This will be my first 2 stroke rebuild, and I'm probably going to have a lot of questions if you guys don't mind answering them too much..hah.. It's a 2003 viper er, the mag side cylinder ran lean and burned up the piston. I'm not sure what caused it to go lean. the other two plugs looked golden brown. I noticed that the carb vent hose that goes into the airbox wasn't hooked up, could that have caused this? wouldn't that have affected all 3 cylinders? Otherwise maybe a bad crank seal, but again wouldn't that affect all 3 cylinders? I haven't checked out the mag side carburetor yet, maybe something got plugged again?
Anyways, besides replace the piston and rings, what else do I need to look for or replace? Does stuff tend to get down into the cases when this happens, will I have to take those apart to clean them out? Any advice at all would be great, I've done 4 strokes before but this motor is new stuff to me. thanks
YAMAHIZAL700
New member
First of all its not a crankseal cause if it was it would be pto cylinder. It wont skip over the cylinders to the mag side. My guess would be clogged carb on that side. Just a guess. You at least need to get a small enough vacuum cleaner and rig some sort of nozzle so you can get down into the bottom case. I used a shop vac with a small piece of hose and duct taped it so i had a good seal and I could all over the place with it. I am no a professional but have replaced my own crankseal with the help of the real professionals of this site any they will give you much mor e extensive directions that I have but good luck and I hope you get her going soon!
YAMAHIZAL700
New member
You also need to check fuel lines and the pulse line cause if you get a leak there that will lean it out as well That cylinder will need to be replaced or at the very worst you can get some acid solvant to eat the piston residue off and rehone it out. I belive it muriatic acid not sure
Is there some sort of seal on the mag side that could leak? What is the pulse line?
I'll probably have a chance to get into the carb tomorrow...how would having the carb vent line disconnected from the airbox affect things? because that was not hooked up like it should have been.
So I probably won't have to take the cases apart if I can vacuum it out down there?
I'll probably have a chance to get into the carb tomorrow...how would having the carb vent line disconnected from the airbox affect things? because that was not hooked up like it should have been.
So I probably won't have to take the cases apart if I can vacuum it out down there?
There is a seal on BOTH sides. Check the seal at the side it buned down. Pretty sure thats your problem.
Call CB performance for all your motor work or parts needs or PM 2ooosrx.
Bruce has everything in stock. Turn around time is less than a day after he recieves your cylinder
Call CB performance for all your motor work or parts needs or PM 2ooosrx.
Bruce has everything in stock. Turn around time is less than a day after he recieves your cylinder
to check the seal, do I take the cases apart? or is there some test I can do? Also, the sled has 1500 miles on it, would I be better off replacing the rings in the other two cylinders too while I have it open?
I pm'ed Bruce
I pm'ed Bruce
no real test you can do now with your top end off and a cylinder and piston blown all the hell but..
When you have the sled running, saray each seal with WD-40 and see if the RPM changes. If it changes than you have a seal that leaks. It should be a pre-season check before you go out and have what just happened.
When you have the sled running, saray each seal with WD-40 and see if the RPM changes. If it changes than you have a seal that leaks. It should be a pre-season check before you go out and have what just happened.
YAMAHIZAL700
New member
RTYsxv said:
Yeah your gonna need to split the case to get the seals out. Thats pretty low mileage you probably wont have to rering but it cant hurt. Before you rip the motor out check out mrvipers carb cleaning thread on here. very helpful. See if you can find any gunk in that carb. Look through pilot and main to see if you can see through it. Good luck. THere are a lot of more experienced troubleshooters that im sure will chime in.
Today I went thru the carb, and I found nothing - everything was clean. I took apart the float valve, checked the screen back there, pilot jet was perfectly clean, the main jet was clean, took out the fuel screw and everything was clean in there..I had just cleaned the carbs a week or 2 ago and found no new gunk. So I think I've ruled out the carb. Talked to a yamaha mechanic today, he was thinking either the cylinder base gasket or the mag side crank seal. I suppose I should also check out the intake on that cylinder...I can't think of any other ways for just that cylinder to run lean and not the others, unless there's some other way I don't know about? So I guess I'm going to be splitting the cases after all. While I have it apart, is there anything down there I should check? Would it be best to replace both the pto and mag side seals, even though I should only need to do the mag side?
I bought myself a yamaha service manual and I think should be able to do this fairly easily, and tips or tricks I should know about before I start?
I bought myself a yamaha service manual and I think should be able to do this fairly easily, and tips or tricks I should know about before I start?
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If your gonna tear it all down, no since of doing a half *** job. all new seals and gaskets. Fresh top end, everything. If you do everything right, you will feel much better about yourself.
Please post some pictures for us
Please post some pictures for us
So here's my plan as of now...
take the cases out (and clean up the engine compartment), split the cases, check the cases for cracks or leaks, replace the crank seals, check the crank bearings, take the mag side intake off and check for holes, cracks, etc, reinstall w/ new gasket, put the cases back together (apparently I use "yamabond #5" for gasket material, is that right? and lube everything up w/ 2 stroke oil before final assembly?), install used (but within spec) piston, new rings, new bearing, install the cylinders w/ new base gasket, clean and adjust the PV's somewhere along the line, put exhaust manifold back on w/ new gasket, head back on...that should cover it? am I forgetting anything? The sled has less than 1500 mi on it so I think I'm going to leave the rings in the other 2 cylinders.
Can I get by without removing the primary and the flywheel, or will that be necessary to get the crank seals installed...I suppose it is.
I won't be able to work on it until monday, and maybe get some pics then.
take the cases out (and clean up the engine compartment), split the cases, check the cases for cracks or leaks, replace the crank seals, check the crank bearings, take the mag side intake off and check for holes, cracks, etc, reinstall w/ new gasket, put the cases back together (apparently I use "yamabond #5" for gasket material, is that right? and lube everything up w/ 2 stroke oil before final assembly?), install used (but within spec) piston, new rings, new bearing, install the cylinders w/ new base gasket, clean and adjust the PV's somewhere along the line, put exhaust manifold back on w/ new gasket, head back on...that should cover it? am I forgetting anything? The sled has less than 1500 mi on it so I think I'm going to leave the rings in the other 2 cylinders.
Can I get by without removing the primary and the flywheel, or will that be necessary to get the crank seals installed...I suppose it is.
I won't be able to work on it until monday, and maybe get some pics then.
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How was that cylinder, able to save it, with the new rings in that cylinder you need to hone it...by the sounds of it you seem to know what your up to...good luck...also just ask some of the pros here about only doing one ring verses all three pistons-how will the stresses play on the crank?
JeepTherapy
New member
As cheap as rings are put them in the other two also.
daman
New member
Sounds like a a good plan, but remember clean is the key here,check that crank out good for any debris, clean the case out good also, and do like jeep Therapy said replace the rings on the other pistons,there not that much and your right there so why not?
yes primary and the flywheel/stator etc. has to come off.
if your cyl's look dull and glazy you could if you want run a 3 stone spring flex hone in 240-280 grit up and down a few passes just to get rid of the glaze alittle.
take your time don't rush and do things right,Oh and use all OEM parts!!!!!!
yes primary and the flywheel/stator etc. has to come off.
if your cyl's look dull and glazy you could if you want run a 3 stone spring flex hone in 240-280 grit up and down a few passes just to get rid of the glaze alittle.
take your time don't rush and do things right,Oh and use all OEM parts!!!!!!
theblues said:
I sent the cylinder to CBPerformance parts, Bruce said he could fix it for $35 as long as it wasn't chipped. I hadn't thought about stress on the crank with only one new set of rings...if I were to replace the other rings, all I need to basically is install them right, after running a hone thru a few passes like daman said? I suppose for the $30 extra I should do it.
Another thing I was wondering about is the head gasket...is it really necessary to replace it? It looks perfectly fine, and a new one is $35.
Thanks for the help so far guys
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Do the other two piston rings...& lightly hone...if you did not damage the head gasket taking it off, then just spray it with gasket tack on each side...after your first head cycle re torque the top end, let the sled cool good to cure the spray tack...should be good after a couple hours of cool down for more heat cycles...the hardest part is bleeding the cooling system out...keep us posted...cheers
daman
New member
no you need to check/set ring end gap for all pistons...RTYsxv said:
^ yes!!!!RTYsxv said:
It's your call but i never reuse a H/G,they may hold today but what about tomorrow when your 100 miles from home and it starts leaking coolant into the motor with out you knowing?RTYsxv said:
Base gasket yes, H/G no, at least no for me.......
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I have done over 6 head gasket jobs this season alone, mostly to have a look at things...reused them all, option was with each owner...I had great success with reusing mine last year, I have over 4300 k's on that engine...not that I'm disagreeing with replacing all seals & gaskets with new ones when you take things apart (engines)...but you can do it to save a little if you know what to look for...years back, I had failures on new gaskets & seal when I worked at a machine shop...when in doubt change it...cheers
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I'll take another close look at the head gasket, but I think I'll probably reuse it.
Do I need to take the water pump cover off and get into there? I'm thinking I should be able to leave that alone.
theblues, when you did your viper rebuild did you have any trouble removing the primary and flywheel/stator? Do they require special pullers? Did you need any other special tools? Any tips you can give me for the whole thing after doing it yourself?
Thanks alot guys
Do I need to take the water pump cover off and get into there? I'm thinking I should be able to leave that alone.
theblues, when you did your viper rebuild did you have any trouble removing the primary and flywheel/stator? Do they require special pullers? Did you need any other special tools? Any tips you can give me for the whole thing after doing it yourself?
Thanks alot guys
RTYsxv said:
For the primary...you need a clutch puller a long bolt like tool...tip add grease inside the hole before threading that puller, it acts like "hydrolic" press & it pops right off...I uasually place a long bar throught the towers of the clutch to hold it while using that puller...some here will say use a air impact...but I don't take a risk the chance at damaging the crank...
When your at the flywheel...If I remember correctly I think its left hand thread...you'll be able to tell when you run your fingernail over it to determine which way its threaded...use a 3 point puller, not an arm type but the one you tread bolts through the puller into the flywheel...tip...don't thread in too far cause you will damage the stator behind it...
For the stator...always use a impact screw driver to shock them loose or you will damage the head...
Any other questions just ask...cheers