ViperTrippleXXX and others on my burning viper

Y

Yamablue

Member
Joined
Mar 7, 2004
Messages
221
Location
Ham Lake, Mn
ViperTrippleXXX I didn't see your response on the TPS adjustment post. I figured I'd address it in a new post. I am burning down around 70 mph so I would figure around 1/2 to 5/8 throttle.

Oh by the way, I burnt down again this weekend. After 200 miles two weeks earlier in 30 degree weather, I burnt it down Saturday in ND after about 3 miles on a river. So I'd be going 70 quite a bit. The temp that day was 7 and I had my needle clip on position 4. I think it would not have burnt if I were on 5, but the motor runs so rich there. It is probably cooling the motor enough to deter Deto.

I am debating pulling the TPS off and fixing it to the WOT position. I think this will pop my power valves open, but the thing has plenty of bottom end power. ANybody else have words on this. How bout an 01 SRX cdi, anybody want to get rid of one of those? I would tend to think it is a timing / detonation issuse simply because my water temps jumped up to 170 before it burnt down, Normally 130-140, My plugs are black (rich), and my piston is burning down on the exhaust side down to the rings. If it were purely mixture, I would think the center would burn.

I'm getting kinda sick of putting new pistons in this thing every trip. I think I may have caught this burndown before it siezed and screwed up my plating. (Don't want to go for a 3rd replating). I really need to get a handle on this.

I should also note. My clutching is only running my motor a 8400 WOT (wants 92-9300) so it is lugging it a little.
 
Fixing your TPS at WFO will not change how your powervalves open and close as they are adjusted by RPM, nothing to do with the TPS. If you are running the motor at 8400 you are getting into the hot spot on the Viper CDI, you need to run above 8600 or below 8200 to stay out of that hot spot. I have a SRX CDI box with the wire needed for the Viper for $175 shipped.
 
I feel your pain dude! You got to get your clutching to spin the 9200+ rpm's, @ 8400 you are right in the timing spike that would take huge amounts of fuel to keep cool.

Are you getting the trapped air out of the cooling system? Olav is telling me that he burps his cooling system 4-5-6 times to make sure all the air is out of the system, He also says that a airpocket the size of a shot glass can screw you in the Viper's cooling system.
 
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Bushman. I don't think I have air in the system, but when my head gasket was leaking, and I cooked two pistons. I cooked the MAG and PTO both on the exhaust side of the piston. My guess is the center gets the most coolant, than the PTO then the MAG. So if there is a pocket in the head it will make the MAG side hot. I though I did a pretty good job getting all the air out this time. When the motor is burning, it is only around 7500. Think maybe the CDI is advancing the motor so much that it can't pull though the RPM? When I get around 100 the motor starts shifting out higher and I pick up more speed. I know when it was 30 degrees out I held the motor WFO for about 3 miles and the EGTs were cooler than the 3/4 throttle reading. I just think it was too rich that day though.
 
Lake race ported cylinders by Bo, Mountain Perf head with 20 and 21cc inserts, CPR pipes, 01 XCR800 38mm Flatslides, Uni air pods, vForce 2 reeds. These cylinders were good for 178ish Hp on the sled they were done for with bender pipes, 38s bored to 42mm, mega power head, done on benders dyno.
 
Yamablue said:
Lake race ported cylinders by Bo, Mountain Perf head with 20 and 21cc inserts, CPR pipes, 01 XCR800 38mm Flatslides, Uni air pods, vForce 2 reeds. These cylinders were good for 178ish Hp on the sled they were done for with bender pipes, 38s bored to 42mm, mega power head, done on benders dyno.
Click to expand...


RedDog is running the Peak head with 22cc inserts, Mountain Performance told me when I ordered the head for him not to run any less than the 22cc chambers flatland on pump gas.
 
I have altered port timing. So I think that may change things. I will need ot clean some aluminum off my 21 inserts if I want to use those again. My cranking pressure with the opticool gasket and the 20 cc inserts is 125 across the board. My squish is about .040 with the full gasket. I had it with one stock thick shim and the 21cc heads at about the same pressure. My squish was about 0.025 at that time. I am always running 92 non oxy. I think I may mix some 110 in there and see what happens. If it is deto and it goes away, my EGT should increase according to theory.
 
I see a couple of problems...

Well, I will assume you dont have the carbs vented to the airbox. TPS is not the problem. You are WAY off on the clutching and this is most likely why your burnin it down, those pipes are designed to run at 9100 rpm, the reason they run at 9100rpm is to get away from the full advance on the viper box, the advance is much larger then a 01 srx is and at 8400rpm you cant supply enough fuel to keep from detonation on a sustained run. Another thing here is with the compression all being the same now, you have 2 differnt timing curves on the viper cdi, the pto is designed to run with less advance and compression, the mag and center have more compression/timing. I bet on your egt's the pto will be about 50-60 degrees cooler then the other 2. A srx cdi will be the fix here, and your clutching will be changed as well, you wont need to go to 9100rpm now, most likely about 8600-8700 rpm with the pipes, ***BUT***, this depends on the exh, port on your cylinders, do you know how high the top of the exh. port is??? post a bit more information, and can get ya some help. Buy the srx cdi to start off with. post the port information and we can dial it in from there. The last thing I see a problem with is the squish, your not gonna be able to run a tight squish of much less then .050" and make it live on pump gas, UNLESS, the squish angle is changed from 14 to 17-19 degrees, I dont know what you have there, you might be ok, but I would check that as well.
 
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THanks Mr Viper. I measure the port height when I pulll the head off, maybe tonight. Wouldn't I need to run the motor at a higher RPM since I have the cylinders to flow the RPM, or are the pipes going to be choking it now. I have a friend with a Land and Sea dyno I can hook it up to in the near future to find what RPM has peak power. Do you want the height of the top of the port to the top of the cylinder or the bottom or the port or both? Do you know for a fact the squish angle is 14 with the Mountain Perf head?
 
Oh, I have no airbox, My venting is just into the belly pan. The Mag carb vent has to take a tight turn since the wire harness and coolant line run right there. I wonder if that could be restricting the float bowl pressure. Taht doesn't explain why the PTO burnt though, that has good venting. The only cylinder I haven't had problems with is the center.
 
I am also not burning on WOT I'm burning at high cruising speeds. If I had it clutched right my RPMs would still be around 8000 for going 70-80 MPH.
 
heads,cdi,etc.

Nope, I dont know what the heads are you have, thats why I said its something to check. The stock yamaha is 14 degrees, as were my mega power head inserts, I cut them to 17-19, this allows you to run the tighter squish and doesnt promote the dead area under the squishband where all the detonation takes place, this is becasue with the shallow angle the mixture becomes trapped and stagnent, and then fires from the heat and causes detonation. By cutting them steeper it forces more of the mixture to the center and improves flame travel on top of the piston. The rpm to run the engine at now will be based off the exh. port and the pipes. The srx cdi will not be able to be run at 9000+ rpm, it goes into negative advance. The dyno will be the best way to find out what you have and where to run it at. If the port is raised, you are correct, it will need to be run at a higher rpm to make power, lets just hope its not anymore then 30mm, if its 29mm or less, your in trouble, you will have to have someone reprogram the srx box to work at a higher rpm.

I understand your not burning downat WOT, your still into the biggest part of the viper timing curve at anywhere near 8000rpm up to 8800 rpm
 
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I will try to get that info as soon as I can.

As far as the squish, thanks for that info. No one could tell me why not to run a shallower angle, just that you want to be between .040 adn .050". I should just cut the inserts for the different angle, then I can get my squish set right with no gasket. The cylinders are cut so I could use O-ring if I want to.
Damn I could have gotten my hands on a Hauck High RPM box last year, but they said not to do it. I even presented them with a lot of details, and it was an 01 box. I wonder if he was actually listening to me. I think I could have gotten it for around 150 or 200 bucks.
 
Blue,
I'm i little confusued on you set-up. Are you running the bender or cpr pipes. Sounds like your running the cpr's. Also on the heads, you said they are mountain perf, which is the peak head? Were you running the full head gasket or were layers removed? you said 125 across the board with .040 squish, and you went to .025 squish with no compression increase? Better check that gauge! Cpr's run good with 125 compression, they don't need alot. I would bring that squish back out to .040-.050 4-shure. Don't worry about the low compression reading (static), you'll get that on ported cylinders, your pipes & porting will increase running compression (dynamic). The short of it is, more fuel and air @ the set rpm = more compression. Sounds like the .025 squish is killing ya, Along with the viper shitazz timming curve, and running that SOB at 8400 Rpm. Get those RPM's up your way out of the power band for CPR pipes. As far as the viper box, I'm still running one, And have not had time to test it to see how the curve works in conjuntion with the position sensor. As for the 01" SRX box, I think it starts retarding @ 8900? No good for CPR pipes? I'm running my tps at .95 volt middle tps wire to forward tps wire. you need to run rich on your pilot/idle circuit, and don't load down the motor, my sled runs above 8000 trail riding. 8BU-10's, 4.5 tip, .8 center, 14.5 rollers, orange haulk primary spring, 45/39 haulk helix, silver yamaha secondary @80-90 twist, 23-37 gears. Thanks on the clutching to SRXMAGIC.
 
Look @ all the information now! Thanks guys because will all the stuff Yamablue changed I was way in over my head lol.

Sounds heat related due to the lack of rpm's, Any chance this is a 02 Viper with the stock fuel pump?
 
I have the peak (mount perk) head with 20cc insert and a full opti gasket right now. I am running CPR pipes. THis is what I jsut burnt down with. Previously I had the 21cc inserts with one of the thick shims for a quench of .025" I was running about 125 with that setup also. I put the 20cc heads in cause I went to the thick gasket again, plus all my 21cc inserts were buggered with alum. I should clean those up and put those in with the full gasket. I have a similar weight setup as you, but I think I have a little bigger rivet in the middle. I was am runnig a dalton blue spring (53 init, 133 total, 2.4 rate) with 14.5 (stock) rollers, my secondary is 52/43 with a silver spring I believe wraped at 90 or 100 (its tight) Stock gearing. I have an O-S-O (35 init, 3.25 rate, 142 total) I was going to try, but I think I might need a different helix. Of course I don't know what I'm doing with clutching.
 
Yes it is a stock fuel pump on an 02. I thought about puttng the corresponding XCR800 fuel pump on it, but it doesn't mix the oil in the pump. I had it set up for direct injection last year, but the shortest hose from the T got the most oil, so I nixed that an went back to original.
 
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