I just dont know what I'm missing here with the way my 98 SRX 700 is taking out pistons and cylinders.Yesterday afternoon while out with my bud,first time out this year for me,all seemed to be going well until the engine lost power and quit,centre cylinder again.After last season and the same cylinder/piston going out from being too lean on the mains for the temps I put the stock jets back in and put the e clip back in the centre knotch with a shim on top and bottom the way it came stock.From looking at the piston wash and the damage to the engine I'd say it's still too lean but it's all stock 
.The centre con rod bearing is also toast so it looks like a complete teardown and we're finally getting snow enough to ride 
.
The old road we were on was good going so there were burst of about 70-75 mph but overall we averaged 55-60 and when the engine quit I was doing mabey 45 mph and the trail was narrow so flat out was out of the question it was all pretty much mid throttle riding.The outside temps weren't even all that cold about -5 to -8C( 26 to 17 F) so I just dont understand why this happened.The gas (92 octane) wasn't all that old about 2 weeks and I did put some isopropyl in before we started out,mabey someone else will see some thing from the pics I don't.Please add some light here.
Pics are centre,mag and pto.
.The centre con rod bearing is also toast so it looks like a complete teardown and we're finally getting snow enough to ride .The old road we were on was good going so there were burst of about 70-75 mph but overall we averaged 55-60 and when the engine quit I was doing mabey 45 mph and the trail was narrow so flat out was out of the question it was all pretty much mid throttle riding.The outside temps weren't even all that cold about -5 to -8C( 26 to 17 F) so I just dont understand why this happened.The gas (92 octane) wasn't all that old about 2 weeks and I did put some isopropyl in before we started out,mabey someone else will see some thing from the pics I don't.Please add some light here.
Pics are centre,mag and pto.
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bluewho
Active member
Are the exshast dounuts all good with tight springs?Was the crank repaired after the last meltdown?
silversnow
New member
Could the center oil line be pluged? Or half pluged? or maybe a pluged jet?
silver
silver
Hey! that just happened to my 02 viper! Center cyl. - rod, piston, jug, and crank, up in smoke! If anyone has any knowledge to this, that makes 2 of us that want to figure this out. Thanks!
Exhaust is tight,crank wasn't touched last time just replaced piston and jug as I did not see any need to remove it,there were no pieces floating around to make me think it needed to come out.I took the carbs apart and everything appeared clean,I did not see any blockages in the mains or other passages.Oil pump seems to be working properly,I dont know this has me puzzled.
greg
New member
You could try pressurizing the motor and looking for air leaks (Crank seals)
woolyviper
New member
looks lean (no wash)
Everything is tore down to the point where I dont think I could presurize it although I did consider a bad crank seal.
I agree with the leanness but as I stated in my original post the jetting is all stock and I can't understand why it was running so lean.Mabey I need to look for a bad seal or reed cage gasket.
I agree with the leanness but as I stated in my original post the jetting is all stock and I can't understand why it was running so lean.Mabey I need to look for a bad seal or reed cage gasket.
woolyviper
New member
Ususally what I see is when a crank seal goes bad its the cylinder closest to the leak that goes down. I see the motor as being very lean.
questions:
1.)have the heads ever been cut on this? have you owned this sled since new?
2.) stock single base gasket in it?
3.) reeds or anyhting added to the motor?
4.)cylinders bone stock?
5.) oil used/ oilpump cable gap?
questions:
1.)have the heads ever been cut on this? have you owned this sled since new?
2.) stock single base gasket in it?
3.) reeds or anyhting added to the motor?
4.)cylinders bone stock?
5.) oil used/ oilpump cable gap?
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If everything is stock, i would check pulse hose from case to fuelpump. Also Check your fuelpump.
I had two burndowns before i check the pump and there was plastick reed with sharp bend. It worked but not enough.
I had two burndowns before i check the pump and there was plastick reed with sharp bend. It worked but not enough.
OK here goes.Heads are stock and never been cut,airbox is stock with all dividers in place,base gasket is stock (1),and as far as I can tell the oil pump is working fine.The only thing I forgot to mention is when I changed the burned piston/cylinder last season the only cylinder I had to put back on it was a ported one that I had taken off before for a stock one put on in its place.
The pulse line from the base is kind of tight as in stretched,can I replace it with any kind of vaccume line or does it need to be a particular type of hose?
I think I'll take the fuel pump off and open it up to see if there's any blockages.Having never had mine apart before is it the same makeup as the old Mikuni pumps with a rubber diaphram that will stretch and wear out?If so that would alomost explain my lack of fuel flow.
The pulse line from the base is kind of tight as in stretched,can I replace it with any kind of vaccume line or does it need to be a particular type of hose?
I think I'll take the fuel pump off and open it up to see if there's any blockages.Having never had mine apart before is it the same makeup as the old Mikuni pumps with a rubber diaphram that will stretch and wear out?If so that would alomost explain my lack of fuel flow.
daman
New member
I would order up OEM,why take a chance...fourbarrel said:
Tip: Dont ever,ever under any circumstances use anything other then the thick walled line that comes on the sled stock for the vac. pulse line, when you run just vac. hose from a automotive store , it becomes soft with the fuel mist/vapors and will suck closed when you are running the engine. This is going to be very ugly when you coast to a stop. You will have leaned out the engine big time and if it only melts the pistons youll be lucky.
So the ported cylinder, was it on the sled before? Where are the heads from that topend then? ported cylinders will have cut heads. Youll need to expalin the ported cylinder and how its on the sled or not, its not a very clear story.
How thick are the heads??, check them with digital calipers from top of headbolt boss to bottom surface and post.
whats the gap on the oilpump cable/adjuster???
what kind of oil are you running?
How thick are the heads??, check them with digital calipers from top of headbolt boss to bottom surface and post.
whats the gap on the oilpump cable/adjuster???
what kind of oil are you running?
Ok here's as much history on this engine as I can remember.My original engine had a major meltdown to the point it was cheaper to look for a complete replacement than fix it so I called around and found one from a sled someone had started to part out.I buy the engine noticing it had one new jug and head put it in the sled and run it.The new parts were as a result of an overheat from a damaged heat exchanger but I was reassured the engine was running strong after the bad jug,head and piston were replaced.It was running fine until I started to play with the main jets leaning it out a bit(1 size down) and consequently burned down the new piston and jug(of course).Upon teardown I find that the other 2 jugs are ported but as far as I could tell the heads were stock but I will double check later and post it.I replace all 3 jugs with stock ones I got from Betheviper (thanks Scott) but did not replace the stock mains in the carbs so now I'm up to last years burndown of the middle cylinder resulting from being too lean for the temps.
Having these other ported jugs and with the miserable winter last year I figured I'd put one back on and run it to save time and money.Got everything assembled but never got out again last year which brings me up to Saturday,and other than a couple of laps around a field totaling about 3 miles,was basically my first run this season.
I'll measure the head thickness and post it here later and tell me what you think I've got as I cant see any machining marks but me not seeing it doesn't mean much.Thanks for all replies so far I've been writing all info down I can to try and avoid future burndowns.
Having these other ported jugs and with the miserable winter last year I figured I'd put one back on and run it to save time and money.Got everything assembled but never got out again last year which brings me up to Saturday,and other than a couple of laps around a field totaling about 3 miles,was basically my first run this season.
I'll measure the head thickness and post it here later and tell me what you think I've got as I cant see any machining marks but me not seeing it doesn't mean much.Thanks for all replies so far I've been writing all info down I can to try and avoid future burndowns.
Here's a couple of measurments I just took.
A) Head thicknesses are 35.15mm (all 3) from the top of the bolt boss to the bottom.
B) The oil pump is set at 22mm.
I noticed just now while looking things over that the oil line to the fuel pump didn't look quite dark enough so I took the bleeder screw out of the oil pump and guess what the damned oil pump must have developed and air bubble because it took about 5 seconds for oil to start running out.
Of all the things I neglected to check I mean how stupid can a person get .
In my own mind I cant see how the engine would have run that long (about 15miles) without oil from the pump being put mixed in so I can only assume that only enough was getting through to make it not totally destroy itself.I dont know.
Anyway what is the opinion on the heads?
A) Head thicknesses are 35.15mm (all 3) from the top of the bolt boss to the bottom.
B) The oil pump is set at 22mm.
I noticed just now while looking things over that the oil line to the fuel pump didn't look quite dark enough so I took the bleeder screw out of the oil pump and guess what the damned oil pump must have developed and air bubble because it took about 5 seconds for oil to start running out.
Of all the things I neglected to check I mean how stupid can a person get
.In my own mind I cant see how the engine would have run that long (about 15miles) without oil from the pump being put mixed in so I can only assume that only enough was getting through to make it not totally destroy itself.I dont know.
Anyway what is the opinion on the heads?
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daman
New member
You think that's what your problem was? looks lean to me.
Sorry to bud in on your thread but what if the jugs were cut down does it make a difference when reassembling or if all three are the same its all good
Yammerhead
VIP Member
I am by no means an expert, but why is there so much detonation in just the "ring" around the piston top? Makes me think something is wonky with the squish...
Also, will stock jetting be OK on a ported cylinder? If its ported, it flows more air and needs a larger jet I would think?
Also, will stock jetting be OK on a ported cylinder? If its ported, it flows more air and needs a larger jet I would think?