BIMOTA GT1 Project

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wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

sportston wrote:
wolfgangh wrote: I just cant stand those ever oil leaking spring mounted race pipes, it is just not adequate for this project. It needs to be clean.
Here, here! I find it hard to understand how you can get consistent back pressure when they are always leaking.
I am quite concerned that you won't be able to ride the bike on the road in Austria. Have you considered putting your baby up for a foreign adoption?
It wouldn't be too difficult to get it road registered in the UK..... :up: if you required financial recompense I could always sell my wife or rob a bank. :ssh:
Please send me a picture of your wife but dont show her mine. Would she consider moving to Austria?
sportston
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Re: BIMOTA GT1 Project

Post by sportston »

Unfortunately she doesn't speak German. But here is a pic anyway.
Image
sportston
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Re: BIMOTA GT1 Project

Post by sportston »

Is the Lancia in the background yours?
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busa1300
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Re: BIMOTA GT1 Project

Post by busa1300 »

That bike is truly a work of art.....beautiful purposeful art.
MY TWO STROKE ADDICTION
TZR250SP 3XV2...
RS 250 Cup bike
RGV VJ21 L
RGV VJ22 FL
RGV VJ23 T
RZ 350
GT 750 J....sold.....
SX-R 800
KD 80
JR 50
RZV 500 R
https://www.youtube.com/@wedgehorsepower9869/videos
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

sportston wrote:Is the Lancia in the background yours?
No the Lancia is not mine, unfortunately. I like that car too, but this one is in a terrible condition.
sportston
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Re: BIMOTA GT1 Project

Post by sportston »

wolfgangh wrote:
sportston wrote:Is the Lancia in the background yours?
No the Lancia is not mine, unfortunately. I like that car too, but this one is in a terrible condition.
Not surprising, they were known to rust very quickly.
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

My project is finished, I already did a short test run. She is weak off idle ( from a standstill) as a result of aggressive port timing and close-ratio gearbox. I may chose shorter secondary transmission ratio or go back to a more streetable cylinde port timing, I have some spare barrels.
Overall, I am more than happy with the result.

https://youtu.be/82bmIdRWD7c
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Alan H
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Re: BIMOTA GT1 Project

Post by Alan H »

Excellent - and sounds good too. :up: :up:
Think of how stupid the average person is, then realise that half of them are more stupid than that.
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

I wonder which sound you were listening to - I only hear the birds and the wind blowing into the microphone
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

Hello Alan
here is some sound now

https://youtu.be/uxcf-r0onqU
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Alan H
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Re: BIMOTA GT1 Project

Post by Alan H »

Last one doesn't work but this does.
https://m.youtube.com/watch?v=rPUDP_pjTKw" onclick="window.open(this.href);return false;
Think of how stupid the average person is, then realise that half of them are more stupid than that.
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

Sorry, I meant this video (it was published as private first):

https://youtu.be/uxcf-r0onqU
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tz375
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Re: BIMOTA GT1 Project

Post by tz375 »

The bike is absolutely gorgeous, but it sounds flat. Almost like it was running on two cylinders.

How is the jetting at idle and off idle? What did you set the timing to? I don't remember what carbs and ignition are fitted but the idle jets and needle position may need to be richer than you might expect. If the ignition is really retarded to be safe at high speeds, that might account for it. I would expect it to be a lot crisper than that.
wolfgangh
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Re: BIMOTA GT1 Project

Post by wolfgangh »

Hello tz375,
I can confirm it is really flat off idle. I have VM34 aftermarket carbs, #30 pilots, #210 mains, P-8 needle jets and needle in 3. groove ( dont remember needle size). Accent ignition with stock timing at 24 deg. JEMCO pipes with larger self-made silencers ( combination of absorption and reflection section).
i have purchased the whole engine from a guy in UK long ago who had ported the cylinders to TR750 spec, when I measured it it is even slightly more radical ( close to 200 deg exhaust timing). Close-ratio gearbox.

I have not started to dial in the carbs since It is still too cold here in Austria. Currently I cannot tell which direction to go, leaner or richer, since I only drove few rounds around my garage. Once moving and above 2500 rpm it accelerates OK but not brutal. I cant rev higher since the longest straight in my yard is 60 m....
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tz375
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Re: BIMOTA GT1 Project

Post by tz375 »

24 degrees is fine to start with, but you may want a little less for higher revs to avoid melting pistons

Try 35 or even #40 pilot jets and see if that makes a difference. I went from P-4 to Q-2 on a similar set up, but not so much exhaust duration. 200degrees exhaust duration is quite a a lot.

When you say the JEMCo's have modified mufflers, could that be an issue? You can test that by pulling the baffles for a test run. It will be noisy, but if it fixes things, the mufflers can be redesigned - again. You could try aluminum outer sleeves for less noise. It typically doen't resonate as much and makes the exhaust more mellow.

With such a long duration exhaust, I hope that you raised compression to compensate. Mine has around 165psi cold compression.
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