GS1000G mods- big bore and fuel injection

[willie]

Personally, I'm very impressed with all you've done on this project. I wish you the best of luck and will continue to follow your progress. I'm really looking forward to learning how it turns out.
Willie

[GS1000G Shopper]

It looks like a simple solution is at hand for the fuel fitting at the tank. After drilling & tapping the junk GSX-G fitting I had, the fittings would hit the GS airbox, which I hope to retain. Since barbed fittings are all that is needed here, and the GSX-G has these fittings, it looks like the GSX-G piece could be used. The trick is to find 5/16 hose wityh a 90 degree bend. When I looked at the old hoses I pulled off my GSX-G project, one has two 90 degree bends and could be cut in half.

I did confirm that the GSX-G fitting with the tube re-bent will bolt up to the GS tank. It's a little taller than the GS feed fitting, so it will be excellent for a return line.

Here is a picture of the part with the added part numbers, all of which are available. They are about $70 or so from the looks of things. The "gasket" is the circular one for the bolt, not the one between the tank & fitting.

[GS1000G Shopper]

I pulled the airbox from the bike today and no surprise, the boots line up perfectly with the throttle bodies. The bad news is the boots are way too large for the throttle bodies. If you reverse the boots, they are a decent fit, but too long. They could possibly be trimmed, but they are also pretty hard due to age, so I'm thinking a plan B is needed. I need to find out the airbox opening diameter of the GSXR600. If it is the same or close to the GS1000, they would likely work as-is. The TB OD is 45mm. The airbox opening is about 52mm+. Here are some test fit pics:

Stock position:


Reversed:





I'm also looking into re-wiring the fuse panel area, as the MS needs several fuses and relays. I found a relatively small (about 3.5" x 4.5") rear terminal panel at Waytek Wire (Bussmann 15303-2-2-4) that allows the use of several relays and 10 fused circuits. From what I can tell, it does not have a common or split bus design like some of their other panels (I have one on my 1975 280Z and 1988 Toyota Supra). A split bus is ideal for circuits that need battery power and others that need switched power. I can overcome this by wiring the terminals to create a bus, just a little more work.

The GS1000G has a steel plate that houses the fuse box, ignitor, and starter solenoid. I took it all apart today and used a cardboard template. The ignitor has a good bit of extra wiring, so I think it can be relocated.

To assess the idea, I cut out a piece of cardboard larger than the plate and marked an area where the fuse panel would be located. Allowing room for the solenoid, it appears I'll be able to use 3 of the 4 fuse panel mounting points. The GS uses a tab in the plate to hold it in place on the bottom. I won't be able to use this as the fuse panel will be in that area, but it looks like I can add a short piece of angle to the slot in the battery tray and extend the mounting point away from the panel. There is a good bit more work to do here, and of course I need to have a panel in hand to try it.

Here's a pic of the old plate with the solenoid and ignitor:

[GS1000G Shopper]

I have cleaned the airbox but it looks like I won't be able to find boots that go from 52mm to 45mm. An eBay seller was kind enough to measure his GSXR600 airbox and the opening are 45mm.

There are at least two things I can do here. One is to run pod air filters. I don't like this idea for two reasons- it takes away from the stock appearance, plus operationally I need to mount an intake air temp sensor. Using pods, I could only get the temp from one pod. I'd also have to plumb in a line to the breather.

The second option seems overly simple, but is more appealing. Reading about silicone hose, the 1.75" ID (45mm) hose is a little over 2" OD. Measuring the openings in the airbox, I get about 2.06". It looks like I can simply get a foot of the silicone hose and cut it into 4 pieces the same length as the GS1000 boots, run each one into the airbox, and then install the airbox, clamping the inside hoses first and the outer ones last. The boots on there now are not 100% sealing, so this would actually be an improvement. I bought a set of used clamps for the GSXR600 airbox boots.

I'm also looking at how to mount the air temp sensor on the GS1000 airbox. I'll likely weld on a small piece of steel and tap it for 3/8 pipe so I can use the GM sensor.

After reading descriptions of the fuse panels, I ended up buying the 15303-6-2-4, which has a buss on the relay side only. I need to have the fuses split onto 3 busses. I found an old panel from a GM truck leftover from an older project that is loaded with mini fuses and mini & micro relays, so that part will not be an expense.

The GS1000 fuse box connector is easy to take apart and replace with better quality wires. I did so on my blue bike after it arrived due to a green fuse for the headlight. It is using two ATC type fuse panels of 4 circuits each. The ATM style I'm planning here will be a much better setup.

I drew up the 15303-6-2-4 panel and applied it to what I'm doing:

[Big T]

3rd possibility, a 79 GS 850 airbox

[GS1000G Shopper]

Are the openings smaller? My airbox is ambiguous- it is stamped GS1000G on one side, and on the other GS750 GS850 DGM31773S GS850G DGM355854S

If this can be confirmed, or if the 850 uses smaller boots at the carb, that may be an easier path.

EDIT
Various part numbers, all show as current:

1979 GS850G boots
HOSE AIR CLEANE
13728-45010


1981 GS1000G boots
HOSE RH
13881-45050

HOSE LH
13882-45050


1981 GS850G boots
HOSE RH
13881-45030

HOSE LH
13882-45030

eBay auction info:

APPROXIMATE DIMENSIONS FOR REFERENCE:

LENGTH: 58mm

I.D. AIR BOX END: 47mm

I.D. CARBURETOR END: 54mm (too big)

FITS YEAR/MAKE/MODEL :

1982-1983 Suzuki GS850G

1981-1983 Suzuki GS850GL


CONDITION:New


SUZUKI PART # :

13881-49070 x4 (Boots)

APPROXIMATE DIMENSIONS FOR REFERENCE:

LENGTH: 65mm

I.D. AIR-BOX END: 40mm

I.D. CARBURETOR END: 43mm (may stretch 2mm)

FITS YEAR/MAKE/MODEL :

1977-1979 Suzuki GS750 (Standard)

1979 Suzuki GS750L

1979 Suzuki GS850G


CONDITION:New


SUZUKI PART # :

13728-45010 x4 (Boots)

[GS1000G Shopper]

After doing a lot of reading about fuel pumps, it looks like the Walbro inline model GSL414 may be a winner, although expensive at $155. I'm attaching a flow/current graph for it. At around 40 PSI, it is only drawing 3 amps and flowing about 29 gallons/hour (GPH).

I also looked into some OEM fitments using 80's model cars such as the Honda Civic- which was how I got the thermostat and fuel pump for the Sabre. According to the listings, a 1985 Civic had a fuel injected motor and used an inline pump. The Walbro # is GCL616, and it is rated for 121 liters/hour (LPH, which equals 32 GPH) at 45 PSI. It is more reasonable at $110. No current chart was available. The GSL414 at 32 GPH is drawing about 4 amps, so I'd say they likely draw the same current.

EDIT
I found this writeup on another forum, and the builder is converting a 1975 GT250 bike to FI and using the GSL414 pump.

Updating the fuel pump info, I found a page (PDF) from Bosch that shows their pump data. The lowest amp (maximum) rating is 5.2 amps for the "911" pump- people refer to the Bosch pumps by the last 3 digits. The 044 pump is popular, but is a very high output pump and rated at 15.5 amps. The 070 pump is rated at 6.5 amps and 3 bar (pressure) and has 3/8 x 5/16 inlet/outlets. 3 bar is 43 PSI, so it may be too power-hungry for this application. The 911 pump is rated at 5.2 amps and 4 bar, so it may be within range, but would require adapter fittings, as it has a 1/2" barb inlet x 12x1.5 outlet fittings. Still looking for some actual test data for amp draw.

UPDATE
I found a page where a fellow has designed a pulse width modulation control circuit for a low-amp fuel pump (he used one from a GSXR600). The big advantage here is it works on a returnless system, just like the GS uses, so you can keep the petcock. The idea is it powers the pump to maintain a set pressure, which is sensed via an OEM type sensor. His page looks fairly detailed. I plan to inquire as to the cost of a completed board. Here is his high level graphic of how it works:


I found a price of $50 elsewhere on his site. The pressure sensors he references are not cheap. The least I could find one for was around $30. I'm not too sure about using an in-tank pump externally. He mentioned possible pump heating problems above 90 degrees. Being in Florida, that's like 10 months of the year.

I will likely stick with plan A.

[GS1000G Shopper]

More fuel math. I used the RC Engineering technical notes/sizing page to do some calculating, I recall using it in the past to size injectors for my Trans Am- which was the opposite of what I'm doing here- it has a 383 CID turbocharged motor, high pressure fuel pump, and an MSD boost-a-pump that increases voltage under boost.

The known factors for the GSXR600 system so far is 43 PSI and 39 gallons/hour (148 LPH) for the pump. From what I have read, the injectors are in the range of 225~240cc/minute at 43 PSI.

According to the RC page, to get 90 HP out of my 4 cylinder engine, I only need 149cc/m injectors at 43 PSI. Since the GSXR600 ones are much higher than this, I do not need to run the pressure as high to obtain the desired output. Lower pressure= less amps drawn by the pump (this is likely why other conversions have used 5 amp+ pumps and still worked). Using the RC page, to get 150cc/m out of my 225~240cc/m injectors, I only need to run about 17~20 PSI ideally. Allowing for variables, it looks like I can operate on under 30 PSI OK. Injector timing will be performed by the MS, and fuel pressure regulated by a regulator.

[GS1000G Shopper]

Next discovery: Fast idle
I was reading through some older FI threads here, and one problem was a lack of a fast idle for warmup. I noted the GSXR600 has a cable and linkage that operates much like a choke- except all it does is tweak the throttle open slightly via a cam on the linkage. The shop manual says it will raise the RPM from 1,300 to 3,000. It appears it may interface with the GS1000G choke cable, but I have not pulled the cable yet. My throttle bodies were complete with the linkage and short cable.

[ArttuH]

I wouldn't go too low on fuel pressure. The injectors need pressure for proper fuel atomization. I think sensible lower limit would be something like 37 psi.

The fast idle mechanism on GSXR600 TBs should work fine with choke lever and cable. I'm using the stock choke lever for that but I can't recall if I used stock cable or if I made new one. Not a big deal any ways.

[GS1000G Shopper]

I will likely stay around 40 PSI then, and allow the MS to adjust the duty cycle to get the proper amount. I added a wiring page for the PWM pump control, and will post it later. If I go that route, I'll likely use one of the AEM sensors since they are pipe thread. I've not heard back from the guy whose site that is on, so he may no longer offer it.

I won the engine removal battle today. I just can't understand why the intelligent people that designed these bikes cannot leave another 1/2" or so around the engine. For a while, I was wondering if the GS was a disposable bike, kind of like the Chevy Vega back in the day- save the oil & change the car. No free lunch- while the carbs are easier to R&R as compared to a Honda V4, the engine is not. When it goes back in, the head will not be on it.

I did hear back from Pit Stop Performance in Orlando. I did some research and the shop is well-liked in the KZ world, and he works on the GS as well. Prices seem reasonable, so I'll be shipping parts to him soon.

The last local machine shop I called here literally laughed when I said I had a 30 year old Suzuki engine I needed bored & a valve job. Great way to get business in what some think is a recession- I guess they are not one of the businesses that think that way, or need any new business. They are apparently out standing in their field:

[john82q]

Watching with interest gs shopper

The PWM pump control sounds like great idea if you can make it work, less plumbing , and less electrical power requirement, win win.

John

[GS1000G Shopper]

The McMaster order arrived today, and like most things some good and bad:
The stainless all thread worked well. I installed it, marked it, and cut it to length.

The 13mm x 6mm spacers worked great. UPDATE- these need to be 19mm with the center linkage.

The secondary shaft openings are different sizes on some of the TB units, so the 1/8 pipe plugs will not work on all of them. I'll need to find some plugs I can press into them.

I also read about a Honda TRX700 fuel injection pump. Seems some Suzuki quad owners don't like paying $300 for a fuel pump, and found the Honda one can be made to interchange with theirs and is less than $100 new. I have to do some more research on it, but it is a candidate for this project.

[GS1000G Shopper]

PWM pump control research-

PWM-1: Another guy that made a controller. It looks like he may have sold it at one time, but nothing is listed for sale. He has a good writeup about the advantages of PWM for controlling DC motors such as fuel pumps. The same principle he lists for a 600 HP V8 would apply to a 90 HP inline 4. His wiring diagram is poor quality (low resolution).

More good reading here:
VaporWorx Electronic Fuel Pump Speed Control Systems

They are talking about late model V8 engines and 5 PSI fuel pressure, but the principle should be the same for smaller engines and lower pressure. I noted they claimed:
Another feature of PWM control is the reduction in the electrical requirement. For example, the 5th-generation pump requires 10 amps to run at full speed at 58psi. At cruise the PWM systems requires approximately 2-3 amps. This reduction in power also means greater alternator life.

I have PWM fan controllers on some of my project cars that use large electric fans such as the Lincoln Mark 8. These work really well, as the fan would normally spike huge amps to start. PWM allows them to "soft-start" and avoid the amps. One of these may be adaptable, using pressure as the input vs. temperature. These would be huge overkill for a <5A fuel pump, as they are designed to run 60A fans.

There is a lot of information on this, but not so many products. I'm sure I'll be able to find a few given time.

I find it interesting how a relatively inexpensive circuit ends up costing nearly $400:
Weldon fuel pump controller

Fuel on demand module


My minifuse panel just arrived, and looks like it will do the trick. I didn't realize that the unused relay sockets can be used for fuse circuits, so this will cut down or eliminate the need for inline fuses.

[GS1000G Shopper]

Some more pics:

New 73.5mm pistons:



Not a job I'd like to do everyday:






New Bussmann fuse panel, cardboard template and sheet metal template (still waiting on 8"x8"x.125" aluminum):






The side cover fits in place with no problem.