Is the Carb vent connected to the airbox? Ive forgot it before and it will cause a rich bog.
Kenora
New member
Kenora said:Thanks, that will save me some work and grief
Unfortunately the airplane engine (Lycoming O-320) has two plugs mounted at an angle.
well with that pic, I have another idea and it looks easy, just take a small flat peice of steel and bend it around so it will catch the tooth/valley on the flywheel up front, drill a hole thru other end ,bolt it to the engine, that will hold it from turning over. just bring up your cylinder you want to check and bolt it on to keep it there while doing the leak down. loosen it up rotate the engine tighten back down and so forth.
drew on your pic, just grind the bottom edge down so it fits nicely in the valley of the flywheel.
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my viper is doing the same thing, plugs look good on 2, but pto side looks washed. mag side shows 25psi less than other 2. what did you find to be the problem?
same just happened to me,bad plugs and crappy gas!!it can happen i had water issues in 91 octane non ethanol gas from my gas station,little star tron and new plugs ,went like a whole new animal.great story~smoke
what gets me is its the same issues on 3 sleds,shouldent have to prime the cylinder with gas to get it to fire,so of course its gonna backfire with all that straight gas,all 3 should start on full choke 1-3 pulls soon as it fires drop to half choke give it maybe 5-10 seconds and turn it off..jmo~smoke
dont know how you store them.alot of factors!!!
what gets me is its the same issues on 3 sleds,shouldent have to prime the cylinder with gas to get it to fire,so of course its gonna backfire with all that straight gas,all 3 should start on full choke 1-3 pulls soon as it fires drop to half choke give it maybe 5-10 seconds and turn it off..jmo~smoke
dont know how you store them.alot of factors!!!
Here's an update.
I think all of my problems are unrelated to that explosion now. Although my neighbor's kid never comes around anymore!! lol Since my last post I've checked many things out and I had multiple ideas of what caused this.
Facts were:
Recently rebuilt engine by yours truely
I modified the opticool gasket taking the center gasket out
I installed 2.3 to 4 inch adjustable risers
With the adjustable riser mod I had a throttle/oil cable fabricated
I found a crank case bolt in the bottom of the engine compartment
I was loosing a small amount of coolant on every trip
The sled had a bog. It started well and ran well but would bog 3/4 and up.
I had about 100 miles on the rebuilt engine
I had already checked:
reed valves
compression check
leakdown test
powervalves checked and adjusted
So on my last ride it was still bogging and I decided to scrap the ride and brought it back home. I decided to take the engine out. I'm glad I did because I found that the skirt of the pto and the center pistons were scored. Pto skirt was worse then the center.
I went thru the bottom end and everything was fine. Put new seals in and now I'm just about to put the topend back together since I just got my cylinders back.
The reason:
After driving myself insane
I came up with a theory of why my engine had problems. I think it was due to the aftermarket throttle/oil cable. The threaded fitting that mounts through the oil pump bracket was longer then the stock one and I didn't catch it. So when I was adjusting the oil cable, the oil pump arm was actually hitting the threaded fitting rather then the oil pump stop hitting it's end. I think this jipped my engine of oil and slowly started buring up the piston skirts. Of course I didn't notice this right off becaue on the first tank I was running pre-mix also. Then on the next few rides, I noticed that although the oil was being used it wasn't as much as I was expecting. Kind of hard to tell though because, I had multiple short rides using only a few gallons each time.
I'm guessing that the engine was overheating without me knowing it and boiling the coolant out the overflow. I found the coolant overflow hose wet at the end as evidence of this.
I have since put the opticool back to origional. Also and more importantly, I have put a spacer on the threaded oil cable fitting. Since, I have recently moded my other two vipers with the same handle bar risers and oil cable, I have made these mods to the others. This time I've used a bore scope to ensure oil cable/pump setup.
I'm still not sure why I had the bog but I'm hoping that it was becase the of the lack of oil and overheating of the engine. I guess I'll see once i get it out again. That may be a cdi or power valve solenoid problem that's unrelated but time will tell.
Oh, I forgot to mention. I ended up finding two crankcase bolts in the engine compartment rather then one. They were from the two most outside crank case bolt holes on the mag end. The four rows of inner bolts on the crank were all there and torqued correctly. My theory on this is that I torqued all the bolts to specs according to the manual. However in the manual, those two bolts are not refered to on that page. I think I must have hand tightened them but when I was following maunal for torquing them I missed that they were only mentioned in a different section. So I most likely missed torquing them.
Hopefully the second time around will be a charm!
I think all of my problems are unrelated to that explosion now. Although my neighbor's kid never comes around anymore!! lol Since my last post I've checked many things out and I had multiple ideas of what caused this.
Facts were:
Recently rebuilt engine by yours truely
I modified the opticool gasket taking the center gasket out
I installed 2.3 to 4 inch adjustable risers
With the adjustable riser mod I had a throttle/oil cable fabricated
I found a crank case bolt in the bottom of the engine compartment
I was loosing a small amount of coolant on every trip
The sled had a bog. It started well and ran well but would bog 3/4 and up.
I had about 100 miles on the rebuilt engine
I had already checked:
reed valves
compression check
leakdown test
powervalves checked and adjusted
So on my last ride it was still bogging and I decided to scrap the ride and brought it back home. I decided to take the engine out. I'm glad I did because I found that the skirt of the pto and the center pistons were scored. Pto skirt was worse then the center.
I went thru the bottom end and everything was fine. Put new seals in and now I'm just about to put the topend back together since I just got my cylinders back.
The reason:
After driving myself insane
I came up with a theory of why my engine had problems. I think it was due to the aftermarket throttle/oil cable. The threaded fitting that mounts through the oil pump bracket was longer then the stock one and I didn't catch it. So when I was adjusting the oil cable, the oil pump arm was actually hitting the threaded fitting rather then the oil pump stop hitting it's end. I think this jipped my engine of oil and slowly started buring up the piston skirts. Of course I didn't notice this right off becaue on the first tank I was running pre-mix also. Then on the next few rides, I noticed that although the oil was being used it wasn't as much as I was expecting. Kind of hard to tell though because, I had multiple short rides using only a few gallons each time.I'm guessing that the engine was overheating without me knowing it and boiling the coolant out the overflow. I found the coolant overflow hose wet at the end as evidence of this.
I have since put the opticool back to origional. Also and more importantly, I have put a spacer on the threaded oil cable fitting. Since, I have recently moded my other two vipers with the same handle bar risers and oil cable, I have made these mods to the others. This time I've used a bore scope to ensure oil cable/pump setup.
I'm still not sure why I had the bog but I'm hoping that it was becase the of the lack of oil and overheating of the engine. I guess I'll see once i get it out again. That may be a cdi or power valve solenoid problem that's unrelated but time will tell.
Oh, I forgot to mention. I ended up finding two crankcase bolts in the engine compartment rather then one. They were from the two most outside crank case bolt holes on the mag end. The four rows of inner bolts on the crank were all there and torqued correctly. My theory on this is that I torqued all the bolts to specs according to the manual. However in the manual, those two bolts are not refered to on that page. I think I must have hand tightened them but when I was following maunal for torquing them I missed that they were only mentioned in a different section. So I most likely missed torquing them.
Hopefully the second time around will be a charm!