spark plug after gordon mods

So I've done the gordon mods along with getting a custom tube made for the exhaust insert (24 I.D.  and flush to spark arrestor along with cold weld to ensure complete coverage so the exhaust only goes out through the inner tube and its tapered past the initial thick tube and about 40mm off the end of the cap) I've tried going with 135main 48pilot and it was running a little rich (always started without choke) and was getting some strange sound sometimes on the freeway, I changed the jets back to stock 132main 45pilot and it does need a choke when the engine is really cold in the morning however I am still not sure if its running right, might be a placebo or just really strong winds after work today but I felt like it was harder to reach/keep 100/110kmph when the winds kicked in on the way back.
This plug has only had 3 rides on it (first 5 minutes to test the jets then to and from work today about 40mins each way)
the grounding insulator is really light grayish and the insulator tip has got a light greyish tinge too, the threads and center electrode are black (center electrode a bit lighter black) is it possible I need to up my main jet to 138 and keep the pilot at 45? I am trying to get the right jetting but I can't seem to find any photos of spark plugs with this colour that indicate a lean condition at WOT, most of the freeway I am probably about 1/4 throttle until the winds kick it then I have to open it up from 3/4 to WOT to keep up with the speed limit, any suggestions? Could it just be the main jet that needs changing? Thanks in advance guys.

IMG_20171113_165151.jpg

IMG_20171113_165326.jpg

 

E: I have just put in a 135 main back in and I will see how I go, I could also regap the plug (its at 9mm/0.35in) right now, if needed, all opinions appreciated :)

E2: Just went for a ride and seems to still be having the same issues as in bogging down at 110 in 6th however in 5th it seems to be pulling even nicer now, past 110 easy, I guess the only way to fix that is big bore as I already upped my gearing, I still want to get my jetting right in the mean time though, gonna have a look at the plug once its cooled down

Edited by Eryk

You didn't say, but I'm guessing from the jetting, you have a 250. Your elevation?

Tune one fuel circuit at a time.

Are you retuning the the fuel screw between pilot jet changes?

If it was starting without choke on the 48, but needing choke with the 45, keep the 45 and retune the fuel screw.

Sustained 110kph is a tall order for a 250. You're not going to hurt it if it's a little rich, but running lean at those speeds is an engine killer.

Is the needle still set to stock position of 3rd from top?

Make sure the air filter is clean.

Is your exhaust stock? Stock air box configuration and air filter?

 

my elevation is pretty much 0, I don't know how to tune the fuel screw as I haven't got a rev meter and I've only ever went up from 45-48 and 132-135 so its not major changes, and I thought so too but if it always starts no choke with 48 pilot then its definitely too rich, feels different now in 1/4 throttle too now that i put the 45 in actually has some response, and yeah I figured its tall I am planning on a 280 kit with oversize valves and pretty much a full top end rebuild but for now I just wanna be able to use it daily with a safe jetting, I don't mind taking apart the carby 10 times if needed, yeah needle is stock position and air filter is clean, the exhaust is stock other than the baffle replaced by an insert of diameters I mentioned as I didn't wanna drill holes or do any of that so I went with a straight tube custom made of stainless steel cold welded, 24id 35od tapered past the joining 35mm pipe thats there after removing the baffle, im also using a xr400 s/a i just redrilled the mounting holes and grinded down the curved edge to flat so theres no exhaust leaks, and airbox has snorkle removed, twin air filter (the aftermarket one thats similar to the uni filter), oiled and waterproof grease around the edges it touches onto the airbox, tried to get it as clean as possible and just playing with the jetting now to make sure the engine doesn't run into any issues before my 280kit in about a months time (trying to source kibblewhite oversize valves, guides, seals etc.)

With a much freer flowing intake and exhaust system, you can't run stock jetting, it's too lean. Would you say your modified exhaust flows better than stock? If so, coupled with the aftermarket air filter and snorkle removal, I have no doubt a stock 132 main is lean at sea level. And with such a system, going up only 1 size from stock doesn't usually cut it.

You don't need a rev meter to tune the fuel screw. It's not so subtle that you can't do it by ear and testing for best throttle response off idle. There are a bunch how-tos here. The fuel screw tunes the pilot jet system. IN on the screw is leaner, OUT is richer. Never go more than 3 turns out. You should at least determine how many turns out it's currently set.

How much higher have you geared it over stock? That's going to have an effect on the little 250 delivering torque and power too.

5 hours ago, Trailryder42 said:

With a much freer flowing intake and exhaust system, you can't run stock jetting, it's too lean. Would you say your modified exhaust flows better than stock? If so, coupled with the aftermarket air filter and snorkle removal, I have no doubt a stock 132 main is lean at sea level. And with such a system, going up only 1 size from stock doesn't usually cut it.

You don't need a rev meter to tune the fuel screw. It's not so subtle that you can't do it by ear and testing for best throttle response off idle. There are a bunch how-tos here. The fuel screw tunes the pilot jet system. IN on the screw is leaner, OUT is richer. Never go more than 3 turns out. You should at least determine how many turns out it's currently set.

How much higher have you geared it over stock? That's going to have an effect on the little 250 delivering torque and power too.

Its definitely more free flowing as its just a straight pipe but its not an aftermarket exhaust and i would say an aftermarket system probably flows better, i only got 135 because thats what everyone recommended and at the moment its summer so 30-40 degrees celcius temps are common in the afternoon so that would be around 0.98 reduction on jets? How many rides should I do before checking my plug again? 

I did first try using the screw but even a full turn I could not tell any difference in sound (the exhaust just sounds loud like a tractor), I've put a 14 tooth front sprocket because gearcommander said it should put out around 116kmph in 6th gear at 8k rpm stock no gordon mods and yeah I can tell it has a bit less torque to it

You can't use a jetting chart correction factor with stock jetting to figure what new jetting should be because the stock jetting is wrong for your elevation and mods. Once you figure out the correct jetting for your bike as configured, then you could use a chart jetting factor on THAT jetting to determine alternate jetting like for going up in elevation and/or extreme weather changes.

If your modified exhaust is so open and loud, you may have robbed the system of too much back pressure and torque. In that case, for the rpms you're turning, it wouldn't matter much what you did to jetting, the engine has nothing to give, spilling its guts over not having the necessary back pressure to make any power at those rpms and loads, especially against the wind.

Edited by Trailryder42
8 hours ago, Trailryder42 said:

You can't use a jetting chart correction factor with stock jetting to figure what new jetting should be because the stock jetting is wrong for your elevation and mods. Once you figure out the correct jetting for your bike as configured, then you could use a chart jetting factor on THAT jetting to determine alternate jetting like for going up in elevation and/or extreme weather changes.

If your modified exhaust is so open and loud, you may have robbed the system of too much back pressure and torque. In that case, for the rpms you're turning, it wouldn't matter much what you did to jetting, the engine has nothing to give, spilling its guts over not having the necessary back pressure to make any power at those rpms and loads, especially against the wind.

yeah I am trying to figure it out now, how many rides would you say I need to do to get a decent color on the spark plug to tell?
I am hoping I kept the back end, it still feels really torquey in all other gears except 6th, the pipe insert length is what someone recommended on here, about 40mm give or take 5 so it should still have plenty back end I assume? I also grounded the headers to 30mm even on both sides (30mm grinding stone in a dremel tool) to get an even flow.

From reading this, the mods you've made and how you've trying to jet the carb you'll most likely blow the engine next time you're on the freeway.

1 hour ago, Eryk said:

yeah I am trying to figure it out now, how many rides would you say I need to do to get a decent color on the spark plug to tell?
 

With 3 rides on it at highway speeds, you should already be there. Look up how to read a plug after doing a plug chop. Depending on the plug and with some good light, you can see way down on the insulator to the area where you look for the dark brown ring, without having to actually cut the plug apart during a plug chop. No dark brown ring, too lean. But, I've come to read plugs well enough without doing a full chop, that in my opinion, the plug in your picture, having been run like it has so far, is showing lean.

What octane gas are you running? And state whether octane is determine by RON, MON or RON/MON.

If I were you, I'd locate some bigger main jets, like 140, 142, 145. If you can't locate bigger jets, raising the needle a position would help.

Edited by Trailryder42
On 14/11/2017 at 11:01 PM, Trailryder42 said:

With 3 rides on it at highway speeds, you should already be there. Look up how to read a plug after doing a plug chop. Depending on the plug and with some good light, you can see way down on the insulator to the area where you look for the dark brown ring, without having to actually cut the plug apart during a plug chop. No dark brown ring, too lean. But, I've come to read plugs well enough without doing a full chop, that in my opinion, the plug in your picture, having been run like it has so far, is showing lean.

What octane gas are you running? And state whether octane is determine by RON, MON or RON/MON.

If I were you, I'd locate some bigger main jets, like 140, 142, 145. If you can't locate bigger jets, raising the needle a position would help.

Ill look up how to do a plug chop is it basically cutting all the threads off and there will be a brown ring where the insulator ends? and ill get a new plug after i get some colour on this one as I just upped my main to 138 and seems to be running WAY better at highway speeds so it must have been starving for fuel in 6th past half throttle, im running 91 standard pump gas here i believe its ron, I will be ordering some bigger jets too as I plan on going 280 soon so I will probably get 140,142 and 145 as i think theyre recommended for the 280 kit?

Thanks heaps

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