Tuning an EFI

[Scotty]

Originally Posted by grbrown

Is that with EFI?

Whichcraft!! (fool injection) No mate, big chunk of aluminium with a stonking big hole through the middle, they called them carburetors back in the day, its first owner was a brontosaurus rex or so the archeologist i bought it from told me..

[simonDyna]

EFI vs Carbs....guaranteed to divide consensus.

The tunability of EFI is far better than Carbs. The breakdown of how much fuel will be delivered at a particular rev at a particular throttle opening is a great step forward. The three dimensional mapping is an excellent way to view what is actually hapenning at any given time. The ability to swap between maps for a given application using a plug-in tuning device or a laptop is another good step forward in my opinion.

In my case, I have a road setup and a track setup. It currently takes me 2-3 hours to swap between the two carbs and inlet tracts. To be able to swap between the two required settings by plugging in the laptop and have it done in minutes is something I would much rather do.

The problem is that it is far more difficult for the "home builder/tuner" to be able to perform modifications on EFI systems because they dont have access to a rolling road/dyno/AFR sniffer. The components and plans are out there to build you own sniffers but as yet, I have yet to see someone put one on the market.

Secondly, it is all very well swapping maps in a couple of minutes but some poor sod had to spend hours writing the map in the first place. Thats the bit that puts everyone off. its bloody expensive.

Writing your own maps is time consuming. Most people wouldnt know how to start. Three dimensional graphs are not the easiest things to understand but once you get the hang of them, they are not rocket science. Deciphering the blocks of numbers behind the maps takes a while to get the hang of but it can be done.

Carbs on the other hand are mechanical. They are something you can strip down, fiddle with, refit and away you go. All in the comfort of your own garage, shed, front room, roadside and so on. They are reletively cheap and simple to work on.

The EFI system that Harley use is actually one of the better ones on the bike market. Compared to a lot of the other manufacturers, they pretty much work straight out of the box and keep working without the need to be updated or remapped. Only once you start changing engine/induction/exhaust compenents do you need to alter the settings, obviously.

With regard to getting more "poke" or more anything from an engine, the induction system will only be complementary to the assembled components. Get the mechanics done first, be that cams, big bore kits, headwork etc, etc and then look to fuel it correctly. No amount of EFI tuning or carb tuning will create torque or horsepower if the correct mechanical components arent in place.

I'm in the carb camp at the moment but the more I see of EFI, the more I like.

[grbrown]

Originally Posted by Scotty

Whichcraft!! (fool injection) No mate, big chunk of aluminium with a stonking big hole through the middle, they called them carburetors back in the day, its first owner was a brontosaurus rex or so the archeologist i bought it from told me..

Don't believe everything you hear. Dynosaurs are extinct.......

[Roy]

Had an initial discussion with Matt at Matts, he says that step 1 is really head work and cams. WHich is along the lines of what SImon and others had said, working up a quote for the work which will probably be done in Oct/Nov time unless I go for a softail..

[simonDyna]

I cant find the article now but Andy Hornsby from American V did a very good write up on fuel injection after spending a day with Matt. I seem to remember they used a certain Road King as the example bike.

If you can track down the article it makes for good reading and fuel injection is explained well.

[Limey_Dave]

Originally Posted by simonDyna

I cant find the article now but Andy Hornsby from American V did a very good write up on fuel injection after spending a day with Matt. I seem to remember they used a certain Road King as the example bike.

If you can track down the article it makes for good reading and fuel injection is explained well.

The only thing I can find is this and part two was never added.

American-V Tech

Also

Harley-Davidson Motorcycle Fuel Injection Explained

Harley-Davidson Fuel Injection Upgrades

[Roy]

I had another quick email exchange with Matt, I explained I am after higher revs torque and his reply was (based on the requirements I sent him):

"the TW 21 is designed forheavy bikes and is designed to increase torque in the lower rpm ranges,not what you have described to me as your needs,I would recommend the S&S 510 or 570,or the andrews tw37b,rough idea of cost for cam & pushrod change,headwork & dyno tuning would be likely to be around £1300,"


So £1300, does not sound that bad. I've replied to say I'll contact him Sept/Oct time to book the bike in and get it sorted. Might change my handlebars from apes though .. not great at high speeds with high headwind ...

[simonDyna]

I'd be looking at the S&S570 or the Andrews TW37B. The S&S510's are for very mild or no headwork.

Are you sticking with chain driven cams or going to gear driven?
Are you going to bore it out to 95" at the same time?

[Roy]

Originally Posted by simonDyna

I'd be looking at the S&S570 or the Andrews TW37B. The S&S510's are for very mild or no headwork.

Are you sticking with chain driven cams or going to gear driven?
Are you going to bore it out to 95" at the same time?

Cheers Simon

Umm .. Matt gave quite a choice, so he was probably listing my options and then seeing how I react to the estimated cost. I probably would not go for headwork unless it is absolutely neccessary, my objective being only to increase the top end torque/cruising speed.

So don't know, not interested in racing the bike just want a bit more oomph (technical term .. ) above 85mph.

Won't go for a 95" as this will be taking things close to it being as cost effective going for a 96" Harley. So gonna see what I can do for a minimum amount of outlay just to increase top end cruise speed torque.

Having said all that, if this turns out to be too painful/costly, will just save the money and put it towards a softail. I am what you may call .. undecided

Cheers, Roy

[simonDyna]

Roy,
Should be interesting to see what a tuned 88" motor puts out. Sounds like you are taking a pragmatic approach to it and considering all the options.

Fingers crossed it will work out.

I'm sending you a pm about something you might be interested in

Cheers
Simon