Srx007
Member
Hey, doing some tech research for the father in law. At the end of the season last year he bought an 03 viper which seemed to run pretty well (8900 rpm, 21-40 gearing, 168km topspeed), this year we start it up and it runs like crap. Little backround--No air box, uni-filters and bender can, thats all I know. Blipped the choke while it was running, rpms came up started to flood close the choke rpms rise a little then die off. Removed carbs for cleaning and noticed the mains are 152.5 on pto 155 center 152.5 on mag. Completed cleaning 1 air screw was dirty and 1 pilot jet was plugged, screens were ok. Noticed choke cable was loose, tightened so there was no slack in cable, sled did run better after, but still didn't seem right. I/we are new to vipers. Looked up the mains on a viper AFTER carbs were installed which are Supposed to be 156.3 across all 3. So now I am worried that the top end is burnt, have not done a compression test which Im pretty sure it is supposed to be 110-pto 120-120...So my question is what should the mains be 160 with uni-filters ad bender can??? Any help appreciated, Have not pulled plugs or checked wash...
bad gas and dirty carbs likely the biggest problem if it was running good when you parked it. But definitely check plug color and piston wash before you go hammer it. temps can make a lot of difference on these motors and with air intake under the hood it can be very difficult to have consistent temps to jet for...
Srx007
Member
I cleaned the carbs, as I pointed out in the 1st post. problem didn't really go away and as far as I know the sled was running well when Father in law put it away but he also thought it was running well until I pointed out it ran/idled the same when I pulled the middle spark plug and started it, which I left out. It was the pto and mag carbs that were 'dirty' if you could call them that. As he bought the sled with-out an air box which provides much more air flow with carbs that have been leaned out from the beginning, the way it was driven that weekend as well as a bender can which Im sure you should jet richer than 2-3 sizes UNDER stock while introducing MUCH more air to the engine would produce a lean condition on top. I really don't know what the jetting should be and I would be out trying to figure this out but it makes it hard when I have to take of my 9 month old. BTW fresh gas.
I have a few questions reading your post,
1.) when you cleaned the carb, you removed them and could you see daylight thru all 3 pilot jets?
2.)did you shoot carb cleaner thru the hole where the pilot jet threads into carb and it came out the idle orfice hole in front throat of carb?
The reason the jets are leaner is because you have the venting of the carbs set to atmosphere now instead of to the airbox like a stock viper is, your jet size will be smaller vented to bellypan. The engines performance is better/more consistant vented to the airbox but the jetting goes up to 156.3 mains and 45 pilots. The exhaust can doesn't make any difference on jetting it just makes more noise. if it were mine I would buy a used airbox and put all that back to stock over using pod filters, too much snow dust and problems with pods on trail sleds.
1.) when you cleaned the carb, you removed them and could you see daylight thru all 3 pilot jets?
2.)did you shoot carb cleaner thru the hole where the pilot jet threads into carb and it came out the idle orfice hole in front throat of carb?
The reason the jets are leaner is because you have the venting of the carbs set to atmosphere now instead of to the airbox like a stock viper is, your jet size will be smaller vented to bellypan. The engines performance is better/more consistant vented to the airbox but the jetting goes up to 156.3 mains and 45 pilots. The exhaust can doesn't make any difference on jetting it just makes more noise. if it were mine I would buy a used airbox and put all that back to stock over using pod filters, too much snow dust and problems with pods on trail sleds.
Srx007
Member
1) Yes. Daylight through all three
2) Yes. Came out idle hole in front of carb
3) Removed pilot air screw, shot some carb cleaner through the hole and came out pilot jet hole where it threads into, installed pilot jet, shot some more cleaner into pilot screw hole and came out various orifices in throat of carbs. Did same on all 3 carbs.
I also checked how strong pulse line was and it took 5 pulls to get the gas to come out of the gas 2 of the gas lines, outside lines, then 3 more pulls to get gas out of the middle line. This was after the sled sat over night, most of day and without any choke.
I did notice, which I forgot to mention, that I could see the magneto even though the recoil housing was bolted to the machine which Im sure sitting outside over the summer and temp differences may have rusted it and I dont think that is proper recoil for that machine, have never owned one where the magneto and stator were exposed. Another thing I forgot to mention, busy every time I get to write a diagnosis, was the sled was able to run without the center cylinder spark plug cap attached, which didn't make a diff even after I cleaned carbs, unplug either outside cyl and sled would die. But the sled did sound and run better after the carbs were cleaned just not as it should.
Im glad someone could clear up the venting issue THANKS.
Sled does die quickly when choke is flipped to half and instantly when flipped to full
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You need to check your plugs and compression. My sled would run on 2 cylinders but shake quite badly and would not rev out beyond 6k or so. definitely WAY low on power. Hard for me to believe you could think is was good and only be on 2...
Srx007
Member
Hell man I didnt think this was good at all, I tried to convince him to put it away immediately. It was father in law that thought it was ok hes the type that knows all but....ya know....Maybe I wasn't clear on who thought it was ok to drive it like that. We didnt drive it on 2 cyl. just started it.
mod-it
Member
A little more description of how it is "running like crap" might help us out. Sounds like it won't stay idling, but choke doesn't help? Or the center cylinder possibly isn't firing? If not, then checking for spark would be the first step.
Sounds like you did fine with your carb cleaning, so fuel delivery should be ok.
When it is running good again, just FYI, 8600 rpm is the peak target rpm.
Sounds like you did fine with your carb cleaning, so fuel delivery should be ok.
When it is running good again, just FYI, 8600 rpm is the peak target rpm.
Srx007
Member
I believe in post 5 and 7 I gave more info on how it was running. It seems like it is running on 2 cylinders, it would be much easier if the sled was"just in the garage" but it is not. When unplugging the middle cylinder and starting the sled there is no difference if I plug it back in while idling or revving up the engine a little which just sounds weak. As in post 5 I did say i could see the stator even tho the recoil is attached so that could be a culprit playing a role, I will eventually get to do more testing like compression electrical check/replace plugs, wash etc but for now I have said everything I can about the issue. I will need a manual to reference resistances unless they are similar to an SRX my time is limited with the sled so I am trying to get enough info from what I can go off of. Like a definite answer if its normal to be able to see the magneto in a viper with the recoil attached. A solid after noon will help. Shit I hardly had time to go through the carbs. I know its vague so far.
yes, a viper recoil has rubber bumpers between the mag housing and recoil, theres a slight airgap there, a srx mounts solid.
when you can pull off a plug wire then that cylinder is not working, so it either doesn't have any fuel(plugged pilot circuit) or a reed is junk, or the piston skirt is broken off it. This is assuming you checked for spark..........
don't get mad at these guys, everyone is trying to help but you can only go off a description of a problem, nobody hear can see it, hear it or help in any way except base the repair or problem off the information YOU provide!
when you can pull off a plug wire then that cylinder is not working, so it either doesn't have any fuel(plugged pilot circuit) or a reed is junk, or the piston skirt is broken off it. This is assuming you checked for spark..........
don't get mad at these guys, everyone is trying to help but you can only go off a description of a problem, nobody hear can see it, hear it or help in any way except base the repair or problem off the information YOU provide!
Srx007
Member
Im not getting mad, and I am glad that people are trying to help and point me in the right direction instead of pulling off random parts. In post 1 that's is all I had time for and whatever free time I can get which is and hour, give or take, is what I can report back. I don't want to come off as an asshole and really don't want to have this account erased... now the next step would, be to check for spark and hope that I have time for more. Again thanks for helping. Are the resistances similar to an SRX for plug caps and stator, coils, etc. Ill also look up yamaha part numbers and cross reference them, as long are the parts are the same the outcome should be similar right.
Also great to know the rcoli cover is designed like that, didnt think of checking reeds, totally forgot about them. In fact that is how I found the newer engine for my SRX, a reed petal broke off on mag side, guy was piecing out sled and I was first on scene, scroe, engine had 3300 kms :-P
Also great to know the rcoli cover is designed like that, didnt think of checking reeds, totally forgot about them. In fact that is how I found the newer engine for my SRX, a reed petal broke off on mag side, guy was piecing out sled and I was first on scene, scroe, engine had 3300 kms :-P