Author Topic: 1975 550k minimal turbo build. (Parts collected, build has begun.)  (Read 9550 times)

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Offline scottly

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #25 on: January 24, 2016, 08:20:39 PM »
hi lost boy , lovely looking work ,  i have a 400/4 turbo , built in '80,

hope you don't mind me picking at something , if you angle the feed to the plenum , you will get no3 running  lean .
robert.
The angle of the feed may indeed be the cause of the current issue; the heavy fuel can't make the sharp transition to feed the left two cylinders?
Don't fix it if it ain't broke!
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Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #26 on: January 25, 2016, 07:53:01 AM »

hi lost boy , lovely looking work ,  i have a 400/4 turbo , built in '80,

hope you don't mind me picking at something , if you angle the feed to the plenum , you will get no3 running  lean .
robert.
The angle of the feed may indeed be the cause of the current issue; the heavy fuel can't make the sharp transition to feed the left two cylinders?

Christ, I hope not. If that's the case I'll have to drill a hole in the back side of the intake and make an even longer diffuser...


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Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #27 on: January 25, 2016, 11:11:31 AM »
i thought there was another unseen bit of pipe inside the plenum making the flow even ?
just do it .

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #28 on: January 25, 2016, 11:17:35 AM »

i thought there was another unseen bit of pipe inside the plenum making the flow even ?
there is, sort of. It protrudes in and then it cut on a sharp angle to try to avoid direct pressure to hit that closest intake port. Now, however I'm wondering if I should take your advice and just weld a pipe straight on the inside of the plenum. I also have to wonder if the 170 jet is flooding the engine. It's strange, because I can't tell if it's overly rich or overly lean. I haven't run it enough to tell. I'm going to try something a bit more lean, and then if that doesn't make it any better I will introduce an even richer jet. In the minute or so that I had it running it drank that little test tank dry, that to me seems to be an absolutely insane amount of gasoline usage.


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Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #29 on: January 26, 2016, 06:09:03 AM »
in case it helps LB , here's  my plenum ,made in 1980 from a bit of window frame box section .




the small dia pipe keeps the velocity up so the mixture smashes into the other side of the right angle and breaks down more ,then the box is thin wall so it warms up quickly and reduces fuel condensation .and its internal volume is enough to get an even shot to all cylinders by slowing the flow down .(its actually a little bit big for low rpm )

regards
robert
just do it .

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #30 on: January 26, 2016, 06:11:54 AM »
That looks like I want one. :) last night I fiddled more and realized that it is grossly rich. It was spitting Unburned fuel out of the exhaust. The idle jet seems fine because it idles really well but pull on that throttle and it floods out. Or so it seems. The two right cylinders get warm at idle but if I rev it up they cool down and the left side gets hot.


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Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #31 on: January 26, 2016, 06:19:22 AM »
I know someone on here knows the science behind what I'm trying to figure out as far as jetting. You're goin from 4 carbs to one larger carb. In my mind, you're still only utilizing fuel for 1 cylinder at a time however the pull from all 4 probably increases the amount of fuel being dragged out of the single carb. (Kind of the same science as to why these bikes run better with a plenum vs pods.) so maybe trying something a bit closer to stock jetting is the way to go. It does idle well on the 45 slow jet, which is just two sizes? Larger than stock. Any input on this is greatly appreciated.


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Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #32 on: January 26, 2016, 06:47:02 AM »
no idea what jetting i have in my xs650 cv carb , i just drilled em  and soldered them up again and drilled etc till it ran well .that change in temp of the cylinders does suggest a mixture maldistribution . as you say ,try it on a smaller jet ,like a 140 ,and work from there .

also , that situation of running ok on tickover ,then on 2 with revving ,is a typical manifold design problem symptom .the added velocity of the incoming gases ,with rpm rising , allows the cylinder bias to become more and more pronounced .
« Last Edit: January 26, 2016, 06:50:14 AM by ivanhoew »
just do it .

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #33 on: January 26, 2016, 06:51:12 AM »

no idea what jetting i have in my xs650 cv carb , i just drilled em  and soldered them up again and drilled etc till it ran well .that change in temp of the cylinders does suggest a mixture maldistribution . as you say ,try it on a smaller jet ,like a 140 ,and work from there .

also , that situation of running ok on tickover ,then on 2 with revving ,is a typical manifold design problem symptom .the added velocity of the incoming gases ,with rpm rising , allows the cylinder bias to become more and more pronounced .

I like the solder idea. Never thought about that. I have enough jets where I can sacrifice one.


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Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #34 on: February 01, 2016, 06:45:58 AM »
Well, Ivanhoew was correct (thank you sir). Had a coil wiring mashup which caused only 2 cylinders to fire. Fixed that. Runs pretty gd good now. Still rich as ever, I ordered some more jets to play with. I think I've answered my own question. Basically, because you only have 1 cylinder firing at a time, but combination of suction from 4 cylinders, a good base line of jetting is closer to stock than what I've been trying. So, when they arrive, A 40 idle and 105main are getting tested. As of now, even with all four cylinders getting hot, there is a mass of unburned fuel spitting out of the exhaust. Its idles high, but starts cold easily with the 60 idle jet, but you can smell (and see) how rich it is. Anyway, thats all for now.
1968 Honda Z50
1977 Honda CB550K
2018 Indian Scout

Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #35 on: February 01, 2016, 01:10:35 PM »
hurrah!
just do it .

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #36 on: February 01, 2016, 02:36:44 PM »

hurrah!

Here's a video... With one problem solved comes another earned. I checked and it's not charging. Have to double check that wiring as well.



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1968 Honda Z50
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2018 Indian Scout

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #37 on: February 04, 2016, 10:30:23 AM »
Made an outlet flange for my turbo. Also 3/8 mild steel.


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2018 Indian Scout

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #38 on: February 06, 2016, 06:34:50 AM »
Another video. Much better! 35/100 jetting. Still a tad rich.


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1968 Honda Z50
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2018 Indian Scout

Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #39 on: February 07, 2016, 05:26:31 AM »
crisp !
just do it .

Offline Lostboy Steve

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #40 on: February 18, 2016, 02:09:52 PM »
Hey Steve (lost boy), why no updates? Ah, well because I have added yet another project to my arsenal.




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Offline ivanhoew

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Re: 1975 550k minimal turbo build. (Parts collected, build has begun.)
« Reply #41 on: February 19, 2016, 01:23:53 AM »
oh good grief....focus man !
just do it .