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91 octane only.hope the dealer or customer eats the bill if the engine sticks and doesnt ripoff cat for warrenty money.
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Scary EGT readings on M8 with SLP pipe with NO fuel controller
- Thread starter Frostbite
- Start date
yeah, no SH*T!!
I needed one real warranty item taken care of, totally legit & got screwed because of (IMO) douchbag dealers that screw cat on mod stuff, total BS.
Thanks guys, I filled the sled up with 92 octane toady and will run it with premium from here on out. I guess it makes sense that the sled should run cooler with 92 octane because it's harder to burn and less prone to detonation. Good tip.
I won't be able to ride tomorrow after all, so i won't be able to give any updates with the higher octane fuel. If the sled runs 75 degrees cooler (92 octane vs. 89 octane) than it would be about perfect. That would leave me at 1270ish on the temperatures.
I also added a SLP 120/340 primary spring last night because I was running 7,900 RPM and SLP said the pipe runs best at 8,100 RPM. I was really looking forward to trying that spring tomorrow too.
Oh well, duty calls, again.
I won't be able to ride tomorrow after all, so i won't be able to give any updates with the higher octane fuel. If the sled runs 75 degrees cooler (92 octane vs. 89 octane) than it would be about perfect. That would leave me at 1270ish on the temperatures.
I also added a SLP 120/340 primary spring last night because I was running 7,900 RPM and SLP said the pipe runs best at 8,100 RPM. I was really looking forward to trying that spring tomorrow too.
Oh well, duty calls, again.
premium is not harder to burn or slower burn its just resists preignition better than lower octane. once the plug sparks the fire is burnin'....
Ok, it's more resistant to detonation and preignition (a little harder to ignite).
I measured from my EGT probes to where I guess the front edge of the piston to be and I'm right about 5 1/2 - 6" from them.
I measured from my EGT probes to where I guess the front edge of the piston to be and I'm right about 5 1/2 - 6" from them.
actually is does burn slower and its less volatile, which is why it resists preignition.
Also - Frostbite, look back a month or two ago and i specifically told you to run 92!!!
You are also worrying about your mid range temps a little too much - 1350ish isn't that crazy in the mid - pretty normal actually. My M7 with twins and fuel control would spike to 1400+ and keep going if i let it... that's scary!
FYI on the probe position too - usually its measure from the PISTON skirt, not the cylinder. 7" is a common figure on the M sleds (from the piston skirt).
Oh I know several said to run premium. The problem was, at least as many people said to run 87. Not knowing who knows what on the forum is why I split the difference.
Don't worry, I will be using 92 octane from now on.
Don't worry, I will be using 92 octane from now on.
Not to be a prick, but you post up with a lot of questions, which is okay, but you don't listen to what people say. It clearly states on SLP's website to run at least 91 octane, which is what everyone said on here - what did you expect running 87???
Actually you did not read carefully - he was running 89. But yes , SLP states clearly to run 91 min.
to confirm, run slp recommendations they do a lot of testing(91 octane) If you are not running there clutching rec. and over loading the engine you could have to put more fuel to keep temps down, thats why they give all the info. It may not always work that way but its better than guessing. also its good to know your F/P and what slp's test sled ran for F/P, just in case yours is a lot lower there might be some concern. I've stuck 3 pistons while riding the trail with the rpm in the mid range, now I am continually burping the throttle, keeps the temps down 1100 ish. All two stokes held in the same throttle position are prone to a melt down. as the engine gets hotter the air fuel going to the cylinder through the crank case gets progressively hotter raises temps. thus the burping method you don't always have to do it but its a fail safe. 91 octane burns slower with less heat, not necessarily harder to burn, 87 go's off with a bang, think of a diesel, all the bang happens from compression not spark. Diesel fuel is basically a low octane fuel say 60 octane but still takes heat to discharge. So when you run 87 octane with a lot of heat it blows on the compression stroke without spark(pinging/pre detonation) and igniting to soon it can't leave the cylinder fast enough and starts melting the piston. the higher the octane the more heat it takes to blow under compression. On a low compression engine you actually get more power from lower octane. the only 92 octane I've seen contains ethanol, I would ask around and find the best fuel you can, maverick in McCall sells none ethanol fuel. Another thing to think about is if the temps get to high the piston expands to much or to fast and seizes against the cylinder wall, like a cold seize, this is what happened to me 3 times(on the trail around 6100rpm). the sled was warm every time and I can't explain it because it shouldn't have happened, and once I nearly melted a piston but at WOT and heard the pinging for a second and it was done.
Thanks for the information.
That's pretty scary really. You've lost three pistons for no good reason. Yikes!
That kind of stuff is just one of the reasons I went to a four stroke in late 02 in the first place. That and being able to hold the throttle in whatever positon I like for as long as I want and not having to continually watch my EGTs waiting for disaster. Running 87 octane in the fourstrokes actually make them run better and my clothes never stunk (unless I was following my turboed fourstroke buddies, because their turbos all seem to leak oil onto the manifold it seemed).
However, even though my RX-1 has never missed a beat, even thoug it's got lightweight everything on it, it's still a bit heavy to be considered a competetive boondocking tree sled. Sure, it works well but, it works me over pretty good by the end of the day or especially a weekend. That's one thing I notice for sure is, I'm not nearly as sore or tired at the end of the day after riding my M8 but, with the M8 I am now again concerned about engine related issues which hasn't even been on my radar screen for 7 seasons.
It seems most things in life have some kind of a trade off.
Reliability vs. weight with a fourstroke
Flickability vs. reliability with a twostroke
Frostbite
That's pretty scary really. You've lost three pistons for no good reason. Yikes!
That kind of stuff is just one of the reasons I went to a four stroke in late 02 in the first place. That and being able to hold the throttle in whatever positon I like for as long as I want and not having to continually watch my EGTs waiting for disaster. Running 87 octane in the fourstrokes actually make them run better and my clothes never stunk (unless I was following my turboed fourstroke buddies, because their turbos all seem to leak oil onto the manifold it seemed).
However, even though my RX-1 has never missed a beat, even thoug it's got lightweight everything on it, it's still a bit heavy to be considered a competetive boondocking tree sled. Sure, it works well but, it works me over pretty good by the end of the day or especially a weekend. That's one thing I notice for sure is, I'm not nearly as sore or tired at the end of the day after riding my M8 but, with the M8 I am now again concerned about engine related issues which hasn't even been on my radar screen for 7 seasons.
It seems most things in life have some kind of a trade off.
Reliability vs. weight with a fourstroke
Flickability vs. reliability with a twostroke
Frostbite
If you want reliable then you stay stock, I road my 07 m1000 800 miles no problems, then burn down then piston scuffs, but that was before I had it figured out. My 09 scuffed on piston when new (57 miles) before I modded it, I think it was a rare fluke. I now have almost a 1000 miles with no other problems and I am continually getting more out of it. So you either leave it alone or figure it out, but there are unknowns in all aspects. So either pull your plugs or burp the throttle, but when your running mid rpm's and the powervalves are shut it can through some pretty high temps(I don't know how accurate they are), I haven't checked my plugs at that rpm I just choose to burp it.
D
Now that you have 92 octain in it, where are your egt's at now?
For what it is worth...
I run a BD box on my wife's 08 M8 w/ SLP pipeset and RKT 13.5:1 head, Boyesen reeds, and STM exhaust valves. Every sled can be slightly different, but FYI, I had to add fuel to the midrange and top end, even when running premium 91 with a 40% blend of C-12 to keep things cool. Tuned to the ragged edge with 91 octane fuel, the sled still has a lean spot in the midrange, but not as bad as it was with the stock power valves. The sled runs better with the extra fuel, too. Fuel pressure was 43 psi, and I'm running Koso guages on the machine - will still see 1370 F in the midrange occasionally, she has learned to drive around it.
I run a BD box on my wife's 08 M8 w/ SLP pipeset and RKT 13.5:1 head, Boyesen reeds, and STM exhaust valves. Every sled can be slightly different, but FYI, I had to add fuel to the midrange and top end, even when running premium 91 with a 40% blend of C-12 to keep things cool. Tuned to the ragged edge with 91 octane fuel, the sled still has a lean spot in the midrange, but not as bad as it was with the stock power valves. The sled runs better with the extra fuel, too. Fuel pressure was 43 psi, and I'm running Koso guages on the machine - will still see 1370 F in the midrange occasionally, she has learned to drive around it.
S
I can't believe you guy's are seeing temps that high, I thought you would burn down at about 1250 or so, I get nervous when I see 1215 I start backing off or flip the choke on, Yeah, still riding an old carb sled, one guy said 1400
Holy chit!!
Holy chit!!
what you guys need to do is start over with your egts. tape the face off so you cant read it. then go out and test, test, test. low, mid and high rpm plug readings and piston wash checks.
get the sled dialed to where everything is where you want it, as safe or ragged edge as you want.
THEN, go back pull the tape, and perform the EXACT SAME test runs. take notes of the egts, and set your warnings on the egt, or make a mental note, or tape a max egt temp on the dash to remind you to LOOK.
just a few mm's in probe placement can make a huge diference in readings. no two sleds are the same. what works for you might burn someone elses sled down, and vise versa. i have saw sleds burn down at 1000* egts. also, i have saw sleds run really good at well over 1400 egts. saw sleds run rich at 1350 (the melting point of aluminum).
testing will show you where you need to go. good luck. ski
get the sled dialed to where everything is where you want it, as safe or ragged edge as you want.
THEN, go back pull the tape, and perform the EXACT SAME test runs. take notes of the egts, and set your warnings on the egt, or make a mental note, or tape a max egt temp on the dash to remind you to LOOK.
just a few mm's in probe placement can make a huge diference in readings. no two sleds are the same. what works for you might burn someone elses sled down, and vise versa. i have saw sleds burn down at 1000* egts. also, i have saw sleds run really good at well over 1400 egts. saw sleds run rich at 1350 (the melting point of aluminum).
testing will show you where you need to go. good luck. ski
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squarehead, 1215 is a little low to be getting worried, your not making enough power until at least 1250, carb sled or not, that doesn't change. I see 1350 or higher on my carb sled all the time, I just don't keep it there for long. The melting point of elemental aluminum is like 1220, but pistons have to have prolonged heat temps higher than that to melt.
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If the temp to melt is 1220 than how can 1350 be an accurate reading, Maybe I should go lower my needles one notch, I don't understand?
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He said elemental aluminum (read pure) melts at 1220*. Your pistons are made of an alloyed aluminum that allow them to be run at higher temperatures (read higher melting point). I'd be willing to bet that it melts at around 1400* +. On my drag sled I was running EGTs around 1250-1300* WOT (this was after confirming via plugs and piston wash). Never had problems with detonation or pre-ignition.
still think mine runs stronger and smoother around 1150 plugs look perfect, the leaner I go the rougher it feels and rpms get fidgety (up and down)