Sumotrack

[Ratranger]

I'm not planning on sticking with carbs. But I have heard that the BS38s on these bikes are different than others.

Got the seat tube mounted on the bike. Next I'll finish bracing the back of the frame and start planning out wiring.

 

[Ratranger]

A few updates, frame is basically done. Modifying the hoop for a flush LED light, and got my wheels. Also should be working on exhaust soon as I ordered the tube for it.

 

[Ratranger]

Rear hoop is almost done, needs some finishing work. And it sits about the same height as stock, tires are shinko 705s, rear is 150/70r17, front is 120/70r17. Looks like I might need to space the rear sprocket out to line up with the stock front sprocket, but it'll clear the tire easy. Unfortunately I managed to pinch the front tube, so the tire has to come half way off.

 

[Ratranger]

So the EFI swap has begun. Respaced a pair of throttle bodies from an early 2000s gsxr600, working on mounting a 36-1 trigger wheel inplace of the points cam. It will all be run by a microsquirt ECU.

 

[TwoManyXS1Bs]

Well, THAT's an interesting transplant...

 

[Ratranger]

Lol, what can I say? I know how to tune and balance carbs from previous 4 cylinder bikes and the dual SUs that were on my spitfire, but I prefer EFI. I'll probably turn some velocity stacks, and I need to make the fuel pump mount as I'm going the in-tank route. The one thing that I'm not sure of mounting location yet is the LQ9 coils.

 

[Ratranger]

So I used my lunch today to make some velocity stacks. They are sized so that a 3" I.D. Uni filter will fit on the end.

 

[ThatXS650Guy]

Way cool Ratranger.
Are you on The Triumph Experience forum as well. I am on there once in a while seeking much needed help with my 1967 GT6.

 

[Ratranger]

Yep. Got a 73 spitfire with a 4AGE under the hood.

 

[Ratranger]

Exhaust is almost done, and rear rotor spacer is complete.

 

[nighthog]

Lots to like on your bike, wish I had your facilities and skills!
On a simple note though, what bars are those? Im looking for something similar in the UK.

 

[Ratranger]

They are the protaper dirt track bars.

Thanks! It has taken years of practice and saving to get where I am.

 

[Ratranger]

Well other than a hanger the exhaust is done, the wideband is mounted in a nice out of the way spot that also hides it. Maybe in the next 2 weeks or so I can finish up the frame and get the exhaust and frame out for coating.

 

[Ratranger]

Header is out being ceramic coated. Rear rotor is now mounted up. Battery tray is started. And finally it has throttle cables. Started with a mition pro revolver throttle that was $60 on ebay, added ducati st4 sheath ends and used bicycle inner cables with some brass knarps I turned out of scrap. Soldered it up and bam, custom cables.

 

[Grimly]

So I used my lunch today to make some velocity stacks. They are sized so that a 3" I.D. Uni filter will fit on the end.

Now, this is very interesting. Not something that's cropped up much on here.
I'm paying close attention to choice of pre-employed parts, especially the throttle bodies. How far up the envelope of the GSXR600 'bodies is the airflow of the XS650 cylinder? My first thought for one of those would be half of a 1200 EFI installation, not so?
Leading from that - is there a massive obstacle to using a (for example) GSXR 1200 ECU, or is it just too much hassle to persuade it work outside its home environment?
I get the Microsquirt, I really do, but I grudge paying the prices.

 

[Ratranger]

The GSXR600 throttle bodies will outflow the XS engine easily. The GSXR600 uses 4 38mm throttle bodies, people have used those throttle bodies on 2l car engines and push around 200hp. Really it would be better to have 32-34mm throttle bodies, it would smooth the off idle and low throttle movements out. The 38mm throttle bodies will flow more air than a 38mm carb most of the time, no slide, no needle, just the butterflies to disrupt the air.

Microsquirt is one of the cheapest smallest ECUs out there. I paid a little over $300, straight from DIYautotune. Problem with adapting an ECU from something else is you have to replicate its trigger signal, buy a piggyback like a power commander, and hope that gives you enough adjustment. So by the time you get a $50 used ECU working you are easily above the cost of a microsquirt.

So far for the EFI swap it has cost:
Microsquirt- $330
Sensors- $50
GSXR ITBs- $45
fuel pump- $30
misc part- $100

So I am about $650 in, and really last couple things are make the fuel pump mount, drill a new fuel rail, and finish wiring. So about the same as getting a pamco, and good aftermarket carbs.

 

[Ratranger]

Exhaust is coated, clutch slave is done.

 

[MaxPete]

This is going to be quite the bike ratranger!

Pete

 

[Ratranger]

Thanks! I'm trying to make up for all the hack jobs I did when I was younger by doing this one right.

 

[MaxPete]

Good for you!