pinging under load

[whc]

2007 400ex 416cc 11-1 comp stage one hot cam 170 main jet, when the quad gets hot she starts pinging under load, runs good otherwise, long as i dont hit the gas too hard she is happy. any thoughts, i am going to go even richer on the main since the only thing I can think is that she is still a bit lean. any thoughs are appreciated, bill

[TRXRacer1]

This is exactly why I tell people that 11:1 is not always a pump gas set-up. If you're sure it's dialed in properly get some race gas.

2x on the race gas (110-116) should be good.

[guenther]

I've got almost the identical set up. I run 91 mixed with 110 to get around 96 and no pinging (3.75 to 1.25 ratio). If I run straight 91 (highest that's on tap here) then I'll ping when I'm under hard load. My jets are 155/42 and elevation in Iowa is around 1000ft.

[fearlessfred]

Originally posted by whc
2007 400ex 416cc 11-1 comp stage one hot cam 170 main jet, when the quad gets hot she starts pinging under load, runs good otherwise, long as i dont hit the gas too hard she is happy. any thoughts, i am going to go even richer on the main since the only thing I can think is that she is still a bit lean. any thoughs are appreciated, bill use only enough octane to prevent pinging and try the coldest factory recommended spark plug and do a plug reading to correct the jetting

[JOHNDOE83]

I agree on the race gas.

Try sunoco race gas, its 110oct, look for a station close by, or try to do a web search for one your area.

170 DJ aka 190 keihin, is a good size jet, next step would be race gas for sure!

[400exrider36]

i had this same problem a few days ago....
turns out the owner before me didn't tighten the head bolts tight enough and they came loose and it leaked through the head gasket under load....
when i took the plastic off i could see the vapors leak out
it was a verrry loud tick tho


this isnt likely your problem, but just wanted to mention it.....

[TRXRacer1]

Originally posted by guenther
I've got almost the identical set up. I run 91 mixed with 110 to get around 96 and no pinging (3.75 to 1.25 ratio). If I run straight 91 (highest that's on tap here) then I'll ping when I'm under hard load. X2, it should only take some blending to fix this one. Maybe even 50/50.

[CJM]

Im near sea level and have almost the same exact setup but a hotcam stg 2 and have no issues with 93 pump gas.

[JOHNDOE83]

Originally posted by CJM
Im near sea level and have almost the same exact setup but a hotcam stg 2 and have no issues with 93 pump gas.

I think the stage 1 allows more compression and the stage 2 has a lil less, which would make sense why it works for you and not him....?

The more valve duration, takes some of the dynamic compression away.

Thats why the stage 3 cam is for strokers, the extra length on the rod makes more compression, in order for you to have the correct balance of compression, the duration is longer.

Atleast thats what I would suspect.?.

[CJM]

Originally posted by JOHNDOE83
I think the stage 1 allows more compression and the stage 2 has a lil less, which would make sense why it works for you and not him....?

The more valve duration, takes some of the dynamic compression away.

Thats why the stage 3 cam is for strokers, the extra length on the rod makes more compression, in order for you to have the correct balance of compression, the duration is longer.

Atleast thats what I would suspect.?.

Quite possible.

But then again Im literaly like 200ft at most above sea level so that might help IDK for sure.

[TRXRacer1]

There's no question, the stg 1 will loose less compression then the stg 2. Everybody rides different, terrain and conditions are subjective, and even in identical builds some will end up with more cylinder pressure then others.

[whc]

wow lots of good info, going to up the jetting to 175 and will try to locate some higher octane fuel, I can get 91 and some places have 93, but who knows what we are really getting. I worked at a gas station for a few years, so you really never know. may also try a cooler plug. that for all the come backs, must be a bit of a common problem? Bill

[fearlessfred]

Originally posted by JOHNDOE83
I think the stage 1 allows more compression and the stage 2 has a lil less, which would make sense why it works for you and not him....?

The more valve duration, takes some of the dynamic compression away.

Thats why the stage 3 cam is for strokers, the extra length on the rod makes more compression, in order for you to have the correct balance of compression, the duration is longer.

Atleast thats what I would suspect.?.
a question for johndoe 83 about the longer rod on a stroker motor. isnt the wrist pin heigth corrected on the piston ( i truly dont know ) if it is than it would not raise compression .now a larger bore would always raise compression (unless head work is also done). i was also wondering why u would recommend 110 octain,when the motor in no way could use over 100 octain. i do believe in being on the safe side and 100 would be on the safe side.anything more than that would cause aloss in performance ( unless u were to advance the timing to counter the slower burn time) .i do agree with your comments on the cam, the more valve overlap the less the compression. and to whc ,i would like to suggest doing 0ne change at a time,just to know what corrected the prob. im only guessing when i say that i dont think u need to go up on the main, if it is pinging at partial throttle openings then i would raise the needle ,seeing as the main mostly effects the last 1/4 of the throttle

[JOHNDOE83]

Originally posted by fearlessfred
a question for johndoe 83 about the longer rod on a stroker motor. isnt the wrist pin heigth corrected on the piston ( i truly dont know ) if it is than it would not raise compression .now a larger bore would always raise compression (unless head work is also done). i was also wondering why u would recommend 110 octain,when the motor in no way could use over 100 octain. i do believe in being on the safe side and 100 would be on the safe side.anything more than that would cause aloss in performance ( unless u were to advance the timing to counter the slower burn time) .i do agree with your comments on the cam, the more valve overlap the less the compression. and to whc ,i would like to suggest doing 0ne change at a time,just to know what corrected the prob. im only guessing when i say that i dont think u need to go up on the main, if it is pinging at partial throttle openings then i would raise the needle ,seeing as the main mostly effects the last 1/4 of the throttle

Im not 100% sure either on the wrist pin thing, That might be very true and probally why they want you to use the stroker piston with the kit....Im sure someone can answer that a lil better then I can. I "think" the only difference is the piston is made to clear the cases when on the down stroke, but Im not 100%.

But even if it were higher on the wrist pin, the down stroke would still be longer +4mm or +7mm, making the up stroke longer also, creating more cylinder air, thus creating more of a dynamic compression ratio...or I would think so anyway? Ive never seen the pistons and rods side by side so I cant be 100%.

I recommended the 110 cause the 93 or 91 was making him ping, he could easily mix it, like the other guys have said, that would probally be the best bet in this situation, unless full 110 actually makes him run better? but we wont actually know that till he tells us...lol.

My 440 isnt that high of compression I tried to keep mine around 10:1, and from time to time I run the sunoco 110 just for chits and giggles, I was actually running the 110 when I ran my 8.83 1/8th mile.

[whc]

wow guys lots of good info, seems like this may be a bit of a common problem? I have not had time to rejet yet, but will check our local sunoco station for 110 fuel, if not available will get some race gas. we have been running 93 octane, but you never really know what your getting. I worked at a gas station for a few years when I was younger and watched cut rate gas go into a name brand station more then once. thinking about the cooler plug not sure if available but my stock car racing bud is not sure if that would help. just thought I would mention that is has been usually warm at the last two races, 85 plus degrees. and that the quad actually pinged a bit when hot before I went 416 and hot cam. will update after we test ride with better fuel in the next couple days. Bill

[fearlessfred]

Originally posted by whc
wow guys lots of good info, seems like this may be a bit of a common problem? I have not had time to rejet yet, but will check our local sunoco station for 110 fuel, if not available will get some race gas. we have been running 93 octane, but you never really know what your getting. I worked at a gas station for a few years when I was younger and watched cut rate gas go into a name brand station more then once. thinking about the cooler plug not sure if available but my stock car racing bud is not sure if that would help. just thought I would mention that is has been usually warm at the last two races, 85 plus degrees. and that the quad actually pinged a bit when hot before I went 416 and hot cam. will update after we test ride with better fuel in the next couple days. Bill on the colder plug i have corrected detonation probs. with the change to a colder plug with no other changes and all plug makers recommend going to a colder plug when increasing horsepower . dont know why people are so risistant to the idea of running a colder plug when they have modded there motors in ways that have increased combustion temps. when combustion temps get to high the tip of the plug will ignite the mixture prematurly,causing pinging or detonation. u should try it and decide for yourself.it does require the overall jetting be more spot on, but that requires work and who wants to do that

[JOHNDOE83]

You can read the plugs ground strap to see if your plug is to hot.

If the color on the ground strap goes all the way to the threads your plug is to hot, if the color is near the tip of the strap its to cold, if the color is in the middlle the heat range is ok and you dont needd to run a cooler plug.

If these arent a problem a colder plug wont do anything, unless your customizing your timing curve, or running alcohol...etc. then you can change the plugs heat range to accomodate what tunning youve done.

[TRXRacer1]

Colder and hotter plugs have nothing to do with the spark, it's a change in the isolator and the exposure to the head. Going colder on an air cooled barely makes a dent in the combustion temps but on a liquid it's much more prevalent. Regardless as said earlier there is absolutely not going to be a loss going cooler in this situation.

On the stroked motor thing it can be done both ways. If the crank is stroked with a stock length rod the pin needs to be moved up in the piston. If the rod is shortened along with the stoked crank then stock pistons may be used as long as they are clearanced for the crank.

[whc]

what will just changing the jetting alone accomplish? if i just go bigger on the jet will that make a diff. ??? Bill

[dalejiw25]

A "cold plug" has a shorter insulator nose, which minimizes the amount of surface area exposed to the combustion gases. Cold plugs are typically used in racing conditions because of its ability to transfer heat out of the cylinder chamber quickly. Most turbo, supercharged and nitrous oxide applications use this type of plug because of the tremendous heat they generate. A colder plug can also minimize the risk of pre-ignition and detonation, however if the plug is to cold there is risk of fouling during extended periods of idling and low-speed operation. So to Avoid Fouling, Never let your meat loaf, Never idle, and Ride it like you stole it !!!! I burn 92 - 94 octane pump gas all day long, Balls out. No prob..

[sc400ex_rider]

time to get a fan. also make sure your using motorcycle oil, it does run cooler. I even found some oil made for air cooled engines!!

[fearlessfred]

Originally posted by whc
what will just changing the jetting alone accomplish? if i just go bigger on the jet will that make a diff. ??? Bill
jetting should be done by reading the plug . a lean condition can cause detonation ,but jetting in excess is not going to help performace and is not a cure all. keep in mind ,that the main jet is not the only part of jetting. the main only effects the last 1/4 of throttle opening. if u are pinging everywere else but there, try the needle. if a person uses overly rich jetting to correct the prob.they will never be able to get a correct reading on the ground strap as johndoe suggested and what he stated is textbook. so what im suggesting is not to throw a blanket over the prob. but to correctly jet by reading the plug and to use the correct heat range by reading the plug and enough octane to prevent detonation.

[dalejiw25]

I use Valvoline Motorcycle oil "4-Stroke" It's made for air cooled 4-strokers and Wet clutches. Same price as regular motor oil. Good Stuff.

[whc]

a couple of you guys have mention using a fan, where do you put the fan? what type of fan? etc. plug reading is tough on four strokes, I have tried in the past to actually cut the plug to read the inner part, didnt work too good, I usually go rich till I start to lose that crisp throttle response then go down one. I will try a cooler plug, but I do a lot of low speed in the woods during a hs race. motor cycle specific oil humm all variable wt. oils contain polymers which cause heat, would a guy be better off running a straight wt.? got some 110 oct fuel today will be running tommorow night, three gallons of 93 to one gallon of 110 to start. will let yeahs know how that works, racing this weekend then three weeks off will test cooler plug and try some different jetting. Bill

[fearlessfred]

Originally posted by whc
a couple of you guys have mention using a fan, where do you put the fan? what type of fan? etc. plug reading is tough on four strokes, I have tried in the past to actually cut the plug to read the inner part, didnt work too good, I usually go rich till I start to lose that crisp throttle response then go down one. I will try a cooler plug, but I do a lot of low speed in the woods during a hs race. motor cycle specific oil humm all variable wt. oils contain polymers which cause heat, would a guy be better off running a straight wt.? got some 110 oct fuel today will be running tommorow night, three gallons of 93 to one gallon of 110 to start. will let yeahs know how that works, racing this weekend then three weeks off will test cooler plug and try some different jetting. Bill good luck and let us know how it works out and i think the way u are jetting is just fine .so u do the same with the needle

[whc]

just got done riding, after riding about 45 minutes noticed a very slight pinging under load and I mean slight, if this was all it did ping I would be very happy , was running 1.5 gallons 100 and 3.5 gallons of 93. temp was mid 70s. also felt a bit stronger? this was the first time I have rode on my practice track since modifing, but it felt stronger with the hotter fuel. am going try try to get a cooler plug tommorow, will not run again till sundays race, oh would being jetted too rich cause the machine to smoke? first I have noticed it since the rebuild, ran the machine for about an hour and a half after the new piston and cam broke it in per the hot cam instructions, then raced it for about an hour and forty five minutes. did not notice any smoking during the race but it was real dusty so may not have been visible. tonight was the only time any one watched me ride since the rebuild and race and it was smoking a bit? but my jetting may be a tad rich. will update after the race. Bill

[whc]

correction it was 1.5 gallons of 110 and 3.5 gallons of 93 bill

[TRXRacer1]

If you're pinging you will for sure notice more power with the proper octane. If you're even getting the slightest amount then up the octane even more.

[fearlessfred]

Originally posted by whc
just got done riding, after riding about 45 minutes noticed a very slight pinging under load and I mean slight, if this was all it did ping I would be very happy , was running 1.5 gallons 100 and 3.5 gallons of 93. temp was mid 70s. also felt a bit stronger? this was the first time I have rode on my practice track since modifing, but it felt stronger with the hotter fuel. am going try try to get a cooler plug tommorow, will not run again till sundays race, oh would being jetted too rich cause the machine to smoke? first I have noticed it since the rebuild, ran the machine for about an hour and a half after the new piston and cam broke it in per the hot cam instructions, then raced it for about an hour and forty five minutes. did not notice any smoking during the race but it was real dusty so may not have been visible. tonight was the only time any one watched me ride since the rebuild and race and it was smoking a bit? but my jetting may be a tad rich. will update after the race. Bill if the smoke is black it could be jetting. i also agree with trxracer1 on uping the octane,mabe 50/50,as air temps rise so will the pinging.i dont believe in using octane in excess,because it can cause a decrease in performance ,but do believe in a safty margin ( a little extra )

[whc]

50 50 will give me about 101 octane, will try, but am going to try the cooler plug first as a test. man i dont want to tear her down again, but I could try a quick hone to break the glaze and hope to seat the rings, or replace the valve guides, that the only thinq I havnt done. later Bill

[whc]

started a new thread, see pinging two Bill