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 Post subject: Cylinder Head for a '900' F1?
PostPosted: Mon Feb 06, 2012 5:04 am 
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Joined: Sat Nov 13, 2010 6:40 am
Posts: 28
Just got my 86 F1 resto on the road over the weekend so have been thinking of the next project which involves an 89 900SS motor in a modified F3 frame, 40mm Dellortos, M1R's off an 851, 17" Marvics etc. The intention is to build the bike the 89 900SS should have been, F1 style, & to keep it looking reasonably 'factory'.

Want it to have a forward facing rear head to so my question is is it possible to weld & build up the inlet on the rear 900SS head, open out the exhaust, install new seats etc, simply rotate the piston, & then install a front cylinder cam, with valve gear also if necessary? Plus twin-plug it at the same time.

Have asked a couple of local mechanics & verdict (with a fair bit of head scratching) was that it should possible if expensive.

The alternative is to machine out a pair of '86 400 F3 heads I have sitting on the shelf. Interested to know peoples thoughts on which option would be the easier route.

Regards Andrew K


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Mon Feb 06, 2012 11:08 am 
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Joined: Thu Oct 14, 2010 11:23 am
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As far as the F3 heads go, the cylinder bolts are not the same; they have a smaller center than any 900. Look at Steve Munro history on Loudbike. And, one expert in the US kept a set of F3 heads I had for almost two years, promising to turn them onto F1 heads, and then did not succeed---did not even get them to Pantah-sized valves. You do know than Jan de Vos (RedFox) sells a vertical head that goes in the "right" direction? Finally, getting back to Steve M, he has plans to convert Pantah heads to at least F1b specs; the more the merrier. MikeV


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Tue Feb 07, 2012 6:53 am 
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Joined: Wed Apr 27, 2011 4:56 pm
Posts: 79
Both Red fox in Belgium and Ducati Kaemna in Germany do a 'right way around' 900 vertical head, each costs around a couple of grand (euros)!


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Wed Feb 08, 2012 8:05 pm 
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Joined: Fri Dec 24, 2010 7:35 pm
Posts: 15
Location: belgium
hi
tried every thing
nothing worked
i made a small production in billet aluminium on a 5 ax cnc milling machine
works perfect and great results in enduring races
see them on www.redfox-grinta.com
ad the end the cheapest way to make the fastest tt ever build

thanks
jan


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Thu Feb 09, 2012 3:23 am 
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Joined: Sat Nov 13, 2010 6:40 am
Posts: 28
Thanks folks, Red Fox head looks great & the way to go to me. Better start saving up my pocket money.

Anyone out there interested in a pair of '86 400 F3 heads?


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Thu Feb 16, 2012 10:41 pm 
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Joined: Sun Aug 08, 2010 4:37 pm
Posts: 360
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Location: Ottawa, Ontario, The Great White North
618F1 wrote:
As far as the F3 heads go, the cylinder bolts are not the same; they have a smaller center than any 900. Look at Steve Munro history on Loudbike. And, one expert in the US kept a set of F3 heads I had for almost two years, promising to turn them onto F1 heads, and then did not succeed---did not even get them to Pantah-sized valves. You do know than Jan de Vos (RedFox) sells a vertical head that goes in the "right" direction? Finally, getting back to Steve M, he has plans to convert Pantah heads to at least F1b specs; the more the merrier. MikeV


Converting a set of later-spec F1 heads to run the wider stud spacing wasn't that bad, really. But we never did modify the combustion chambers to match the big 944 Pistals, so by the time you add up the stud spacing and combustion chamber work (finally being done this year), you start to approach the cost of Jan's head. But there was more to it than just modifying the heads; we had to machine the engine mount bosses on the cases and we stayed with a short stroke crank, so the barrels were shortened by 11mm.

I think that what's missing with the 900-based engines and the small-blocks using the short duration cams (900ie, ST2) is one of the most compelling reasons to own and ride an F1 or TT.

The sound...

To me, it just ain't fun without that small-block Chevy sound you get with the Montjuich, NCR7 or even stock F1 cams. With the 853 I gave up 1mm in additional valve size just so I could stay with the stock F1 cams. I raced Fran's TT1 for years in the endurance series up here (we still hold the record for most podium finishes) and the NCR7s that bike ran made good power and delivered the sensory element that attracted me to the machines in the first place. Not to knock the V2, 900ie or other cams with short duration - or the super torquey 900-based variants - but to me, they just don't sound right. Just one man's opinion though... http://youtu.be/CQCROWYIVuc.

To Mike's point - the other Mike (CrankyRoller) has converted a bunch of small-valve heads to later F1 spec and run them with good results using the NCR7s. We're copying his recipe for the conversion and should have the first set done next week. The service should be commercially available by the middle of next month..

_________________
Steve Munro
loudbike
http://www.loudbike.com
http://www.vintagemotorcyclesforsale.com


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Fri Feb 17, 2012 2:59 pm 
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Joined: Sun Oct 17, 2010 3:26 am
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Steve, you are soooo right.


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Fri Feb 17, 2012 3:46 pm 
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Joined: Thu Apr 28, 2011 8:52 am
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keep posting guy's, it is all so fascinating !


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Fri Feb 17, 2012 3:46 pm 
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Joined: Thu Apr 28, 2011 8:52 am
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keep posting guy's, it is all so fascinating !


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 Post subject: Re: Cylinder Head for a '900' F1?
PostPosted: Wed Mar 21, 2012 12:08 pm 
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Joined: Wed Mar 21, 2012 9:56 am
Posts: 104
Hello to all of you on the forum.

Although this is my first post on the site I have been reading the content for some time and thought some input may be useful on this topic.
Regarding "reversing" later heads to re-model the ports back to Pantah style. Amongst so much other stuff in progress I am currently doing exactly this to a small batch of both 750 and 900 heads. The number of TT1/2's possible is exactly the same number as rear heads available.
The process in a nutshell involves machining out the current inlet/exhaust stubs to suit the shape of the Pantah stub profiles. then build the new holes up with weld to re-form the new stub profiles. Then back onto the cnc to m/c the new in/ex stubs and internal port shapes.
The valve seats are also removed and welded as they need to work the other way, then machined and new seats fitted to afford 41/35 valves for the 750 and 43/38 for the 900 head. The combustion chamber is also machined on the cnc to match the later tri-spherical shape which will no doubt already be in the matching front head on your donor engine.
I looked into casting new heads but decided to go this route for a number of reasons.

When finished in the near future they will be available on an exchange basis.
So there we go, no more shortage of rear heads and heaps more TT1/2's out there to enjoy.

Sounds simple ! -- But believe me its not quite so easy.


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