Author Topic: 3MA trackbike project  (Read 36194 times)

casal-fan

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Re: 3MA trackbike project
« Reply #15 on: October 17, 2014, 09:14:49 PM »
Time to start kicking some live in this thread.
Started dissasembly today... OMG, itīs even worst then the 3XV, wires and hoses all over ;D
Got the pipes, radiator, airbox out... and when I got to the carbs, and saw all the hoses... I went home ;D
Continuing dissasembly tomorrow, Iīll take some fotos.


casal-fan

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Re: 3MA trackbike project
« Reply #16 on: October 18, 2014, 10:42:49 PM »
So, here it goes.
Dissasembly started of course with the tank, and seat fairing. After that I came to the pipes.

Pic.1 I was interested in having a better look at the hole muffler mekanism... I did, and surprise surprise... a pseudo tuner just like me had been at work ;D Pipes still have the header ring fitted.

Pic.2 After that, the interest came to the airbox, maybe there had been some attempts at making the bike faster there...my guess was Wright, airfilter from kitchen exhaust apparatus. Pic2

Pic.3 Now, I could have a grasp at the powerplant... just.

Pic.4/5 Was of course interested in having a look at the plugs... they were lanmower plugs. After struggling ― an hour to unplug the carbs I took them out, quick look, all seems OK. Just one airscrew is screwed, canīt get it out, because its all mushed.

casal-fan

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Re: 3MA trackbike project
« Reply #17 on: October 18, 2014, 11:05:01 PM »
Pic.1 Very important moment, tapping gearbox oil. It can say a lot of Things. Oil was clear, absolutly no shinny Things running around, very good.

Pic.2 Finally wrestled the engine out of the frame. Having had my "engine wrestling" kicks with 125ccs lately... this one is quite heavy.

Pic.3/4  Meaning was I should keep on with dissasembly of ancilleries as breaks and so on... but with the engine on the bench, I couldnīt resist taking some Measurements.
Started with squish. All this Measurements will help me with engine setup later on. Squish measured at 6 points, 4 in one cylinder and 2 on the other. Minor Measurement was 1.1mm, the largest number found was 1.2mm

Pic.5/6 Couldnīt stop investigating, head had to come of... it was tight. Pistons look good, very good, they seem to reinforce the info on the dash, Only 14000km. Deck clearence itīs not zero, a 0.2mm catches a bit... but itīs VERY close to zero.





« Last Edit: October 18, 2014, 11:07:59 PM by casal-fan »

casal-fan

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Re: 3MA trackbike project
« Reply #18 on: October 18, 2014, 11:21:29 PM »
Pic.1/2/3  Head back on, and it was time to get scrubbing... and it went on for a loooong time. The most boring in any rebuild, cleaning.
Result came nice though. Not as new, but a lot better then it was before.

Pic. 4  Plan for NeXT time is to go on with dissasembly, so I can get to the rolling chassi stage. Clean and rebuild what it needs to be rebuild such as brakes, suspension etc... by then I should have saved enough time ;D to get some new rubber, and then the process gets reversed - assembly.
Still donīt know how setup will be... cylinders, exhaust, all the Electronics... right now Iīm thinking simplicity, this will be a track bike only. Has no tittle, and in my country Theres not a chance in a million years this could get plated.

Also looking forward for suspension rebuild and finding out what Iīll do with that. Forks with max. preload are showing 31mm rider sag already, and that was before breakfast... time will say

Louis

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Re: 3MA trackbike project
« Reply #19 on: October 19, 2014, 11:46:50 AM »
Quote
Started with squish. All this Measurements will help me with engine setup later on. Squish measured at 6 points, 4 in one cylinder and 2 on the other. Minor Measurement was 1.1mm, the largest number found was 1.2
Yes, most off them are just a touch above the 1mm :)

A the stock head volume is already close to a 11cc, if you want to skim the head to go closer on the squish you need to open the bowl as you go quick at ten or under it. So be careful if you are going that route.

Quote
Still donīt know how setup will be... cylinders, exhaust, all the Electronics... right now Iīm thinking simplicity, this will be a track bike only
Yes, that is what I have learned within the years to :)
Keeping it as simple as possible, that is exactly what my track bike three is gona to be.

You are going great, think you will love her in the end ;D
King off all twostrokes ''TZR250 3MA''

casal-fan

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Re: 3MA trackbike project
« Reply #20 on: October 19, 2014, 12:35:47 PM »
Hi Louis thanks for the reply, and encoragement. Nice to know that people are looking over my shoulder and will probably say something if I do something drastically bad ;D

Louis, right now, when I think simple... I mean ALL Electronic aids off, and ALL fancy gismos off.
Fixed ignition curve, no VAJ, no TPS, no balance tubes. Just plain 2stroke engine... and take it from there. It would also be interesting to dokument how a 3MA runs like that. Havenīt found info on anyone that has tryed that.
But for this to be possible, you have to find out, what the RPM numbers on the igntion advance map are ;D

The head will be O-ringed. I measured the head gasket to be 0.3mm. O-ring conversion would bring squish down to 0.8-0.9mm
11cc gives a comp.ratio about 1:12.4
Without 0.74cc wich is the volume the gasket occupies, comp. ratio comes up to about 1:13.2 wich I belive still is a safe number for say 98 or aral 102.
Does 1:13.2 on a 3MA sound too high for youguys?

Louis

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Re: 3MA trackbike project
« Reply #21 on: October 19, 2014, 01:19:56 PM »
Quote
I mean ALL Electronic aids off, and ALL fancy gismos off. Fixed ignition curve, no VAJ, no TPS, no balance tubes. Just plain 2stroke engine... and take it from there.

That was completely my first intension with my trackbike three project to :)

Also found a ignition system that could do the trick.
http://www.ebay.co.uk/itm/yamaha-250-350-400-rd-lc-rdlc-tz-banshee-complete-new-ignition-racing-/181539245947?pt=UK_Motorcycle_Parts_13&hash=item2a44950f7b

Its a very clean ignition system (no magnet to see) no battery needed, just a push and off you go.
The 3MA1 flywheel does have the same tapper cone as a RD350, so this system should fit.

But i have delayed it because so much thinks need to be done for this project, and have so much thinks going on.
First now is to make it ready, those thinks can be ad later. ;)

Quote
Does 1:13.2 on a 3MA sound too high for youguys?
Don't think its to high, but the question could be. How much do you gain?

Higher compression, tighter squish will probably gain you some HP's but will it make the engine reliable?

I can imagine if you are racing on the last 0,1 seconds you can use all the hp's you can get.
But for enjoying your bike, reliability is something you need :o (certainly with a 3MA)

Think more Hp's can easily be gained by removing the airbox completely and go to fully open carbs.
(like the TZ250 3TC and 3LC)

This is something I will be testing next year on my road bike. (remove airbox, adjust jetting and see what it brinks)

Just a thought off me. You free to do what you want to do of course ;D
King off all twostrokes ''TZR250 3MA''

casal-fan

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Re: 3MA trackbike project
« Reply #22 on: October 19, 2014, 04:43:43 PM »
Louis, that ignition costs as much as the rebuild budget on this bike ;D
It would be nice to try, but Iīm sticking with the stock ignition box... lots of Things to play with there ;D
Its just a shame that nobody found out the correct RPM for the ignition curves ;D

About reliability... well, if I manage to get the bike dialed up correctly, I do tops 8-10 trackdays a year and I have 2 more bikes to ride at the track.
A trackday has about 1― hours of riding at about an average of 100km/k. Even if I use the bike for 5 trackdays, in one year (wich I wont), that would be 7― hours on the bike a year, and only 730km. And thats a bright perspective because I usually crash or melt the engine long before that... or crash because I melt the engine ;D Riding fast is still an ungoing project for me...
But, itīs just to say that with these timeframe numbers, if the engine is setup correctly even for a bit more harder specs, it will still have A LOT of time between rebuilds. A road bike is of course VERY different.

I would love to try settings without airbox... problem is noise. In Scandinavia pretty much max. 95dB is std. for the tracks... and the 3MA is not the best exemple of a quiet bike ;D

Look forward to see the ideas on your trackbike3... I personally am very excited about working on my bike.
Itīs all good, as long as someone trys different Things, bad or good, everybody learns and there is a contribution to keeping the 2strokes going!

casal-fan

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Re: 3MA trackbike project
« Reply #23 on: October 21, 2014, 12:27:37 AM »
Interesting picture.
Added a few more curves for comparison.
250GP curve is "pushed back" 2000RPM, so peak power would be at 11000RPM
Wonder how 0-1/8 curve would work with a pipe toping at 11000rpm or even just a tad over...

Louis

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Re: 3MA trackbike project
« Reply #24 on: October 21, 2014, 09:51:19 PM »
The 0-1/8 is certainly not bad for a 89 ignition curve, it has potential. ;)

Making a pipes for the 10.750 a 11.000 RPM range is on my to do list. Just for testing that theory
King off all twostrokes ''TZR250 3MA''

Edd

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Re: 3MA trackbike project
« Reply #25 on: October 22, 2014, 10:35:13 AM »
Hi

Read the last few posts so I might have miss some of the detail. Cant help to think you are going down my street and I have a lot of issues to sort and to deal with but I am getting there ;D. I run a compresion of around 1:11 with new squish I have a compression of around 1:12. (These are guestimates) havent calculated the numbers my squish measured was 0.76mm and with head gasket back in 0.89mm now. I think I am with Louis on a squish of about 0.9 to 0.95 but school is not out on this verdict. I am still experimenting on this ;).

Will love to see your results. I run the tz 250 curve but have moved it down by two degrees across the rev range. I still have carb issues to sort in my view.

Eddie
TZR 250 3MA1
TZR 250 3XV RS(Track)
TZR 250 1KT
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RZ 350 Hybrid
YZ 250
RD 350 Hybrid

casal-fan

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Re: 3MA trackbike project
« Reply #26 on: October 22, 2014, 10:57:45 PM »
Jes, Edd... going pretty much down your road, I know. Not a case of "copycatting" though. I just think that we both are planning to use our bikes in a similar maner, so itīs not that odd that the final setup will be similar.
I have no previous experience with the 3MA... I only know what it has been written here.
Since there seens to be so many hick-ups on setup with all the management aids in this engine, I am inclined to remove them all, treat it as a plain simple 2stroke, and take it from there... if it doesnīt work, well... then it doesnīt work ;D
As I wrote before, this bike will not be used for road riding, track riding is different, itīs just open or closed throttle with a bit maintainence throttle here and there ;D.
Thanks for the squish info, appreciate it.

Louis, I just found a post by you, where you writte about the 0 curve in association with a higher RPM pipe. I also belive this would be interesting to experiment, specialy with the chance of retarding the curve 2-3 degrees by use the "pickup move" you invented.
I tryed to measure the 00 pipe today. It is quite hard because of the curvy and box shape. I measured diameters in intervals of 10cm with a line, and converted the "straight line" measurement to perimeter measurements. Not very accurate Iīm sure, but the results are not what I expected.........

More to come soon...

Edd

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Re: 3MA trackbike project
« Reply #27 on: October 23, 2014, 07:23:13 AM »
Like to see what the standard cdi will do with those mods, I have a zeel fitted and that is also maybe another tumbling block. Remember dont remove the neutral switch and wire when you do your mods with the standard cdi if neutral wire is not connected no spark with std cdi.

Edd
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TZR 250 3XV RS(Track)
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TZ 250 3YL
RZ 350 Hybrid
YZ 250
RD 350 Hybrid

casal-fan

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Re: 3MA trackbike project
« Reply #28 on: October 23, 2014, 10:40:27 PM »
Found some time to put the pipe measurements I took together, and have a good look.
Have to emphasize that these measurements are simply the ones I was able to take, to the best of my ability.
By no means I am 100% sure these are the real dimensions of the pipe.
The header for instance... it is very hard to fing the precise spot where the tapper begings to deepen, and I just used my best judgement and so on...
Still, I am confident the dimensions are not tottaly off, and can give a good pointer.

Lenghts: cylinder-60mm / header-330mm / divergent cone-300mm / belly-100mm / convergent cone-220mm(???)

But, the real surprise was that these dimensions are close, to what the latest pipe building softwares spit out when asked to design a good pipe that tops at 10000rpm, combined with 195* exhaust duration...
Just looking at them... would never have guessed.

Next step, try to find out how to best modify these pipes, so they can can mimic a good design for a bit more top power RPM, and just a tad higher exhaust timing.
If some of youguys has measured the 00 pipes and has some comments on the measurements I took, Iīd appreciate it.
« Last Edit: October 26, 2014, 08:56:57 PM by casal-fan »

Louis

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Re: 3MA trackbike project
« Reply #29 on: October 25, 2014, 09:00:10 AM »
Not bad designed for a 89 bike isn't it :)

It is certainly difficult to measure the diameters as the material is thick and probably the pipe has some internal plate work to inside.
The manual says this 34 - 108 - 23


A stock pipe doesn't perform badly, in fact I think it will be difficult to outperform it by making a new pipe designed to peek at 10.000rpm





King off all twostrokes ''TZR250 3MA''