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PostPosted: May 27, 2016, 10:24 am 
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Joined: February 25, 2014, 7:37 pm
Posts: 8
Hi,

Long time lurker now finally building an Exomotive Exocet with Ecotec LE5 and side exhaust with 1.8 Miata running gear. Sort of a heavier seven with more side impact protection. I'm hoping to keep it under 1500lbs.

I am trying to decide between itbs and standalone ecu and bike carbs with electronic ignition. Both can be supplied with some basic setup to get the car mobile but not optimally tuned. Bike carbs are half the price but need a rolling road to setup. Ecu arguably also needs RR, but has some potential to 'learn' via intrinsic software.

Any comments and recommendations for rolling roads in or around Portland ?

Thx
Beardy


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PostPosted: May 27, 2016, 11:12 am 
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The voice of reason
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Joined: January 10, 2008, 4:47 pm
Posts: 7563
Location: Massachusetts
I don't have pointers to local dynos. I did used to mess with carbs on a GS1100 though. It's a lot of work to tune those things That was on a motor they came with that had exhaust and intake tract mods. A different motor and displacement with different cams etc. - sounds a bit like a nightmare to me. Different needle heights, different needles and different jets times 4 carbs and you are looking at many, many carb rebuilds. Not real rebuilds, but open and adjusting parts. It's time consuming and you can only do 4 carbs so many times in a day.

So that's a vote for an ECU....

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PostPosted: May 27, 2016, 6:00 pm 
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Joined: February 8, 2014, 10:47 pm
Posts: 492
Location: Cornholio OR "Where the magic happens"
Portland Speed Industries.

http://www.tunedbypsi.com/

but they dont do bikes

http://www.yellowpages.com/west-linn-or ... s-24701329

Larry Cook does them well

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PostPosted: May 28, 2016, 6:37 pm 
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Joined: April 1, 2010, 10:26 am
Posts: 358
The problem with bike carbs is that (assuming they are from and 4 cylinder across the frame engine) is.

Bike don't take lateral G forces, the bike leans the cancel them out.

So the carbs are not designed to take lateral G's the floats are very cylindrical across the engine, so under braking and acceleration the floats stay just about level. But you mount the carbs sideways and you now have great float action for lateral G. But the moment your brake or accelerate your floats slam shut. You will get them setup perfectly on a RR only to find the engine goes lean under acceleration. So tuning can be a nightmare, if not impossible. If you want to reduce cost use bike individual throttle bodies to make an injected itb setup.

Graham


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PostPosted: May 28, 2016, 11:33 pm 
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Joined: February 25, 2014, 7:37 pm
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Many thanks
sounds like the consensus is injection.
cheers


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PostPosted: May 29, 2016, 10:05 am 
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Joined: February 8, 2014, 10:47 pm
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Location: Cornholio OR "Where the magic happens"
I do MegqSquirt systems.

No dyno needed, except for the the illegal areas of the tables.

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