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| Voxonda |
 Posted: Tue Jun 26, 2007 7:09 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Hey to you all,
Have bought a 65.5mm (850cc) piston kit from the USA. Looks pretty nice and at this moment I have the barrel take on some Bol Dór bushes, because their wall is thicker, so that gives me a better 'feeling'. Then it is bored out to +0.05 mm clearing. The head is getting some treatment also, a squish and some minor flowing and a set of new outletguides.
Anyone experience with the kit from Cycle-X?
Cheers, Rob |
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| Satanic Mechanic |
| Posted: Sat Jul 14, 2007 12:28 pm |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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Rob,
Voxonda wrote: Anyone experience with the kit from Cycle-X?
Not yet but I am considering it for my next engine project. Please keep us posted what your experience is.
Cheers, |
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| Voxonda |
| Posted: Sun Jul 15, 2007 8:07 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Satanic Mechanic wrote: Rob,
Voxonda wrote: Anyone experience with the kit from Cycle-X?
Not yet but I am considering it for my next engine project. Please keep us posted what your experience is.
Cheers,
Hey axl,
Will do that. The work on the barrel and head is done, will collect it sometime next week.
Cheers, Rob |
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| Voxonda |
| Posted: Sat Oct 27, 2007 7:29 am |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Have chosen a new path, TURBO-charging. Have sold my Keihin CR's in favor of a Garrett T2/Mikuni HRS42 setup. Have most of the parts in house now and will start the build very soon. Just wandering about the strength of the rods and the compression ratio of 10.5:1. Maybe I can solve both by using the shorter DOHC750 rods?? The setup will be for street and not for track.
Any comments on this are very welcome.
Cheers, Rob |
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| Satanic Mechanic |
| Posted: Thu Nov 01, 2007 5:26 pm |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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The 750 DOHC rods are 1.5 mm shorter, which will add roughly 5cc combustion volume - that should bring your c/r down from 10.25 to about 7.5, which is a good value for a turbo motor.
The rods are a bit stronger - depending how much power you expect or want (in other words how much boost pressure you have) they may in fact be a solution. |
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| Voxonda |
| Posted: Thu Nov 01, 2007 8:23 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Satanic Mechanic wrote: The 750 DOHC rods are 1.5 mm shorter, which will add roughly 5cc combustion volume - that should bring your c/r down from 10.25 to about 7.5, which is a good value for a turbo motor.
The rods are a bit stronger - depending how much power you expect or want (in other words how much boost pressure you have) they may in fact be a solution.
Hey Axle, In fact I've just bought a set of DOHC conrods, think it's a more advanced technical solution then just put a spacer beneath the cilinderblock. It is not my intention to try an wring the neck of the bike and try to achieve as much power as possible, but try and make a rideable bike with a lot of torque.
This is the Garrett T2 I've bought.
Cheers, Rob |
Last edited by Voxonda on Thu Nov 01, 2007 8:28 pm; edited 1 time in total |
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| Voxonda |
| Posted: Thu Nov 01, 2007 8:27 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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This is the Mikuni HSR42 that I have received today:
Cheers, Rob[/img] |
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| Satanic Mechanic |
| Posted: Sat Nov 03, 2007 11:25 am |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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Voxonda wrote: Hey Axle, In fact I've just bought a set of DOHC conrods, think it's a more advanced technical solution then just put a spacer beneath the cilinderblock.
Certainly  |
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| cafebob |
| Posted: Sun Nov 11, 2007 9:57 pm |
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Rookie
Joined: 16 May 2007
Posts: 7
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From my understanding, CR of 7 to 8 is what you want for a turbo SOHC motor if you don't plan to run and electronic ignition, with spark retard...If you do you might be safe in the 8-9 range. Plus better CR gives you a better low end power...
however, lower CR means easier time running higher boost with or without ignition control. Anyway my point is you can run a higher CR, it just will take a little more work.
bob |
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| Voxonda |
| Posted: Mon Nov 12, 2007 6:28 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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cafebob wrote: From my understanding, CR of 7 to 8 is what you want for a turbo SOHC motor if you don't plan to run and electronic ignition, with spark retard...If you do you might be safe in the 8-9 range. Plus better CR gives you a better low end power...
however, lower CR means easier time running higher boost with or without ignition control. Anyway my point is you can run a higher CR, it just will take a little more work.
bob
Hey Bob, thanks for your advise, I have a complet Dyna setup, but with the original advancer that I'm planning to use. Do you think I have to do something with that advancer?
Am using shorter conrods to lower the CR.
Thanks, Rob |
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| Tim2005 |
| Posted: Tue Nov 13, 2007 10:59 pm |
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Member
Joined: 06 Sep 2005
Posts: 43
Location: Norfolk UK
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One of the Dyna systems includes various ignition maps, one of which is a retard option for turbo engines; would be worth checking that out. I investigated turbo-ing a 400f last year in some detail and this was the only one I could find at the time.
By the way, I'm curious about your carb- are you intending to fit it upstream of the turbo or between the turbo and the head? For the 400, I was planning on fitting the turbo (Garrett T12 probably) in front of the engine with a (pressurised) duct back to the carb then head. This was primarily in order to try to reduce the heat issues by having the turbo in the airstream, near to the oil supply and a large oil cooler, and also hoping that the duct would act as a bit of an intercooler (400s have serious heat problems). However, I haven't got much further with the plans as low compression pistons for 400s are unavailable.
Cheers |
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| Voxonda |
| Posted: Wed Nov 14, 2007 12:07 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Hey Tim,
Thanks for the Dyna-tip, will look in to that.
I am planning to fit the carb in a draw-through style upstream of the T2, just like in the old days.
A shame to see that you're not going further with the 400 project. I am using the 1.5 m/m shorter con-rods of the DOHC 750.
Cheers. |
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| Voxonda |
| Posted: Thu Nov 15, 2007 8:48 pm |
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Member
Joined: 01 Nov 2006
Posts: 42
Location: The Netherlands
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Made up my mind after mailing with Boyer & Bransden in England. With a little fiddling with a resistor I can retard the advance curve of the digital ignition I have. So the complet Dyna setup goes to my other bike, the JAPAUTO.
Here is their answer to my question:
Re: CB850 Turbo ignition
Dear Sir, The standard ignition curve is not adjustable, the maximum advance point of the ignition can be retarded by simple angular adjustment of the stator plate.
A small reduction in the advance range can also be sought by modifying the resistance of the stator plate.
Lowering the effective resistance by introducing a 300 ohm 0.5 watt resistor across the terminals of the stator plate could shorten the advance range by 3 degrees.
Kind regards,
Boyer Bransden Electronics
They reacted within 2 days. Think that's great.
Cheers, Rob |
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| Tim2005 |
| Posted: Fri Nov 16, 2007 9:34 pm |
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Member
Joined: 06 Sep 2005
Posts: 43
Location: Norfolk UK
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Interesting info from Boyer there; 3 degrees isn't much but may help (you could even put a switch in line to the resistor to give more variable timing!).
As for the 400f turbo project, it's not completely abandoned as it is not impossible to decrease the compression by using extra base gaskets or a thicker head gasket, though I've yet to find a suitably sized carb that would cope with the pressurisation of being downstream of the turbo- any ideas? |
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| Satanic Mechanic |
| Posted: Sat Nov 17, 2007 10:36 pm |
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Moderator
Joined: 04 Sep 2005
Posts: 309
Location: Munich, Germany
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Basically, a blow-through setup is preferrable to the draw-trough all the earlier turbo kits were using - especially better throttle response.
But you need to prepare your carb(s) for the pressure, you will need a fuel pump, and you will need a pop-off valve between the turbo and the carbs to relieve the pressure peak when you close the throttle while the turbo is still in full spin.
On the other hand, you may keep your stock carbs and you may use intercooling with a blow-through setup.
You will have to pressurize the float bowls, and often you also need a way to control fuel pressure - the float valves are designed to close against gravity pressure only, and not against the pressure a fuel pump may deliver. On the other hand, you will need substantial fuel pressure once your turbo is at full boost. |
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