VTR Down Under

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Twitchy
Posts: 161
Joined: Mon Feb 16, 2015 2:14 am
Location: Perth, Western Australia

Re: VTR Down Under

Post by Twitchy »

tony.mon wrote:
Mon Apr 27, 2020 10:52 am
Recommend you don't spend too much money on this, I made a large airbox and dyno'd it, no gains....
Interesting.... I wonder what the post filter airbox capacity of the RC51 is then? They seem to run alright 8)
06 VTR1000F; bits by Jack Flash, Erik Marquez & Jamie Daugherty. Tuning for fuel pump & completing Moripovic exhaust.
Build thread; http://vtr1000.org/phpBB3/viewtopic.php?f=41&t=36638

tony.mon
Posts: 14193
Joined: Wed Jul 25, 2007 9:46 pm
Location: Norf Kent

Re: VTR Down Under

Post by tony.mon »

I haven't measured it but it's not visibly much bigger, if any bigger at all.
But the SP breathes straight in through the headstock so is much more efficient, and there will be better airbox pressure at speed.

The interesting difference is the exhaust port, smaller and d shaped instead of round, with a flat at the bottom.
The pipe is round, though, so you get a step at the transition between port and header.

When I was playing with my storm engines I bought a scrap SP1 engine just to have a poke round.
It's not falling off, it's an upgrade opportunity.

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Twitchy
Posts: 161
Joined: Mon Feb 16, 2015 2:14 am
Location: Perth, Western Australia

Re: VTR Down Under

Post by Twitchy »

A bit of a callout to Mik_str if possible. I have been mucking around with the jetting after installing the fuel pump and not sure how far to go.

First, when I bought the velocity stacks from HPower, Bill suggested going down 2 on the mains, which took me to FP 172 front & 175 rear. I have removed the high mount Jardines, and working on a Mori titanium system with Akra cans. Because I am not finished with the exhaust, the old exhaust seals are still in the head, so I may have a slight leak there. Apparently low mounts require smaller mains and larger pilots from high mount systems. Not wanting to run too lean at high rpms, I went down 1 main size, to 175 & 178, and went up 1 pilot to 50 f&r. Absolutely stank my shed out it was so friggin rich. I could shut the front screw completely and it did not affect the idle, winding the rear screw in increased the idle quite a bit. So that means the pilots are too big right?

Today I have put the 48s back in, and dropped down to Bill's recommendation of 2 mains lower (before the stacks I ran 178 & 180), mains at 172 & 175. Ended up with the screws out 3 1/8 and 3 1/4 f&r, but still getting a hang up at 2200. And when I blip it to 4k, it is not the clean snap it used to be (full throttle blip easy with HRC throttle tube), it feels flat, which tells me its too rich still. With the (apparent) lean situation causing the hang up, I know each circuit affects the others, would the mains affect the fuel screw, idle and blipping? I am considering going down on the mains again, to 170 and 172.

So my question for Mik is(or anyone for that matter), with fuel pump, how many mains should I go down? I am concerned if I go too low, when I take it for a spin, she will run way too lean up top. If the stacks require dropping the mains by 2, the low mount exhaust requires 1 size lower, and maybe the pump means dropping 1 size main, total 4 steps down. Seems a lot.
06 VTR1000F; bits by Jack Flash, Erik Marquez & Jamie Daugherty. Tuning for fuel pump & completing Moripovic exhaust.
Build thread; http://vtr1000.org/phpBB3/viewtopic.php?f=41&t=36638

tony.mon
Posts: 14193
Joined: Wed Jul 25, 2007 9:46 pm
Location: Norf Kent

Re: VTR Down Under

Post by tony.mon »

The more tuning you do, the smaller the mains need to be- which seems counterintuitive.
I ended up with sizes in the 160's.....
Ideally it needs setting up on a dyno, an alternative is to fit wideband lambda sensors in each downpipe with a display, which is what I did.

Another possibility is to fit main jet circuit Flo commander systems, this gives you the opportunity to "spoof" one size bigger or three sizes smaller main jets, and you adjust with a screwdriver at the side of the road in two minutes rather than having to remove the tank and airbox to change jets.
You can also get a pilot jet circuit version to get it just right.
It's not falling off, it's an upgrade opportunity.

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Twitchy
Posts: 161
Joined: Mon Feb 16, 2015 2:14 am
Location: Perth, Western Australia

Re: VTR Down Under

Post by Twitchy »

So if I go down to a 168 front and 170 rear for example, how much will that affect the pilot circuit? The 48s with 3 1/4 turns out hangs up, but with the 50s I could close the screw and not affect the idle. Would the smaller main essentially reduce the flow of the pilot? I do realise with these carbs to start with the main and work down, but don't want to go too small on the mains and risk damage. Maybe I do need to look in to the Flo Commander...

Regarding the lambda setup, I do have an Innovate LM-2 O2 meter with 2 sensors, and the titanium bungs to weld into the front & rear pipe. The controller will go under the seat, where I can upload the graph to my laptop. I also need to wire in the analog cable to track rpms.

And bloody bugger, Jets R Us aren't shipping internationally due the dang Rona virus. Have put feelers out to a couple of Oz distributors. The 172 and 175 I have in the bike at the moment are the smallest I've got!
So now I wait on more shipping :roll:
06 VTR1000F; bits by Jack Flash, Erik Marquez & Jamie Daugherty. Tuning for fuel pump & completing Moripovic exhaust.
Build thread; http://vtr1000.org/phpBB3/viewtopic.php?f=41&t=36638

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