Fuel pump for turbo

[Wheelie]

I'm setting up my turbo on the '80 GS1000. The original fuel pump and regulator are missing. I was wondering what size pump to get. The turbo is a draw through carb set-up. It will be running at 10 psi max.
I found a few pumps that seem to be in the ballpark. One runs 18 gallons per hour at 5.5 psi, another is 35 gph at 7 psi and the third is 42 gph at 4 psi.
Any of these sound like they'll do the job?

Steve

[Big_T_111]

Pump

My kit pump made 5 psi which is only good up to 15 pounds of boost. It came with the Mr. Turbo draw through kit. It's just a small automotive type pump. Be careful what pump you use or it will push the needle off the seat and flood the bike. I run over 20 pounds (race gas) so I got a blue Holley pump and put a regulator on it. Worked really well. If you are not going to make over 10-11 pounds of boost and just run pump gas I would still put one of the cheap Auto Dial regulators on it and set it for 4 pounds.

[Wheelie]

Thank you Big T.
I'll get the 7 psi pump and a regulator. Sounds like a better idea than relying on the regulator in the pump.

Steve

[lecroy]

It's not only the pressure, but the flow rate you need to spec. A pump that can reach a dead head pressure of 7 PSI but can only flow 1GPH is not a good choice. Start by looking at how much HP you plan to make then size the pump.

Carb will be another factor when selecting the pump. I am currently using a Mikuni HSR-42. You have to change the needle and seat to make it hold 7PSI. It has much less surface area and can't flow as much as the stock parts for a given pressure.

I check the flow rates by putting a graduated cylinder under the HSR's drain. I measure how much flow in 10 seconds. When I calculated the flow I needed I padded it by 30% just to make sure it would never go lean.

[Wheelie]

O.K., so who knows how much horsepower I'll make with an '79 GS1000 motor in stock trim with a turbo at 5-7 pounds of boost? And then, how do you calculate fuel requirements?

Thanks
Steve

[lecroy]

What carb?

[Big_T_111]

Turbo H.p.

5 to 7 pounds of boost expect around 120 ish or so H.P. at the wheels. My Kaw 1000 made 160 at the wheel at 15 pounds of boost. It was a 8 valve motor similar to the 8 valve suzuki. The 16 valve 1100/1150 really like the turbo and produce good HP. What you don't want is to suck the fuel bowl dry on extended high speed runs. This will cause a lean condition and a melt down will follw. But if you keep the boost under 15 pounds then a nice 5 to 7 pound pump with regulator should work for you. If I remember right after 8 pounds of boost every 1 pound more of boost was about 7 HP. It's been a while so I may be off on that some.

[Wheelie]

Carb is a Keihin 42mm butterfly.

[lecroy]

My favorite carb. to chop up. Yours may have been the original carb that came with the kit. These took very low pressures, more like 3 PSI. They had a much larger needle and seat and could get away with it.

When I bought my kit new in the early 80's, it came with three different main jets for this carbb, each with a different color code on it. You would just pick the color for the amount of boost you planned to run. This is going way back. My kit came with a RaJay FF40 turbo. The fuel pump was a small pulse type and it also had a dial type regulator. The pump was made by P&R and was called a Handi Pump. The regulator was made by CR. They were similar to these:

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2005660/p-2005660/N-111+10101+4294966549/c-10101

http://www.jcwhitney.com/autoparts/Product/tf-Browse/s-10101/Pr-p_Product.CATENTRY_ID:2011023/p-2011023/N-111+10201+600002063/c-10101

I used to run this system on a stock GS1100. I had a little tank in the rear of the bike mounted to the license plate bracket. You would fill this with a mix of water and methanol. There was a little pop off valve that was fed from the manifold so once you got above a certain boost pressure the tank would see that pressure and force the mix into the carbs inlet. It all came from Mr. Turbo. I think the limit was about 7 PSI on pump gas of the day, without this.

Hope this helps.

[Wheelie]

I just picked up both those pieces from Auto Zone with the Mr. Gasket labels on them. I wonder which Chinese company makes them.

I'm not sure what model my turbo is because when Mr.Turbo rebuilt it they lost the tag. They said it was small for a 1000, would be better on a 750. The notes I have from talking to them say it should be able to produce about 10 pounds of boost max on the 1000 and run out of steam when the motor hits 9000 rpm.

So it sounds like I have a viable pump and regulator. Any suggestions on jet sizes for the carb?

Thanks
Steve

[lecroy]

What brand is the turbocharger?

If Terry say's it's small for a 1000cc and it's a RaJay, it must be a BB or FB something. If it is you need to be careful that you don't over speed it.

To tell you the truth, I was running methanol thru that carb (or attempting to). I gave up and went back to gasoline and switched to the Mikuni at the same time. No looking back.

I am not even sure what the stock sizes were any more. My guess it that who ever had the bike had it set close. Just start there and get a reading.

[Big_T_111]

carb

I used a Mikuni HSR 42 on mine with a 230 main jet. A Honda XR650L CV carb with a 220 main jet worked well also. I also used a Carb from a sportster but I just drilled the main jet on it and shimmed the needle and tried matching the 230. The two CV carbs offered excellent throttle delivery but limited HP at higher boost.

[lecroy]

I used a Mikuni HSR 42 on mine with a 230 main jet. A Honda XR650L CV carb with a 220 main jet worked well also. I also used a Carb from a sportster but I just drilled the main jet on it and shimmed the needle and tried matching the 230. The two CV carbs offered excellent throttle delivery but limited HP at higher boost.

That's a problem with the HSR too. They don't make big enough jets for it.

I was drilling jets up to 0.127" dia. The walls were paper thin. Then I gave up on Torco fuel and switched to VP. I think I am close to 0.108" dia. now. Seems fine so far but I have not been able to get over 16 PSI boost yet so the bike is still pretty tame.

Just make sure that it stays rich, or get ready to open your wallet. When you do get it out for the first time, just make short runs with it. Start at 100' and keep working your way out further, checking the plugs between runs. Hard to believe you would have problems at 7PSI, but it's cheaper to take small steps.

[madjack57754]

I'm (or was, a sad story chronicled here in the gsr forum) running a 44mm mikuni snowmobile round slide smoothbore with e/f40 hybrid rayjay housings. Easy to tune and cheap. usually under $30 on fleebay