Author Topic: 2T supermono  (Read 2565 times)

ybk

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Re: 2T supermono
« Reply #15 on: January 16, 2019, 01:16:40 AM »
Nice to have the parts coming in :)

Have you tried DHL for the shock from Japan? They will probably still ship it.

casal-fan

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Re: 2T supermono
« Reply #16 on: January 16, 2019, 08:49:07 AM »
Nice to have the parts coming in :)

Have you tried DHL for the shock from Japan? They will probably still ship it.

Hej Ybk
Thing is that I have used the same pusher from Japan for many years.
He´s expensive, but provides a really good service.
If he says no, then its no... risking would be asking for trouble.

Also, shock price from Japan + shipping costs + a good rebuild would probably cost 3/4 of what a new topline wilbers f. instance would cost.
Also, YSS importer here in Denmark is a well known 2stroke guy. Even if YSS still only has a "road biased" shock for the 3XV, they offer a line of more advanced track biased products for other bikes. Since they already cracked the measurements on the shock body, it should not be impossible to provide this more advanced shock for the 3XV if the importer pushes a bit... I think...

We´ll see, I have the std. one for mock-up, I´ll take a decision on rear shock further down the line.

Cheers
Rui

41juergen

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Re: 2T supermono
« Reply #17 on: January 16, 2019, 09:14:01 AM »
Hi Rui, interesting change within your project route, but I fully understand and agree on your arguments...  :D
As you have seen I have worked already with the 3XV parts in my 4FL project and the only thing to mention is that you need to make up your ming which engine you want use and how to mount that into the frame. I think you have seen the "special" setup have a engine mount bolt going through the swing arm, so that would may be not work with cutting off the 3XV swing arm. Also have in mind that the 4FL frame looks very similar (and is in most things), but the swing arm pivot position is different to the 3XV frame (because of the engine mount and therfore the longer swing arm)...
I had the plan to get a 3MA swing arm into the 4FL frame, but that would mean that I have to extent the 3MA swing arm to get the same wheel space as the stock swing arm defines...
But that project will be (as always) a very interesting, so keep us updated.  ;)
Juergen

casal-fan

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Re: 2T supermono
« Reply #18 on: January 16, 2019, 03:54:02 PM »
Hi Juergen

I´ve looked with interess at the latest developments on your 4FL. Looks good, really good (-P)

You caught me on the swingarm pivot being positioned more upfront on the 4FL frame.
I´ll dobble tjek, but even if the pivot in the 4DL frame looks to be further upfront - the measurements I took, points to the longer swingarm being the one that gives the extra wheelbase on the 4FL...
Will have to tjek that... not that 10-15mm will make such a difference can be corrected if wanted with an ekstra link on the chain...

About mounting the engine, well, cutting on a 3XV swingarm has been done.
http://pure2strokespirit.net/forums/index.php?topic=1353.45

While this would work, attaching an engine to a swingarm bolt is not the greatest of ideas... cheap and practical, but the vibrations will interfeer a lot with the shock.
Some other factors - like the use of bigger chain sprocket on the front, moves me towards fabricating an engine mount that will attach to the chassis... not a big problem (I think... wish, maybe, who knows ;D)

Thanks for the answers, always nice to have some constructive criticism as well, helps one stay sharp (-P)
Thanks!
« Last Edit: January 16, 2019, 04:01:30 PM by casal-fan »

casal-fan

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Re: 2T supermono
« Reply #19 on: January 17, 2019, 02:06:01 PM »
I´ll be da**ed ;D
Juergen, hats of for your sharp eyes.

Its gonna be a short wheel base bike ;D

5KE - 1342
3XV - 1340
4DP - 1328
4FL/3XV - 1315
4JT - 1242

13mm shorter wheelbase then 4DP - all dependent on the adjusteres, there is at least 10mm one or the other way...
That is a ramping 60mm shorter wheel base in relation the the earlyer thought cagiva mito chassis...
Interesting enough, I considered a 4TJ frame, and a metrakit preGP framebut a lot of IFs came with that consideration, especially engine fitment...

I kind of like this... compact, must be a good thing.



« Last Edit: January 18, 2019, 10:47:01 AM by casal-fan »

41juergen

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Re: 2T supermono
« Reply #20 on: January 18, 2019, 09:30:40 AM »
Thank's Rui for summerizing the data, I was not really aware of the differences... Interesting to see the the 5KE longer wheel base, I think the YAM engineers were looking for more grip at the rear...
When I rode my "3FL" first time (with stock rear shock) it felt a bit slow in the corners when turning in. So then I tried to fit a 3XV R shock (which I had laying around after my conversion to the SP shock) which is a bit longer and finally gave me the same distance from the rear axle to a fixed point at the rear frame as I have on my 3XV (with a 5mm spacer at the rear top mount) and the bike felt dramatically better, very close to my 3XV....

casal-fan

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Re: 2T supermono
« Reply #21 on: January 23, 2019, 09:10:37 PM »
Good info there Juergen (-P) Thanks

Moving a little bit forwards...
More measurements, this time, engine related.
These done the right way. The coin measuring methode for port width, had to be a biiiig one to measure exhaust port... its biiiiig :))


41juergen

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Re: 2T supermono
« Reply #22 on: January 24, 2019, 09:13:10 AM »
That looks big  ;D But from spotting the ex can be a bit higher, right? And finally it's a ll about the balance between blowdown and transfer TA's.... Looks like a very interesting project, BTW: do you use EngMod to get the "magic" numbers?

Martin77

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Re: 2T supermono
« Reply #23 on: January 24, 2019, 01:28:46 PM »
Modelling the engine is something I was going to do for him, but as he will have to measure everything, it may take a while to work out. I think the engine is proven, it's just for our curiosity that we will have a go.

41juergen

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Re: 2T supermono
« Reply #24 on: January 24, 2019, 02:01:12 PM »
got it, sounds good!

casal-fan

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Re: 2T supermono
« Reply #25 on: January 24, 2019, 09:50:54 PM »
Yes, Martin is helping with running the data through engmod.
As Martin says, the engine is proven. Analysing the data will be more an exercise for analysing engmod accuracy.

This engine with the data (pipe, ignition, etc) I got from the manufactor of the kit should be good for a tad over 65 RWBHP.

It would be very interestning analysing the dynamics aspects that engmod shows, as well as perhaps improving a bit here or there by modding the pipe a bit or so...
Martin will also be comissioned the pipe, should he choose to accept this mission ;D

A dyno chart from a Viper racing prepared cr250 honda, more or less the same top power, but the wiwa should be stronger from below and have a bit more overrev


casal-fan

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Re: 2T supermono
« Reply #26 on: January 28, 2019, 11:26:49 PM »
More important parts.
Front end, f.pegs, and other chassi related items, complete suspension Linkage included wich is nice, as std. As possible, even with the Shorter wheel base.
Same for front tray, plug/play.
Besides saving time and Work, its a proven recipe.
Front braking system arriving Soon... Exciting (-P)

casal-fan

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Re: 2T supermono
« Reply #27 on: March 17, 2019, 10:53:10 AM »
Another page to the parts gathering log book.

Always good offers when kart teams decide to upgrade.
Now, There are some dedicated 2stroke datalogging systems.
Older good functional systems that more or less can do the same, they Sell quite cheap.
Complet michron 3 with egt, temp, rpm, speed and laptime beacon aquired from a kart team.
IT Will look good I think(-P)