Just installed a Hauck big bore kit in my Viper. After having it melt down 3 times prior to doing this I was a bit nervous and installed three pyrometers. I was unsure about location and what max temp should be. I found some instructions online that stated the thermocouples should be 10-12" from pistons and temps should be 1000-1300 degrees.
My question is: Is this location correct, what should temps be, and should center cylinder run exactly 200 degrees hotter than the other two? I just put about 80 miles on it yesterday and at trail cruising speeds the two outside cylinders were running 1080-1150 and ceter was 1280-1350. Do I need to fatten up the ceter or all the cylinders?
Thanks in advance for any advice
My question is: Is this location correct, what should temps be, and should center cylinder run exactly 200 degrees hotter than the other two? I just put about 80 miles on it yesterday and at trail cruising speeds the two outside cylinders were running 1080-1150 and ceter was 1280-1350. Do I need to fatten up the ceter or all the cylinders?
Thanks in advance for any advice
no1chevyboy
New member
are those temps at wot? if so fatten up center or check for leaks,if not check sync
only about 1/4 to 1/2 throttle. I was going easy on it trying to break it in. when I give it full throttle it doesnt seem to get much hotter if any.
Hauck had me run 155 mains in all three I am afraid of going any bigger than I have to since it seemed to do quite a number on MPG's
Hauck had me run 155 mains in all three I am afraid of going any bigger than I have to since it seemed to do quite a number on MPG's
i'm running 160 in a srx and its not a huge difference .... maybe if u keep it at full throttle all day
no1chevyboy
New member
you dont worry about mpgs when you jet especially with a big bore and 2stroke, you could raise the needle on middle carb to fatten it up in that range,bigger pilot, check for intake leaks,check sync.carbs clean,float hieght
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thanks for the input. Is thermocouple in the right place and are those the right ranges for EGT's
mopar1rules
Active member
155's on a viper big bore are too small. i would be at 160's at least. don't jet to a specific temp reading either on your egt gauge. go off of piston wash (most important) and then plug readings next. don't be afraid to stagger jetting either, to get correct piston wash and plug coloring on each cylinder. the egt gauge is just that. once you have correct plug coloring and piston wash, take note to what temp that the egt is displaying. write that number down and now you know that if it gets 100-150deg hotter than that value, that something is up. know what i mean??
Just a suggestion... concentrate on plug colour / piston wash @ 1/4. 1/2, 3/4, full throttle to be sure your feeding it enough fuel at different throttle settings, then referrence back to the temps you see on the gauge. Fuel (relatively speaking!) is cheaper than pistons. I'm thinking that it's more important to make sure all 3 probes are at the same distance from the face of each piston. I would rather start "pig rich" and work down. Good luck... hope that helps!
mopar.... I type tooooo slowwwww LOL
mopar1rules
Active member
i forgot to say to start out at 4.0 position on the needles, 50 pilots, and have carbs unvented from airbox. are you vented to airbox yet?
not sure how to check piston wash, actually not even sure what it really is.
I'm a diesel mechanic and have very little understanding of 2 stroke setup.
Yes the vent line is disconnected
Should I step all three up to 160's or larger then go from there? I looked at shimming the needles when I installed the jets but it looked like a real pain.
I'm a diesel mechanic and have very little understanding of 2 stroke setup.
Yes the vent line is disconnected
Should I step all three up to 160's or larger then go from there? I looked at shimming the needles when I installed the jets but it looked like a real pain.
check in the tech section mr viper explain the wash on piston ....needle are not that bad to play with ...i think u should run 160 atleast but ur alone on that ..no sled are the same jetting
mopar1rules
Active member
what head are you running w/your hauck big bore? i don't care how big of a pita that adjusting the needles sounds to you....do you want your motor to live, or do you want another burndown? your call.....you put in the effort, you'll be okay. you get lazy and booooom.
this is piston wash....notice the area of clean piston crown, where ports feed in the mixture. you want your piston top like this....
http://www.hydrotoys.com/gpr/stockcenter20hrs.jpg
this is piston wash....notice the area of clean piston crown, where ports feed in the mixture. you want your piston top like this....
http://www.hydrotoys.com/gpr/stockcenter20hrs.jpg
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The head is my stock one machined by hauck to go with their kit. as far as the needles go, I wasnt getting lazy and not doing what I was supposed to. Hauck said to leave them in the stock position but a local Doo mechanic suggested that I shim them .020 to help with the ethanol problem. They are seeing a lot of melt downs this year and blaming it on that. I seems that I need to pull the head after each run if I'm supposed to check wash? Not easy since we have no snow and I have to travel north 3 hours to ride.
mopar1rules
Active member
a simple piped viper w/OEM cylinder bore, hardly wants to survive, w/stock needle height, especially if cruising at 1/2 throttle alot. i would suggest you move clip on needle down (towards pointy end) one groove from the middle position....place both plastic shims underneath the clip too. now, start out w/160 mains and go from there. you said carbs aren't vented to the airbox anymore, so that's a good thing. you'll need like 47.5 pilots for sure, if not 50's. what pipes you running on that viper?
This is exactly what Hauck sent for jetting specs.
155 mains
52.5 pilots
1.2 air jets
std needle pos.
2 turns on mix screw
It is running early design Hauck husher pipes since 02. Burned down 2 times before Hauck told me to unplug vent and sent a revised set of jets. One of the pipes keeps cracking, I've welded it at least 4 times.
I will gladly take your reccomendations and fatten it up as you said then go from there. I'm tired of melt downs and that is why I am asking about this stuff. Especially since it sounds like Hauck likes to run them lean.
155 mains
52.5 pilots
1.2 air jets
std needle pos.
2 turns on mix screw
It is running early design Hauck husher pipes since 02. Burned down 2 times before Hauck told me to unplug vent and sent a revised set of jets. One of the pipes keeps cracking, I've welded it at least 4 times.
I will gladly take your reccomendations and fatten it up as you said then go from there. I'm tired of melt downs and that is why I am asking about this stuff. Especially since it sounds like Hauck likes to run them lean.
mopar1rules
Active member
sounds like you might have the cpr built pipes. also, w/the stock head, i would run a 162.5 main jet in that cylinder instead of the 160 like in pto and center. oh, no need to pull the head off of sled to see piston wash. you can put piston to BDC and then use a pen light and shine down in there. you can view wash just fine. at least i can that way....LOL. you know what, heck....start out w/162.5 pto/center and 165 mag and then go from there. sounds like you have ok pilots to start out with. did you have a idle hang before?
do you have your pipes wrapped w/heat tape? if not, that will keep them from cracking.....says so in the instructions and it will keep heat in the pipes for more hp.
do you have your pipes wrapped w/heat tape? if not, that will keep them from cracking.....says so in the instructions and it will keep heat in the pipes for more hp.
So do you still suggest raising needles and using shims? I just pulled the needles and they were in center position and were using both shims.
The local shop only had 160 and 165 mains so I picked up a set of each and I'm thinking about trying the 165 first then go from there.
Thanks again for your interest and great help.
Actually I just realized that the center only had one shim and the other two had both. The factory shims appear to be .017" and I have a set of .030".
I am thinking about using one factory shim in the center and one .030" and two factory in the other two. The reason for this is that the center was running hotter than the other two in the midrange.
The local shop only had 160 and 165 mains so I picked up a set of each and I'm thinking about trying the 165 first then go from there.
Thanks again for your interest and great help.
Actually I just realized that the center only had one shim and the other two had both. The factory shims appear to be .017" and I have a set of .030".
I am thinking about using one factory shim in the center and one .030" and two factory in the other two. The reason for this is that the center was running hotter than the other two in the midrange.
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mopar1rules
Active member
start w/shim on 4th clip position (1 down from middle towards pointy end) and place both stock plastic shims underneath. i would suggest just getting a new OEM plastic shim, to replace the one that's missing for center cylinder. yeah, starting out w/the 165's sounds good. can you post pic of your pipes? i would like to know for sure what version of hauck hushers you got.