Jump to content

Malpassi regulator question


Recommended Posts

Hi, I'm using a stock malpassi regulator for my turbo. I turned the screw in until it hit the spring, and then added a quarter. my pressure gauge reads 0 psi at idle, however I get an almost perfect 12.5 afr all the way through 8 psi of boost. 

I've read some people cut their springs, and that idle psi should be 1.5 to 2. My question is if anyone else has theirs at 0 idle psi without issue, because if not I must be getting fuel from somewhere I shouldn't, or maybe having a choke issue? Thanks.

Edited by rerb
Link to comment
  • rerb changed the title to Malpassi regulator question

Idle pressure can be whatever the carbs can tolerate without overflowing!. 1 - 2psi is reckoned to be about right to obviate vagaries of gravity / atmospheric pressure delivery. Takes a good gauge to read accurately at very low pressures. 

Link to comment
1 hour ago, Gixer1460 said:

Idle pressure can be whatever the carbs can tolerate without overflowing!. 1 - 2psi is reckoned to be about right to obviate vagaries of gravity / atmospheric pressure delivery. Takes a good gauge to read accurately at very low pressures. 

That might be it. My gauge reads to 80 PSI and is a basic marshal one. Definitely looking into EFI conversion, these carbs are getting annoying :S

Link to comment
12 hours ago, Gixer1460 said:

Joking aside - EFI for all its complexity is Soooooo much easier to work with on boosted engines - I wouldn't swap back ever!

Only thing stopping me is $$$. No idea the cost of all the parts, plus if I go EFI i'm going with an ignition controller as well. All or nothing!

Link to comment
11 hours ago, rerb said:

Only thing stopping me is $$$. No idea the cost of all the parts, plus if I go EFI i'm going with an ignition controller as well. All or nothing!

If you are handy with a soldering iron, a megasquirt or a Speeduino DIY kit is a cheap option for a EFI controller including ignition control. A few on here are using Megasquirt so there is a knowledge base - being careful with the pennies i'd guess a working system could be done for 300 - 350 £ or $ - certainly cheaper than a good set of used RS flatslides !

  • Like 1
Link to comment
4 hours ago, Gixer1460 said:

If you are handy with a soldering iron, a megasquirt or a Speeduino DIY kit is a cheap option for a EFI controller including ignition control. A few on here are using Megasquirt so there is a knowledge base - being careful with the pennies i'd guess a working system could be done for 300 - 350 £ or $ - certainly cheaper than a good set of used RS flatslides !

I would say around 1000€ is quite realistic ballpark figure for basic low cost setup. You can reach that by using some used parts and sourcing new ones carefully. Naturally you can make it cheaper if that's the main goal. Building the ECU by yourself, sourcing all the components from junkyard, cutting corners here and there and so on. Might be interesting as a challenge but I'm not sure if it makes sense if you want a well functioning bike with reasonable efforts.

The ECU itself can naturally use big part of the budget but I would say you shouldn't concentrate too much on price of it. The cheapest DIY version are maybe 150-200€ while you can get reasonably good ones for 350-600€. The rest of the stuff will still cost the same no matter how cheap or expensive the ECU is.

  • Like 1
Link to comment
3 hours ago, Arttu said:

I would say around 1000€ is quite realistic ballpark figure for basic low cost setup. You can reach that by using some used parts and sourcing new ones carefully. Naturally you can make it cheaper if that's the main goal. Building the ECU by yourself, sourcing all the components from junkyard, cutting corners here and there and so on. Might be interesting as a challenge but I'm not sure if it makes sense if you want a well functioning bike with reasonable efforts.

The ECU itself can naturally use big part of the budget but I would say you shouldn't concentrate too much on price of it. The cheapest DIY version are maybe 150-200€ while you can get reasonably good ones for 350-600€. The rest of the stuff will still cost the same no matter how cheap or expensive the ECU is.

True, when the time comes I'll keep this advice in mind. I think the fuel pressure gauge is too crap to read low psi, as pinching the line from the fpr with my fingers i can feel that fuel is being pumped through at more than 0 psi. 

Link to comment

Cost of bits I am assembling for my project (GS1100G) Speeduino kit is around $A230.  https://www.everythingfuelinjection.com/store/   Most expensive part would probably be the GSXR600 throttle body GSXR600. Not sure what they go for in UK but I got one in NZ for $250.with injectors, TPS, etc. Pump from ALiExpress about $NZ70, Madhu regulator $US30 https://www.madhu.com/content/Main/FuelPumpController  Tuner Studio (free to $US100) Bits and piece will no doubt add far more than I expect

  • Like 1
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...