JL GP Pipes

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maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

JL GP Pipes

#1 Post by maser01 » Mon Aug 15, 2016 5:06 am

Hey Chaps,
have above set of above pipes in stainless on the way . Any suggestions on tuning with stock carbs to get the most out of them or are they pretty good without too much done ie jetting etc. Have fitted fibre reeds and rebuilt top end but that's it. May have a play with airbox lid to let breathe better as I have a spare? :twisted: I'll do a plug chop to check mixture and go from there!

Any info from people who have the above pipes would be grateful. :smt006

Cheers,
T
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

Questo vecchio rz
Posts: 198
Joined: Sun Aug 30, 2015 2:36 pm

Re: JL GP Pipes

#2 Post by Questo vecchio rz » Wed Aug 17, 2016 4:04 am

There are many many here who have Lomas pipes that will surley chime in.
Some thoughts on your plug chops, here in the U.S. majority of our unleaded pump gas has ethenol and fuel mixes that , make plug chops unreliable if not impossible to do correctly. Using specific "race fuel" will bring about better more accurate results. A very experienced ex factory. builder whom did a dirtbike build for me, schooled me on this. If youd like I can forward you the link from their website, if you have not read it already, it makes for a intresting read if anything.
As far as adding holes to the airbox? Im not sure if its worth the added potential jetting hassles and pitfalls, especially vs indavidual filter retrofits, but again others here might have actual 1st hand input or advise regarding that modification.
Last edited by Questo vecchio rz on Wed Aug 17, 2016 4:19 am, edited 1 time in total.
Banshee (Baja) Full Tilt desert race bike
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96 GSXR SRAD, Future Yoshimura TT-F1 Lucky Strike rep.
85 custom Tri-Z
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86 VFR750 Flying Fred Merkel replica (project)

rich bullock
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Location: Gloucestershire

Re: JL GP Pipes

#3 Post by rich bullock » Wed Aug 17, 2016 4:14 am

Hello T
have same pipes on my RD500 and all I have done based on reading loads of posts on here is changed jets from 185 to 175 for fronts and 195 to 185's in the rear carbs. Have not adjusted needles or anything else and seems to run okay to me. Have a set of unifilters and Ivan's jet and needle kit to fit but have yet to do.
Rich.
Rich B

maser01
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Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: JL GP Pipes

#4 Post by maser01 » Wed Aug 17, 2016 8:54 pm

Thanks for the info chaps.......
Granted, fuel quality does come into it Questo but done correctly plug colour on a 2 stroke is I think the best way to get a true gauge on it's state of tune for both oil and fuel mixture's. Please pm me the link will make for some interesting reading :-)

I would have thought the pipes would have resulted in a "Leaner" state of tune requiring slightly larger mains, this is the normal practice as the engine has more ability to pump more air requiring slightly more fuel to correct the slight mixture change?

NEVER TUNE A 2 STROKE TOO LEAN FUEL/AIR MIXTURE UNLESS YOU WANT A HOLE IN YOUR PISTON CROWN! But I don't mean Rich B is wrong as I'm in a very different location which changes things!

RE- airbox.............as the pipes will allow the engine to "Expel" exhaust gases more effectively the engine will need to "Breathe" slightly more air IN to balance this otherwise it will hinder the ability of the JL pipes performance. I'll open up the airbox lid 1 small area at a time (Using a neat holesaw) so I don't go too far and see how it performs.............just about guarantee it will make a positive difference without going to the pod filter mod! It's all about the "Balance".

I won't be having a play until the pipes are fitted in a few weeks so I'll keep you all informed. After all we all want these old girls running as sweet as we can get them WITHOUT having to rob a bank and bring unreliable into the frey!

Cheers,
T
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

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nzminis
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Location: New zealand

Re: JL GP Pipes

#5 Post by nzminis » Thu Aug 18, 2016 4:32 am

If i recall
im at 195 all around . new jets from john (economy cycle )
n8 14 hole
needle in the middle
yz125 reeds
stock airbox

from std Rzv tubes and 165

few track days pushing the old girl and its been perfect

If i were you just do the same as mine .
My opinion its not worth the hassle of tuning pod filters and the needle kits
whats the point ?? the bike rips

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: JL GP Pipes

#6 Post by maser01 » Thu Aug 18, 2016 6:51 am

Thanks for the post NZ. Pretty sure the RZV model is jetted different to the Oz RZ bikes as they were restricted for the JAP market.

Runs nice as it is (In stock form) but just have that urge to get some more punch from it as I know how good you can get these things going with a little sensible "Tweaking"! I'll do the below improvements and see how it performs over STD,

- Stainless GP JL pipes
- Fibre reeds
- Airbox lid mod
- Brisk Race plugs
- 520 chain conversion 14/40 gearing
- Jetting changes as required on main only

Will keep all informed ;-)

Cheers,
T
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

Questo vecchio rz
Posts: 198
Joined: Sun Aug 30, 2015 2:36 pm

Re: JL GP Pipes

#7 Post by Questo vecchio rz » Thu Aug 18, 2016 12:37 pm

Here is the link, you can find a basic rundown of his plugchop concerns/facts w pump fuel under the Tech Tips titled Mikuni Carburetor Tuning for Vintage 2-strokes

Here is the website link: http://www.klemmvintage.com/" onclick="window.open(this.href);return false;

Harry is a very experienced builder with quite a resume, and helps anyone with quite alot of good solid information.
Like I said , good reading at a minimum take from it what you choose.
Enjoy your bike, will sound nice.
Banshee (Baja) Full Tilt desert race bike
Royal Enfield 500
96 GSXR SRAD, Future Yoshimura TT-F1 Lucky Strike rep.
85 custom Tri-Z
RZ421/YZR track bike(project)
86 VFR750 Flying Fred Merkel replica (project)

begbie
Posts: 289
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Location: UK

Re: JL GP Pipes

#8 Post by begbie » Thu Aug 18, 2016 2:57 pm

An after market pipe will quite often want to make peak power higher in the rpm range and be more efficient at scavenging the cylinder, sucking air at a higher velocity over the main jet, this is why quite often you will want to drop a jet size...BUT, a sure fire way to tell what your engine, with your mod's, in your climate wants, is to put it on a dyno with an A/F sensor.
also remember you may look at the air box intake and think that looks way to small for a 500 but there are only ever two cylinders breathing through it at a time.
Last edited by begbie on Thu Aug 18, 2016 8:29 pm, edited 1 time in total.

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nzminis
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Location: New zealand

Re: JL GP Pipes

#9 Post by nzminis » Thu Aug 18, 2016 7:01 pm

You will find the oz one will have n-8 or 0-o tubes . So the only thing that may differ between our bikes would be the air jets , the rzv is not restricted as much as you think

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: JL GP Pipes

#10 Post by maser01 » Fri Aug 19, 2016 12:15 am

Yes..........thanks to all for your valuable input, this is why I enjoy a good forum. I'll have a read Questo many thanks.

Yep Dyno results are a very good indicator begbie and I understand this but I'll start with the simple plug read first as not tracking the old girl just yet! Understood Re; Airbox intake.

NZ you would be in the know having an RZV and I'll double check jetting No.s next time carb's off. I do know the STD pipes on the RZV were smaller for JAP market BUT Allu frame and better suspension was a bonus at the time! ;-)


Cheers to all.
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: JL GP Pipes

#11 Post by maser01 » Fri Aug 19, 2016 5:00 am

nzminis wrote:If i recall
im at 195 all around . new jets from john (economy cycle )
n8 14 hole
needle in the middle
yz125 reeds
stock airbox

from std Rzv tubes and 165

few track days pushing the old girl and its been perfect

If i were you just do the same as mine .
My opinion its not worth the hassle of tuning pod filters and the needle kits
whats the point ?? the bike rips
NZ......quick? Just clarifying mate........ :-?

Re; n8 14 hole?
are you referring to needle jet tube?

From std Rzv tubes and 165?
Are you saying you changed std Rzv needle tubes & mains to n8 14 hole tubes and 195 mains?

Cheers,
T
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

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nzminis
Posts: 479
Joined: Sat Aug 04, 2012 2:29 am
Location: New zealand

Re: JL GP Pipes

#12 Post by nzminis » Fri Aug 19, 2016 5:12 am

yes the emulsion tubes

n8 14 hole are the Rz/ Rd ones
the Rzv had n6 8 hole in front and n8 8 hole in the back

n-6 lean , n-8 richer , 0-o richer again

even know i did run it with the Rzv tubes and it was fine . i found a set of new RZ/Rd tubes so why not

im still dont know what to think about the whole 195 jets are 165 jets just with different numbers , or what ever order that was to be

so yes i have N-8 Rz/Rd tubes and new 195 mains

i just kept bumping up the main untill it got a little burbley , then backed it off one so landed on the 195

rd84
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Re: JL GP Pipes

#13 Post by rd84 » Fri Aug 19, 2016 7:04 am

Why don't you start the airbox mod by just removing the baffles from the inlets .

Cheers
Paul

maser01
Posts: 56
Joined: Tue Oct 02, 2012 8:16 am
Location: Australia

Re: JL GP Pipes

#14 Post by maser01 » Mon Sep 19, 2016 8:03 am

Ok...........Stainless GP JL's arrived and look great :grin:

Thanks for the jet info NZ and yes Paul I'll try the baffle out first 8-)

NOW TO GET THEM ON AND GET TUNING...........Converting to 520 chain also so will be a positive improvement :smt003


Cheers,
T
Love classic 2 Strokes
Regards,
T Newts

1984 Yamaha RZ500 L
1981 Husky WR430
1974 Yamaha DT175 B
1995 Suzuki RGV250 T
1979 Suzuki GS850 GN
2000 Husaberg FE600E
2004 Aprilia RSV1000r
1981 Yamaha IT250H

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