MicroSquirt.com read only forum (Jan.15,2018)

Hi,
we are currently building a lightweight dragster based around a mid 70's 750 bonnie. The bike features a chromoly frame, spoked wheels, reversed head and a circa1969 bulletnose fairing.
The bike will compete in the up to 750cc, pushrod class in New Zealand.
Proposed/current specs:
Fuel: methanol
Weight: 100kg/220lb approx.
Trans: 5speed.
Clutch: dry multiplate.
Bore & stroke: 77.5 x 82mm
Compression: 9 -10:1
Inlet ports 30mm (stock)
Exhaust: twin 1 3/4" x 39" headers
Fuel tank: 600mls/1 pint
Fuel system: currently twin 30mm mk2 amal concentric
Cams: spitfire inlet & 650 bonnie exhaust 3134
Ignition: currently boyer electronic
Battery: Lipo
Charging: none
Barrels: stock cast iron with fins removed
Head: minor headwork, competiton double valvesprings.
Crank & rods: stock, balanced.
Primary: tooth belt drive
BHP: 70 -75?... (hopefully more with microsquirt)

The motor will be blueprinted. It will feature a reversed cylinder head so the carbs face forward. Injection will take better advantage of this.
The entire bike will be lightened as far as possible. Considerable attention to detail just to save a few grams here and there.

We've been studying the issue of microsquirt and adapting our bike for some months now.
A few questions please:
1/ Where can we get a fuel pump that suits methanol, is lightweight and draws low amps? We read where many pumps are unsuitable because of the resin used to bond the magnets and also issues surrounding the conductivity of methanol. Of interest on ebay is this: Alkycontrol Methanol Injection Mini Pump . Has anyone tried it and can it handle straight methanol?
2/ Our inlet ports are 30mm and we'd dearly love to acquire throttle bodies of similar size or slightly larger. Does anything come to mind?
3/ Is there any specific wideband o2 sensor that suits methanol better than others?

Comments and suggestions invited. Thanks.

Not sure what your budget is but http://www.jenvey.com/~Bodies1.htm has what you are looking for.

Thanks for the help. We've been drooling over those the last few weeks. Perhaps as a last resort?
Just yesterday, a friend announced he had an old Nissan motor with some of the parts we can use.
He said we could take anything we wanted. This will give us some sensors and harness/connectors.
Looks like the injectors are too small though and the throttle body will be too big.
Another friend, who is a small engine mechanic, said he may have some throttle bodies off some
of the modern lawnmowers that are injected. Google tells me the turf tiger is a possibility.

GPz 1100 B2 has 32mm throttle bodies. Early ninties bike (?) parts should be cheap at salvage yard.
I'm using one for my fiat 500 project.

Brgds
Justus

Bike completed now and we won both the competition drag meets so far, so are leading on points.
It's set up with old school 30mm amal mk2 carbs but now we want to squirt it.
We've spent long hours studying the subject. It's complex so we're putting the effort in.
One question we're struggling with. Being a dragbike, want to log extra data like accelerometer, speed, etc. Is this possible via microsquirt & a datalogger like the LM2?
Our motor runs methanol. Some years ago I run racing fuel no.5 which had castor oil & acetone as additives amounting to 3%, methanol 97%.
The thought occurred that additives especially oil could harm the o2 sensor. Indeed our motor is obviously using some engine oil, though it doesn't smoke.
Has anyone any practical experience with oil usage causing problems with the life or readings of the o2 sensor? Engine oil is castor based Castrol R.
Thanks.

Excellent project!! And congrats on success. I have started similar project on 1971 750 Triumph with NRE 4-valve head+cylinder. Going to use MicroSquirt running on petrol.

I have run few thousand kilometers on old Triumph with o2-sensor assembled with no problems. Old design consumes some oil allways. If it is within reasonable limits I wouldn't worry.

Have you dynod your bike? I am really curious what kind RWHP you are getting. What inside diameter exhaustpipe are you using? My cylinder head has 34mm intake and 38mm exhaust. I think I should use 1 1/2" diam. for the begining of the exhaust. Do you guys have understanding if the intake dimensions change when you are using efi instead of carbs. One would think that it is possible to use larger diameter for efi because you don't need the vacuum the same way as w carbs getting the fuel out of mainjet. But would it be any use.... I am newbie to tuning engines but played a lot with all sorts of standard ones. And just finished squirting 1-cyl 50cc 4-stroke engine for learning purpose. I have to say that I am very impressed on how MS2-Extra firmware and TunerStudio works. It has been very educating experience and gained a lot of confidence to dare to start squirting the Triumph engine.

Regarding intake or carb sizes. I started with a stock 2001 53 RWHP 640cc Husaberg on a 40mm Dellorto. It had 74+ on a 44mm snowmobile carb rising to 78, and when the head was reworked to have twin inlets, one 40mm carb per valve it reached 82+ RWHP. It also had higher compression, different cams & reworked ports. Perhaps peak hp isn't that relevant, but the difference in the 40mm & 44mm carb at 9000 rpm was 35 RWHP, the stock bike had 35, the modded one 70!

Never did EFI this thing, but huge generalisation coming, port shape is important for maintaining cylinder filling inertia usually at part throttle, bigger throttle bodies generally give higher flow rates at WOT. Folks say that carbs give better atomisation, maybe it does, but I remember a Ducati that was quicker than all the rest, only difference was he didn't have the single pintle type injector nozzle, but a multi instead. The other guys couldn't work out why his bike was better.

Thanks for the comments.
The bike hasn't been dyno'd but we can deduce that HP is around 65+HP given our 11.5 ET and rider/bike weight at approx 390 lb (177kg).
50+HP is indicated for rear wheel.
Exhaust headers are made from old speed-twin header pipes from the 1950's. These pushed over the stock exhaust stub so I think they are 1 3/4" OD.
These were already rusted thin from use and age so gave a useful saving in weight! The bike, now named Excalibur, weighs in under 95kgs now.
We're looking to get some 34mm throttle bodies as we also reason that larger throats can be used.
We have the module and the MAP sensor already. Also some other used bits like TPS, injectors, regulators etc to choose from.
Sadly Dragmeet Competition #3 has been cancelled due to a passing cyclone. Anyway we lead the points with a maximum of 1000 at mid season.
One of the areas we believe we can have a reasonably good gain in by using forced air induction. The advantage being that we can taylor the fuel calibration to the mainfold air pressure, whereas carbs don't like be force feed.
Find us on Youtube. SmokeOnTheQuarter (one word). Also our blog address is amongst the comments there.