Author Topic: 2ma conversion  (Read 15902 times)

xracer

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Re: 2ma conversion
« Reply #15 on: February 19, 2014, 11:17:30 PM »
Currently attempting to compile the tyre sizes / weight of Tz Yamaha to see which way the top guys were going with their development prior to the ultimate class being dumped. Its easy to get old stuff ( my era ) but information on the reed valve V twin yams , chassis  and tyre dimension are a mystery to me . From the old stuff it would appear that as the development increased so did the tyre sizes , with a reduction in both weight ( more use of special alloys ) and rake .My old bike had ,on a good day , approximately 55bhp and weight 106kgs dry , probably closer to 130kgs with all fluids ( Japanese specs always a bit out ) a Steering head angle of 24.5 degrees and a wheelbase of 1320mm. The Tzr 2ma is a remarkably close road going version having a dry weight 144kgs ( Japanese specs again ) wheelbase 1375 , and a rake of 26 degrees. My hopes are to remove quite a large amount of the excess weight ( road pipes weight a ton !! ) and with some of the excellent knowledge gained from this forum and other French speaking sites increase the horsepower both midrange and top end . In the end if I can get someway close to the handling , steering and general confidence inspiring grip that my old Tz offered then Ill be a happy man .

tzr-v4

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Re: 2ma conversion
« Reply #16 on: February 19, 2014, 11:50:14 PM »
As I'm living in France so no fancy 3XV or 3MA for me...  >:(

I'll stay with my 2MA or 2XT and not moving to RGV or Aprilia RS...

In fact as as you say :
 - 2MA parts are available and not so expensive
 - well sorted with decent race pipes (like Martin77) not so far from 50-55hp
 - put a TZR125 (4FL) rear wheel or FZR250 3LN in 3.5"x17" and get a sticky 140/70 tire
 - put a FZR250 (3HX1/3HX2/3HX3) front wheel in 2.75"x17" and get a sticky 110/70 tire
 - rise the rear suspension to reduce the steering angle and get more clearance
 - adjust the seat position according to F3 seat
 - ...

For FZR data -> http://www.atelier-nii.com/motorcycles/fzr_data/index.html
Olivier.
TZR250 2MA & 2XT, RD500s et TZR-V4 building...

mboddy

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Re: 2ma conversion
« Reply #17 on: February 20, 2014, 10:51:34 AM »
Most of the changes are attempts to modernize the appearance of the bike

Are you wanting to modernise the appearance of your bike or improve the handling?
It is easy to make the 2MA handle worse. It is one of the few bikes that was designed by a race team.
Lots of good books are available on handling. Some easier to read than others.
A good start is John Robinson's book: http://www.ebay.com.au/itm/Motorcycle-Tuning-Chassis-Robinson-John-Good-Book-/360849342082?pt=Non_Fiction&hash=item54044bfe82&_uhb=1

I race my TZR and so I do not care less what it looks like.
I choose my tyres first and then find wheels to suit.
Best tyres for a track 2MA are 125GP slicks. The best size rims for them are 2.5" and 3.5" and so that is what I use.
My race bike weighs under 100kg dry.
Most important place to save weight is the parts that are not sprung. i.e. wheels, tyres, disks, sprockets, callipers, swing arm, chain, front guard.
If you add weight to any of these then your suspension will have a harder time and the bike will probably handle worse.
On a bike this light you don't need twin disks.

A couple of good suspension books available too.
Wilbers book is a good start: http://www.ridermagazine.com/gear/book-review-motorcycle-suspension-technology-in-detail-3rd-edition.htm/
Or if you want more detail, there is the Race Tech book: http://www.ebay.com.au/itm/NEW-Race-Techs-Motorcycle-Suspension-Bible-by-Lee-Parks-Paperback-Book-English-/151089337569?pt=AU_Non_Fiction_Books_2&hash=item232da054e1&_uhb=1


TZR250 2XT, IKT F3, TDR250, R1-Z

tzr-v4

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Re: 2ma conversion
« Reply #18 on: February 20, 2014, 01:37:45 PM »
I race my TZR and so I do not care less what it looks like.
I choose my tyres first and then find wheels to suit.
Best tyres for a track 2MA are 125GP slicks. The best size rims for them are 2.5" and 3.5" and so that is what I use.
My race bike weighs under 100kg dry.

Agree 100% but if you want to be road legal maybe 3" front is better to get paired good tires.

I went to FZR400R front end with TZR125 3" rim and twin disk but I'm only doing very few track days...
Maybe not the best setup but enough for my riding skills  ;)
Olivier.
TZR250 2MA & 2XT, RD500s et TZR-V4 building...

xracer

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Re: 2ma conversion
« Reply #19 on: February 20, 2014, 05:14:02 PM »
Hi Al
Thank you for your interest and advise. I've no currently plans to return to racing despite several others trying to tempt me . I can however see the benefit of a few track days to assist with set up when the bike is fully completed, always providing I don't bin it . I've yet to read the article regarding suspension etc ,but hope to do so in the not to distant future. I read nearly anything to do with two strokes ( bit of an addiction ) and am amazed at others who take for instance, an RGv250 chassis ,and replace everything bar it's beam frame ,with more modern engines /wheels/ suspension etc and still end up with something considerably better than the original. I have no doubt Mr MBoddy is a very accomplished and talented rider , who's knowledge of the 2ma is considerably greater than mine, But , and correct me if I wrong , are you competing in a class which is governed by very strict regulations on machine modifications. If the class was " open " to mods would you consider different suspension, wheels, discs etc . I know from my days as a competitor than as soon as another competitor got something different that I assumed made him better I wanted it to ( unfortunately you can buy talent ). I'd love to see how a 3vx would compare to a modified 2ma , are all the advancements in chassis , tyres , brakes etc really going in the right direction , don't get me wrong , what you have achieved is amazing and I'm sure you know your stuff I just want to see how it all works out for me 

mboddy

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Re: 2ma conversion
« Reply #20 on: February 21, 2014, 12:15:27 AM »
No worries.
In the class I race the bikes to beat are the Reverse cylinder TZs and the Honda RS125s.
But we also have RGVs etc.
You cannot turn a 2MA into a better TZ than a TZ. You have to keep and build on it's strengths.
The A Grade riders on the RS125s are so fast because they have higher corner speed than anything else.
So we try to make the 2MA more like a RS125 rather than like a TZ250.
So it is short, light and runs GP125 tyres to try to match the 125 corner speeds.

My road bike is a 1990 Yamaha R1-Z 250. It has 17 x 2.75" and 3.5" rims and 110 and 140 tyres.
It feels like it steers like an aircraft carrier compared to the race bike with it's narrower 90 and 120 GP125 tyres.
The R1-Z performance mod that they do in Japan to improve handling is fit 100 and 130 tyres.
That is what my next tyres on the R1-Z will be. And I will also go down to one front disk.

Note that on all my bikes I fit Cartridge emulators in the forks and sort out the springs.
The race bike has a Wilbers 641 shock and a 3LN swing arm which is stiffer and 500gm lighter.
I will post some more pics of the 3LN arm once it is back from getting a few extra mods to allow me to raise the rear a bit more.
Webike Japan sells a nice Carbon front guard that weighs 250gm including mounting bracket.   
TZR250 2XT, IKT F3, TDR250, R1-Z

xracer

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Re: 2ma conversion
« Reply #21 on: February 21, 2014, 01:03:44 AM »
Hi Mark
Repect to anyone even attempting to race a modified road bike against full blown TZ racers . Your right of course in many ways, it has be known for years that the  "top class" racers corner  considerably slower than the 125's .Very interesting to note that you also compete against the reverse cylinder Tz , my conversion will have the complete front and rear of the road going 3ma , wheels ,disc ,forks,yokes ,swing arm , calipers , everything in fact .I will see if ,during the conversation, if I can record details to ascertain where weight is gained or lost . The balance between sprung and unsprung weight is only one of many factors that have to be considered during this process. The weight distribution between front and rear , ride height,  wheelbase etc are fully all adjustable and will require time . Your knowledge is very helpful, many thanks

mboddy

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Re: 2ma conversion
« Reply #22 on: February 21, 2014, 02:38:40 AM »
Thanks.
It will be good to see what it all weighs.
I currently have 51% weight bais to the rear when dry. This will only get worse when the alloy tank goes on.
Need a bit more height at the rear too.
TZR250 2XT, IKT F3, TDR250, R1-Z

xracer

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Re: 2ma conversion
« Reply #23 on: February 21, 2014, 03:34:35 AM »
Balance and especially front end feel are such personal things , I remember reading that Rossi kept the same wheelbase for the whole season once he'd found his set up , adjusting the gearing by changing internal gears , nice for some !!!

old smoker

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Re: 2ma conversion
« Reply #24 on: February 21, 2014, 10:23:52 AM »
Hi Guys I have been following Marks lead somewhat , he has done everything correct on his 2ma , as far as I am concerned.
I also have a race 2ma , not quite as developed as Marks , but any more and it will take a lot of time and parts to keep it going,
that  effort will mainly be directed at the TZ 350 F.
If I started again I would go straight for 2.5 " front and 3.5" rear rims with the 125 slicks, drop the forks as far as possible,only hike the rear if ground clearance is needed,find some "good" pipes,one day I will measure my J pipes,Mark was going to post his dimentions also I believe,get a good head job ,with orings ,try C.B.Tuning,an adjustable power valve controller ,two stroke race lab, adjust the exhaust port to the chamber dia , cut down the power valve, Mark has some big  lectron carbs , if I go this way I will try Mikunis as they are way cheaper.
And finally a  total loss ignition, Mark and I have HPI , there is some talk about the integrety of their stators ,mine are OK ,touch wood,and I don,t believe Mark has had any trouble.
Some people are using programmable ignitions , but unless I am mistaken all these use the std flywheel which you need to ditch,therefore,a total loss is the only way to go.
Finally get out there and ride it , the more you do the faster you and the bike will go , the limiting factor of these machines is the pilot. 
old smoker

mboddy

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Re: 2ma conversion
« Reply #25 on: February 21, 2014, 10:46:29 AM »
My TZ350F has to wait until next year.
Sorry, but I forgot about the pipe dimensions. Should get to look at it next week.
My Two Stroke Race Lab modded YPVS controller died just before last race meeting - no fault of theirs
- but I will fit a Zeeltronic PPV-RZ2 when I have funds again.
The HPI Ignitions have been totally reliable in the 3 years that I have had them on my TDR and TZR.
TZR250 2XT, IKT F3, TDR250, R1-Z

xracer

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Re: 2ma conversion
« Reply #26 on: February 21, 2014, 02:19:55 PM »
Used 38mm lectron powerjets myself on my old tz , obviously in those days no airbox , we use to grind the taper down  towards the threaded bit so it could be drop further into the carb body, helped with mid range from low gear corners , ( no reeds valves then , although I had looked  at the possibility of making my own -but as usual ,lack of funds prevented it ,)

xracer

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Re: 2ma conversion
« Reply #27 on: February 21, 2014, 05:25:14 PM »
Hi Bngt
Slowly working away , not progressing as quick as I would like ,but hey that's life. Here's a few photo's of my solution to the rear spindle issue . I want to keep the 3ma bearing sizes as that's what Yamaha intended and they know better than me. I've decided to sleeve the 2ma spindle with a 20mm stainless tube, internal bore 16mm, 2mm thick . The end cap inner washer is on order, 46mm outer diameter 16mm hole , 2mm thick .Just need the swing arm machine from 214mm to 200mm and then I'll be happy. Well almost, its only the beginning !!!

Jim Lyon

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Re: 2ma conversion
« Reply #28 on: February 24, 2014, 04:21:17 PM »
<SNIPPED>
 As my name suggest I have in the past competed in many road and short circuit events ,including the NW200 and Manx GP , I am aware it will take time but that is all part of the challenge .

 Thanks for that! It always helps me to understand others better if I know where they're coming from. :) - For my part, I'm a Scots ex RAF aircraft engineering technician ( airframes ). So I guess I tend to give due emphasis to engineering rigour. I'm also trying to be a B.A.B.,  (having been in a bikeless wilderness for FAR too long, thanks to my "X" preferring divorce to facing up to her toxic childhood ). While I feel my theory is fairly reasonable, I must confess to being lacking in recent practical experience ( the last bike I had much to do with was my Beckett tuned LC350 ). So if I ever come over as being "intense" or persistent, it's only me trying to play "catch up"- deep sigh ! - :)
YAMAHA RIDERS GO IN DEEPER AND COME OUT HARDER

Jim Lyon

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Re: 2ma conversion
« Reply #29 on: February 24, 2014, 04:27:37 PM »
 Part 2 - USD FORK CONVERSIONS

 For those of you who've read Part 1 you'll have worked out that I think that whoever designed the chassis of the RGV250 series produced something that, while it may have been fashionable, & even  impressed those who didn't know better, I can't help feeling that they missed the mark ( of achieving the optimum balance ). Now, I've seen plenty of pictures of bikes on the RD Yamaha forum, particularly of 350 YPVS with Suzuki RGV250 front & rear ends grafted on, & I
accept that's probably better as it's more modern, & the parts were available, but just because something is "do-able" that's not to say we can't do better! - Tied in with my comment in Part 1 about the best way to improve the RGV250 is to drop an RG500 engine into the chassis, I also think that given the size & weight of the RGV250 forks, I'd be reluctant to use them on anything less than a 500-4.
  While many 2MA production racers were quite happy to race on the stock 2MA forks, it's difficult not to be seduced into fitting more modern USD forks on the 2MA series.  But what to use? Given that the USD forks off the SP version of the 3MA & 3XV seem a tempting source, but I suggest that, like the forks on the RGV250, they're just too heavy ( & while in Part 1 I suggested that such concepts as [un] sprung weight ratio & polar moments of inertia, etc ARE important, I'm also well aware that, in our positions, more carefully selecting components in order to reduce weight can not only improve handling & road holding, but less weight also equals FREE horsepower ! ) e.g. comparing the forks & yokes of a SZR660 ( made by Paioli & similar to SP USD forks, etc) with those of a R/RS, the latter are approx 2.5 + lbs lighter, both with clip ons ( To put that in perspective, the R/RS USD forks & yokes are 4 lbs heavier than the stock RWU 2MA forks & yokes. And while I prefer to make a bike lighter, I also accept that, if we need to add weight to a chassis, then we should @ least try to get improved strength & performance in return, & if we have to add weight anywhere on a chassis, I'd rather put it on the front end in order to make the front tyre grip better.
As the SZR660 USD forks that I mentioned seem to be fairly typical of RGV/SP forks, then we can expect them to be around 2.5 lbs heavier than the R/RS forks
& yokes ( both of those with clip ons ).
So it would seem that again the R/RS forks are closer to the optimum.
   As a suitable source of USD forks, I initially considered the R/RS range but there are a couple of problems:-

1) The R/RS range only has externally adjustable preload, but not externally adjustable compression & rebound damping, which the SP series has. This problem can be overcome by upgrading R/RS USD forks with a cartridge type damper kit. If you were to get that from e.g. Maxton, then if you also upgrade your rear shock with a Maxton one, then you have a chance of having your front & rear suspension not only properly balanced, but set up for your own weight & preferences.

2) So, while the R/RS series of USD forks are light, & can have a meaningful upgrade by means of a damper cartridge kit that also allows external adjustment of compression & rebound damping, they do come up short - quite literally, by about 2".  To be precise, measuring up a 2MA front end from the top of the top yoke to the middle of the front spindle is 740 m.m. & the equivalent on the R/RS is 690 m.m., i.e. 50 m.m. shorter ( measuring it this way allows me to ignore the different clip on positions of both sets of forks. N.B. these forks were both measured in an UNcompressed condition ).
  Now I've heard some people say that the 2MA steers a little slow, so that shouldn't be a problem. While I'm not going to get sucked into an argument aboutother people's subjectivities & what constitutes "good" steering, I'll mention another experience I had with my LC350 which hopefully will give some perspective.
I replaced the original LC350 tyres with a set of Dunlop K181s, 3.60" front & 4.10" rear which were quite good in their day, except that it gave me an understeer problem e.g. to the extent that riding on roundabouts was forcing me to take a line like a "three penny bit" ( i.e. a sereies of short straight lines, rather than a smooth curve ).
After some fiddling around I settled on droppimg the yokes down the legs by about 4-5 m.m. ( & an extra 2 psi in the front tyre ) i.e. about 1/10 th of how short the R/RS forks are compared with those of the 2MA. Whilst fiddling around with these adjustments, I did learn that if you drop the yokes too far down the forks, it doesn't take too much to reach a point where the bike suddenly starts to behave as if the frame has developed an extra hinge in the middle - somewhat less than entirely pleasant. From that, I'm concerned that having forks that are 50 m.m. shorter than stock are going to cause this problem.
 So, while it's possible to get round this problem by accepting the extra expense of a "one off" top yoke made that's cranked or "gull wing" so that the middle can sit on the steering head but still reach down 50 m.m. to the top of the fork leg ( that's having the fork leg flush with the top of the top yoke, which may be OK if you end up with an understeer condition, then you can always slide the fork leg up through the yoke to correct it, BUT if you have an OVERsteer condition &  wish to  correct that by sliding the forks down/yokes up, then you're screwed with this set up. So presumably you'd have to try & adjust the ride height @ the rear?
  A further consideration is that while, for road use, I don't mind moving the clip ons down to immediately under the top yoke, I'm not so sure that I want to drop them down a further 50 m.m. IF they'll clear the fairing?
  Given this, I'm now wondering whether we should start looking round for another possible source of lightweight ( by which I mean the diameter of the lower chromed part @ the bottom of the leg is 39 m.m. )  USD forks to fit the 1KT/2MA/2XT series of TZRs?
  Anyway, that's as far as I've got on that problem ( of finding suitable USD forks for a 2MA, etc ), so has anybody else got some input to progress this further?
« Last Edit: February 26, 2014, 08:38:38 PM by Jim Lyon »
YAMAHA RIDERS GO IN DEEPER AND COME OUT HARDER