staggs65
Moderator
lean burndown
^^^
X2
X2
rx1jim
New member
That is EXACTLY what the center piston on my 2000 SRX looked like after a 20 miles ride with an air temp. of 35 F. The entire 20 mile ride was at a relaxed, easy pace, crusing at about 35 MPH. It was RIGHT after we gassed up the sleds: 1 SRX 700 and an 03 RX1. The carbs were spotless, had just been cleaned two weeks earlier. This happened after 13,000 miles of perfect running. When I did a post mortem on the engine to determine the cause, the carbs were still spotless.
It could be from a lean condition OR detonation from crappy(lower octane than needed) gas. Both causes result in the same result, Huge amounts of heat that causes massive destruction.
I will only run my rebuilt SRX with an octane booster to help, no guaranteees.
Jim
It could be from a lean condition OR detonation from crappy(lower octane than needed) gas. Both causes result in the same result, Huge amounts of heat that causes massive destruction.
I will only run my rebuilt SRX with an octane booster to help, no guaranteees.
Jim
I do have SLP pipes on this sled and this tank of gas I was not able to get the 91 octane fuel. So this is 87 octane fuel with probably 10% ethonal. So if this is related to the fuel, wouldn't I see a lean issue on all 3 cylinders rather than just one?
rx1jim
New member
I forgot to mention, at the time of the burndown, my 2000 SRX was completely stock, running all the stock jetting. The 2001 jetting was leaned out in the mid range then fattened up in the top end. I have since set it up with a combination of the pilot jet from the 2000 and 2002 spec: 42.5 and the main jetting from the 2001 specs: (1) 150 and (2) 148.8.
Lean burndowns REALLY suck since they cause so much damage. Here is what I replaced as a result of the gift from hell:
1. Complete engine disassembly and reassembly: all new gaskets and seals. It was time to do a complete overhaul anyway, approx. $90.
2. New oil pump: After sinking so much money into the rebuild, I figured it would be good insuarance to use a brand new pump, approx, $150.
3. Repair of the crankshaft: replacement of the center connecting rod and bearing, $275. Jeff at Midwest Cranks did an excellent job.
4. New pistons, rings, wrist pins and bearings: I replaced all three piston sets since the engine had a lot of miles. I had the new pistons coated by Swain in Rochester NY. I had them put the thermal barrier on the domes and the poly-moly low friction coating of the skirts. I had these coatings put on to extend the life of the pistons realizing I should replace the piston rings every 5000 miles or when a leak down test says it is time. Approximately $550
5. New head, actually a good used head from a fellow TY member. $40
6. Replated cylinder from Millenium. The shrapnel from the burn down gouges the cyliner walls pretty bad. Approximately $250
7. All new coolany hoses. being a 2000 model year, I did not trust the hoses, easier to replace now than after overheating the new engine. Approximately $75
8. ALL new jets for the carbs. Updated to the 2001 main jet specs.
All total, the cost was PAINFULLY high, about $1400!!!! I spread the costs out over the 7 months between seasons to keep the costs under the "radar", if you know what I mean. BUT having a brand new SRX engine is worth it.
The biger cost was the complete loss of peace of mind while riding this beast. I always worry about detonation biting me again, hence the mandatory octane booster, although that may be false security as well.
You really need to make sure yor crank is OK as a result of the burndown.
Jim
Lean burndowns REALLY suck since they cause so much damage. Here is what I replaced as a result of the gift from hell:
1. Complete engine disassembly and reassembly: all new gaskets and seals. It was time to do a complete overhaul anyway, approx. $90.
2. New oil pump: After sinking so much money into the rebuild, I figured it would be good insuarance to use a brand new pump, approx, $150.
3. Repair of the crankshaft: replacement of the center connecting rod and bearing, $275. Jeff at Midwest Cranks did an excellent job.
4. New pistons, rings, wrist pins and bearings: I replaced all three piston sets since the engine had a lot of miles. I had the new pistons coated by Swain in Rochester NY. I had them put the thermal barrier on the domes and the poly-moly low friction coating of the skirts. I had these coatings put on to extend the life of the pistons realizing I should replace the piston rings every 5000 miles or when a leak down test says it is time. Approximately $550
5. New head, actually a good used head from a fellow TY member. $40
6. Replated cylinder from Millenium. The shrapnel from the burn down gouges the cyliner walls pretty bad. Approximately $250
7. All new coolany hoses. being a 2000 model year, I did not trust the hoses, easier to replace now than after overheating the new engine. Approximately $75
8. ALL new jets for the carbs. Updated to the 2001 main jet specs.
All total, the cost was PAINFULLY high, about $1400!!!! I spread the costs out over the 7 months between seasons to keep the costs under the "radar", if you know what I mean. BUT having a brand new SRX engine is worth it.
The biger cost was the complete loss of peace of mind while riding this beast. I always worry about detonation biting me again, hence the mandatory octane booster, although that may be false security as well.
You really need to make sure yor crank is OK as a result of the burndown.
Jim
Devilin AblueDress!
New member
Probablly doesnt make you feel any better but I have a sick feeling in my stomache looking at that pic. I feel your pain. Have you tore into carbs yet? If other 2 cylinders look fine then wouldnt it have to ben caused by something exclusive to that cylinder? Leaking donut,sucking air case seal/boot/reed? Partially blocked circuit with combo of 87 with 10% ethanol started the chain of events?
staggs65
Moderator
could be the mag side crank seal as well
I have not tore into the carbs yet. So not sure it it could be leaking air or is a plugged jet in the carb.Devilin AblueDress! said:
motorhead327
VIP Member
I have an srx but have read alot about vipers on this forum. The magneto side has more compression. You need to do the opticool gaskets, the needle tricks, and maybe the srx cooler. Here is a good link. http://www.totallyamaha.net/forums/showthread.php?t=87822&highlight=viper+needles
I do have the Opticool head gasket and I also have the SRX heat exchanger in the rear. However I do not change the needle settings from the recommended setting from SLP.motorhead327 said:
motorhead327
VIP Member
dcfjef said:
I would have to say then the forced use of the 87 octane caused it to build more heat on that cyl and caused the burn down. Are you using the srx base gasket also. I would still bump up the needles. Maybe Mr. Viper will chime in!
I am not using the SRX base gasket. Yet ... I will be installing that this time when I put it back together.motorhead327 said:
Do any members here redo cylinders? There is some metal on the side that came from the melt down. So I need this cylinder redone.
Thanks.
Thanks.
staggs65
Moderator
post a pic. if its just melted piston it will come out with a good honing
chris700readhead
Member
Mrviper700 (Don) can get your cylinder done at a good price. He's doing two of mine as we speak. Real nice Guy too. Might even be able to talk to him on what needs to be done to keep this from happening again.
from reading this thread and looking at the pic its obviously a lean burn down, and contributing to the fact you used 87 octane in a piped viper with stock head is most likely why it went down. The mag and center cylinders have more compression then a srx does, add in the mag cylinder gets the worst cooling from the stock head and then added ignition timing and you have a sure result for detonation with low octane fuel. The slp jetting specs are good for the pilot and mains but the needles need to be raised up for todays lousy gas quality. The needles and nozzles are also leaner in a viper then a srx so thats why they go down more often, too many cards not in thier favor.
If you look or post pics of the other piston tops it will likely be eveident of detonation on the center cylinder as well, the pto survives more often because it has a lower compression ratio so it runs a bit cooler.
Really the srx base gasket will not make and wouldnt have saved you in this instance. the only differance is the holes for the coolant are slightly bigger for 2 of the cylinders but it really doesnt make the sled cool another 10 degrees or anything.
if you have smeared aluminum on the cylinder you can use muratic acid to eat it off, it wont hurt the plating, just will eat off the aluminum, use it outdoors and wear a mask ,nasty vapors off it. You can then hone the cylinder if the plating is not messed up and reuse the cylinder. just depends on how bad its damaged from the burn down.
If you look or post pics of the other piston tops it will likely be eveident of detonation on the center cylinder as well, the pto survives more often because it has a lower compression ratio so it runs a bit cooler.
Really the srx base gasket will not make and wouldnt have saved you in this instance. the only differance is the holes for the coolant are slightly bigger for 2 of the cylinders but it really doesnt make the sled cool another 10 degrees or anything.
if you have smeared aluminum on the cylinder you can use muratic acid to eat it off, it wont hurt the plating, just will eat off the aluminum, use it outdoors and wear a mask ,nasty vapors off it. You can then hone the cylinder if the plating is not messed up and reuse the cylinder. just depends on how bad its damaged from the burn down.
Bluemonster2
New member
another thing I want to add is a 2 stroke that stays at the same operating rpm for a long time runs the risk of the exhaust side of the piston to slowly get hotter, so that with your pipes, crappy fuel,etc. prob caused this.
YAMAHIZAL700
New member
Hard to really see but it really doesn't look to bad too me.(cylinder) I would pour the acid to it and hone away and see how it comes out. Can u catch ur fingernails on the scratches in the cylinder? After u use the acid and hone it wipe it down real good with a rag to remove excess acid.See if u can catch ur fingernail on any of the scratches, if u can't ur good to go!