3cyl 2stroke brainstorming

For discussing injector selection, manifold modifications, throttle bodies, fuel supply system design and construction, and FIdle valves and IACs.
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rb855
MegaSquirt Newbie
Posts: 3
Joined: Wed May 23, 2012 6:39 am

3cyl 2stroke brainstorming

Post by rb855 »

Hello all,
Have been putting together a monster of a project for a few years now. Long story short, We have taken a Suzuki GT750 liquid cooled 3cyl 2stroke, added reed boxes, some radical porting, GS750 transmission, R6 throttle bodies, and shoved it all into a late 90s GSXR frame. Now heres the fun part... We have a microsquirt, and have been crunching the numbers. Since this is a 3cyl that leaves us with the only option of running batch fire, as the micro sequential has never come to market (unless I'm blind?) We are using LS Truck coils, and IIRC 250cc @45psi injectors. The concerns I'm having right now is at redline 8krpm (3 ignition and 1 fuel per rev), that will mean only having about a 7.5ms injection window (6ms at 80% duty), and only 1.5ms of dwell. That honestly does not sound like nearly enough time. The bike is nearing completion and nearing its first attempted startup, so looking for a little advise if this is a futile effort to run batch. 3 coils, 3 injectors, 3 throttle bodies, 1 tps, 1 map, 1 baro, iac undetermined, 36-1 crank w/ VR.

Thoughts?

Thanks!
Ryan
Matt Cramer
Super Squirter
Posts: 910
Joined: Sat Jul 03, 2004 11:35 am

Re: 3cyl 2stroke brainstorming

Post by Matt Cramer »

The MS2/Extra code can be used to run the coils sequentially and free up more dwell. The injector amount can be solved with large enough injectors.
Matt Cramer at DIY Autotune
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banzairx7
MegaSquirt Newbie
Posts: 19
Joined: Wed Aug 05, 2009 2:59 pm

Re: 3cyl 2stroke brainstorming

Post by banzairx7 »

I'm a little late to the party here but I think your injectors will not be nearly large enough. I'm running a 170cc single cylinder two stroke and ended up using a 490cc injector. I am in the high 70% duty cycle at peak power of 25whp which occurs at 9,750rpm. I started with a 260cc injector and quickly maxed that out.
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