while building my viperstein project i found an odd thing.
when i used my temp guages at first they were on a viper with slp pipes. they told me to install the probes 7in out from piston. i did so and set the guage limits to 1275 as they told me to do. the sled run fine, jetted it to their specs, watched guages, checked plugs and piston wash. worked great.
then installed srx pipes and srx cdi box. after getting used to watching the guages from the last pipes i was scared to see 1300 within seconds of hitting the throttle and climbing. of coarse i never kept holding it. checked piston wash and it looked rich. my mind just wouldnt let me believe the temps i was seeing was going to let the motor live. the following year i accidently left the viper box in for the whole season. with this box in the temps were lower and could be controled with what i thought was large jetting for the pipes, 162.
this year sled is back together with the srx box. the first ride i installed 157mains and went for a ride. the first thing the temps went way over1300. i didnt even check the pistons and jetted it up to 162 thinking i might be able to ride the sled for the day that way. the temps still would spike up. i gave up and left the party and came back. on the way back i pulled the vent off the air box to see if i could jet it up richer. this is about 10size difference. still would drive the temps way up.
now i come home and go get my viper box. plug it in and go for a ride. guess what, temps are in the 1275 range and climb a little from there. i was watching the tach a little too long and burnt it down around 1325.
now i know that something is up. i cracked open my 12pack of pistons and installed a couple more. this time (after being told to put a piece of tape over the guage by don, thanks don) i jetted the sled to 156mains and rode it hard, checking the piston wash often. jetting was fine. i even leaned the needles one clip. sled ran great. i have stock srx clutching in front and a 54/44in the secondary (good trail srx setup). the sled will now over rev this setup by 3-400 rpms.
now for the end to this long winded rant. i felt safe enough with the jetting and then turned the temps on while at the lake. temps read 1480 at one point. this is the difference in what timing advance will do with your guages.
you guys that have guages on your srxes, what do you see for temps?
when i used my temp guages at first they were on a viper with slp pipes. they told me to install the probes 7in out from piston. i did so and set the guage limits to 1275 as they told me to do. the sled run fine, jetted it to their specs, watched guages, checked plugs and piston wash. worked great.
then installed srx pipes and srx cdi box. after getting used to watching the guages from the last pipes i was scared to see 1300 within seconds of hitting the throttle and climbing. of coarse i never kept holding it. checked piston wash and it looked rich. my mind just wouldnt let me believe the temps i was seeing was going to let the motor live. the following year i accidently left the viper box in for the whole season. with this box in the temps were lower and could be controled with what i thought was large jetting for the pipes, 162.
this year sled is back together with the srx box. the first ride i installed 157mains and went for a ride. the first thing the temps went way over1300. i didnt even check the pistons and jetted it up to 162 thinking i might be able to ride the sled for the day that way. the temps still would spike up. i gave up and left the party and came back. on the way back i pulled the vent off the air box to see if i could jet it up richer. this is about 10size difference. still would drive the temps way up.
now i come home and go get my viper box. plug it in and go for a ride. guess what, temps are in the 1275 range and climb a little from there. i was watching the tach a little too long and burnt it down around 1325.
now i know that something is up. i cracked open my 12pack of pistons and installed a couple more. this time (after being told to put a piece of tape over the guage by don, thanks don) i jetted the sled to 156mains and rode it hard, checking the piston wash often. jetting was fine. i even leaned the needles one clip. sled ran great. i have stock srx clutching in front and a 54/44in the secondary (good trail srx setup). the sled will now over rev this setup by 3-400 rpms.
now for the end to this long winded rant. i felt safe enough with the jetting and then turned the temps on while at the lake. temps read 1480 at one point. this is the difference in what timing advance will do with your guages.
you guys that have guages on your srxes, what do you see for temps?
DoktorC
Member
I don't have gauges on my sled (yet) but on my car when it pulls the timing (over active knock sensor) I can put the guage over to 1600...all the flame is out the exhaust port and not in the combustion chamber. Freaks you out the first time though!!
Srxspec
Your #1 performance shop!
Who runs guages? Jet down till she blows then jet back up one! 
DoktorC
Member
That is soooo true lol...I've got the pictures to prove it!!
Junior
New member
seems counter intuitive for me, more advance would mean more heat out the pipe, but doesn't the viper box have more timing in it stock? on the one cylinder atleast. I've noted temps over 1350 without a burndown, infact from the piston wash there was abit left to go.
temp readings also depend alot on how far your probe is from your combustion center (sorry to state the obvios) so temps that you see won't likely coincide with what others have seen.
jet by wash, forget the gauge, then once you have good jetting figured, check what the EGT is at and set that as your "redline"
cheers man, hope that sleds rocking and rolling
temp readings also depend alot on how far your probe is from your combustion center (sorry to state the obvios) so temps that you see won't likely coincide with what others have seen.
jet by wash, forget the gauge, then once you have good jetting figured, check what the EGT is at and set that as your "redline"
cheers man, hope that sleds rocking and rolling
vipertripplexxx
New member
ya man it's confusing! Less timming actually throws more fuel into the pipe, making it hotter at the probes. You would think that more jetting would do the same but usually not the case.
DoktorC
Member
Less timing throughs more flame into the pipe..the fuel charge is still burning as the exhaust port opens..when timing is retarded the exhaust port is open that much longer...letting more heat and flame out. That's why rich jetting doesn't do the same thing.
jwiedmayer
New member
One other hicup is the the probe is calibrated for a certain ambient temp. If the connetors are a degree colder than calibrated the gauge will read a degree higher. So a pyro calibrated for an ultralight(airplanes) 68degrees F is ran in a sled at 32F the thing will read 36' high.
I have anolog gauges but when I get up around 1300 I staart worring although I'm running ultralight probes. My piston look rich and I have them ceramic coated so maybe its throwing a little more heat out the port.
I have anolog gauges but when I get up around 1300 I staart worring although I'm running ultralight probes. My piston look rich and I have them ceramic coated so maybe its throwing a little more heat out the port.
i tosted another this weekend, all i can think that did it was i had one exhaust probe blow out of the hole.
has anyone else had this happen?
has anyone else had this happen?
vipertripplexxx
New member
never heard of that, but I have heard of sleds with a crack in the pipe at the spring mount, close to the cylinder, burning down. Suppose it would be the same.
Junior
New member
vipertripplexxx said:
crack in the pipe at spring mount would bring unwanted air into the system during the backpressure pulse from the expansion chamber... not to mention throwing the ex-chamber outa tune....
you're not frying cylinders to when you're doing this are you scott? that could get expensive fast
no just the piston, it didnt even burn to the ring. it will still show 120lbs compression on that cylinder. the others are 130
Scott......
unhook the vent lines and leave them unhooked, leave them down below just like a srx is, then you will be back into the correct jet sizes, all the way thru. You cant run a small main and have the vents hooked up to the box, plus as soon as you have pipes on a viper your playing russian roulete being hooked up to the box. hence thats why you have to drown them with 160+ mains and pilots big enough to throw a dog thru. Remember, your using viper cylinders, these are "hotter then a srx" in the way of port timing, so your most likely gonna be with the vent "UNHOOKED form box" around a 150-152.5 main. I would also venture to say youll need to run it at 85-8600rpm with the exhaust port being 30.5mm.
unhook the vent lines and leave them unhooked, leave them down below just like a srx is, then you will be back into the correct jet sizes, all the way thru. You cant run a small main and have the vents hooked up to the box, plus as soon as you have pipes on a viper your playing russian roulete being hooked up to the box. hence thats why you have to drown them with 160+ mains and pilots big enough to throw a dog thru. Remember, your using viper cylinders, these are "hotter then a srx" in the way of port timing, so your most likely gonna be with the vent "UNHOOKED form box" around a 150-152.5 main. I would also venture to say youll need to run it at 85-8600rpm with the exhaust port being 30.5mm.
Junior
New member
BETHEVIPER said:
well atleast it was just the egg?
I agree with Mrviper on this one, playing with viper CDI is a dangerous game. go with the SRX timing curve on those pipes, the porting will wanna rev higher and you're already into negative advance on the CDI at that point, however, you might be able to make some of that up by advancing the timing manually some. downside is she's gonna have a hotspot between 8000-8400 where the box starts to try to shut down the fun.
sorry guys, this reply has been up for 3 hours, I'm getting dragged off into school work, I'll follow up later
Srxspec
Your #1 performance shop!
I believe he was running the SRX cdi box, right Scott?
airbox, not cdi box
I was talking about the airbox, I have no idea why junior was talking about a cdi box...
I was talking about the airbox, I have no idea why junior was talking about a cdi box...
Junior
New member
Srxspec said:
SRX CDI this time around and it fried again?
mrviper700 said:
I think scott was running viper CDI when he burned down? not sure, that's where I'd go first when looking for the problem. plus the "hot spots" on those box's are different so clutching is gonna make a big difference on reliability.
that being brought up, what are you revving her at scott?
the probe pulling out seems to be the odd variable out this time.
it does get a little confusing.
burnt three making a too long run testing for grass drags. ran sled with three slightly burnt pistons (two thirds, not bad)
rebuilt, was messing around with the two cdi boxes, comparing piston wash and exhaust temps between the two and was watching the tach a little too long with the viper box in. poof, two pistons, one just rounded and the other burnt to first ring.
rebuilt, went riding srx box, left the guage off and watched piston wash, sled ripped ran it accross the lake and checked wash, looked good, leaned the midrange down later with some long half trottle pulls and checking piston wash to make sure.
now the clutching is off quite far
the next weekend i go riding to do some clutching and sled is going good, i try changing some parts this doesnt work that doesnt work and on and on. finally give up and ride the rest of the day. later in the day i look under the hood and notice there is a probe out, figure that is the power loss, hook it up and it is noticably better but still is lacking in power. im hoping for a dropped valve or something. when i got back looked in the hole and one piston was torched a little, about half way to the top ring. enough to lower compression and close the port late.
buisy this week so it is still not fixed. maybe sunday morning.
that is the play by play so far, if i had known it would be this long a deal i would have kept a journal.
burnt three making a too long run testing for grass drags. ran sled with three slightly burnt pistons (two thirds, not bad)
rebuilt, was messing around with the two cdi boxes, comparing piston wash and exhaust temps between the two and was watching the tach a little too long with the viper box in. poof, two pistons, one just rounded and the other burnt to first ring.
rebuilt, went riding srx box, left the guage off and watched piston wash, sled ripped ran it accross the lake and checked wash, looked good, leaned the midrange down later with some long half trottle pulls and checking piston wash to make sure.
now the clutching is off quite far
the next weekend i go riding to do some clutching and sled is going good, i try changing some parts this doesnt work that doesnt work and on and on. finally give up and ride the rest of the day. later in the day i look under the hood and notice there is a probe out, figure that is the power loss, hook it up and it is noticably better but still is lacking in power. im hoping for a dropped valve or something. when i got back looked in the hole and one piston was torched a little, about half way to the top ring. enough to lower compression and close the port late.
buisy this week so it is still not fixed. maybe sunday morning.
that is the play by play so far, if i had known it would be this long a deal i would have kept a journal.
yamaholic22
Active member
wow, how many times has she burnt down now total?
another post on viper / srx for a lurker