40mm Motorbike carbs on a triton (2.6L Astron)

[Superscan811]

Due to the triton being so gutless, and I have 2 rather long trips ahead of me, I have decided to make up a manifold to suit one of the many sets of 40mm motorbike carbs I have laying around.



Took a day to make (my welding still needs to improve) but it should hold together.

These are the carbs.



The other reason for the carbs is fuel economy.. I'm currently getting less than 450 kilometers to 65L (6.9k/l) city driving and only marginally better, 500 k's(7.7k/l) on country runs.

The old wagon, even when fully loaded up, would get over 9.2k/l on a country run.

When you have a 4600 kilometer drive planned, an extra few k's per liter helps the hip pocket..

I'm also putting on an M8 head which I have mildly ported, larger valve seats, 1mm OS stainless valves, bronze valve guides and beehive springs, and 1.5mm shaved off. Should give it over 11:1 compression ratio.

With the head off, the silent shafts will also be deleted and the oil pump checked and a spacer put in to take up the extra chain slack.

A cold air induction system and possibly water injection are on the cards, time permitting.

Hopefully this will turn the slug into something a bit more fun to drive..

Will post a few more pics tomorrow..

Cheers.

[bruggz351]

I like this, because it's out of the square.
Everybody is either twins or EFI.

I'll be interested in the fuel efficiency and power improvements.

Lookin good Superscan...

cheers

[cheaterparts]

When you have a 4600 kilometer drive planned, an extra few k's per liter helps the hip pocket..

Cheers.

so this is a 1500 km trip and you are using your GPS for directions again is that right

[A112H]

He needs to take into account the fuel and kilometers clicked over trying to climb trees half way down a barron road only to turn around at the end and come back.
Of course the next trip the L200 will be 4x4 so I suspect he will attempt to navigate a direct route from his place to Adelaide, lol

[Superscan811]

Hmmm....

I think you pair might be be having a bit of a go at me, but not too sure...

Anyway, I picked up my M8 head yesterday but it requires a bit more porting work, now the larger valve seats are in.


Once I finish porting it, I'll lap the valves in ant then it will be ready to put in the ute.

Cheers.

[A112H]

Hmmm....

I think you pair might be be having a bit of a go at me, but not too sure...

Cheers.

I think I can safely speak for Cheater and myself in saying I have no idea what you are talking about good Sir.

[Superscan811]

For some reason, I doubt that good Sir...


Anyway, today I finished removing the extra aluminium around the bottom of the valve seats and smoothed the internal radii a bit, so tomorrow there will be a bit more of a tidy up around the valve seats and then out with the old, in with the new.

Pics to follow tomorrow.

Cheers.

[Superscan811]

Only a little bit of work has been done but I expect to have it running tomorrow.

The M8 head I was preparing was thoroughly stuffed by the shop so I shall have to run with the existing head for now.

On the good side, I've removed all the studs and used socket headed cap screws instead, the manifold is on, the vacuum lines are almost finished, the fuel pump and pressure regulator are mounted.



Things to do tomorrow.

1. Wire in the fuel pump.
2. Re-plumb the heater hoses.
3. Finish the vacuum lines.
4. Modify the throttle cable and add a TPS.
5. Wire in the data logger.
6. Take it for a test flog...

Cheers.

[Superscan811]

Forgot to add, modify Fuel Pressure Regulator for the lower pressure required by these carbs.

I use the "Holley" style low pressure regulator because they are easy to modify.




Remove the 4 bolts and you have this.




What you want to do is "squash" the spring about 5mm.


From this



to this.




The tricky bit is to keep the spring ends still flat AND don't flatten the larger coils, as these are required to give you the fine adjustment.

First thing, check, before modifying the spring, is whether the FPR will work properly. It's easy, just remove the cap, with the spring and diaphragm it, plumb the body in and turn on the fuel pump. Without the cap there should be NO fuel, not even a slow drip, coming from the unit. If there is, take it back.

This is one of the things that hamstrung me today.

After squashing the spring, dummy assemble the regulator and check that the spring is just slightly loose in the housing. If it is, you should easily be able to adjust down to 1/2psi.




Cheers.

[DriveBy]

Should work well, a lip on the runners to attach the carbs using their factory bike joiners will be far better than just hose. My Honda I converted from EFI to R1 carbs worked out far more fuel efficient, HP and delivery were massively improved. also the guy who previously owned my GE put the 4g52 on GSXR carbs and that worked very well too apparently.

Look forward to seeing the fruits of your labour

[geezer101]

Nice work as always Superscan. Welding the die cast thermostat housing onto your manifold must've been tricky - die cast really hates being welded. I'd really like to have a shot at building an engine with quad carbies one day...

[Superscan811]

Should work well, a lip on the runners to attach the carbs using their factory bike joiners will be far better than just hose.

Too true, but this is just for my daily drive, a twincab ute.
Fuel economy is what I'm mainly chasing along with some HP gain.

My Honda I converted from EFI to R1 carbs worked out far more fuel efficient, HP and delivery were massively improved. also the guy who previously owned my GE put the 4g52 on GSXR carbs and that worked very well too apparently.

I had a set of 38mm GSX 750 carbs on my 4G54 and was able to make over 133hp at the rear wheels (approx 180hp at the flywheel). They do work well.

Look forward to seeing the fruits of your labour

Me too.

Nice work as always Superscan.

Thanks..

Welding the die cast thermostat housing onto your manifold must've been tricky - die cast really hates being welded.

My MIG has a "Clean Width" adjustment which you wind right up when welding die-cast. It balls the electrode very quickly but gets the job done.

I'd really like to have a shot at building an engine with quad carbies one day...

Just do it. You'll enjoy the difference.


Cheers.

[Superscan811]

Well they are on and running.

Just require a bit of tuning, along with some pod filters..



My throttle position sensor and cable adaptor work well. There is 70mm of pedal travel but the carbs only need 25mm of travel plus the TPS will only move 1/3 of a turn.



BTW: the big canister behind the TPS is a bypass oil filter.


Cheers.

[75wagon]

Why don't you spend some time cleaning your engine bay while the carbs are off?

[Superscan811]

It's all about the "GO", not the "SHOW".

Cheers.

[DriveBy]

Worth mentioning another easy way for coping with the difference in throttle cable travel is to just move the pedal attachment closer to the pivot point reducucing the throw.

Can't wait to see these in action as the previous owner of my sig said they worked incredibly well. Post a vid soon man

[Superscan811]

Worth mentioning another easy way for coping with the difference in throttle cable travel is to just move the pedal attachment closer to the pivot point reducucing the throw.

I did that to my Sigma wagon but it made light throttle control a bit more difficult and the accelerator pedal was too close to the floor to effectively "brake/accelerate" on hill starts etc.

Can't wait to see these in action as the previous owner of my sig said they worked incredibly well. Post a vid soon man

Will do.



Cheers.

[A112H]

So I am guessing you have time to knock up a second set before coming to SA and will have time to fit and tune to a Scorpion??

[Superscan811]

So I am guessing you have time to knock up a second set before coming to SA and will have time to fit and tune to a Scorpion??

Probably not.



I've been having an issue with the carbs running rich from just off idle to 25% throttle (cruising and general city driving), but I have finally figured out why.

The problem is the motorbike carbs don't suck like a normal carb do, both figuratively and literally ..

On light throttle, below 30%, you usually have quite a bit of vacuum, but because the 40mm motorbike carbs aren't as restrictive as the standard carb, the vacuum drops off enough that all vacuum advance immediately disappears when you touch the throttle. Didn't have this problem with the 38mm motorbike carbs but the 11% difference in flow is just enough to be an issue now.

When the AFR is lean, it requires a lot more time to burn, hence the use of vacuum advance. With no advance, the majority of the fuel is still burning as it's going out the exhaust, causing a very rich reading. Because the burning fuel hadn't reached peak pressure before TDC, most of the power is also going out the exhaust.

Since the majority of driving is done on light throttle, the fuel economy will be crap..

The answer is trying to find a "SOFT" vacuum advance or using a programmable ignition unit, like the MegaJolt Lite Jr.

While I would prefer to use the "Old School" vacuum advance unit, the ute needs to be up and running efficiently ASAP, so out with the dizzy, in with the EDIS and CDI and Programmable ignition unit...

Updates to follow shortly.



Cheers.

[Superscan811]

Just so you get a better idea




Green is AFR
Dark Blue is vacuum
Light blue is RPM
Red is Throttle position


Cheers.

[DriveBy]

Can't you improve it with a small vac take off from each runner into a small vac reservoir cannister? Were the carbs rejetted to suit the car application?

[Superscan811]

Can't you improve it with a small vac take off from each runner into a small vac reservoir cannister?

I'm currently running the vacuum off all runners, but the pulse is still too low..

Were the carbs rejetted to suit the car application?

That's what I've been doing. The pilot jets are the smallest availiable (0.3mm) and I have the largest air correction jet (2.4mm) but it's not the fueling that's the issue, just the amount of advance on light throttle, which is currently zero.

At 7% throttle I have approx 75% atmosphere, and at 15% throttle, its almost 95% atmosphere, both are way too low, to activate the standard vacuum advance canister.

From the factory manual, I've come up with a base timing map for the TPS. Hope it works..





Cheers.

[Superscan811]

Installed the EDIS pulley I bought a while ago but had to remove it, because the the teeth were off center by 2.5mm, not a lot, but it's enough to cause the pickup some major issues.

Took it off, put it in the lathe and trued it up.

Back on and the pickup installed.


Another issue is the fan is a bit too close to the back of the pickup, and I haven't put on the plug yet..


I'll modify the plate tomorrow but then there is the issue of what do I run with.

Standard Ford coil pack, Coil on Plug, CDI and Ford coil pack.




Tried the Magna dizzy yesterday, because it has 2 vacuum ports on the canister and I thought it might work but no luck.

FYI: this is how I "adapt" the dizzy.
I use a 10mm piece of aluminium (because it was there and it already had one hole in it ).
Put a couple of washers between the plate and the head, to space out the plate out to the same height as the dizzy.
Make plate long enough to turn the dizzy approx 1/4 of a turn.
Grab a spare 8mm nut, bolt and some washers.
Nip everything up and then time it.
DONE








Cheers.

[Superscan811]

Not much progress today but at least the wiring harness is finished.

FFR (for future reference). DO NOT space the fan closer to the radiator..

I made up a spacer to move the fan out approx 20mm towards the radiator. It left 20mm between the blades and the radiator BUT when I revved the engine, the plastic blades flexed enough to hit the bottom cap, which then propelled them into the core.

It has JUST holed the core but it is still salvageable. I have clipped the edges of the blades and this seems to have fixed this problem..


Anybody have a spare 4cyl Triton or Pajero radiator???


Cheers.



EDIT....

The reason for lack of progress was the Megajolt I purchased a while ago only had the components for a MAP sensor so I had to do a bit of a mod to it so it would work with a TPS..

It's working now so it should be installed tomorrow.



Cheers..

[damian]

one very talented madman in our midst

[A112H]

[Superscan811]

one very talented madman in our midst

Talented, not so much.

Madman

The "cough, cough", standard Ford EDIS system, is in and working, the midrange is dramatically improved.

Will need to modify the the ignition map a bit for the cruise advance but it's a lot better than it was.




BTW: Cost involved in doing a fully programmable ignition system is around $500.

The 2nd hand Ford EDIS components cost $100 delivered.
The Megajolt (programmable ignition unit) cost $200 delivered.
Miscellaneous cable, machining, and other bits and pieces, $200





Cheers.

[DriveBy]

Great to see so much progress! hope my suggestions don't sound infuriating. Just trying to think of the bugs I had to iron out.

My vac take off was a 5mm in #4 runner near the head 5mm bore pipe feeding the brake servo with a 2mm T off 4 inches from the runner. Vacuum pulse was a little OTT with closed throttle at idle but worked well on the move. Addition of a small cannister (even an inline fuel filter was big enough) reduced the pulse but maintained the vacuum.





If it helps good if it doesn't just ignore me

[geezer101]

Nice set up you've got there DriveBy. Looks like you were using vertical carbs off a newer GSX-R? The manifold is a very tidy bit of fabrication work. p.s. - Superscan, why didn't you eliminate the pump mounted fan? They work back to front on an engine! (needs to be spinning faster at idle to maintain air flow and not needed while cruising under normal conditions...)

[Superscan811]

Nice set up you've got there DriveBy

+1

Hopefully my welding skills will get that neat one day..

My vac take off was a 5mm in #4 runner near the head 5mm bore pipe feeding the brake servo with a 2mm T off 4 inches from the runner. Vacuum pulse was a little OTT with closed throttle at idle but worked well on the move. Addition of a small cannister (even an inline fuel filter was big enough) reduced the pulse but maintained the vacuum.

If it helps good if it doesn't just ignore me

All information is good especially since I have a few sets of those carbs as well..

The Megajolt works well with my TPS and it's relatively easy to set up. The ignition map v Throttle position (load points) takes a bit to wrap your head around, but now I have a better idea with what is going on, I have a spreadsheet to do the rough calculations.

Input total mechanical advance, total vacuum advance, max RPM, and now, at what RPM the mechanical max's out, it then spits out a 10x10 ignition map.

I tried the 35º total advance today. There was a bit of detonation around 2800-4000 under full load, but the carbs were running a bit lean, around 14:1 AFR, on wide open throttle. All the other areas seemed to work ok except for a fair bit of popping when backing off and idling.


A bit more tinkering and probably 2 sizes up in the main jets and all will be good. Currently running 152.5 Mains but may have to go to a 157.5 or possibly a 160.

Engine response is a lot better, even for a stock clunker with over 300K on the clock.

Superscan, why didn't you eliminate the pump mounted fan? They work back to front on an engine! (needs to be spinning faster at idle to maintain air flow and not needed while cruising under normal conditions...)

Was waiting for this Ebay auction for a 16 INCH THERMO FAN & THERMAL SWITCH to finish.




Cheers.