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PostPosted: Sun Sep 10, 2017 10:12 am 
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Joined: Thu Jun 23, 2011 2:26 pm
Posts: 1752
Location: Running Springs Ca
Iv'e been jetting 2 strokes since the 70's but my current bike is being a struggle to dial in. This is the 72 H2 that I bought from Fran
a few months ago. It has a FBG top end with heads that have been modded. Running 34mm VM Mikunis witch I know well and have
lots of Needle Jets and needles for. So it came with Q-6 NJ's and 6FJ6 needles set at clip 3 and 230 mains. Being at 6000 feet here the first thing I
did was try P-2 NJ's and 6Dh4 needles/ The 6FJ6's are a very lean needle so I can see how the Q-6's may have worked at lower altitude.

Keeping the mains at 230 and using the P-2's with 6DH4 needles it ran best on clip #1. Also the slides are 3.5 (leanest) Tried 2.5 slides and
they make is 4-stroke off idle. Also tried my other needles, 6DH7 (leaner needle) 6FJ6 (leanest needle I have) and a 6DP1 (richest needle I
have but taper is very different). Result was the 6DH4 gave the best but likes to be in clip 1. Since NJ's are number by a linear size I tried
a P-0. To lean with the 6DH4 and trying the 6DP1 that needle starts out way to rich. Tried a P-4 NJ and my 6DH4 works the best out of all
my needles again but once you get to about 1/2 throttle it goes rich. So I'm thinking I need to go back to P-2 NJ's and maybe get 6DH3 needles
(just a hair leaner than 6DH4's) or go back to the P-0 NJ and get 6DH8 needles ( just a hair richer).

From reading the needle chart the 6DH needles seem to run similar tapers but the 6DH8 has a longer taper with length "B" being a much shorter length.
With the porting the motor seems soft up to the power band, softer that a stock ported one. Once it hits, it pulls really hard. Fran thought it
was the 120hp porting. At this point I think it's time to find someone with a dyno and get it dialed in for sea level to give me a good base
to work with.


Last edited by 67lotus49 on Sun Sep 10, 2017 11:10 am, edited 1 time in total.

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PostPosted: Sun Sep 10, 2017 10:42 am 
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Joined: Tue Jun 07, 2011 6:37 am
Posts: 9809
Location: Rio Rancho, New Mexico
That's the exact reason I do my reed conversions. Hard porting kills the rideability. That's why I have 100's of conversion kits out there. Get the dyno done and see how you like it, but I seriously doubt it will be a fun bike on the street. :wtf:

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PostPosted: Sun Sep 10, 2017 11:07 am 
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Joined: Thu Jun 23, 2011 2:26 pm
Posts: 1752
Location: Running Springs Ca
I could always put on a stock set of cylinders and be done with it. Reeds would be the way to go if I want to keep this set of cylinders John.


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PostPosted: Sun Sep 10, 2017 11:58 am 
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Joined: Tue Jun 07, 2011 6:37 am
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Location: Rio Rancho, New Mexico
Always a few options. Just pointing out the downside of hard porting on a piston port.

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I can teach your triple how to "reed"........
http://kawatriple.com/aylor


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PostPosted: Sun Sep 10, 2017 1:07 pm 
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Joined: Thu Jun 23, 2011 2:26 pm
Posts: 1752
Location: Running Springs Ca
I would have preferred it didn't have a ported top end but just trying to make it ride as best that I can with these cylinders and then decide.
Just tried another jetting setup and got it much closer so making progress today. Have more jet needles and mains on the way, at least
these carbs have any size jets still available. Tempted to try a set of RGV 250 carbs but no baseline to start with.


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PostPosted: Sun Sep 10, 2017 2:39 pm 

Joined: Tue Jul 24, 2012 6:06 pm
Posts: 821
Location: Honolulu
I feel your pain after having jetted TM34's. However Soflah (Chris) saved me a lot of time when he shared his jetting info. With his help I bought just two sets of needle jets and one set of needles. The jetting is not perfect but it's close and the bike is fast. I might add Moo's reeds to this bike in the future.


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PostPosted: Mon Sep 11, 2017 8:31 am 
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Joined: Thu Sep 29, 2016 4:32 am
Posts: 227
Location: Indianapolis, IN
Too much inlet timing will make for difficult lower speed jetting, try longer intake runners to contain fuel/ air standoff, pods will hurt if directly on the carbs.

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1974 Kawasaki H2B 750, 1981 Yamaha XV750 Cafe, 1983 Kawasaki KZ1100 Spectre, 1986 Kawasaki KDX200, 2003 Honda XR100, 2004 SDG140.


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PostPosted: Sun Sep 17, 2017 2:13 pm 
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Joined: Thu Jun 23, 2011 2:26 pm
Posts: 1752
Location: Running Springs Ca
Have the jetting sorted, runs better than it should with the porting it has. Nice day up here in the mountains so took it out for a good ride.


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PostPosted: Sun Sep 17, 2017 3:01 pm 
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Joined: Wed Jun 13, 2012 9:00 pm
Posts: 790
Location: Eagle Wisconsin
What did you end up with on the jets ??


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PostPosted: Sun Sep 17, 2017 3:22 pm 
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Joined: Thu Jun 23, 2011 2:26 pm
Posts: 1752
Location: Running Springs Ca
I'm at 6000ft so keep that in mind. FBG 120hp porting and heads have been modified too. Stock timing with uni filters and Jim's All-in-one CDI box
230 mains
P-0 NJ
6DH4/1 needles
42.5 pilot
air screw 1 1/4
2.5 slide


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