El Gringo

Erm........ not yet, i was away racing over the weekend so didn't get chance to test it It's all back in one piece now though so that's a start I had a look at the breather system, i tried to separate the carbs to measure up for the plugs but they were stuck on one of the long bolts, so rather than break something i put them back together again. 1&2 and 3&4 are already cross linked by the vents so my blanking caps have the same effect as the plugs would. So I think they can stay as they are for now.

That's what i figured, Ta

One thing that has just occurred to me, would the bore of the pressure reference hose to the FPR affect how it operates?

That's kind of why i started the thread, there's a lot of info available on the subject, some of it more helpful and relevant than other bits, and as seen in the post through the thread there's more than one way to skin a cat. I had a vague idea of where to start with it but it's been (il)logical trial and error really This has certainly been a journey and it's not over yet, but if it helps other people looking to go through the process over come some of the pitfalls that's great. It's also testament to how awesome OSS is with the level of replies and advice received

I think the next course of action will be...... Remove the plugs I put in the drilled holes Get some link bits turned up to go between the breather ports Re-test with 2.5-3 psi base fuel pressure, opened out pitot and boost controller removed If that doesn't illicit the correct response then i'll look at moving the FPR pressure feed somewhere else and add another pitot and run one to each pair of carb bowls

I'll try and remember to take a picture of my pitot later but it basically looks the same as above. It's mounted in the straight section of the ally tube before the bend where it goes to the plenum - the BOV is just infront of this bit in the silicone tee

I am known to do stupid things! That might have been the bit where i compared the size of the hole i drilled to under the diaphragms to the 2 slide holes - originally the drilled hole was a smaller area than the 2 slide holes combined - hence why i made it bigger

You Sir are a legend! - i also followed the instructions on the old site/in the vault Right i can answer most of this now Right then, i drilled a hole in each carb to get boost under the diaphragm. Yep done that, 5.5mm hole straight down into the inlet I did NOT modify the slides at all. This concerns me that you have. I haven't touched the slides, they're all stock Boost referenced the fuel bowls (overflow) of each set (1/2 and 3/4) of carbys via its own pitot pipe I've got 1 pitot feeding the 2 float bowl vents via an 8mm hose and tee'd down to the over flow connections Floats at Stock height Yep, stock float heights, holding 3psi when running Sealed the diaphragm breathers all together. I've got the 2 breathers blanking capped - will look to link these with inserts Removed the fuel cock (hehe) and made new one that is free flowing out and a return that goes to the TOP of the tank. This is a must as the fuel return must be free of pressure. I've got quite a long return hose but it's an 8mm bore and returns above fuel level Trade off with the fuel cock (hehe) i made is i don't have a reserve now. STD one is a massive restriction. Fuel delivery block houses the flow at 14mm bore to the pump and the 8mm return If its returning to the bottom of the tank you are fighting the petrol level pressure already in the tank. Nope, above fuel level I sealed the petrol cock (hehe) feed pipe thingy on the carb rubber. I'm using that for the FPR boost feed I used ALL 4 ports in the carby tops to get vacuum for the blow off valve. Yep, got all 4 linked that feeds the BOV and a line tee'd off that feeds the boost gauge I didn't cut the spring in the fuel Reg... bad idea in my opinion as it changes the spring rate to make it harder, i made a spacer for the reg that let me lower the std setting. Might look at getting a new spring so i don't have to wind it up as far Fuel Reg has it's own Pitot pipe. As above, from the manifold take off Wastegate controller has a reference off the plenum Currently got a line from the turbo outlet to the wastegate via a boost controller - this is currently backed right off - i might take it off to rule it out I machined the ignition plate so i could get up to 5 degrees retard Ignition is currently stock but i do have a modified pick up that allows 3 degrees retard to be fitted when it starts working properly When tuning, i had 1 AFR in the pipe and 4 EGT's, 1 in each exhaust port on the headers. I got the exhaust temps within 20 Degree C and the AFR happy Nothing fitted at present, AFR on the Dyno was pretty good until it hit the bit it wouldn't pull through each carb has different Main Jets and different needle heights Will Faff with this bit later Boost and Fuel Pressure hooked up too and made sure i had 2.5 to 3 PSI more fuel pressure at all times. I think part of the issue might be the base pressure was too low in the first place, will re test, holds a steady 3psi when running now but haven't tried it since this I'm pretty much bang on the same as what you did so i'm a bit puzzled as to why it's not working, Thanks for your help, will give it another go and report back

Cheers Chap, Much Appreciated

Cheers Chap, thanks for the reply Pitot is into the air flow but flat end on rather than slash cut, that might be something to look at I feel a conversation with my tame machineist coming on, i hadn't thought about cross linking the ports. My drillings are straight up and down as opposed to face on to the air flow like your which might also be something to look at

Cheers Boss, that's very helpful I think the GK76 carbs are very much like the 38s - they do have the breather set up between 1&2 and 3&4 (but not between 2&3). I have this blanked off with a blanking plug on each inlet at the moment. Is the hole in the picture above at the top of the inlet the one you drilled? If not have you got any pictures of that hole please? I've got a single pitot that I opened up to 7.5mm last night both ends although there is a spot in the middle on the bend that is still narrower The FPR input is coming from the pressure reference on the manifold that would normally go to the vacuum tap, it does raise the fuel pressure when it starts to boost. There's several things it could be as far as I can see/others have suggested Pitot isn't working right to compensate for the boost in the float bowls There wasn't enough base fuel pressure when running The holes in the inlet don't need to be there (although i'm still pretty sure they do) I think i'm going to have to book a day on the dyno, take all the stuff with me and go through it systematically If you've got any more pictures of your carbs and that extra hole in particular that would be great

Ta!

Thinking a bit more on the pitot setup, It's 6mm ID in a 30mm id pipe. Consensus/Guide on the interwebs suggests 1/4" of Pitot per 1" of Up pipe. Which broadly works out that i've got just under 1/4" (6mm instead of 6.35mm), if we stick with the theory it should be closer to 7.5mm. Would this being 1.5mm undersize cause that much of an issue? I need to run it up again with the 3psi fuel pressure and the holes blocked off to see what it does. Anyone know the cylinder spacings on the 34mm Tin Tops? I looked at the carbs on my Bandit 4 and it won't work with the clamp/silicone set up i've got at present.

Quick update Haven't tested it yet but it's holding 3psi of fuel pressure when running with no over flowing I've run it with the plenum off and it doesn't appear to be pissing fuel out of any of the air jets etc Pitot is 6mm ID in a 30mm ID up-pipe I've also blocked off the holes i drilled with some aluminium two part epoxy stuff so we'll give it a go and see what happens The slides were lifting when running and revved in neutral which proves nothing i realise Now, just need a bit of good weather to give it another test!

Many Thanks Bruteforce. That's awesome. I've got a pitot tube feeding the carb float bowls. I'll try blocking the holes that I drilled and go from there Cheers for your help

I've got a 1mm jet in the oil feed. Although that wasn't an issue it does seems to have a lot of oil in the up pipe it appears so maybe a i do need a smaller jet. In other news, i'm wondering if I cut the FPR spring down too far. It took a lot of winding in to get it to register on the gauge - it all seems very inconsistent at the moment. Next course of action, new spring, set the FP with it running accurately. When i did ramp up the FP it seemed to run rougher off the bottom which i'm assuming is it being over rich - i ended up back on stock float heights so perhaps i need to look at lowering them again? Also need to find a new test site......

YeGads! An Update! It still doesn't work. The sun finally stayed out long enough for a sneaky run up the village Several things occured It takes off like a scaled cat and lifts the front in first which surprised me It still gets to mid throttle and goes flat, same as on the dyno I think i got my picture taken by an angry local - i await the pitchforks and burning torches I also now better understand the addiction to the noise - it really is awesome when it starts spooling. Next steps? I have no idea, i tried upping the fuel pressure but it didn't appear to make any difference

Had a very quick measure - widest point across the rocker cover on the 1100 motor (not including the cam links) is about 450mm The gap between the wrap around spars on the Bandit frame is roughly 350mm so it would need some major surgery The other thing is the height, the oil cooled motor is a lot taller than the w/c 400 so would probably make the rear mounts a pain

The B4 has a smallish radiator to look like an oil cooler I might cast a tape measure over the 400 and the 1100 later to see how far out it is..........

The B4 lump is much much smaller than a full sized oil cooled motor so i'm pretty sure it's not a straight fit (i wish it was) It'd probably go with a fair amount of chopping about though

Ahhhhhh, errmmmmmm, ya see, ummmmmmmm, the dog ate my home work........... I really do need to get on with it, i might change the front tyre this afternoon to make it a bit more road test friendly (it's got an ancient slick on it at present)

Ooooh i can play this one now Akrapovic 4-2-1 from a Bandit 12, home made link pipe and a jauntily angled Akra Titanium can from an SRAD

Haha, not quite. It's currently sat under a sheet in the naughty corner. I've actually made a start on refreshing mt 1216 to keep me amused. Just waiting for a better days weather still to give the turbo a run - we've got snow coming in later! I have however spoken to Mr FBM and he gave me some pointers, next things to try is a higher base fuel pressure, then with the bigger holes drilled as they are now and then with them blocked off (as Dave suggested) One way or another we'll get there, it's just going to take a bit of time

Not yet chap, been away for a couple of weeks and the weather has been less than helpful Just waiting for a reasonable day for a sneaky road test

Not quite, that actually turned out to be the ignition pick up being knackered, but at the time i thought it was something in the carbs As it turned out once i'd changed the pickup it ran perfectly, in neutral anyway, and the floats and settings were good even with pressurised fuel input