motor is relatively slow to rev up.
There is no limit to what mods can be done to achieve whatever you want as far as motor performance goes. Probably the most common thing is to trim some of the standard steel flywheel band away until you are happy with the motor pickup. Many people ride with no band at all but when I tried that, I found it was too easy to stall in rock riding. I like the middle ground with some trimmed off.
If you want to get more grunt and don't mind using up the rebores in one of your barrells, you can rebore it 4 mm oversize with the standard sleeve. I'm not saying it needs it though. I have a few bikes with TY250 motors and they all pull like trains and rev to the moon and from memory the biggest is only 1mm oversize. Another thing some people do if they want to pull a sidecar or just love big power trials bikes is to make the motor 320cc or 360cc. The 320cc requires a resleeve and crankcase mods and the 360 requires an RT3 or DT360 cylinder and crankcase and crankshaft mods.
Yes the WES end muffler does make them run nicer - and sound nicer too.
I'm not sure if Boyesen reeds do anything except remove the risk of one of those stainless steel reeds going through the motor but some people find they make a difference to the way the motor runs.
They run great with the standard ignition, but there are bolt-on electronic ignitions available that have an advance curve, if that sort of thing floats your boat.
The standard jetting in the standard OEM Yamaha-Mikuni carby on C and D models is perfect.
I reckon if you post a photo of that odd barrell someone will know what it is. If it is attached to a TY250 bottom end but has a larger reed casing, it is probably one of the other Yamaha 250cc dirt bike motors of the 1970s -(IT,YZ,MX,DT) Yamaha barrells usually have an ID number cast into the side of the reed case or around the base of the barrell.

Re: Basket Cases

Posted: Thu Dec 15, 2011 9:44 pm
by Greg Harding
Hi Everyone,

Thought I would share something that I found out recently. :D Smiley face was designed in 1964 by Harvey Ball, a graphic artist in just ten minutes! :D Coincidently, about this time my mould was quietly being destroyed which makes me the same age as smiley face :D

This year in trials has given me quite a few things to smile about with plenty of good times! Competing in northern New South wales and South East Queensland, I have always been impressed with how friendly trials is. Our friendly northern neighbours have always treated me like a local, even when they give away trophies. For some reason, the conversation always turns to football????????????? :? Not sure why so I smile and think to myself, if only they knew that I have never really been interested in AFL!

Anyway, here is a holiday snap of some new friends enjoying the Coffs coast! :D

Re: Basket Cases

Posted: Fri Dec 16, 2011 3:56 am
by Mark K
Greg Harding wrote:.......... :D Smiley face was designed in 1964 by Harvey Ball .......

Apparently he stole the idea from a muddy faced Forrest Gump, but that’s another story.

Anyway, of all the pictures of bits of bike in a basket, that one has to be the prettiest in all of these pages. I hope the rust adequately filters out through that basket, and the bits stay in good condition so that someone else might get some use out of them in the future.

Well done Greg !!!

Re: Basket Cases

Posted: Sat Dec 17, 2011 12:29 pm
by David Lahey
Very nice photo there Greg. I couldn't help but wonder what message is being given by you using that famous landmark in your photo. My first idea is:
Something to do with a NSW/Queensland rivalry thing? Maybe those two states being the main banana producing states represents the close ties you have with the SE QLD trials community? Well Queensland usually produces lots of bananas but 2010 was a banana producing year that Queenslanders would like to forget. AHA! I've got it - 2010 was the year that NSW (Greg Harding) was the biggest banana producing state (won the most coveted Twinshock Trials awards)

Ok maybe not

Next idea:
You were wanting to publicise how cool living in Coff's Harbour is - (because of the Big Banana being there)?

Next idea:
You were in town having a picnic lunch beside the Pacific Highway, got bored and decided to create a photo that would stimulate forum postings about Twinshock trials?

Next idea:
You really think the smily face was designed by someone who looked at a banana?

Next idea:
You have ridden (and won) so many trials in Queensland that you have become an honourary "banana bender"? (queenslander). I think Steve Holzhauser has earned that honour too.

Re: Basket Cases

Posted: Sat Dec 17, 2011 3:34 pm
by billy
Next year, all I want to hear resinating through parc ferme is,


and have as many Barry Gomersall look-alikes marking sections as possible :)

Re: Basket Cases

Posted: Sat Dec 17, 2011 7:50 pm
by David Lahey
I think this story fits well enough here is Basket Cases. The bike in question was a non-goer with the main problem being it had been ridden to death. The autopsy report concluded that it was the big end bearing failure that was the final straw.
Anyway, this M138 Alpina has been the subject of my attention since about 1996 when it came into my hands as a part-trade for a Suzuki TM125. The motor was soon rebuilt and as part of the work it went from being a 350cc motor to something bigger - 370cc I think - because the only piston I gould get was from an uncommon model Bultaco that has a piston a couple of mm bigger diameter than the 350 Alpina motor. Anyway that went together OK on my third attempt at reassembly. I had not rebuilt a Bultaco motor since I was a kid and was obviously not paying close attention to what I was doing because I didn't notice I had fitted the crankshaft the wrong way around until the motor was bolted into the frame and I was preparing to fit the primary drive parts. Oh well, start again (I didn't have kids back then so I had all the time in the world to do things like this)
Next time I got everything right - or so I thought until I found it would only select first and secong gears!!! This time the motor was in the frame, primary drive in place, barrell and head in place. Oh well, start again.
Upon splitting the cases again, I found that I had fitted one of the shift forks upside down - yes it is quite possible and I'm sure I'm not the first person to do just that. Anyway third time lucky and still not hassled in the slightest (no kids remember)
I did a lot of boring things to it too like rebuilding wheels and forks etc so I could actually ride it, converting it to RH braking at the same time (Greg Harding will be impressed with that) by using a Pursang type two-piece wheel that has the brake on the opposite side to the sprocket, and making the loop on the brake pedal go inside out so it worked on the other side. All well and good. I had heard that AMAL concentrics could be a bit of a worry, so I bought all the usual bits to make it as good as it could be (slide, needle, float needle and needle jet) and a new fuel tap just to be safe. Slight issue emerged when I was doing some needle position adjustments to the AMAL, was that to get the slide out of the carby, you have to either remove the carby from its mounting flange or take the tank and head steady off!! I just figured this was something that missed the design checking at the Bultaco factory and went on to do test riding. Anyway with the advent of Vinduros (vintage Enduros) starting up in earnest this year, I thought that there might finally be a suitable use to put the Alpina to. This prompted me to think about what needed doing to get it ready, and the one thing that has bothered me each time I have "test ridden" the bike over the past 15 years is that it runs like a pig. Starts well, plenty of go but no finesse. I figure it will be a handful in serious riding terrain unless I can get it going a bit more smoothly, and the thought of all that drama just to fiddle with (or get water out of) the carby so today I tried a couple of different Mikuni carbies on it. The first was a (26mm) TM125 carby I recently bought (sight unseen). That is the one in the photo. First thing I checked was that the slide could be removed without any ergonomic issues - yahoo - yes. Unfortunately that carby didn't work out as it had so much wear that the bike ran even worse than with the worn-out AMAL concentric. It has slide/body wear, the float needle leaked terribly, the needle was worn down, and the float pivot pin was worn to half the usual diameter where it goes through the mounting posts. I swapped the float needle and seat for one I knew worked well, but it still ran poorly.
OK next step, try a decent (26mm) KT250 carby. Happy days when I found it also could be worked on in position without any issues, despite being quite a bit taller than the TM125 carby. Even more glee when the bike ran so well. I'm now happy to do the rest of the stuff on the bike to make it Vinduro-ready.

Re: Basket Cases

Posted: Sat Dec 17, 2011 11:13 pm
by Bully fanatic
Hello David. Well I told you a KT Mikuni would probably work fine on a Bultaco even if it is an Alpina. I would say you have a 340 piston in it as over here they are rare. They are an 85mm bore compared to an 83.2mm bore. It could also be a 360cc Pursang piston as well which with a 64mm stroke would make it a 370cc. I can`t remember what the Pursang bore was off hand. The Sherpa T that Martin Lampkin was using in that 1976 superstars trial was a Reg May 370. Normally the Alpina`s are a 349cc using a 64mm stroke and a 83.2mm bore. Being that size a 28mm Mikuni would be a better choice but if you have a 26mm sitting around you might as well use it. Hope it goes well for you. Good luck. Graham.