Pilot jets and mixture screws

[nitro3custom]

The bike (GS1000gl) runs really good After the new pistons (1085 wiseco) and the Web cams (118 grind). I think I have the right main jet as it pulls really hard at WOT. And the needle is pretty close, I may move it up one notch. I also have a K&N stock type filter and jet kit that I put in the bike a few years ago. The question is at what point should I consider changing the pilot jet? I am already 3 3/4 turns out. It was 3 1/4 and I was getting a lot of backfire on decel. after turning out 3 3/4 some but not all of the backfire is going a way. Other wise I am thrilled with the way the bike runs. I still need to sync the carbs but I don't think that is the issue. Just tossing this out to see what more experienced tuners think.

(These are CV carbs) So that this doesn't get to far of topic

[hampshirehog]

Which carbs - VMs or CVs?

[Steve]

Which carbs - VMs or CVs?

Considering that the 1000G (and GL) did not appear until 1980, they are going to be CV-type carbs.

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[hampshirehog]

Considering that the 1000G (and GL) did not appear until 1980, they are going to be CV-type carbs.

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That's what I thought. But I saw one on Ebay UK last month wearing VMs. Might have been mucked about with but it had that air of originality about it that hinted that maybe they did knock out some from the factory like that.

[Steve]

Yeah, look at the GSes with the Katana wheels, etc. to see how "natural" some mods look if they are done just 'right'.

The VMs that you saw might have been some larger flat-slides to go along with some other performance mods, you don't really know.

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[nitro3custom]

They are CV's

[hampshirehog]

Well you're right - I don't and can't know for sure with that particular bike but we do know for sure that Zook didn't hold the models exactly the same in each year all time. For example, we definitely had 1000Gs fitted with VM28s from the factory, same as we had the 1980 fuel tap on some 1979 bikes, the square indicators on some '79s, a real mish-mash of speedos / tachos that 'universally' fitted from 77 to 80 (and maybe later) and so on.

Maybe this parts bin hotch-potch was peculiar to Europe (or the UK) - I've batted this across the pond a few times and you guys do seem pretty adamant about fixed features to a particular year. I know we never had the 85mph speedo for instance and our 1100s stayed 1100s (never became 1150s) and of course the GS / GSX difference.

I was putting most of this stuff together out of the packing boxes back in the day and I know my memory isn't playing tricks. I never put a 1000GL together (they were never popular here plus the shop I worked in had a sports bike tag) so I am floating a boat but that ad had all the hallmarks of a bog standard, never played around with bike.

[trippivot]

If your fuel mixture screws are a full 3-3/4 turns from seated I have to say you have 1 maybe 2 sizes larger pilot jet to go. Get the fuel mixture screws to tune in closer to 3/4 ~ 1-1/2 turns and you'll have the pilot-bypass circuits flowing to full potential. This is going to effect the needle setting you have at the moment.

good luck