johnnyjazz

mechanical maestros, if you could tolerate yet another question from the ignoramus..... i realized at 160lbs (72kg) i'm on the border between 40 and 50 lb springs. maybe i should have got 50 lbs as i ride mostly road here in NYC but i went with 40lbs on the new falcons as that's what the guy sent me from the UK. i know the 40lbs are perfect for trials use however now methinks maybe i need to set them on max pre load as they seem a tad soft. im used to the thread/tool adjuster and the original step adjuster type pre loads, but not sure what the procedure is for these cir-clips? no doubt its super easy and you're all laughing, but i don't want to damage them! ... just not sure how to release them and move them down... -also, if i did step up to 50lbs spring (im not getting any smaller) would going to 345mm or 350mm necessitate a change to front end or is 340mm the way to go on the TY? many thanks as always my cyber trials friends. best regards from the headquarters of overpriced living and $1 pizza! johnny

thanks feetup fun! you the best. yes, now that you point it out..of course! thanks for helping me figure it . the bike came with the long seat and long brake pedal, so it figures it could have had the trail kit pegs fitted. someone must've taken them off and kept the longer spindle. i see i can pick up those foot peg lowering brackets still...though im assuming down and forward isnt the best for trials, would it be more down and back? - though seeing as the ol beaut is street legal and 90% riding i do is on road maybe it might make it better sense? - though probably make much more sense to get a decent road/trail bike! haha great to know inner bush isnt wierd and no shims isnt a problem if i dont need them. thanks always man. really!

hi feetupfun/anyone else, i took your suggestion and today inspected the swing arm for wear. the bolt and steel inner bush just slid right out (thankfully) but i noticed a few things on the way and am just curious. i know there's no such thing as a silly question and we are all ignorant about something, so if you might indulge me.... i noticed there were no shim/spacers in the thrust covers...does that matter? also noticed i seem to have two extra lipped washers that don't seem to be listed in my parts manual (top far right in pic). they go at either end of the swing arm bolt on the outside of the frame. is this normal or has someone done something- should that bolt be up against the frame? and lastly, i noticed my inner steel bush has holes in it. i can see how this would help distribute the grease, but in my parts manual the bush looks solid as it does on tytrials website of their swing arm replacement kit. wondering did someone do this themselves or was this standard? maybe its all exactly as it should be or maybe not...but i'm certainly no expert! learning so much on here from you all. as always pics attached and many many thanks!!!

Geof, mine is the 26mm OKO .im still learning about jetting, so im sure some others are way more savvy than me to your question re altitude issues , but i do know that mid atlantic trials has great customer service and will help you get it running right. mine worked fine straight out the box here in NY and did come with spare jets and extensive instructions on set up, but im sure they will provide you with everything you need if its something special. but man, i nearly dropped $75 on a new slide alone for an original TK oem...ouch. but feetupfun steered me to the OKO and i read on here from a wise elder of the trials tribe that a new carby on a 44 yr old bike is never a bad thing! and the OKO is crispy clean with a D slide rather than a round one and the peace of mind everything is new and fresh is worth a lot!

hola, im a beginner at this stuff, so please take my suggestion as such. but from the fantastic info on this site i replaced my original 74 tk carby with an OKO. it runs awesome!!! the cost of replacing parts for the original was getting out of hand and it was still running rich., i got mine off eebs from mid atlantic trials who were great to deal with. it seems a perfect fit (to me anyway) and for a $115 cant go wrong. (i just put the original TK in a box for if and when i sell the bike). hope that helps! best, johnny here is the link.. https://www.ebay.com/itm/Yamaha-TY-250-OKO-Carburetor-Kit/113198094760?hash=item1a5b21d9a8:g:YVsAAOSwlsda9fDS

Hello esteemed, revered and acclaimed masters of mechanical know how! i have found tillerman6's posts/replies enlightened learning and would like to thank you all for your input. Thank you sincerely as no here (in NYC) even seems to know what a trials bike is! so question 1, as a noob who is trying to get more confident, i was feeling inspired to try and do a top end tear down and learn more about the piston/chamber etc and at least assess current conditions and hopefully allow me to feed the addiction of buying new parts if needed and replacing (or stashing for later)... having already asked on here about the oil seals, and been encouraged to go down the route of 'if it ain't broke don't fix it'...i am wondering should i apply the same philosophy to the top end as i did a compression test today and got exactly 7.0kg/cm2 as per the manual. (fyi, it had been idling for about 10 mins so was warm and i kicked it 5 times without adding any oil to the chamber) deep down i feel to leave it alone even though i want to learn more..... question 2, when taking the clutch cover off, i noticed the friction plates looked like they were rusty.. is this normal? the clutch feels and works fine and the bike was stored inside for the last 30 years with only little farm use from new...could it be feasible...gasp...that its actually still ok or is it likely i should replace the springs at least? i want to measure the thickness of the clutch plates/springs as per the manual but am curious if getting the clutch apart is something that a noob could tackle and does it need the clutch holding tool just to check the plates? again, thanks all so much for your help. And tillerman6, god bless ya man...riding out into the sunset on ol' mellow yellow 70 years young....i hope it goes well getting your new piston sorted. best wishes from a sweltering NY johnny few pics for you.

this is the inside...but like you say, more trouble than its worth. i quite like the look of that all in one seat/tank unit from ShedWorks if i start getting better and riding more aggressively.... i appreciate the guidance!

Awesome! thank you. i had seen these but wasn't sure if they fit the 74A model. good to know they do! that other tank may be more trouble/cost than its worth so i'll pass methinks and head to shedworks. As always guys, thanks so much for the help!... ?

Salutations oh ye revered masters of mechanical knowledge and expertise! johnny here in NY with (yet another) question. im sorry if im asking too much, but my wife seems to be of no help and completely uninterested. This tank just came up for sale and the guy only wants 100 bucks for it. i was thinking of it as a spare but i am out of my depth in assessing the rust damage on the underside of the tank. the seller says it has pin holes leaks and will need work but i think it looks in ok condition other than the outside rust? if that rust went all the through then would it need to be welded and would this strip off the last of that nice paint? On my current original tank (in great condition) it was only rusted inside so i was able to clean it all out with rust away and then red cote it, but it has been suggested getting an older 'beat up' tank might be a wise move if i choose to ride the bike more aggressively. as always, i humbly beseech myself at the feet of you wise ones who all have way more experience with this than me! if it looks like its more trouble than its worth that'd be good to know, but im thinking its pretty cheap so maybe not much to lose? any thoughts gratefully received as i am a little nervous of the rust damage and it turning into a nightmare to fix as the seller said some of the holes have rusted through.

mellow as a cello now thanks!.

i have the 250a manual and parts list as a pdf if youd like? pm me. more than happy to share and put something back. Ive learned so much from the awesome mechanical wizards and trials masters here!!

hola,- just my two penneth fwiw- but i found a complete original seat assembly, pan, and hardware for the TY250A in fantastic condition on the bay recently for $175 so don't give up hope! it originally had the long trail seat so i was keen to find the original as its a few inches lower and narrower. hope you find what you need!

Thanks guys, really appreciate the input! i'll just leave em..i did the oil/seals a while ago and if you think the springs look fine and the shorter length is ok then that's all i needed to hear! i know a lot of this knowledge comes from experience so thanks again for sharing thoughts totally take your point about new techniques on old bikes but having just watched these two vids really made me rethink my game!

hello wonderful trials forum! so...another question from the newbie in brooklyn...thanks for all your help and patience so far ive been trying to practice front wheel hops and really having to work hard at it. now, im aware my technique is ***** and even trying to do these 'modern' things on an old twinshock requires a lot more effort and diligence than on a mono shock, but i pulled my fork springs again and measured them against the 400.5mm i have in my manual and they came up a wee bit short.. would this little difference have a big effect on the rebounding of the spring? i see i can get a new pair from b and j for $90 so happy to take a hit if need be? few pics showing lengths...the silver lines are at exactly 400.5mm... can any of you experts tell me if i should just get some new ones or i just need to leave em and work harder at technique? thanks always so much!

im no expert by any means...but ive had the bike about a year. here is what i have from the manual with regards your oil question, but im sure there are a myriad of options that are available since 1974.....oil has come a long way! cant remember exactly what i used...probably something cheap and cheerful i 'borrowed' from work...

Hola, i thought i would chip in with my two penneth as i was asking exactly the same questions here recently.... I live in brooklyn NYC (hardly a trials mecca!) and last year an original gorgeous ty250a found me that had been stored indoors for 30yrs. i took it on as a project instead of having a mid life crisis It originally had 12/53 gearing and i found this a bit too slow to keep up with 40-50mph traffic in the city. Perfect for trials though with tons of low torque and great for practicing wheelies and super slow speed stuff in a few secret spots i know (construction sites). having been struggling with highway speeds, at feetupfun's suggestion i switched to 16/53 and the bike is much happier pottering around at 45mph and the engine isnt working too hard. However, it's a double edged sword as i lost all the ability to practice my trials! its way too fast gearing to even think about having the bike move at walking speed without slipping the clutch. and its much harder (for me) to get the front wheel up...fyi, the original gearing on the bike was 14/53 and the subsequent models (b/c/d/e) all had 13/53. but feetup's recommendation (and he is a giant of knowledge and experience) of 12/53 is where you need to be for trials. as an aside...i dont think a ty250a is really all that stable above 50mph? i went on the highway last week and at 55mph got pretty nervous as the bike seemed to be doing wierd gyroscopic things as the road surface changed...not fun and pretty dangerous. maybe there's something wrong with my bike as i have read on this forum a ty250a can go 80mph but i find that hard to believe from my experience mucking around with gearing but who knows!?... also, i read that someone rode coast to coast US on a ty250a... so i guess anythings possible! anyway, hope that helps...best vibes from a sweltering NYC! johnny

Thanks so much Feet up fun! you are the best as always. Macy's here i come! your kindness to share is always legendary. very best wishes from NY! johnny

Thanks so much Section Swept! really appreciate your input yeah, i took all the auto lube system off and blanked it properly etc interesting for road use you recon 60.1? i know its a trials bike and not built for road use....but it kinda found me so we just coming to a compromise what with being in the city. obviously brooklyn NY not best place to find many trials spots! i had a few i used to use but the cops not so keen. everything is suddenly 'private land'... so trying to make it more a green laner.. but yeah, i hear ya...brakes suck, geometry sucks...just re living my youth and trying to save a piece of history... re the two position air screw you mentioned, the guys on here told me previously that the choke can be used in that way. they would put it on during long road sections and ride through the 'burbles'...had the effect of cooling the engine i learnt. and re the seat gap...i agree, it def seems like it wants to go an inch or two forward but on all the original photos i've seen they all seem to have that gap. i enclose a pic here..unless im mistaken this is how they came? and your bike looks beautiful sir, magnificent work!

Hello dear friends, Johnny here in NYC hoping to get some advice from some of you super knowledgeable folk few things if i may.... 1, When i got the bike it had the long trail seat. i recently scored a really nice original seat and pan which i'm super happy about. however, i didn't realize there was such a big gap between the seat and the tank. i think having the old trail seat sit flush with the tank has maybe discolored/chipped it. Q/ what would be the easiest way for a novice to clean that bit up so it looks a little more aesthetically pleasing or would i need to really re do the whole tank? maybe there is a generic yamaha touch up white? ive attached some pics so you can see what i'm talking about. 2, I am replacing the the top cylinder fins as the original has a cracked/broken fin. Q/ other than a new copper gasket is there anything i should know or look out for. Is it pretty straightforward and i'm presuming it's ok to swap them between bikes? 3, Having set my bike up for more road gearing (at feetup funs suggestion 16/53) i can comfortably sit around 45mph now. I use a pre mixed 50.1 synthetic husqvarna high octane ethanol free fuel (i can get it at work) and the original B7ES plug. Q/ For more of a road riding application should i be using 40.1 and a B8ES? or am i ok where i am...im terrified of blowing the engine up but also dont want to gunk it up with unnecessary oil....i know pre- mix ratios are highly controversial but i just don't feel i know enough myself to make an informed decision. 4, and lastly...Q/ correct/optimum tire pressures for street use? any insights into any of these questions would be gratefully received. Thanks so much for all your help. i learn so much here at trials university. many thanks in advance and bright moments!

Thanks scifi,- when i got the bike the air box hose and lid were in a box of parts, so im assuming someone had taken it off at some point! i've hooked it all back up with a nice new universal filter and 'no toil filter oil' and at feetupfuns suggestion i will refresh the tired TK with a nice new OKO hope the engine didn't got too damaged from the chrome slide chips! Thank you all for being such an amazing forum of knowledge and kindness to share it! best wishes from brooklyn...

Thank you so much as always for such knowledgeable help! New OKO carb it is! i'll put the TK in the box along with all the other stuff ive been replacing on the bike

Hello again friends and greetings from NY. Hope you are all well! sorry to be such a noob...but i was hoping if someone with more expertise and experience would tell me if my slide is worn past the point of no return and needs to be replaced? bike seems to run ok but trying to give it as much TLC as possible while its in my custody! i recall 'feetupfun' saying the TK carby was really awesome and when working as intended is hard to beat, though if the the slide is worn it can run rich. however, im looking at $50 on eebs for a new slide but can get a whole new OKO carb from mid atlantic trials for $100 so not sure which my best option would be.. any ideas/opinions? and also, in my parts manual it says my slide is a #3 but the only one i can find online is a #2.5. would this matter much? many thanks always, johnny

ah! yes of course thanks tony...choke = more fuel not air. my bad. and does that mean if the manual says a #114 main jet when the bike ran the oil pump from new then premix would require like what a 116 or 118 jet or something? this is all new to me jetting and stuff... but exciting. thanks so much for your help and input

wowsers guys, you are all the best! coming here is like going to school for me so thank you senor feetupfun, thank you always for such valuable chunks of knowledge and experience. i totally understand now how the choke would help cool the engine by letting in more air. however, after much trial and error, at your recommendation i stuck with the original 12/53 gearing and just working on super slow stuff. trials all the way! i have the carby set to all the correct specs as are in my manual, 114 main, clip position 4 etc. she's running a beaut now after replacing that o-ring, i feel so lucky and pleased to have her in my care for a while. Trials is so great and just as in music, the slowest stuff is the hardest and most challenging. im utterly rubbish mind you, but getting better in the empty parking lots and industrial estates around Brooklyn! the cops haven't been best pleased at times, but having it all street legal w/ insurance etc really helps. but wow, good to know potentially with right jetting and gearing a ty250 motor could do 80mph and one question, hypothetically, if i were to be riding on a highway at 60mph what size main jet would i need? bigger yeah to let more fuel through? and presumably at higher speeds 40/1 is a much better choice than 50/1 pre mix? not that i'd run her like that, but great to know just in case... really inspired to be learning so much about something new. thanks again to all. best wishes, johnny

sorry to revive an old thread...hope thats ok! but 80 mph!! really?? you kiddin?....im lucky to get 40-45 out of mine, tops!!! (w/14-53) though interesting you talk of the choke as an 'enrichment valve'. does that really work like a booster switch or something at high speeds? i'm curious also when you say you could never overheat the ty250a motor...can you rev the absolute beejezus out of the thing? im just worried about blowing the engine in case i got the pre mix wrong!...(.im at about 45.1....) thanks for any advice, johnny