Vieux Rouge

[Joseph]

Right. As from the other day I parted ways with my Katana and obtained the beast of a slabside known as Ol' Red 

I am new to slabbies, and obviously am new to turbocharged oil boilers.

And this bike needs a few mods to be ridden in France.

Questions and stuff will be posted here.

[Joseph]

First off. Here is a zone that needs my attention, mainly for the addition of a full exhaust system.

So here we run into a bit of interference.

Questions :

- the scavenge pump obviously needs to go. I will make up a plate and put it like it is but other side of the frame. I'm guessing it's best if it is low down ?

- i'm guessing that braided line near the exhaust is the oil feed to the turbo. That needs to be fitted with a 90° bend, because i want it to run inside the frame closer to the engine and away from the exhaust. Would this be made with just the same stuff as brake lines ? I can just use any compatible fitting on it ?

- fuel related question : i'm going to renew all the lines, they are getting a bit past it. The bike has a fuel pump and Malpassi regulator, with 10mm diameter lines throughout. Could 8mm be used, or would that hinder fuel flow too much ?

Dealing with the cheap and easy stuff first

Thanks

[clivegto]

Yea it's best if the oil pump can be lower then the turbo. Brake line stuff is OK for turbo oil feed there will probably be a reducer of about 1mm in the oil feed banjo bolt. Don't use thin 8mm pipe internal dimension wants to be at least 8mm thin pipe will cause you all sorts of problems. 

[Joseph]

Cool. I will get on with those points. It's currently fitted with automobile fuel hose, i'll stick with 10mm i suppose it's best to use the thicker wall stuffed with a pressure fed fuel system

[clivegto]

Had no problems with the ones in the picture & when I have looked at the pipe it is closer to 8mm id. Did have a cheaper one split in the past squirting fuel all over the back wheel. I was lucky to stay on the bike shal we say 

[Paulm]

Make sure none of the fuel or  fuel return pipes are kinked when you fit them and definitely braided or reinforced as my good friend Clive has already said,my scavenge pump is mounted on a plate at the rear of the engine on my GS750 Turbo build,works fine there and may help you for space with the exhaust.Take a pic of where all the fuel lines go as well.

Edited December 19, 2021 by Paulm

[Joseph]

Having this system to work on reminds of the very few couple of "modern" FI bikes (ZX12R and K4 1000) and the fuel lines on them are not made of drinking straws 

But although i have had it running the order of how it the fuel system is plumbed in makes me wonder if there is not a bit of a mix up.

I'll whip the tank off and take a couple of pics

[Joseph]

Right so here is whats what when i got the bike. (Bearing in mind it was a non runner, and Viz just put it back together just bolted up because of a house move.)

I put fuel in, ign on, fuel pump whirring but would not start.

I ended up working out that the pump was wired in reverse, making it not suck from the tank but blow into it. So I swapped it over and then had a shower of fuel under the tank because the return line wasn't tightened  After that the bike started fine.

Now unless I've got things badly mistaken about how turbo bikes are fed, this seemed wrong.

 

Only thing is, the pump terminals were not the same size screw, so you can't swap over the ring terminals ?

 

Other than that, here is plumbing list in it's current order :

Petcock on PRI > Inline fuel tap > electric pump > Brass T connector : one end of T goes straight to carbs, the other end goes to the fuel pressure regulatore > Return line plugs into the filler cap drain pipe under the tank that has been cut off

The T piece jobby seems weird ? Surely it should be :

Fuel pump > Regulator > One line to the carbs, one line back to tank 

?

[Paulm]

My fuel reg is as your last statement

[Arttu]

Both versions should work the same. If a regulator has multiple pressure side connections they usually are going into the same space inside the regulator. So effectively the same than a T before the regulator.

[Joseph]

But in my case it looks like the FPR has no influence on the carbs since the fuel feed to the carbs doesn't transit via the FPR. 

If the T at the pump exit has one line straight to the carbs and one to a FPR that then goes to the return in tank, surely the carbs are getting full pressure ?

[Arttu]

Nope. The regulator works by bleeding excess fuel to the return so everything between the pump and regulator stays at regulated pressure. Even if there are multiple pressure ports on pressure side of the regulator there are no specific inputs or outputs. All of them are just ports to the pressure side of the regulator.

In some cases there might be minor differences in resulting pressure depending how you route the lines, through the regulator or from T before it. That's because of pressure drop in the lines. But usually that difference is neglible.

[Joseph]

Despite your explanations I don't understand why my system is fitted like this :

 

 

Edited December 21, 2021 by Joseph

[Joseph]

Need to check what Malpassi model i have. But the way this is set up seems to make sense :

[clivegto]

44 minutes ago, Joseph said:

Need to check what Malpassi model i have. But the way this is set up seems to make sense :

That's the same as I have on my turbo bikes. 

[Arttu]

3 hours ago, Joseph said:

Despite your explanations I don't understand why my system is fitted like this :

 

 

Like said, that works the same than if feed to the carbs would go through the regulator. A return style regulator keeps the whole pressurized system after the pump at the same pressure. In that regulator picture both "high fuel pressure in" and "to carburettor" connections go to the same chamber so that second connection is essentially just a T piece that is integrated into the regulator body. (Disclaimer: haven't checked exactly that Malpassi regulator but all the return style regulators that I have seen are that way).

So if the regulator works like it should there isn't any "high pressure" anywhere in your fuel system. The highest is what the regulator is set to.

[Joseph]

Hmm, right, i see what you're getting at but i think that while i am renewing the lines i might as well plumb the system as per the regulator instructions and see how that goes. 

[Arttu]

Yep, definitely shouldn't hurt doing it that way. My main point was that there shouldn't be any fundamental problem with your current setup either.

[clivegto]

A long time ago I put the return pipe to the carbs and the carb feed to the tank. Every time I opened the throttle it starved the carbs of fuel causing engine to shut down, as soon as I shut throttle away it went again. Live and learn lol.  

[Joseph]

Hehe. So basically this fuel setup is kind of verging on a fuel injection feed system, sort of ?

[Joseph]

Right, i've been using it some, and have now experienced what had been mentioned as top end fueling issues.

Open wide and it goes ratatatata and doesn't pick up smoothly.

If you nurse it gradually, opening, pulling back a slight bit, then opening a bit more, pulling back a bit, etc power/speed goes up and up and up no problem.

As if the carb bowls were getting emptied in a blink when opening the throttle fully ?

[clivegto]

So what is the fuel pressure set at ? 

[Joseph]

No gauge, no idea ? 

[clivegto]

7 hours ago, Joseph said:

No gauge, no idea ? 

Best get one then. 

[Joseph]

Yes and a turbo pressure one as well could be useful. Is there a benchmark fuel pressure level these turbo bikes seem to need ?