Author Topic: my 4FL...  (Read 1896 times)

Mick

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Re: my 4FL...
« Reply #15 on: December 01, 2017, 02:00:26 PM »
It might be a case of having the wrong pump fitted to the clutch cover..The earlier electric start 3mb00 engines pump location is different to the later version fitted to 4fl/4hw and the later DT125r..
In picture upper casing is from earlier models and below that later models. The later one just uses a flat plastic cover over the top..
Twitchy left hand rider ;-)


Martin77

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Re: my 4FL...
« Reply #16 on: December 01, 2017, 04:57:29 PM »
I didn't know that.. maybe there was an interim year where the 4FL didn't have the updated clutch cover? Because mine is certainly all yamaha, it has a special little cable holder where the cable goes on. It was only when the later DT came out they thought they'd better make a proper cover..

41juergen

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Re: my 4FL...
« Reply #17 on: December 01, 2017, 06:57:07 PM »
Perfekt guys, thank's a lot for all the help. Exactly that's what I found too. I have got a spare engine from a DT125. It has the later clutch cover with the flat oil pump cover with a 4FL pump fitted. I will take that for my project..
cheers
Juergen

41juergen

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Re: my 4FL...
« Reply #18 on: February 13, 2018, 04:47:27 PM »
Just another question: what is the largest front sprocket a 4FL can be mounted on? Is it 17 teeth or does even 20 teeth fit? And is there any difference between the model years or to the DT bikes?
cheers
Juergen
« Last Edit: February 13, 2018, 04:57:19 PM by 41juergen »

Louis

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Re: my 4FL...
« Reply #19 on: February 18, 2018, 03:11:11 PM »
Hello Juergen,

To be honest I don't know.

Looking to the space between chain and housing at the front sprocket think 20 should be doable (if they sell it)
But way so large?

Louis
King off all twostrokes ''TZR250 3MA''

41juergen

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Re: my 4FL...
« Reply #20 on: February 19, 2018, 02:10:59 PM »
Hi Louis, thank's for the feedback. Last Saturday I got a 17 and a 20 teeth one and yes, it looks like it fits!
The reason is that I need to gear up to approx. 190 km/h for that engine....  :D (okay, assuming that I really can get about 45+ HP out of it).
cheers
Juergen

41juergen

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Re: my 4FL...
« Reply #21 on: February 19, 2018, 05:20:12 PM »
Here is an update of the last month work. The frame and the swing arm was painted like the 3XV. The front end are the 3XV4 parts I had after putting the SP things into the 3XV. The body work she got loaned from here bigger sister. I also modified the parts around the 3XV cylinder  / head to fit into the frame. Next is the engine itself, I have started to modify the inlet to take up the 3XV reeds.



Louis

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Re: my 4FL...
« Reply #22 on: February 19, 2018, 09:15:19 PM »
Hello Juergen,

Your 4FL certainly looks great that's for sure. It's almost like a 250  8)

45HP wow you are asking something, I'm having trouble to get a solid 30
Hoping that with higher transfers I'm getting close to 29HP and then with a free programmable ignition and perhaps some exhaust tricks hope to see the +30

We going almost the same route, me to will be widening the reedblockspace (not that big a yours) to fit a honda 125 reedblock
Will be watching your project Closely :)
King off all twostrokes ''TZR250 3MA''

Warwick

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Re: my 4FL...
« Reply #23 on: February 20, 2018, 12:07:43 AM »
That looks terrific, Jeurgen!

Does a 3XV swingarm fit in the 4FL frame by any chance?  ?:-| 8)
Still Smoking...

41juergen

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Re: my 4FL...
« Reply #24 on: February 20, 2018, 02:21:33 PM »
So of course the 45+ HP is more a Christmas wish rather then an "easy to archive" thing... ;)
However a solid 40+ should be possible as the TZ250 short stroker from middle of the 90's were capable to do that, so let's see. And when getting in this higher power range you need to have the larger reed case, otherwise you get short with the reed area (may be except with the VForce setup).
The 3XV swing arm will not fit (or at least not easy) as the rear engine mount goes through the swing arm pivot. I'm looking for alternatives, may be a 1KT swing arm with some significant mods would do the job. The other solution would be a 3MA swing arm turned upside down, but these are far to expensive.
« Last Edit: February 20, 2018, 02:33:22 PM by 41juergen »

maccas

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Re: my 4FL...
« Reply #25 on: February 20, 2018, 03:41:21 PM »
Wow Juergen, how did you mount the 3xv cylinder? I'm intrigued!

Dan

41juergen

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Re: my 4FL...
« Reply #26 on: February 20, 2018, 05:07:00 PM »
Not yet...  :)) So I'm on the way to get a stainless steel (3,0mm) laser cut of the 3XV base gasket. With that I need to weld a bit more "meat" around the future stud positions. Than it will be cut flat and the new threads for the studs needs to be done. At least that's the plan... I also get back soon a 31K con-rod (110mm) which got a 2mm smaller small-end and will be used in that crank.

loor

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Re: my 4FL...
« Reply #27 on: March 04, 2018, 01:15:01 PM »
Great Job so far. Looking at your intake, the guy with the welder will have to do some extra hours! Hopefully the case doesn't get too much heat distortion! I'm really excited to see some progress!
Also I like the fact that you build an 1,5xv engine and Louis is building one with the 3ma cylinder. Let's see what works best :)
Regards Lorenz

TZRtim

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Re: my 4FL...
« Reply #28 on: March 07, 2018, 07:27:27 PM »
Admiring your work , i spotted the chain guard on the 4fl swingin arm ? Is it a 3xv one and does it bolt on? My plastic long one is quite hideous . Thanks for sharing .
May the wind blow light and your groups shoot tight - UKV...  Biker and shooter for life ...

41juergen

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Re: my 4FL...
« Reply #29 on: March 08, 2018, 10:34:28 AM »
@Lorenz: the plan is to pre heat the case before welding to minimize distortion... hope it will work out.
@Tim: yes, its from the 3XV. Its not a bolt on, but I drilled a hole into the upper frame/rail of the swing arm to fit a rivet bolt (for the black plastic piece). To fit the alu piece I made a "bolt on" bracket which is mounted with the bolt below of the fender...