running on one cylinder

TonyV · Post by **TonyV** » Sat Jan 09, 2010 5:18 pm

My son was riding his VMAX lastnight without a problem it ran great he was getting cold due to temps dropping and he parked it and we came in for the night. I was ouside this afternoon and I started both indys up and then walked to my sons VMAX it wasnt starting and that was weird because this thing runs like a top (new rebuilt engine) Well it would fire then quit I did this a few times and after hearing backfiring or that spitting sound that a fouled plug gives I thought well plug is bad ???

I grabbed to new plug walked back out and installed them it still started kind of hard but it then fired up it sounded normal firing smoothe from both cylinders I thought GREAT!!! It idled for abot a minute or 2 then I heard it fall on its face again I messed with it tried more new plug sets switched plug around even tried the old plug buit it still fires on one cylinder we checked spark and all was good on both plugs.

I looked at plugs and they both seemed pretty wet so I am thinking because of how extremely cold it got last night that the chokes are stuck so I used a hair dryer on the carbs and choke cable junction where the single cable connects to the dual cables that leads to carbs this didi not help anything as I said it will start but it spits and sputters from the exhaust like a bad plug would and I tried flipping the choke on and off and no difference in the way the engine runs.

Someone brought up the idea of needle and seats being bad leaking gas into the cylinders and into the crank case but would this cause it to fire on one cylinder or is the choke sticking gonna be more on the lines of what is happening here? Like I said this thing has been great and was great lastnight and was shutoff afor the night and today a headache. It was extremely cold lastnight which could have and mostlikely contributed whats happening today. I looked for crankcase drain plugs like our indys have which are right on the front bottom of the engine below the exhaust . does this Vmax have a drain bolt if there is gas in the crank case??

agfirecat · Post by **agfirecat** » Sat Jan 09, 2010 7:32 pm

their no drains like the indys have. did you shut the fuel supplys off when you parked it? i would try and get it in where its warm for a night you may have ice in the fuel system somewhere. hope ya find the problem.

TonyV · Post by **TonyV** » Sun Jan 10, 2010 9:19 pm

Well Im thinking I should have waited to9 let my sons phazer go I looked at this Vmax today and left cylinder has no compression I put my thumb over the right sparkplug hole my son pulled and pop !! pressure pushed thumb right off. Then to the left cylinder head pulled plug put thumb over the hole my son pulled the rcoil and there she was!! Not enough pressure to push my thumb off no pop of air soooooo that tells me that this new motor now has a bad cylinder we broke it in lightly as a matter of fact we were still breaking it in!!!

Always start the sleds and left them idle and warm up for atleast 10 minutes while we got dressed to ride 10 minutes to me was plenty of warm up time I never had a problem with anyother of my sleds I have no idea what happen here as a matter of fact Mason was riding his Vmax Friday night for about an hour or so and he was getting cold so he parked it I was out there the whole time and the sled was running fine when he turned it off.

As I said Satuerday I went out to take the dogs out and figured Ide start the sleds and let them warm up get dressed call Mason down and go for a ride I fired up both indys but this Vmax would start and when it did like I said it was firing on one cylinder popping sputtering out of the other like a fouled plug so thats when we changed plugs 3 different times to make sure plugs were not a bad set.

Well now I have to decide what to do if this cylinderr is bad why did it happen and is this gonna repeat itself?? Im tellin ya I thought this was gonna be a good investment and my wife LMAO!! Boy is she impressed!! Is this a known issue with some of these and would you mess with it or find anther motor or sled alltogether?? I feel horrible for letting his phazer go lastweek I learned a lesson forsure I shouldve held on to the phazer until this other machine proved itself LOL.

Anyideas what might have happened? these were brandnew cylinders to top it off!! weird thing is there were no metal chips on the plug that a typical burnt up piston or busted ring would have left so its got me baffled thats forsure

sxr1000 · Post by **sxr1000** » Sun Jan 10, 2010 9:58 pm

We have sleds going down left and right here, all are useing the same jetting that has been in them for years,I think it is BAD GAS, I burned down my vmax as well, mag side.

Bob Vehring · Post by **Bob Vehring** » Sun Jan 10, 2010 10:05 pm

It sounds to me like you had a problem caused by something, and when driving it, the problem hurt the cyl.
I bought my VM from someone who said the engine was just rebuilt, by looking down the plug holes I could see the pistons were new. He couldn't get the engine to run or even start, so he sold it. I found the problem to be his carbs, fixed them and it started right up. With in 3 min of just idling, it started to get tight, I heard it and shut it off. A pond looking, I found the engine builder had only 1 1/2 tho piston to wall clearance on one side, .002 on the other. I sanded the pistons smooth where they scuffed, and honed the cyl's to .003, the engine has run fine since then. Had I not heard,then looked for the problem the engine would have destroyed itself in minutes had I choose to ride it.
The point here is, and I understand not everyone is a mechanic, but, if theres a problem, there,s a reason for that problem. If you drive it, the problem will go from little to big.
My guess is you either had a problem from the engine builder doing something wrong, clearances set to tight, or maybe a mis ajustment on the oil system or timing, or you had a carb problem from dirt, bad gas, or wrong jets if it was that cold causing that side to run lean and burn.
Now what you need to do is take things a part and find out why. If the hole in the piston is in the center, I would check timing and jets. If it is near the ring lands on the edge of the piston, probably near the ex port. I would look at the carbs and jetting. If it is on the piston skirts, I would check the P/W clearance and the bore for taper and runout..
I hate to say it but often sled engines are rebuilt by car mechanic who think they understand 2 strokes. That often is not the case.

Bob Vehring · Post by **Bob Vehring** » Sun Jan 10, 2010 10:10 pm

sxr1000 wrote:We have sleds going down left and right here, all are useing the same jetting that has been in them for years,I think it is BAD GAS, I burned down my vmax as well, mag side.

Being from a very large metro area, we have had reformulated gas for over a decade. Now that type of gas is showing up everywhere and to some, its a new problem. Jetting that WAS safe no longer is if your gas supply has change. I have said for many years, a good EGT gauge is cheaper then a rebuild.

TonyV · Post by **TonyV** » Mon Jan 11, 2010 2:04 am

I have a sled mechanic thats going to fix it I honestly dont think its a hole in a piston because theres no metal flakes on the plug or even shooting out the sparkplug hole when plugs removed and sled turned over.

The crazy thing was yesterday when it wouldnt start I put new plugs in it and it was hard to start but it did start after a few pulls and was idling fine both cylinders and I thought all was good after a minute or so it dropped back to one cylinder and had that sputter and spit that a fouled plu would do.

But I have not got it to fire on both cylinders since even if it starts on the one cylider theres no grinding scraping or anyother abnormal noises no rattl;ing clunking nothing antifreeze still full and good so head gaskets are good I am just confused here tomorrow the mechanic told me to pull the exhaust off thast side and look at the side of the piston. Or I am thinking Im just going to pull the atifreeze hose off and remove the head since its going to half tyo come off anyway and I can look at the piston top.

I know its not the high grade gass because its not the formulated stuff and mine my wifes and kids other sleds dirtbikes ATV's gokarts all use this fuel. What gets me is it was fine when Mason (my son) was riding it I mean I was standing right there watching him drive arounf our alfalfa field he drove around our shed up a small hill into the yard parked next to the indys and shut it off . I asked if he was done he said yeah dad Im gettin cold I said ok and that was it it never ran funny spit sputtered nothing I was right there it was idling and he hit the stop botton and got off and we went in.

Saturday I went to start it to let it warm up and was gonna finsh feeding the dogs so we cpould go ride and my indys started and this vamx wouldnt i tried and tried thehn as I said I changed the plugs and pulled until it actually started and was idling normal but as I also explained it whithin a minute or so fell back on its face ot to firing on one cylinder .

I know that there are no reed valves in these correct?? I mean I am just litterally baffled by this FRUSTRATED AS ALL GET OUT!! N metal particals on plus no other sings like noise grinding rattling nothing.

Post by **Vmax540** » Mon Jan 11, 2010 8:16 am

With sleds this old I always wonder if the engine C.C. seals, carb flanges and fuel pump vaccum hoses were inspected or replaced ?

chrisrider63 · Post by **chrisrider63** » Mon Jan 11, 2010 8:47 am

This is a good point also, and I also looked over the post on the GAS being crap now. I was at the pump yesterday and the gas smelled sweet and I swear it smelled like sweet corn lol. And then i thought ETHANOL!!!!!!!!!!!!! Im sure theyre putting ethanol in tanks to save money why wouldnt they the only people that would notice is the small market of guys like us that need good fuel especially for the cold temps in the winter to keep sleds from burning down. ALso I Dad told me yesterday when he worked on sleds back in the day on exciters 340's 440's guys would come back from riding up north and the machine would backfire. Well as it turns out my Dad had a buddy that worked at EXON and they would make batches according to the area they were going to, pertaining to elevation etc. Just what I heard.......

TonyV · Post by **TonyV** » Mon Jan 11, 2010 9:49 pm

If there was a bad seal on the crank would it make it lose compession or is this deffinately a piston .ring, cylinder issue?? Like I said theres no sign of metal flakes /chips on the plug and the way itr ran fine when shutdown is whats eating at me

Bob Vehring · Post by **Bob Vehring** » Mon Jan 11, 2010 10:24 pm

Like someone else said. If you take off the two springs and pull the pipe out of the way, you can look in the ex port and see the sides and top of the piston, a small mirror will allow you to see inside, the CC and ft of the cyl. It takes about 5 min. to do and you'll know what you have

TonyV · Post by **TonyV** » Mon Jan 11, 2010 11:16 pm

Im going to do that I think tomorrow and maybe even remove the head after draining some of the anitfreeze .

TonyV · Post by **TonyV** » Fri Jan 22, 2010 4:39 pm

Ok I pulled the head off and its bad clutch side piston that wasnt firing piston top is pitted and melted and head not in to good of shape either cylinder Im not sure but Im guessing it needs to be redone.

My question is are these sleds known for these issues?? Is it worth a few hundred to have it redone or will this motor do this again??or should I get my son a different machine? It seems every Vmax I see out here in Wisconsin forsale has a bad cylinder or piston

chrisrider63 · Post by **chrisrider63** » Fri Jan 22, 2010 5:03 pm

If its melted through the top you could need new crank seals or it just needed a rebuild and popped...

Bob Vehring · Post by **Bob Vehring** » Fri Jan 22, 2010 5:43 pm

Personally, I have never hurt a seal from a burn down. I would say this happens for a reason, often dirt in the carb somewhere that causes it to happen.Maybe the wrong or plugged jets. Other reasons could be bad or leaking gaskets in the intake tract, a bad crankcase seal. or maybe just bad/old gas.
The point is, now that it happened you have to find the reason why, or yes, it could happen again. Its not the design of the sled, something made it burn down