V&H 4:1 & K&N Inbox - suggested jetting

[KEITH KRAUSE]

Sounds better. I hope a longer test gives good results.
Can't truly judge jetting performance until you do a good synch. Hopefully a little mixture screw tweaking will rid you of any stumble you mentioned.
Jeez, I gotta get to bed. Good luck!

[salty_monk]

Thanks Keith, seems I spoke too soon, it went from running great on that 2mile test to holding back on me when I rode it the next day. Still runs better than on the 122.5's but not like the scalded cat it was the night before. Very strange!

Still didn't ride it far so I am going to test a bit further before I make any more changes.

Dan

[KEITH KRAUSE]

Hmmm. Well, it's about throttle position. If a problem is positively at approx' 3/4 to full throttle, then it's the main. If before that, under 3/4, then it figures to be jet needle related.
Now if the ONLY change you've made since the last test is the larger mains, and you're sure they are the reason for the improvement and there IS definite improvement, then it appears you need even larger mains. I'm just a little surprised based on the info you've supplied but it wouldn't be the first time a bike wanted a little more jetting than what's the usual. I'm still not 100% sure what you're working with regarding exact carbs and exhaust. But as long as you're testing correctly, and based on your latest test, I'd go up a full size again (5) and test.

[salty_monk]

Thanks Keith. It's the 34mm CV's with inbox K&N (new airbox boots & well sealed) & a new V&H 4:1. The 125's are definitely an improvement as now I don't get any backfiring etc.

All new O rings on carb intakes & in carbs & they are meticulously clean. Vacuum holes in slides are now back to stock.

I'm using the Canadian needles (But I've measured them very accurately against a stock one & they are identical apart from the notches).

Stock Petcock, no in-line filter. Stock airjets - 180. Stock pilots - 40. Stock bit that the main jet screws into (forgot the name...)

No other mods apart from Dyna coils.

I ordered the 127.5 along with the 125 mains so I think I will give them a go first as I have them on hand.

I also have 42 pilots on hand too but I'm only 2.5 turns out so I don't think I need them. It runs fine on the pilots & then holds back on higher throttle openings.

Will report back. Seems I'm getting there.

Dan

[KEITH KRAUSE]

Right. V&H pipe. I did remember but didn't edit my previous post. It was the carbs I was unsure about and if there could be unknown differences between U.S. and Canadian models, other than the adjustable needles.
Backfiring seems an odd issue because I can't imagine you're that far from getting the main right. But I won't wonder about it. The bike is getting there and it seems the main just needs to go up some and you'll be good. If indeed that's all you need to do then I wish I could have guessed better for you. I figured a 10 increase over whatever is stock would be enough. But you did buy 127.5's anyway so I hope they work and you don't need to buy more. That's good news actually because it says the bike is flowing pretty good if it wants even more fuel up top.
I don't think you need to change pilot jets either.