Calling Jetting Experts, Single carb 686 - Yamaha Raptor Forum
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post #1 of 10 (permalink) Old 12-18-2016, 05:41 PM Thread Starter
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Calling Jetting Experts, Single carb 686

So I converted my raptor 660 to a single carb, using a HSR48. I love the bike and everything I have done, except one thing. I haven't really been able to really ride it as jetting this thing has me going crazy. The bike is running a 14/42 gearing and 22" tall tires, both in dirt and sand. Elevation is about 2200'

I will list the mods-

2005 Raptor 660
Had curevo do a killer port and polish on the head, valves, they did the works
Running monster duals, big bore pipes with shorty cans
X4 Cam with wellers racing decomp pin kit
Had falicon installed a knife connecting rod, not trying to split the cases here lol
Single carb HSR48
FCI/custom intake, using FCI filter and pre wrap
2 into 1 manifold for the carb
ARP main and head studs
Eliminated a lot of wires (lightning, dash lights, just the random useless wires to me) Ground the "known" wires reverse, cdi, and all that
Modified the reluctor wheel so only two pins that are 180 degrees out
Complete hinson clutch setup
Installed a 12.5:1 CP piston
102 MM big bore
Custom made oil lines
Terry dual gasser
CFM oversized oil tank
IMS oversized fuel tank

Should be a solid 70 hp from Daniel at Cuervo. I am running the stock plug and run 100 octane race gas, and sometimes mix with U4, C16, or 110. Have NOT heard any detonation at all.

**I run the trail tech vapor and tapped the top of the stock thermostat for coolant temps using the supplied probe that came in the trail tech kit. I still run the stock fan so when it gets however hot 220 or something the fan WILL kick on. Been there and heard it happen.

I have checked for air leaks and none to my eye.

I read the manual and it said that 140 degrees is operating temp. I looked around and other guys riding seem to be at 170-190, sometimes 200 beating on it. I ride mainly wide open stuff, desert, dunes, some trails up in the mountains/hills. Yet, the bike was built for desert racing and to be a duner if it wanted.

As you can see, no expense was spared. So it is nerve racking to get this jetting figured out. Carb came with a stock 25 pilot I want to say and I have up to 50, in 5 increments. The main jet came with 165. I have from 170 to 200 in 5 increments. I started with what was in the carb and worked my way to the following. Seems to be getting better, worse and such. At first with stock jetting the head pipes would glow cherry red. So kept upping the pilot and main and needle and going round and round. I got to here and it is getting much better and can ride longer. On the flats at the dry lake bed, the bike will bounce off the rev limiter, so looking into the dynatek programmable CDI with tunes from Kenz once I get the jetting figured out, hoping sooner, than later!

Here is what I have done-
180 main
45 pilot jet
2-1/2 turns out on air/fuel screw
Needle 2nd from the top
Coolant is running about 160-180 in the sweet spot.
It will creep up to 200 when letting it idle for a min or two and just gets hotter and hotter.
Riding in 70 degree weather for this trip. Maybe an hour of run time total.

Looking at plug showed was lean, bike felt sluggish while riding also. Had a stumble in 3rd gear when hitting it to go wide open so played with jetting again.

-So tried this

175 main
50 pilot
2-1/2 turns out on air/fuel
needle in the middle
Coolant temp on trail tech is about 130-140 cruising and when I beat on it maybe gets to 160.
I am riding in 45-50 degree weather for this trip, yet I feel that shouldn't make a difference. My dirt bike gets to temp in this weather. Also did maybe 20 mins and could tell it was lean.
Takes a good 3-5 mins to get up to 200 degrees at idle, hell probably longer.

Plug tip is white, yet base is brown/black and almost looks wet. Rode it and hauls the mail, yet when coming to a stop from 1/2 throttle or more it will die and have to refire. When cruising it will bog/lean out I am guessing, than gets up and goes. Also, on decel it will backfire some. So it is lean.

-My next try for jetting is-
180 main
45 pilot
2-1/2 or so turns out on air/fuel
needle in the middle and see where that goes.

Correct me if I am wrong, yet from what I gathered is pilot is stock to about 1/8 throttle and controls the idle temp from what I was seeing, as well as the air/ fuel.
The main jet controls 3/4 to wide open.
The needle is 1/4 to 3/4 throttle.

Also referencing the tuning manual for the carb.
http://www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf

So any tips and advice? I love the bike and determined to dial it in. Just looking for another brain to bounce ideas off of.

Also, those who run monster pipes do your head pipes, coming out of the head, maybe 2-4 inches get cherry red hot were at night you can see them glow? Or is it just me and my jetting? LOL
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post #2 of 10 (permalink) Old 12-18-2016, 09:38 PM
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Most aftermarket exhaust will glow a little at night. As for the carb there isn't to many people running a single. And you are correct about wich jetting functions control what area of throttle. Along with needle diameter at 1/4 throttle, and needle taper angle at 3/4 throttle, and slide cut out in the same area as the pilot circuit.

2003 Limited Edition Raptor
Kenz 720cc 11:1 stroker, +1 valves, Mega Cycle X-4 Cam, Sparks 6x Big Core, Keihin 35mm FCR's. 158 mains, 52 pilots, fuel screws 2 turns out.

97 Banshee
F.A.S.T. Dune Ported 4mill, CPI Inframes, Keihin PWK33's, Direct Drive Lockup. 158 mians, CEL needles second clip, #48 pilots, air scews 2.0 turns out.
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post #3 of 10 (permalink) Old 12-19-2016, 12:59 AM Thread Starter
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So tonight I did the following
45 pilot
Left the 175 main
Needle is all the way rich
Air/fuel 2-1/2 turns out

I plan to get some more plugs and try to ride it and see how it does.

That has me somewhat relieved, I was hoping with the monsters they wouldn't, yet I'll just learn to live with it if the jetting is dialed in and quad runs great.

Sometimes I wish I stuck with FCR's, yet I'm sure once I get it dialed I will be extremely please. I spent a lot of time on Harley forums as they run this carb and that was leading me to try out the 3 other needles they offer for this carb. One is leaner and the other two are richer, yet most of them say changing needles aren't needed, granted it is a street bike and not a quad LOL. I sure I do not have to mess with the slide as that will really having me wish I went the FCR route.

I will report back my findings with the current jetting setup and go from there. Slowly but surely I feel I am getting a handle on it, one way or another.
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post #4 of 10 (permalink) Old 12-20-2016, 09:07 PM
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Let us know, I'm curious what you find out.
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post #5 of 10 (permalink) Old 12-26-2016, 01:39 PM
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I'm not sure why more people don't add an O2 bung to their exhaust. Wide band O2 setups are pretty affordable these days. Here's a pic of how I located mine. I run an old PLX M300 setup and being able to immediately see what impact a jetting change made ... I wouldn't go back.
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post #6 of 10 (permalink) Old 12-26-2016, 02:43 PM
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Quote:
Originally Posted by Nocturnal FabWorx View Post
I'm not sure why more people don't add an O2 bung to their exhaust. Wide band O2 setups are pretty affordable these days. Here's a pic of how I located mine. I run an old PLX M300 setup and being able to immediately see what impact a jetting change made ... I wouldn't go back.
Mine is about 1/2 way between where the primary pipes come together, and muffler attaches to the header on my sparks.

2003 Limited Edition Raptor
Kenz 720cc 11:1 stroker, +1 valves, Mega Cycle X-4 Cam, Sparks 6x Big Core, Keihin 35mm FCR's. 158 mains, 52 pilots, fuel screws 2 turns out.

97 Banshee
F.A.S.T. Dune Ported 4mill, CPI Inframes, Keihin PWK33's, Direct Drive Lockup. 158 mians, CEL needles second clip, #48 pilots, air scews 2.0 turns out.
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post #7 of 10 (permalink) Old 01-03-2017, 04:43 PM Thread Starter
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So I am at

45 pilot
175 main
Needle in the middle
2 turns out on air screw

I need to drop the pilot to a 35 I am thinking as it is fat and still running cool coolant wise, about 130 or so, and the base of the plug is black. I need to get a richer needle as with the 175 main and needle all the way rich ended up poorly running and a black plug, so I changed the clip to the middle and showed lean on. Making progress, slowly but surely!
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post #8 of 10 (permalink) Old 01-05-2017, 11:51 PM Thread Starter
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The 35 pilot and needle 2nd from the bottom was the ticket for me! It pulls like a freight train and pins you back. Feels good to finally have the jetting dialed in! Now to do a +2 swingarm and programmable dynatek with tunes from Kenz.
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post #9 of 10 (permalink) Old 01-07-2017, 09:03 PM
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Sounds like you are getting there


686 three plugger with HV porting, 39 FCRS, Curtis Sparks exhaust, Dyna FS CDI
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post #10 of 10 (permalink) Old 01-08-2017, 12:54 PM
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I would also suggest putting a afr gauge on the quad takes all the guesswork out of it.


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