Microsquirt with Yamaha Virago

rotus7 · Post by **rotus7** » Tue Apr 24, 2007 9:47 am

I'm in the process of building an Eaton m45 supercharged chaindrive 920 Yamaha V twin which has the 1100 crank and will be bored out to something close to 1200cc.
This package is being fitted to a custom built Norton slimline Featherbed frame equipped with a later Yamaha front end from the 920 plus spread rear swing arm to take a 18x4.25 rear wheel.
From what I can see hear the Microsquirt system should offer the best replacement for both the old carbs and ignition system.
The M45 will offer what I believe to be correct sizing for the engine at about .625 of engine displacement but I would appreciate any and all input re this project.
Ken S

gboezio · Post by **gboezio** » Wed Apr 25, 2007 5:57 am

I don't know much Eaton SC, but I'm in the same boat for a V-twin converted to injection and it's getting a turbo. The tough part is to fabricate the intake manifold/throttle assembly, it will require a good deal of fabrication. What kind of trigger your stock ignition is using ??
This will be a fun bike to drive !!

rotus7 · Post by **rotus7** » Fri Apr 27, 2007 8:58 am

Right now I'm in the process of determining all these bits.
There appears to be a pair of coils mounted within the engine side cover positioned next to the stator/rotor which I assume (Yes..I fully appreciate what that word can do for us!!!) are the triggers for the ignition.
As to the manifold I trust that by supercharging the task of tuning the intake will be somewhat reduced as it is pressurized and all.
I do not plan on running any more that 8 PSI tops...probably starting out at 4-5 PSI.
I like the packaging of the Microsquirt and plan to mount it on the front fairing strut which should get it away from as much engine noise/static as possible.
Are you planning engine mods at this point or just keep it stock?
How are you planning to build the intake with enough volume to service the sporatic need of the motor? I'm planning to make the bulk of the intake length between the huffer (mounted low in front of the crankcase) and the heads out of 3" dia. aluminum pipe. Hoping that this will offer a volume for the huffer to fill with a blow-off that cycles back into the intake upstream of the huffer.
The only things, besides the huffer and the injection, that I'm planning at this point will a)a new exhaust, b) forged pistons, if I can find them, to drop the compression to about 7.5 to 8.5 to 1 and 3)the ported/polished heads that I had done a number of years back.
Your engine if I remember correctly is a 45 deg. motor while mine is 75 deg. Leaves me with a bit more room between cylinders for an intake manifold but that will be no problem for either.
Look forward to hearing from you.
Ken S

gboezio · Post by **gboezio** » Mon Apr 30, 2007 1:22 pm

Nice setup, my engine will stay stock for the first part, I may buy a second engine and build it on the side. For internals, I may order custom CP pistons and customs Eagle or Pauter rods, up to 15 psi or 8 stock engine. The angle is 90 degrees, but they set the new code to be able to trigger the second output with an user selected offset in wasted spark mode. My project is on hold since the riding season is on already. I'm doing this by pure insanity because the bike don't really needs more power except on the long straights.

rotus7 · Post by **rotus7** » Thu May 03, 2007 6:08 am

Somehow I had it stuck in my mine that you were talking about the cruiser motor not the crotch-rocket!!!
You've got a lot more potential to deal with than I have.
I'm hoping to get 100HP to the ground but I don't think that the stock 920 crank can do much more than that and stay reliable.
I'm hoping to stay south of 400 lbs. so 100HP and a bunch of mid-range torque with the bike wrapped in an Avon Clubman fairing should allow it to see 160 MPH on a good day.
I would trust that with your final target of something like 200HP you're heading for something much higher?
As to what exhaust system you're planning from what I understand the target is to collect the exhaust together ASAP and get it to atmosphere with as little back pressure as possible plus keep the O2 sensor as close to the engine as possible to keep it hot. My plan at this stage is to pull the primaries together at the base of the cylinders to a collector and then run a 2.5" to 3" secondary down and back to a Super-Trap muffler. The O2 will be at the top of the collector.
Are you considering some form of intercooling and if so how are you planning to plumb it?
Right now neither of my 920's are on the road so this effort continues unabated.
I look forward to hearing from you at you leisure.
Ken S

gboezio · Post by **gboezio** » Thu May 03, 2007 5:15 pm

I figured that with the firing order, front-450 deg-rear-270, front.... the rear should travel further than the front to make the pulses as close to each other than possible so the turbo will be close to the front cylinder on the side of the bike, then the turbo exhaust(2.75") will be bigger than the primary(1.5") and will be inside the turbo exhaust going toward the rear keeping the rear primary pipe hotter than the open atmosphere, and exit close to the rear cyl outlet going down to 2 " toward the back muffler(D&D). This is to minimize the heat loss from the rear, if the primary have an inside charge of 1500 degrees and is inside a 1200 deg pipe, it will loose less heat than on the open air. Other solution is a good heat wrap but don't look as cool...

rotus7 · Post by **rotus7** » Fri May 04, 2007 5:58 am

I have a pair of mid 80's Turbo Thunderbirds (84 & 85) so I've been playing with turbo motors for a wee while.
Most of the info/knowledge I've gained/shared has been on 'turboford.org'.
I've always found that I could post virtually any question there and get an informed answer.
Turbos are especially sensitive to exhaust phasing.
A good example being the Honda 500&650 turbo sport bikes of the mid 80's.
In that they were 90 deg V-twins it might be a good idea to review that application to see how Honda did it from the factory.
As for the Heat-Wrap on the exhaust 1)it does a great job of holding the heat in to assist with spinning the exhaust turbine,2) it protects legs/arms from being burnt,3)to my it adds a racer's look but 4)it can tend to cause cracking of the tubing.
Are you considering any form of alcohol/water injection or actually a little squirt of NO2 to actually cool the intake charge?
In some respects I wouldn't mind putting the effort into something that has more potential than my 920 but if you have ever heard of an old British drag bike called 'Super Niro' this is what I'm trying to repilcate in my own way.
It was a supercharged 1000cc Vincent that was competing in the mid 60's and it was laying a bad beating on the Harleys of the day.
Have a great week-end.
Ken S

gboezio · Post by **gboezio** » Thu May 10, 2007 4:38 am

Part of the plan was to completely remove the front fairing and headlight and replace it by a 919 assembly, but I may cut on the streetfighter look for a bit depending on how much time it takes to get the whole thing together.
The two side radiators will be removed and replaced by an underseat rad. On one side will be the turbo and on the other the intercooler, true sleeper look.

As for your drag bike, it will definitely look cool.