TOPIC:

We are here for you Drew.

Check for vacuum leaks?
Valve clearances in spec?

CoreyClough wrote: We are here for you Drew.

Check for vacuum leaks?
Valve clearances in spec?

Yes Corey, and I appreciate every one of you!


Valve check out and no vacuum leaks detected.

We'll keep at it bit by bit.

I'm curious about the needles. Has anyone experimented with different tapers?

Drooz wrote: I'm curious about the needles. Has anyone experimented with different tapers?

I am familiar with changing he seating position on the needles via shims or cir-clips but through all the reading, browsing and research I have dug through I can't recall any changes on the actual needle itself and the taper it has. Would be curious how much that would affect it since it would ultimately perform the same effect as changing how deep the needle is via shims or cir-clips Drew

If you find an answer definitely share as I would definitely be curious what you find out either way.

Best of luck,
Brett

The design and the taper of the needle that comes in the jet kits that's where all the engineering has been done. I'd recommend to use the needle that comes in the jet kit and if you want to have the bike tuned on the Dino do that. I have not used a different needle from a different jet kit.

Irish-Kawi wrote:

Drooz wrote: I'm curious about the needles. Has anyone experimented with different tapers?

I am familiar with changing he seating position on the needles via shims or cir-clips but through all the reading, browsing and research I have dug through I can't recall any changes on the actual needle itself and the taper it has. Would be curious how much that would affect it since it would ultimately perform the same effect as changing how deep the needle is via shims or cir-clips Drew

If you find an answer definitely share as I would definitely be curious what you find out either way.

Best of luck,
Brett

CoreyClough wrote: The design and the taper of the needle that comes in the jet kits that's where all the engineering has been done. I'd recommend to use the needle that comes in the jet kit and if you want to have the bike tuned on the Dino do that. I have not used a different needle from a different jet kit.

Thanks for the info lads. I didn't remember reading about different needle tapers, so thanks for confirming that. We've been doing lots of experimenting with shimming, so we'll keep reporting in!

In regards to the different needles- when I did my build, I bored my 650 out to a 720 wiseco kit. With the bore, and pods, and a 4-1 pipe, I went with a stage 3 jet kit from Dynojet. When I opened the package, it had 2 sets of main jets, new needles, clips, and half step washers for the needle. The new needles are DRAMATICALLY more tapered than the stock needles are, which lets the mains open up quicker and the pick up from mid range to WOT is alot quicker. Not sure where you're having the issue, but it also took me quite some time to get my mid to WOT range dialed in with the new mains and steep tapered needle. Once you have the set up tuned in, you'll know. Hope this helps!

Devin

650mod wrote: In regards to the different needles- when I did my build, I bored my 650 out to a 720 wiseco kit. With the bore, and pods, and a 4-1 pipe, I went with a stage 3 jet kit from Dynojet. When I opened the package, it had 2 sets of main jets, new needles, clips, and half step washers for the needle. The new needles are DRAMATICALLY more tapered than the stock needles are, which lets the mains open up quicker and the pick up from mid range to WOT is alot quicker. Not sure where you're having the issue, but it also took me quite some time to get my mid to WOT range dialed in with the new mains and steep tapered needle. Once you have the set up tuned in, you'll know. Hope this helps!

Devin

Good point there Devin! We swapped in a Dyno-jet kit in it a while back, so the needles may vary well be much different than the stockers. I'll have to have a look-see.

Our issues are in the upper rpm range. there's a stumble as it approaches red line.

Needles for the ZX550 TK27 Carbs left to right. Stock 4A10 ZX/GPZ, Dyno Jet or K & N Stage 1 and 3. The one on the right is a Factory Pro Needle for a Valkyrie, and I never used it. Dynojet Needles have 6 clip settings, and Factory Pro have only 5.

Great comparison pic Corey!

Ours are the Dyno-jet Stage 3, so I'm assuming the middle pic. I'll have a look to confirm.

Drooz wrote:

650mod wrote: In regards to the different needles- when I did my build, I bored my 650 out to a 720 wiseco kit. With the bore, and pods, and a 4-1 pipe, I went with a stage 3 jet kit from Dynojet. When I opened the package, it had 2 sets of main jets, new needles, clips, and half step washers for the needle. The new needles are DRAMATICALLY more tapered than the stock needles are, which lets the mains open up quicker and the pick up from mid range to WOT is alot quicker. Not sure where you're having the issue, but it also took me quite some time to get my mid to WOT range dialed in with the new mains and steep tapered needle. Once you have the set up tuned in, you'll know. Hope this helps!

Devin

Good point there Devin! We swapped in a Dyno-jet kit in it a while back, so the needles may vary well be much different than the stockers. I'll have to have a look-see.

Our issues are in the upper rpm range. there's a stumble as it approaches red line.

Great info and share Devin thanks!!

Drew, question for you... You said the issue is at the upper rom range. That would mean based on my amateur understanding of carbs that the pilots and needles no longer have much if any effect at the top end and it's all main jets. That being said there are two other things I can think of that could potentially contribute to high-rpm performance. Any chance you are maybe getting spark scatter at the top end which isn't properly igniting your cylinders? I know on Pops' SR650 that in the upper rpm range on the stock ignition he was getting some scatter and causing a few problems. When he switched to a Dyna ignition the top end suddenly became smooth as glass and really made a difference. The other thing I could imagine potentially affecting this is valve float. If the springs are getting tired or depending on what specific rom range you are talking about they simply may not be up for the job. On a street bike I would never consider that an issue but since this is a track specific bike I could see how your riding style would dramatically change and could start to run into those problems. Can't remember exactly what you've done with ignition and valve train without reading back through everything, but I hope that maybe sparks an idea or two for you

Brett

I agree with having a good spark. Coils wires and plugs properly gaped correctly. Spark plug wires should be flexible. Hard and stiff spark plug wires are a sign of being old, I have updated my bikes to Accel Coils and Wires, and initial start up was very obvious. Search ebay for "dragbike" then "Accel", or "Dyna", as there are a lot that come up for sale, and I have not had any of my accel coils go out since buying them used in 2003. Just saying. You could buy new and be done with it.