Main Jets?

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Main Jets?

Postby FZR750R » Mon Apr 05, 2021 4:10 am

Hi Guys
Need a little experience here
I'm just working on my mates TRX which he just got back from the Mechanic? :shock:
He brought it to me to see what I thought ?
It was running as rich as all get out ....
So i did the hours to get the fuel / float level right, 5mm below mark etc
Refitted the Factory Pro nickle plated emulsion tubes
Changed the pilots back to #37.5 from #42.5
And looked at the main jets to find that they are #75 ????
Checking across this forum I see that European TDM 850 did have #75 mains
I thought the Australian TRX had # 140 as stock ???
I'm about to order some main jets so I would like some experienced thoughts here please
Cheers
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Re: Main Jets?

Postby dicky » Mon Apr 05, 2021 6:03 am

Get the files for both the service manual and the parts manual. And a stiff drink.
The parts manual refers to three different items as main jet, and two different items as pilot jet. No differentiation between fuel or air jets. It's a pain in the arse.
The service manual refers to them correctly, but you still need to look at the parts manual to get the right part number.

Pilot fuel jet, parts manual #34, service manual #7, size #45
Main fuel jet, parts manual #36, service manual #6, size #142.5
Starter fuel jet, parts manual #31, service manual #5, size #75

Pilot air jet, parts manual #32, service manual #13, size #1.4
Main air jet, parts manual #33, service manual #12, size #70
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Re: Main Jets?

Postby FZR750R » Tue Apr 06, 2021 3:34 am

dicky wrote:Get the files for both the service manual and the parts manual. And a stiff drink.
The parts manual refers to three different items as main jet, and two different items as pilot jet. No differentiation between fuel or air jets. It's a pain in the arse.
The service manual refers to them correctly, but you still need to look at the parts manual to get the right part number.

Pilot fuel jet, parts manual #34, service manual #7, size #45
Main fuel jet, parts manual #36, service manual #6, size #142.5
Starter fuel jet, parts manual #31, service manual #5, size #75

Pilot air jet, parts manual #32, service manual #13, size #1.4
Main air jet, parts manual #33, service manual #12, size #70


Hi Dicky
That's exactly what I needed to know =D> Thanks mate
Even the Yamaha parts guy wanted to argue the toss with me saying the mains are #75
I'm amazed that his thing ran at all given its was so rich down low and so lean up high
Maybe it's the old
If you have your head in an oven and your feet in a fridge the middle of you would be just right :lol:
Ordering jets right now
I'll let you know how it goes 8)
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Re: Main Jets?

Postby Rod.s » Tue Apr 06, 2021 8:00 am

The issue with the parts list is the wording...."Jet, Main" or "Main, Jet", so there are two "Jet Mains" and one "Main Jet". Which confuses the inexperienced parts muppet :roll:
If it's not made in China, it's a fake!
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Re: Main Jets?

Postby FZR750R » Fri Apr 09, 2021 8:11 am

Hallelujah \:D/
Praise the Lord carburetion
So this TRX is singing the song of a good fuel mixture
And the owner is a happy camper
Here is what's what in the Carby now
Pilot Jets are # 37.5 down from #42.5
The needles are Factory Pro Ti # 1175i-90q-70r-45t-TI
Clip is at #3 with one washer above the plastic spacer
Emulsion tubes are Factory Pro Nickle Plated from the kit with no markings ( or I forgot to look)
Main Jets
Listen up people as Dicky pointed out the parts manual and the Haynes Service manual are WRONG
They have them arse about face
So this has gone from #75 Main to # 135 Main the real main not the Jet Mains but the Main Jet
Getting a drink about here #-o
And it as sweet as a bird
So thanks Guys I appreciate the help =D>

PS It has Staintunes Pipes and has clocked around 100,000K's
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Re: Main Jets?

Postby dicky » Fri Apr 09, 2021 9:06 am

Glad to hear that you got it running better.
I had no joy with the Factory Pro needle, I found the taper to be too aggressive. I used the standard needle in the FP tube. It's the tube that wears out anyway, not so much the needle.
The standard 142.5 main jet is probably a bit rich for normal Oz conditions, so the 135 sounds about right.
Staintune cans sound grouse.
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Re: Main Jets?

Postby FZR750R » Fri Apr 09, 2021 9:23 am

dicky wrote:Glad to hear that you got it running better.
I had no joy with the Factory Pro needle, I found the taper to be too aggressive. I used the standard needle in the FP tube. It's the tube that wears out anyway, not so much the needle.
The standard 142.5 main jet is probably a bit rich for normal Oz conditions, so the 135 sounds about right.
Staintune cans sound grouse.


OK I have a spare set of Carbies and I will set them up as suggested
Thanks again
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