I put about 250 miles on a new top end with modification work done by Hauck before the piston broke on #1 on a Vmax 800. It appears to me a ring hit the bottom of the exhaust port. Hauck is telling me it is probably bad gas or running too lean.
Before I do the repairs I want to be sure it won't happen again. Anybody had breaks like this and know the cause???
I checked plugs and piston wash every 50 miles since this was a new set up and the burn was perfect. The engine was also warmed up before any riding.
Before I do the repairs I want to be sure it won't happen again. Anybody had breaks like this and know the cause???
I checked plugs and piston wash every 50 miles since this was a new set up and the burn was perfect. The engine was also warmed up before any riding.
Attachments
Ot sounds like he cut too ,uch off of the bottom of the cylinder if your ring is hitting.
need to see the piston better, some views of the exh side, intake side, and a cylinder exh port from back of cylinders pic
I lost an alignment pin last season and had similar results.
ModMMax
New member
The pitting around the perimeter of the piston top and the matching pitting on the head chanber indicates something called squish detonation. Generally, related to low octane fuel as opposed to not enough fuel. Lean failure will show piston slump at the exhaust port side withut the pitting shown in your photo, although high engine temp can sometimes produce a detonation look. Subsequent ring isues can be part of it.
aSRX600guy
New member
doesn't look like detonation, it looks like some metal was bouncing around in there. probably a failure of a ring, c clip, or the ring retainer. either way, its piston related.
sometimes you get a bad one, no real way to predict it.
I'd be surprise if hauk, or virtualy any other shop out there would do whats right. I once had one jackass screaming at me thet hed bean fixing sleds for 20 years and no one ever acused him of making a mistake. the carb had a 210 jet when it was supose to be a 270, he had just gone over the carbs.
sometimes you get a bad one, no real way to predict it.
I'd be surprise if hauk, or virtualy any other shop out there would do whats right. I once had one jackass screaming at me thet hed bean fixing sleds for 20 years and no one ever acused him of making a mistake. the carb had a 210 jet when it was supose to be a 270, he had just gone over the carbs.
bluehammer
New member
Too early to tell without more pics, but it appears the ring caught the port (too wide?) or not enough chamfering in that area.
monkey man
New member
- Joined
- Oct 27, 2005
- Messages
- 59
check the gas tank for water and recheck your carbs.make sure nothing blocked and jets are the right size.usually if lean the piston fails starting at the exhaust port.top of piston melts away then the ring hits the exhaust port and breaks.the metal embeded in the piston is mpart of the ring and melted piston.water in the gas will also cause this to happen.we have had to rebuild a few motors because of this and tell everybody to check their gas for water regularly. especially if the weather is cold and alot of long pulls are being done
Thank you for the replys. Here are a couple more photos.
When I talked to Pat Hauck about doing this mod, one of the criteria was that it had to be able to run on 91 octane. He raised the base gasket from 0.019 to 0.031 and cut the heads 0.050 plus redid the squish, enlarged the piston holes and added holes to the intake side of the cylinders.
When I talked to Pat Hauck about doing this mod, one of the criteria was that it had to be able to run on 91 octane. He raised the base gasket from 0.019 to 0.031 and cut the heads 0.050 plus redid the squish, enlarged the piston holes and added holes to the intake side of the cylinders.
Attachments
You got a better photo of the top of the piston?
From you first photo it looks like you may have been just lean enough to start eating the piston then ring hooked a port and started dancing in the combustion chamber.
Perfect jetting is one step away from bad fuel or a cold day ruining your week.
From you first photo it looks like you may have been just lean enough to start eating the piston then ring hooked a port and started dancing in the combustion chamber.
Perfect jetting is one step away from bad fuel or a cold day ruining your week.
Ya what happened was that a piece of metal got in the chamber and it caught on the exhaust side ..poof ...there goes your ring... possibly an electrode from a spark plug. or sombody just plain droped a piece of wire or some sort of metal in the jug ...who knows ....If the ring broke It woulda shut down almost imediatly!
im glad i went with don to do my motor work and not pat
I don't blame Pat, I'm just looking for feed back from you guys that have more experience with this than me. The adjoining piston and jug look excellent. I have not opened the other side but I'm guessing the other jugs are OK.
I do a lot of work on car motors with turbos. I have seen cases with too lean of mixture making the steel brittle on valves but usually just melting anything aluminum.
I do a lot of work on car motors with turbos. I have seen cases with too lean of mixture making the steel brittle on valves but usually just melting anything aluminum.
Your adjoining piston and jugs may be fine, but you had a piece of ring bouncing around in the bore for a while. This may or may not have left metal chunks in the bottom end.
The right thing to do is to split the cases and clean em to be sure, neglect this and you may grenade the bottom end in another 250 miles.
The erosion on the piston is on the exhaust side correct.
Your piston and head look very similar to my destruction which cost me a crank.
The right thing to do is to split the cases and clean em to be sure, neglect this and you may grenade the bottom end in another 250 miles.
The erosion on the piston is on the exhaust side correct.
Your piston and head look very similar to my destruction which cost me a crank.
Canuck
New member
Do you know what your compression pressure was after the mods?
It might also be worth pulling you other head if you haven't already and have a look at the other cylinders.
Did you check the squish when you put it together? If not I'd also check the squish on the other side to see what it is.....this might show if there was a machining error.
It might also be worth pulling you other head if you haven't already and have a look at the other cylinders.
Did you check the squish when you put it together? If not I'd also check the squish on the other side to see what it is.....this might show if there was a machining error.
The compression after the break is #2 - 132 psi, #3 - 134 psi and #4 - 127 psi. (3000' with engine luke warm.)
I did not pull the other head but examining it with a scoping light the sidewalls are not scored at all and the top piston edges look sharp with no pitting.
I did not check the squish. Hopefully, Hauck earned his money for machining the heads to match. Maybe not?
I did not pull the other head but examining it with a scoping light the sidewalls are not scored at all and the top piston edges look sharp with no pitting.
I did not check the squish. Hopefully, Hauck earned his money for machining the heads to match. Maybe not?
well a few guys hit it right here, the piston simply eroded the upper ringland and then the ring takes all the heat, it bends with the movement of the piston up and down, then it simply breaks off, the pitting in the head and piston dome top are from the pieces of ring bouncing around in there, if you place the head on a lathe and try to resurface the head, youll find there are tiny little bits of ring embedded in the aluminum. The ring is steel and is much harder then the piston(alum) and head, so the alum. loses the war. Looks to me like you had a cylinder go lean ,some, didnt go lean that bad, but once the ring is exposed to the combustion flame, its downhill after that, I would also say possible water in fuel.
Looking at the cylinder, the exh port is no where near being too wide, if it was overly widened, it would have less then 2-3 mm to the triple exh port, and while I cant measure it from a pic, I can see from the pic its large enough to not be a problem.
One of the guys hit the nail on the head below and said, perfect jetting is very close to destruction if you simply get a drink of water or temp changes too much.
Any chance you could snap a photo of the other cylinder (good one)with the piston a TDC?
lastly, going back and looking at the 2 piston pics, I also note that the upper ringland looks like it broke, and didnt melt, if it melted it would be drooped and its a clean break from what I observe. This is a sign of detonation, maybe a squish check would be good to do and we can just have a tad bit more information to go on and make sure this doesnt happen again in any other cylinders. I would also inspect the other cylinders by pulling off the other head and peeking thru the exh port at upper ringland, to see if any cracks are developed.
Looking at the cylinder, the exh port is no where near being too wide, if it was overly widened, it would have less then 2-3 mm to the triple exh port, and while I cant measure it from a pic, I can see from the pic its large enough to not be a problem.
One of the guys hit the nail on the head below and said, perfect jetting is very close to destruction if you simply get a drink of water or temp changes too much.
Any chance you could snap a photo of the other cylinder (good one)with the piston a TDC?
lastly, going back and looking at the 2 piston pics, I also note that the upper ringland looks like it broke, and didnt melt, if it melted it would be drooped and its a clean break from what I observe. This is a sign of detonation, maybe a squish check would be good to do and we can just have a tad bit more information to go on and make sure this doesnt happen again in any other cylinders. I would also inspect the other cylinders by pulling off the other head and peeking thru the exh port at upper ringland, to see if any cracks are developed.
Last edited:
yammy said:
It did! Couldn't hear it over the roar of the hot rod SRX right beside me but the engine must have killed while I was accelerating near top end. I pulled the plugs and saw #1 plug had been bent down but not hit hard - almost like it was lightly dropped. Put my light in the plug hole and saw no burn hole in the piston and no shrapnel so I pulled the rope a little. It was free. Decided to start it and it fired right up, no bad engine noise but occasional backfire. I could tell it was only hitting on 3 - didn't have that distinct 4 cylinder stock car sound. Originally suspected a blown head gasket but...
mrviper700 said:
Happy to take whatever photos you guys would like to see. I really appreciate the feedback.
Here is #2 piston - this was an original piston with about 2000 miles on it before the top end mods were done (another 250 miles). #1 plug as it was when removed right after the break. The photo shows it lighter colored than it actually looks - probably from the flash.
Attachments
Last edited:
front looks good, how about the top of it??
do me a favor and check the squish on the other side, place a piece of lead solder like "L" in the spark plug hole , left to right, above the wrist pin, not the front or back of piston, make sure you can feel the side of the bore with the solder, its real smooth feeling,and rotate the engine over, smashing the solder, check the thickness out on the edge, then at the inside with some digital calipers and let me know what it is. Have you put on a compression guage since you put the sled back together originally?
do me a favor and check the squish on the other side, place a piece of lead solder like "L" in the spark plug hole , left to right, above the wrist pin, not the front or back of piston, make sure you can feel the side of the bore with the solder, its real smooth feeling,and rotate the engine over, smashing the solder, check the thickness out on the edge, then at the inside with some digital calipers and let me know what it is. Have you put on a compression guage since you put the sled back together originally?