TM 32 jetting

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T.RexRacing
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Re: TM 32 jetting

#106 Post by T.RexRacing » Fri Jan 03, 2014 11:22 am

I'll get you one if ya want it. be forewarned it's big and made for a large butterfly carb. I've never installed one on a slide carb with the exception of a CV. On which it worked great. You'll need to modify the float vent,float bowl and be willing to experiment with drilling air bleeds for effectiveness. You also need American standard drills and taps.

At this time I've no dyno to use. There was a hostile takeover and I was the first casualty 'cause I couldn't stand the new boss and took every opportunity to point out he had no idea what he was doing. But we're trying to find some $$$$ for an EC997.

Why do you say you have no credibility? You have more experience with a dial a jet than I do as I said before. And with the deafening silence concerning them here I'd like to hear about you results with them.
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Re: TM 32 jetting

#107 Post by South_Oz » Fri Jan 03, 2014 11:49 pm

Ive got these on my RGV. works well.

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Re: TM 32 jetting

#108 Post by tankslap » Tue Jan 07, 2014 11:21 am

I'm a little confused, so to clarify, do the Thunder Jets or any other 'power jet', Oem or aftermarket, come with air correction/air bleed or other?

I found the Dial-a-Jet originally because I went in search of power jets to jet an Athena 421 that I was having trouble with.
The rich mains I was running in it were still allowing the the thing to rev hard and cleanly once in the band but in it's most VE dead zone (5500-7000rpm aprox) it just wanted lean, lean, lean.
It had been a long time since I had played with two strokes and realistically I had bugger all direct experience let alone an available local dyno!

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Re: TM 32 jetting

#109 Post by T.RexRacing » Tue Jan 07, 2014 12:32 pm

Yeah if you look at the photo I posted earlier you can see the air bleed at the base of the T-Jet. Don't believe the PowerJet does.
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Re: TM 32 jetting

#110 Post by tankslap » Thu Jan 09, 2014 10:15 am

I noticed that black dot in the photo but ignored it thinking it was a grub screw to hold the thing together!
When I wread the product description on the T-jet I didn't recall anything being made note of an air bleed/ emulsion etc. hence my confused state!
What you said about metering before emulsion is starting to have a different connotation to me now that I understand that the T-jet feeds emulsified fuel via an infinately adjustable needle/ needle jet arrangement.

Under what circumstances do you start to drill air jets when using this arrangement?
Coupled together with the variable air bleed block supplied with the Intelajet would give an extra easy level of adjusting things do you think?

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Re: TM 32 jetting

#111 Post by tankslap » Thu Jan 09, 2014 10:25 am

As a side note, it appears that my large Keihin, D/J and pod filter is giving better mileage than stock quoted figures on my Aprilia.
It is hot here at the moment and correct jetting should give good mileage I suppose but fuel economy is one of the claims made by Thunder Products, so read into that what you will!

South Oz, are they round slide Mikunis on that there RGV? What's the story there?

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Re: TM 32 jetting

#112 Post by T.RexRacing » Thu Jan 09, 2014 10:54 am

tankslap wrote:I noticed that black dot in the photo but ignored it thinking it was a grub screw to hold the thing together!
When I wread the product description on the T-jet I didn't recall anything being made note of an air bleed/ emulsion etc. hence my confused state!
What you said about metering before emulsion is starting to have a different connotation to me now that I understand that the T-jet feeds emulsified fuel via an infinately adjustable needle/ needle jet arrangement.

Under what circumstances do you start to drill air jets when using this arrangement?
Coupled together with the variable air bleed block supplied with the Intelajet would give an extra easy level of adjusting things do you think?
Actually there are 2 air bleeds to a proper set up. One on the mount and another installed into the carb body. The T-Jet is metered before emulsifying the fuel. Under the knurled top on the T-Jet body is a Mikuni round main jet.

It's rare to need tuning with the air bleed on the T-Jet,mostly using the one installed in the carb body is sufficient. When it's needed usually a second T-Jet is installed to create another circuit to spread the load.

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Re: TM 32 jetting

#113 Post by EEKNOWS » Fri Jan 10, 2014 7:44 pm

Does anyone have a program to plot the fuel curve of mikunis? Recently been using a similar program for Dellorto's and the interesting aspect is the needle and needle jet have a far greater influence than I ever thought. The main jet only becomes dominant when the area of the needle and needle jet become bigger than the area of the main jet. Some times that is not until 90% throttle.
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Re: TM 32 jetting

#114 Post by mkane » Fri Jan 10, 2014 9:41 pm

Damn near the same for mikuni's.

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Re: TM 32 jetting

#115 Post by Bngt » Wed Jan 15, 2014 12:03 pm

Which means that if you increase main jet just a little, it will never be dominant. That is why I think that running 420 in a VM 26 with stock needle/needle jet is not giving you more fuel than for instance 360s.
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Re: TM 32 jetting

#116 Post by tankslap » Thu Jan 16, 2014 11:21 am

"The main jet only becomes dominant when the area of the needle and needle jet become bigger than the area of the main jet. "

For the sake of clarity I think this should read,
The main jet becomes dominant when the area between the needle and needle jet becomes 'smaller' than the area of the main jet 'orifice'.




Please correct me if I'm wrong.

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Re: TM 32 jetting

#117 Post by Bngt » Thu Jan 16, 2014 12:27 pm

You are wrong.
Think again.
Dominant here means that it is where you have the restriction. The smallest jet in a sequence is dominant.
F2 1986 project (ZX636R suspension)
F2 1987 The mule, test bench for tuning.
31K 1984 Donor
TZR 2MA 1986 Racer
TZR 2MA 1987 Stock
ZX10 1988 Cruiser
VTR 2005 (with CBRRR suspension, brakes and wheels)
Husaberg FS 570
GSX-R 1000 K5

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Re: TM 32 jetting

#118 Post by tankslap » Fri Jan 17, 2014 7:05 am

How embarrassing! Right you are.

I totally confused the logic there even though I got the concept.

So changing the main jet also changes the throttle position where it takes over right?

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Re: TM 32 jetting

#119 Post by Bngt » Fri Jan 17, 2014 11:28 am

I had to think twice myself.

This is different from when you have systems in parallel like the idle system and the main system. Here the main system becomes dominant when it provides significantly more fuel than the idle system.

Correct the smaller the MJ is the earlier it becomes the restriction. If it is bigger than what the needle system can be you can just throw it away it will never influence the flow. There is a recommendation to run without MJ to find out if and when there is to much flow. On Mikuni you cannot do it because you need the MJ to keep the NJ fixed. I drilled the MJ in the stock carb to a very large size and found that I could still not get the bike to fourstroke. This was an indication that the NJ/N is too small when running without airbox or with an open airbox.
F2 1986 project (ZX636R suspension)
F2 1987 The mule, test bench for tuning.
31K 1984 Donor
TZR 2MA 1986 Racer
TZR 2MA 1987 Stock
ZX10 1988 Cruiser
VTR 2005 (with CBRRR suspension, brakes and wheels)
Husaberg FS 570
GSX-R 1000 K5

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Re: TM 32 jetting

#120 Post by EEKNOWS » Fri Jan 17, 2014 8:45 pm

Bngt wrote:I had to think twice myself.

This is different from when you have systems in parallel like the idle system and the main system. Here the main system becomes dominant when it provides significantly more fuel than the idle system.

Correct the smaller the MJ is the earlier it becomes the restriction. If it is bigger than what the needle system can be you can just throw it away it will never influence the flow. There is a recommendation to run without MJ to find out if and when there is to much flow. On Mikuni you cannot do it because you need the MJ to keep the NJ fixed. I drilled the MJ in the stock carb to a very large size and found that I could still not get the bike to fourstroke. This was an indication that the NJ/N is too small when running without airbox or with an open airbox.
interesting the aprilia gp dellotos have 2 different stepped holes in the needle jet. With that it is possible to change the mixture over 10% of throttle position sometimes the main jet doesn't become dominant until 95% throttle
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