carls 910 seems thermostate??

[pharotek]

i am running ~3gals of sunco 110 with ~4-5 gals of 93 ATM, gauge says i have half tank. i am also thinking i will drain the tank and start over with the gas... I was told if i did the head work by removing 6CC more in each dome i could run with out 110. I will start over and drain it all and put only 93 in and will have to run it on stand since were i live we have no snow.........

 

[Goinboardin]

You're going to take out a rod bearing if you keep riding it with it detonating.

Double check your ignition timing (probably have to call Carl's, as it might not be the factory spec), and check your TPS voltage. Look up how to do this, there is a good video on youtube. You can use a USB cord for your 5.0V supply voltage.

When you take the head off, look really close at the pistons. Are there any tiny craters in the dome? That's indicative of detonation.

I had my det sensor mounting bolt fall out once, temperature light was flashing, bolted sensor back to head and all was well. Might as well put a strip of silicone on exhaust springs anyway.

But don't ride it if its detonating. It seems you have it backwards, if anything you want to run MORE race fuel than you have now. Don't "start" over and run straight pump gas.

Running on a stand I doubt you'd see deto. You need to load the motor to test, and a free spinning track isn't load.

 

[pharotek]

You're going to take out a rod bearing if you keep riding it with it detonating.

Double check your ignition timing (probably have to call Carl's, as it might not be the factory spec), and check your TPS voltage. Look up how to do this, there is a good video on youtube. You can use a USB cord for your 5.0V supply voltage.

When you take the head off, look really close at the pistons. Are there any tiny craters in the dome? That's indicative of detonation.

I had my det sensor mounting bolt fall out once, temperature light was flashing, bolted sensor back to head and all was well. Might as well put a strip of silicone on exhaust springs anyway.

But don't ride it if its detonating. It seems you have it backwards, if anything you want to run MORE race fuel than you have now. Don't "start" over and run straight pump gas.

Running on a stand I doubt you'd see deto. You need to load the motor to test, and a free spinning track isn't load.

once i can build a TPS tester i'll try all the above, were should i start with fuel, i was told yellow is from bad gas... SO i plan to drain it all out, and start over with fresh. What do you suggest straight 110?? or 50/50 or ????

 

[BILTIT]

What elevation?

I am at 2200' and they recommended 30-40% 110 for me, depending what head is on it.

As stated i would NOT run just premium, if i recall carls said they run 20% 110 up to 8000'.

Its hard to get a straight answer out of anyone at carls though, i am not real impressed with the technical service.

 

[pharotek]

they had me remove 6cc from the heads on my motor for my elevation. Said after doing that i should be fine..... But i run 0-3k elevation. The heads were stamped with 50cc so they are now 56cc.

 

[sled_guy]

I run the hi compression heads and ride above 8k feet and I run 3 gallons of Av gas to 7 gallons of premium.

Timing should be advanced 4 degrees from stock.

sled_guy

 

[pharotek]

Okay so i made a TPS checker today, i found it was @4.47... I have set it too 4.00 and my meter goes to open for split second around 3.87ish, I am taking it as i need a new TPS sensor.... I have one on another set of carbs for a 600 and will check Part# and see if they are the same and will install that one and see whats up. As far as timing goes I have manuals i just have to read them over cause i have no idea on how to even check let alone adjust the timing.

also when checking the timing should i be doing it with the Premium light on or off?? I was told and have always rode with it on, and even in my 800 edge i keep it on and always only run 91/93 in it.

 

[Goinboardin]

That is a high voltage for the TPS. If I'm not mistaken the higher the voltage the more advanced the ignition timing is at all throttle positions.

The regular/premium key settings switch between two different timing curves. I bet you'd see the deto sensor go off less often on the regular setting as the sled is currently set up. The regular setting pulls a couple degrees out of the advance, while the premium setting is a little hotter curve.

To check ignition timing you'll need a timing light. I've read you need some special two stroke compatible light but have no issue using my regular strobe timing light. I use my truck battery as the voltage source, clip the magnetic clip over a plug wire on the sled, point the strobe at the opening atop the ignition housing, and with sled running (TPS unplugged and motor warm) squeeze the timing light trigger then rev motor to 3300RPM and see what number is illuminated. Stock spec is ~29* BTDC, SledGuy says advance it 4* for that 910cc, so you want ~33* BTDC (seems like lots of advance!). The adjustment requires pulling the flywheel, loosening three allen bolts that hold the stator in place, then turn the stator clockwise to retard timing or counterclockwise to advance timing.

I'm not sure about the compatibility of those two TPS's. It shouldn't go to open though, so I think you are correct in replacing it. But of course swapping to check could save you some $.

 

[pharotek]

i'll pick up a timing light in morning(work nights) and check it. I did find hout the TPS are the same Part# and i already checked the extra one i have and it show no "dead" spots, thus i'll install it in the am.

Based on what both you gentlemen said, i'm drain/clean my tank and add 2gals 110 to 3gals 91/93(think i can only get 91 non E in my area, so i may add little more 110 to make up for it) Silicone up the springs and exhaust fittings and go from their... I also have picked up a new temp sensor and DET sensor. I was told the DET sensor needs an extact Tourqe spec or you can damage it.. Hopefully the repair manual or performace service guide i have will have it in their some where.........

Thank you guys for all your help! i will report back soon as i can, my work week just started, so with 14hr days i dont' get much wrenching time in..

Aaron

 

[sled_guy]

And you want to check your timing with the TPS unplugged.

And don't trust the flywheel marks, verify them with a TDC check with a micrometer and degree wheel.

And I check my timing at 8000 rpm

sled_guy

 

[Goinboardin]

Why at 8000RPM? Just seems sketchy...

Spec is @ 3250RPM, 29* BTDC, TPS unplugged, engine warmed up.

Good idea to check flywheel marks. SLP has some how to stuff on their site about that if you (anyone) needs guidance. I'll admit, I never checked my flywheel...

EDIT: I checked my flywheel marks, 0.5* retarded. Thanks for the motivation to check this out SledGuy, your posts are always very helpful.

 

[sled_guy]

There is a high RPM spec also. You run the motor at high RPM most of the time. The CDI can actually be dead on at low RPM but not advance(retard) correctly at high RPM. I've had that happen on 2 sleds. So I check it at high RPM.

sled_guy

 

[pharotek]

Okay so i'm Confused here on what to do.... I still have to check my Timing, but... I was told today by Carls...

19°@8100rpm
31°@4000rpm

Now once i figure out were i'm at who do i listen to..............

 

[Jay]

I think everyone is telling you the same thing, Carls is giving you specs and sledguy and goinboardin are telling you how to check it. Don't get rattled, you're getting good advice. Sledguy runs a 910 and in his experience the engine likes more advance. That thing will pull like a freight train either way you set it up, don't worry, be happy.

 

[pharotek]

Okay so i'm Confused here on what to do.... I still have to check my Timing, but... I was told today by Carls...

19°@8100rpm
31°@4000rpm

Now once i figure out were i'm at who do i listen to..............

i am thinking i may have miss under stood him, cause their should not be that far of a gap in readings.

think he meant 19@4000 elevation
31@8100 elevation
or idk lol???? i'm start with the settings sled guy said to go by anyhow..


I do agree i am getting great advice, and will check tomorrow for i could not get fresh 93 today, but got the 110 in needed.

 

[Jay]

No he isn't talking about elevation, he means degrees of timing. An engine needs more timing advance at a lower rpm, because, well, it's lower rpm. 31 degrees before top dead center gives the fuel mixture that split second it needs to burn before it gets to tdc and push the piston down, thats at 4000 RPM. At 8000 RPM the piston is moving faster so you have to fire closer to tdc because the piston is going to get to tdc alot faster. All ignitions are programmed to lose timing as the RPM increases if they didn't you would just fry your engine. If you have a higher octane fuel you can get away with more timing advance because the fuel burns "slower" and is more stable, less prone to detonation. Detonation is when the fuel charge doesn't burn completely, it burns part way and then does explode whatevers left, due to heat buildup mostly. Thats the "ping" or knock you hear with detonation. I hope this makes sense, I know these other guys could explain it better.

 

[w browning]

Jay, that is probably the best expanation I've ever heard for timing, advance, and detonation. Well done!!

 

[BILTIT]

So did carls say 19@4000, 31@8000 or the reverse? You have it stated both ways above.

 

[BILTIT]

Unless 2 strokes are radically different, you want more timing advance as rpm increases. Atleast that is how it works on 4-strokes, or am i missing something????


"The ignition timing will need to become increasingly advanced (relative to TDC) as the engine speed increases so that the air-fuel mixture has the correct amount of time to fully burn. As the engine speed (RPM) increases, the time available to burn the mixture decreases but the burning itself proceeds at the same speed, it needs to be started increasingly earlier to complete in time."

 

[BILTIT]

My bad, i see 2 strokes are different!! Learn something new everyday!

http://www.dragonfly75.com/motorbike/timingcurves.html