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Carb settings with high comp. pistons & cams

Old 07-01-2015, 11:21 PM
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Carb settings with high comp. pistons & cams

I recently installed 11.5:1 JE pistons, Webcams cams (grind #189), and cleaned up the heads a little, stock ignition rotor, lightened flywheel, sub gear delete, and F.I.L. mod.

My question is, do I set up my carbs differently than I am running now with high comp pistons and cams? I'm assuming, I will need slightly larger pilots and possibly mains as well. I tried searching for this, but didn't find anything, even when searching with the term "stage 1", but my Search fu sucks. I know quite a few people have made these engine mods. What were thier carb settings?
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Old 07-01-2015, 11:37 PM
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keep in mind that with new cams, you have longer opening, delivering more fuel into cylinders.


Just for interest, my experience:


before HC pistons and new cams: 48 pilots, 178+180 mains, Dr Honda stacks, stock filter


after stg1 assemly (including ported heads): 48 pilots, 182+185 mains, stock filter - it was way too rich


after dyno: put Pipercross filter, which makes it significantly leaner everywhere, 48 pilots, 188 mains


Question is about slide holes, I tried setup with one (HRC), but two slide holes works much better. I also think that I could use 45 pilots, will see on anothher (hopefully final) dyno run.
I have no idea how FIL will affect the things, probably it will be leaner than stock airbox with Pipercross.


Another thing to consider from my experience: longer needles (FactoryPro in my case, I assume Dynojet will be similar) makes leaner condition on the top (WOT), so this is not fully applicable for stock needles, which can make richer condition at top revs.

Last edited by Stephan; 07-01-2015 at 11:47 PM.
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Old 07-02-2015, 12:08 AM
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The FIL thing is an unknown but the ones I have done I have just gone up one size on the mains for a starting point.

The slide hole issue has more to do with running a full exhaust system than a STG1 issue IMHO.
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Old 07-02-2015, 12:44 AM
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Originally Posted by 8541Hawk View Post
The slide hole issue has more to do with running a full exhaust system than a STG1 issue IMHO.


slide holes was side point from me, not really relating this topic :-)


Another thing to consider, Roger D recommends two slide holes everywhere except of full race setup (3 holes). But this donīt devaluate other ways (HRC, Dynojet) ...
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Old 07-02-2015, 02:37 AM
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Hey guys,

There is always much debate about the jetting on our bikes.

With high comp pistons a little bit of head work, standard filter, no cams, lightened flywheel, 4 degree advancer , no anti rattle gear, electric water pump with water pump gear and chain removed , no pair , plus a couple of other tweaks ,Dynojet needles 48 pilots 180 in the front and 182 in the rear and modded exhaust my bike runs great.

Never been on a dyno, my butt and brain tell me things are good.

Revs like a banshee and runs great.

All this was done to get my bike to run as it does now and I drilled the slides only to put standards back in.

No two of our bikes are the same, and what I have may not work for you, all I know is that my Bro can't catch me on his Suzuki TLS 1000 that has some similar mods so I am happy!

Good luck chasing the holey grail, I for one believe I have found it and apart from the odd carb sync and valve adjustment I am leaving well enough alone for now!
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Old 07-02-2015, 10:38 AM
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Thanks guys. So it sounds like my 48 pilots, FP needles and 205/210 mains should be okay to start out with. I would hate to drill my mains to 210/215, if I don't have to. However, my Flo-Commander was almost turned all the way in before my bike was tore down, meaning I probably needed to up the mains anyways. After engine break in, I will find out.
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Old 07-02-2015, 10:49 AM
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That should get you close enough to get it running.

One of the nice things about the VTR is that she will tell you that things are running lean (we all know the lean "pop" if you have done a bit of tuning with this bike) long before you get to a dangerous lean condition.
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Old 07-02-2015, 01:52 PM
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You can try to seal the air jets, as it is setup for open airbox. I assume mains would go some size down.
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Old 03-23-2016, 10:21 AM
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Just revisiting this, since my bike will be back together and running soon. I am very curious about what Stephan mentioned. I also heard this mentioned by someone when I was in the infancy of tuning the FIL mod.

When my bike first fires up, I am not going to touch the carbs, so it will be at the same settings as mentioned above. However, if it does need to go bigger on the mains, would plugging the air jets be the way to go and tune from there? Or, should I continue to drill out my mains?

I'll try searching for a thread about plugging the air jets.

EDIT: I found a post by Mike that says this about HRC and air jets (bleeds?)

...I can't say for sure about the Moriwaki kit, as I only saw one and it was at least 10yrs ago but the HRC kit comes with 2 sets of needles.

One for an airbox with a filter and one for "ram-air" or no air filter.

Also, for these types of set ups they had you plug the airbleeds and run different mains.

All good stuff for top end power but not so great if you ride the bike on the street as the bottom end suffers badly.
I find this very informative, since my bike is likely to see 90% of its life on the street.

Last edited by CruxGNZ; 03-23-2016 at 11:32 AM. Reason: Info
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