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El Gringo

Turbo plumbing for a simpleton

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I cant play the video as I'm on the work computer but give me a shout tomorrow and I'll have a listen @El Gringo! No Vale Speed for a hang out this week so you'll have to host.

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Next stage of testing is done,

Re-introduced the blow-off valve - connected to the carb top cylinder 1

Re-introduced the FPR signal line - connected to the carb rubber stub (Normally for the vacuum hose to the fuel tap) cylinder 3

Also added the Boost gauge by tee-ing into the FPR line - mainly as the hose it came with won't fit over one of the carb tops

Still starts okay but the idle is now a bit poppy/coughy at times - they are all a good fit with clips so it shouldn't be an air leak 

Still rev's okay which is good and it even started off the small lithium battery which was nice

Boost gauge flutters all over the shop at idle, it was a cheapy one so i shouldn't be too surprised.

I might try disconnecting them again to see what difference it makes to the idle.

I may also lean the mixtures off slightly as it seems a bit rich - i think they're only a 1/4 turn past standard  but it may help with the stumbly idle

Any thoughts?

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Usually blowthro' carb installs have a Pitot tube in the charge pipe from the turbo (you make no mention of this?) - this supplies boost pressure air to float bowl vents and to FPR (can't see point of trying to reduce fuel pressure with vacuum - it's virtually flat lining now @ 0.5psi!) BOV gets signal from an inlet runner - IMO - ideally all 4 to minimise fluttering at idle due to single cylinder pulses. If the boost gauge is the multi coloured thing on the bars - throw it away and get a proper oil filled gauge - you don't need to know vacuum, take its signal from the plenum if possible. Around idle the mixtures should be just about as if it was NA ie. no different as the BOV will be fluttering supplying idle air........unless its got a stupidly strong spring in it.

But there again............... I know jack about carb'd blow throughs - I do know EFI blow through though LOL!

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Ta! That makes sense

I've got a pitot tube in the up pipe running to the float bowl vents so that's ok.

I guess its the BOV fluttering causing the popping allowing a bit of extra air in. 

I think i'll tee them all together to the BOV and tweak the idles back to stock.

Tank going back on later this afternoon

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7 minutes ago, Tombola said:

How big is your pitot tube? 

I think it was about 6mm ID if i remember correctly

I disconnected the BOV earlier and balanced the carbs which helped a great deal with the popping and coughing at idle - the carbs were massively out of balance.

I've got some more vacuum hose and tee pieces coming to link together for the BOV feed.

Got a damper for the boost gauge take off which works well to settle the needle down

It's all coming together nicely.

Didn't get the tank back on today, might as well wait until i've sorted the BPV feed



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Right then

A quite momentous thing has occurred,

I went for a ride on the turbo.

It was only a short low revs trundle up the village but it has now moved under it's own steam, nothing fell off, nothing leaked and it ran pretty damn well!

Gearbox seems really really slick too which is nice

I balanced the carbs which helped with the popping and coughing at idle, and i made a new manifold that fits all 4 carb tops to even out the feed to the dump valve to stop it fluttering

23842697728_0aec0986d1_c.jpgDSC_0712 by Chris Jennings, on Flickr

I need to add a tee from this line to the boost gauge to stop it flapping around

*Fuck knows why it's formatted like that?!

23842697198_d7d69b90c5_c.jpgDSC_0714 by Chris Jennings, on Flickr

23842695868_3988430cdf_c.jpgDSC_0716 by Chris Jennings, on Flickr

23842695288_b8bb3d7b31_c.jpgDSC_0717 by Chris Jennings, on Flickr

37663510472_327a2981f1_c.jpgDSC_0718 by Chris Jennings, on Flickr

The fuel pressure is at exactly 2psi on the gauge which is higher than before but..... the dynamic fuel level in the float bowl is actually now lower than it was previously which is awesome because it means it's not over fueling at idle.

So next up is to finish the oil cooler hoses and sandwich plate and probably make up a new exhaust with some form of silencing (it's ridiculous even by my standards!) and a lambda bung port so i can set the fueling up when we get to the dyno,

Also need to sort out the fucking horrendous mess under the tank, so many hoses and wires, so little space!

But, for now, i'm having several celebratory beers as it's been a long time getting to this point!

Edited by El Gringo

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41 minutes ago, Gixer1460 said:

Maybe not yet ............................but you're gonna need MORE brakes at the front - trust me!

Haha, funnily enough that had crossed my mind :D

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Haven't had much time on the bike since my little test run but i've been able to crack on with the oil cooler.

I bit the bullet and ordered up some hose and some (alot) of fittings - it's actually worked out really really tidy, well happy with it.

2 x 120 degree fittings at the top pull the hoses in the right direction to run down the side of the headstock and then down into the sandwich plate take off which has been thinned down to make it as narrow as possible and with a shorter filter (as per earlier in this thread) "just" fits under the turbo - i had to skim a little bit off the back of the lower outlet flange bolt hole but it's in and is a big thing knocked off the list!










Also, been and picked up a gallon of oil ready to re fill it and i finished off re doing the boostgauge feed.

Wiring under the tank has been shortened so the tank actually fits now.

Just need to find a home for the ignition switch now and re do the idiot light wiring and that's about it!

Then on to the dyno hopefully

Edited by El Gringo

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It may have been a ballache but this is going to be awesome when its done. Attention to detail and getting it all to fit neatly is great. Love it

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Thanks Guys

It has indeed been a ballache but i think once it's done it will be worth it (provided i can get 100hp out of it! lol)

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I'm just faffing now, getting some of the little bits finished up.

Bought a new sandwich plate adapter and re threaded it properly this time so it's nice and square, oil lines are finished and it's now full of oil

No leaks so far which is excellent!

Made a start on redoing the idiot lights - the LEDs were just too fragile and were just touching on the top of the upper oil line

Soooo, new idiot lights acquired and are now off with a mate being recessed into the front of the top yoke to keep it neat -


Managed to keep the nice 12pin plug which is good as it was a ballache doing all that wiring!!


Will fill the now redundant holes in the switch plate. Will also redo the switch wiring so it's tucked up neat under the clock bracket


I did check the wastegate opening pressure (mainly to make sure it actually worked), it started to crack at around 5-6psi and fully open by 8-9ish, i've no idea what this tells me other than it works and is presumably about 7psi when it starts properly venting.

It wasn't the most scientific method using a footpump and a beachball inflator on a length of silicone hose but i can't really think of another way to do it

Also found a nice home for the ignition key out of the way and once it's all painted black it should be nicely hidden


Hopefully my next post will be a nice video of me having a little ride to see if it makes vrooom and ptssssch noises!

Edited by El Gringo

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