Help with 04 Viper Engine Rebuild

RevAgent

RevAgent

VIP Member
Joined
Oct 25, 2012
Messages
93
Location
Maine
UPDATED: Help with 04 Viper Engine Rebuild

Hi All,

I'm new to Yammy's but not to snowmobiling. I've been a Polaris guy all my life, but looking for something different.

I'm looking for a winter project and I have a chance to pickup an 04 Viper S for pretty cheap. The guy said it ran for about 20 mins with a bad oil pump while he was trying to diagnose the problem. He said the motor isn't seized but he heard bearing grinding. The rest of the sled is mint.

Now I've redone top-ends before, but never done any kind of crank work, etc on the bottom end. I know I'm looking at new bearings, probably new top-end, perhaps even a crank? The crank new from Yamaha is over $1000, and I know a 00 & up SRX crank will work, but what is the worst case scenario for the engine rebuild?

Like I said I want a project but not something I'm going to have to drop $2000 into.

Thanks in advance for your insight.

-Rev
 
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you can get a good used crank in the 3-4 hundred dollar range. Vipers and SRX's have different style cranks. They can be interchanged but the engine characteristics will change some. also it's not too common to have a failed oil pump and I thought they were designed to fail wide open.
 
Thanks for the response.

I haven't been able to find a used Viper crank - been looking all over. Found a used '00 SRX crank for $500, also looking at a new top end kit for $300, crank bearings are what $125? Any chance the power valves will be damaged as a result of no oil? Cylinders may be scored too, correct?

Just trying to get a worst case scenario top-dollar amount...
 
first, where in Maine are you? If you want to just buy a SRX crank look at this http://www.totallyamaha.net/forums/showthread.php?t=87947, if you dig through the classifieds here and post an ad in the wanted section you should come up with a Viper one. Depending where you are and how bad the crank truly is I have a guy in Greene that rebuilds all my cranks for a fair price. Used cyls can be had anywhere from $100-$150 if you look hard enough. I know of a few around that can be had in that price range. You can get used powervalves here for dirt. depends on the route you want to go. If you're patient and frugal you can put together an engine fairly cheap. Odds are you wont need to replace everything.
 
I'm in the Bangor area. I think I might do it. I can get the sled for $800 and it is literally mint. I've got other sleds to ride but like I said I do want a project. I'm just not too sure I can do the rebuild myself and I don't want to pay someone $600 in labor alone...
 
Alright. So I have a new oil pump on order. Where should I start with this thing?

Should I just start with the top-end and check the cylinders for scoring, pistons, rings, etc and if all look OK reassemble them nicely lubed up as well as load up the bottom-end with some oil?

Also, what type of damage, if any, should I look for in the power-valves?

Or, should I tear it down to the crank and go from there? I'm sure tearing it down to the crank would be the wise decision. Keep in mind I have never done any kind of lower end work or completely rebuilt a 2-stroke. I've only replaced top-ends in my experience.

I appreciate everyone's help and insight in advance.

Thanks,
-Mark
 
tear it all the way down. it's time for crank seals anyways. it's also a good time to change the seal washer, mechanical seal and oil seal in the water pump. check all the crank bearings for slack/movement perpendicular to the crank shaft. get yourself a genuine yamaha service manual for the sled or become a VIP member here and I can help you out with that.
 
staggs65 said:
tear it all the way down. it's time for crank seals anyways. it's also a good time to change the seal washer, mechanical seal and oil seal in the water pump. check all the crank bearings for slack/movement perpendicular to the crank shaft. get yourself a genuine yamaha service manual for the sled or become a VIP member here and I can help you out with that.
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Thanks staggs. I'll get tearing into it. I'm going to count on the crank bearings needing to be replaced due to lack of oil. Hopefully the crank itself I'd fine. Ill post some photos of the crank after removed as Im not sure what to be looking for damage wise.

I'll also up my membership. Thanks again for your help! Im sure that I'll need more guidance once I get further into this.
 
the oil pump problem concerns me they are designed to fail wide open. Might want to check all the lines and tank for debris maybe that is starving the pump for oil. heck maybe even verify the tank vent is clear it sounds crazy but you never know. also ive come across people who have had the gear on the crank that drives the pump slip i think this was more common on the twins but again you never know inspect it closely when you have the crank out. i wouldn't put a whole bunch of oil in the crankcase i would use an assebly lube on the bearings and a layer of 2 cycle oil on the cylinders it doesnt need to be puddled up in there though lol when you go to start it you can disconnect the oil pump cable and hold it wide open independently of the throttle this will feed the engine extra oil i do this when i summerize the sled to get a little extra oil on everything. also do a search on here about bleeding the oil pump. some would reccomend mixing the gas for the first tank to help oiling some will not because the extra oil causes the engine to run lean so ill leave that up to you ;)!
 
Thanks for the insight guys. Here are some photos of the new girl. Looking forward to tearing into the motor and getting it rebuilt within the next few weeks. :letitsnow

-Mark

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IMG_20121028_181932.jpg
 
srxman72 said:
That thing looks great, nice find
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Thank you. Couldn't pass it up. Has a nearly new Predator track on it as well. Even if I have to spend $1000 on engine rebuild parts I think it would still be a great deal.

Now if I could only find a damn tank or windshield bag I'd be happy as can be! I've been looking all over and cannot find either one anywhere, not even ebay...
 
If I were you, I would disassemble the entire engine and give every part a thorough inspection and measurement where applicable. Get yourself a copy of the factory service manual. I suggest you send the crankshaft to Jeff at Midwest Crankshafts in Green Bay, WI, phone no. 920-434-3630. Jeff is VERY experienced with Yamaha SRX and Viper crankshafts. Jeff used to perform warranty work on crankshafts for Yamaha. Jeff will give you an honest appriasal of the crankshaft. He has repaired/rebuilt 3 SRX carnkshafts for me. I trust him completely. The cost has varied for $175 to $375 for my three crankshafts since they all needed something different.

Replacing the oil pump is a very good idea, when in doubt, replace it since the engine's survival is completely dependent on it working properly.

Replace every gasket and seal. Give all the parts a good cleaning. These engines are easy enough to rebuild if you take your time and follow the service manual. There are several members on thei site who are very knowledgeable on rebuilding engines.

Make sure you lube up all the bearings with 2 stroke oil. Make sure the carbs are spotless. Make sure you use only 93 octane gas. Use ONLY Yamaha parts!!!

Post any and all questions as you go through the process. You will get plenty of help.

Jim
 
staggs65 said:
nice score, I wish you would have passed on it.
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;)!

The photos just don't do it justice. I'll get it up on the lift and take a few photos of under the tunnel and skid - you'd never believe it has 6200 miles on it. Not a speck of rust or corrosion anywhere.

And I cannot get over how comfortable the seat is.
 
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