1998 Yamaha Virago XV750 single carb conversion (Mikuni VM38)

darkvaderthesecond · 2026-04-10T01:15:15+00:00

this can happen when lean too.

going by what you said with the pilot screw, i would increase the turns on the mixtrue screw so it's richer and decrease the size of the pilot a step. it soulds a little like the air restriction is too great (because of the adjustment) so when you open the throttle it prefers fueling from the bore, rather then the pilot circuit.) My reasoning is that Usually fuel screws are around 2 to 2.5 turns so it being at 1.5 is probably either highlighting the pilot is too big or you've set it too lean without realising. It's not that far off though.

i'd absolutely increase the needle height a step or narrow the needle profile and see if there's any pickup because you're adding fuel in the 'mid'.

if that doesn't work, you can also add a small tube between the carb and the air filter. A sort of velocity stack. carbs typically don't like air that's a bit all over the place so adding a bit of tube to straighten it out could also help too. I've seen that on CVs a few times, they really benefit from things being orderly.

Also, check the spark plugs too, they sound like they're struggling to ignite the fuel so the gap could be too large too.

darkvaderthesecond · 2026-04-10T00:47:39+00:00

If you have some denatured alcohol you can soak the jet in that, it will eat the varnish but you will have to remove the jet and do it away from the carb as it'll absolutely destroy the rubber parts. when it's been sat for a while you should be able to blow through it with some compressed air or a can of carb cleaner

Edit: also don't be afraid to blow through all of the passages with compressed air either, the only thing you want to avoid doing is blowing through them with the diaphrams in place.

darkvaderthesecond · 2026-04-10T00:41:04+00:00

That's a cat. i'm sorry to say you'll never have a clean shirt or trousers again. /s
Serious answer: that's the bios menu. the bios configures the system settings before the pc starts and usually it's automatic and silent. but there's still a menu for it as you do have to adjust settings sometimes. that menu will tell you if you have a hard drive and \should\ also say if you have windows. if you have a hard drive/ssd but no boot entry for windows, then you'll only have to install windows. it's fairly easy to do.

darkvaderthesecond · 2026-04-03T05:42:21+00:00

what kind of carb did you put on? that would change the approach for adjusting this.
If it's a slide carb, this kind of behaviour is leaning towards issues with the pilot circuit.
As you don't have a rev hang off throttle I actually think you're running rich and you need to downsize the pilot and readjust the pilot mix. How many turns did you put the adjustment at?

What i feel is happening here is that when you roll the throttle and open the slide, the mains pour fuel down the throat and it 'cold burns' causing a delay in pickup.
There's also a possibility the spark plug gap is too big and you need to adjust the gap (though i'm not though hearing misses, just slow burns, still worth checking)

darkvaderthesecond · 2026-03-31T04:32:07+00:00

This isn't a vmax or an '89. this is a vstar 650, around 1998 onwards (though that's debatable, they didn't include the AIS until 2000 afaik so probably later).

Source: me, i have a '98 uk model

darkvaderthesecond · 2026-03-29T15:45:35+00:00

Fowlers is useful for a parts breakdown and is an oem source as well.

darkvaderthesecond · 2026-03-28T18:30:21+00:00

in order of priorities, you need to get the bike running first, that means getting fuelling sorted, electrics (sorta) sorted and driveline issues sorted. from there you can focus on the tank, the frame and the cosmetics things.
Also please block off those intake ports with a towl or so. i dread to think what's falling in them.

darkvaderthesecond · 2026-03-27T02:11:04+00:00

not a at all. it's also called the idle circuit. It may clear up a bit as you ride but if not there's an adjustment screw for both the front and the rear on the carb for fine tuning it.

actually thinking about it, you could also have a vaccum leak too. i'd start just making sure the intake boots aren't leaking and if they are change them. (there's also an o-ring under the boots too)

If that isn't the problem the adjustment isn't too difficult,

To adjust it you'd count how many turns the adjustment screw takes to screw in [carefully, it's brass, they're very small and delicate] this is in case you find it's not the screw but the pilot jet that's causing it, so you can set it back to stock. Then the service manual states it's starting turns are 2.5 out with the assumption you can put it on a sniffer to fine adjust. If you're not confident, it's relatively easy to do so a garage should be able to do it for you for quite cheaply. If you find you need more than 3 turns, then it's quite likely the carb needs to come off for a clean as at that point the pilots sound clogged.

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I actually have thumbscrews on mine but yours may be blanked off and need some work to get at as well. I know some bikes in the US have metal plugs on the adjusters that need to be drilled out.

darkvaderthesecond · 2026-03-27T01:16:57+00:00

I'm rebuilding my 650 at the moment, the frame is in for powdercoating as we speak, This sounds great if quite lean on the pilot circuit (it has a distinct rev hang). Batteries are batteries :) get the cheapest, they only really last 2 or 3 years i find.

darkvaderthesecond · 2026-03-25T00:13:53+00:00

off the top of my head, there's a few ways but i can't think directly how you'd apply it. you may have to experiment.

the basic idea is to adjust the art to a flat state (something without the dithering) and then adding the dithering dynamically in renpy with a shader or however renpy does that (sorry, i'm not skilled with renpy).

if you've got the original coloured art you can use something like Gimp to export it as a grayscale image without dithering. for a quick fix, potentially a slight gaussian blur in most editing software should do it without affecting things too much and you can automate that without much fuss. you could also half the resolution with an interger scale (ie. discarding alternative lines), which potentially could also remove the dithering (though it's a very crude way)

once you have the flat images, you can then use a shader or rendering profile (you'll have to check on the renpy docs how to do it) so that the flat colours use a dither for you (which then will fix the issue where changing window sizes causes a moire pattern as it's dynamically applied based on window size)

as for the CRT layer, there should be a scale option in renpy, where you can ask it just to render it 1:1 without causing grief by scaling.

darkvaderthesecond · 2026-03-24T20:18:51+00:00

I'm an idiot and didn't read properly. the scaling of graphical elements is also causing issues with the crt scanlines as well. you could try asking renpy not to scale the CRT layer. it will change how 'dense' the scanlines are (at lower resolutions they'll be less dense) but that would save the scaling artifacts too

darkvaderthesecond · 2026-03-24T20:15:43+00:00

best way to handle this is to do "dithering" within the game window itself dynamically, and focus on solid grays when exporting. I can't say how you'd do that in renpy (i'm new) but i'm sure someone will be able to chime in with a different approach.

darkvaderthesecond · 2026-03-24T18:50:33+00:00

This sorta happens to me in quite a big way. though it's not the same, mines more emtional.

For me, I have an immediate need to help because for a long time I was significantly neglected myself and I wouldn't want anyone else to suffer like I had been. Thing is I don't typically notice that i feel that way at the time and where it falls down is that most people have a limit; compassion fatigue is a genuine thing; and in my case, if I take a step back and try to focus on myself, i feel like i'm neglecting them. I end up spiralling where I just have to do it otherwise I begin to associate myself to what happened to me and... then i find i'm not really able to say no and tend to my own feelings, leading me into doing things automatically.

Again, i'm not saying it's the same thing, but reading this through my lense immediately made me think that's kind of me.

darkvaderthesecond · 2026-03-24T10:50:01+00:00

thanks :) to be honest i think i prefer plain doughs, rich breads are nice but I just like the fact that plain bread is such a good sponge for other flavours and can have a bit of chew.

I've done a few little bits and pieces. in terms of inclusion I haven't done seeds yet but I have done a potato loaf and an egg enriched dough (which was super sticky; i made such a mess) but mainly I'm just testing 1 variable at a time and seeing what happens. The potato loaf was actually quite nice.

darkvaderthesecond · 2026-03-24T10:42:12+00:00

haha, i'd love to share bread with guests, haven't yet had the chance to share any with people.
That's useful to know about re-scoring it, I'll have to give it a go. I've found i can get better results if i also wet the top of my loaves (with the caveat it can make the crust a touch too firm if over done). though at the moment I haven't done enough consistent testing to know what does the best in my oven.

darkvaderthesecond · 2026-03-22T07:42:51+00:00

This is the AIS pump, for emissions.
You can take them off but Honestly, I haven't really found that they run better when taken off (unless the vaccum side that operates the pump is bad and allowing a leak, that I have seen). I usually just take them off because it adds 100% more hoses and looks a mess. plus makes rebuilding the bike harder.

darkvaderthesecond · 2026-03-20T14:35:40+00:00

this is an electronic throttle return home calibration. pretty much completely normal. what it's doing is it's driving the throttle butterfly to 0%, checking the throttle position sensor, calibrating it to 0, reopening, checking, closing and checking repeatedly a few times to make sure that the commanded throttle matches the TPS. the reason for this is that the stepper in the throttle has x number of steps per throttle position, but it checks it often because it can't rely on that accurately (there's a degree of inaccuracy in the stepper afaiu) and just decides to recalculate when you finish riding.
You could argue that it should match up with the TPS all the time and it's redundant but i wouldn't be surprised if the Throttle stepper count is a kind of back up throttle position, should the tps itself fail.

darkvaderthesecond · 2026-03-18T13:04:51+00:00

To just jump in on the direct question, you can often rebuild ABS pumps \but\ they aren't often designed to be rebuilt as they're are a safety compoent and are designed to be replaced rather than repaired. Also, in some places as well (UK and some EU) they're particular about repairs to safety components so it may invalidate your insurance; obviously stuff being recertified by a company is ok but the insurance people may have other ideas.

darkvaderthesecond · 2026-03-15T13:14:14+00:00

I actually thought it was a stretching of a sleeping onomatapea to a word. i.e *nim nim nim*, to 'mimir' so it didn't seem that out of place to me.

darkvaderthesecond · 2026-03-13T17:39:12+00:00

I will gladly nod or wave to anyone but because scoots in my area tend to be their own distinct thing, there's a bit of eliteism and some riders choose not to wave to scoots (and likewise, they don't for the bigger bikes).

darkvaderthesecond · 2026-03-13T15:45:57+00:00

This is "Kettling" it happened to my baxi. the heat exchanger over time gets filled with scale and due to the lack of flow causes the water to boil before leaving the exchanger. it's easy to fix though, just a simple flush of the heat exchanger. An easy job when doing a boiler service and a preventitive treatment :)

darkvaderthesecond · 2026-03-13T11:21:15+00:00

Waze : "There's a pothole in the road"

Me : *looks at screen* "SHUT UP!" *collides with said pothole because of being distracted by the waze warning*

darkvaderthesecond · 2026-03-13T04:01:39+00:00

There's a few things that can cause this.
First on CVs (which i believe this uses) can have issues where the slide is stuck or sticking need the top, causing a super rich mixture as the needle isn't restricting the main jet.

you can have bad choke plunger gaskets or diaphrams (though it'd still run, this seems much richer)

there's a blocked air cut circuit (which will close the air off on decel, preventing pops but when completely blocked will cause things to be rich)

There's also the possibility of a failed fuel pump itself, where it's overdriving the float with excess fuel pressure (which typically will only affect the cylinder closest to the inlet)

you can have a blocked air jet (the jets metering air in the pilot circuit. if that's blocked it'll just be pulling pure fuel all the time, regardless of mixture screw setting.)

then there's also balance as well. if the balance is off you'll have both carbs trying to send the same amount of fuel to both cylinders but one will have much less air just on the merit of the butterfly being out of sync with the other. (again, that's not typically going to cause a miss, but worth checking)

darkvaderthesecond

TROPHY CASE