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Post by carasdad on Aug 4, 2013 8:10:05 GMT -5
Is this even feasible or plausible? Ok ..I have a 2T that soft seized 4 times..then finally died from all the soft seizues. Compression was about 60psi. The oil pump failed so I replaced it with a Mikuni..bought a new 50cc top end and ran some 32:1 premix in it to be safe..and to check flow from the new oil pump. New pump flowed well..but to be on the safe side I ran 2 more tanks of 32:1 in it..along with whatever the oil pump puts out. So 32:1 plus the 40 or 50:1 the oil pump puts out. This is a stock 50cc with a Tecnigas Next R pipe and #82.5 Main jet. 4 more times it seized until it killed the new top end.  A 'Shade Tree' Chainsaw mechanic down the road that owns a tree removal business told me the soft seize was from lack of fuel. Said the premix along with the pump was putting me about 16:1..and with that much oil it was taking the place of the gas..causing me to run lean on fuel...hence the soft seizes. Is this possible and true? Anybody seen or heard of it? Just ordered my 3rd top end a few minutes ago..this is getting ridiculous and expensive. Lean runs?? when the #82.5 main jet is massive for a stock 50...I am Confused..  |
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Post by gatekeeper on Aug 4, 2013 9:30:04 GMT -5
Not really a 2 stroke guy but that doesn't sound valid to me. If it was the case wouldn't you be able to richen it up with the mixture screw?
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Post by carasdad on Aug 4, 2013 9:48:02 GMT -5
Not really a 2 stroke guy but that doesn't sound valid to me. If it was the case wouldn't you be able to richen it up with the mixture screw? I did richen it up jet wise... I ran a #105 main jet in it..and I have been using the stock air box...still soft seized with the massive #105 Jet... |
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Post by scootnwinn on Aug 4, 2013 9:59:07 GMT -5
The chain saw dude is absolutely right. You leaned it out by replacing fuel with oil and though it had plenty of oil in ran so lean it seized. Very common mistake don't feel bad like gatekeeper says it doesn't seem right but it is. No matter how much fuel you added to the fuel air mix it was never enough because there was just too much oil in the way. Build it again and just let the pump do its thing. Take it easy first couple tanks but the last thing the motor needs is the extra heat while breaking in. When you soft seize it is your bike screaming at you that something is very wrong...
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Post by skuttadawg on Aug 4, 2013 10:15:48 GMT -5
How does the plug look ? I run a 120 MJ on my 2T with a 45 IJ oil pump and I give it a sip of 2T oil in the gas tank
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Post by scootnwinn on Aug 4, 2013 10:24:47 GMT -5
Bad idea actually skutta you are asking for the same issue. The pump is sufficient really trust me
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Post by skuttadawg on Aug 4, 2013 10:29:29 GMT -5
I have the stock pump and I have a Mikuni on hand just have not installed it yet . Yes I have heard too much oil is bad which one would think otherwise . I only pour in a sip . I have never had a seize on premix nor on my Honda scoots but I did on my stock 50cc engine long ago
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Post by carasdad on Aug 4, 2013 12:50:02 GMT -5
The chain saw dude is absolutely right. You leaned it out by replacing fuel with oil and though it had plenty of oil in ran so lean it seized. Very common mistake don't feel bad like gatekeeper says it doesn't seem right but it is. No matter how much fuel you added to the fuel air mix it was never enough because there was just too much oil in the way. Build it again and just let the pump do its thing. Take it easy first couple tanks but the last thing the motor needs is the extra heat while breaking in. When you soft seize it is your bike screaming at you that something is very wrong... Thanks Rob...does kinda make sense. It runs like a champ all day...but as soon as I hit WOT for even 2-3 seconds..you can feel it start to seize..even with a massive jet. @ Kevin...mine won't even run with a jet that size..it just gurgles and slobbers gas. I did use the #45 pilot jet..vice the stock one...sure smoothed out the low end and idle..  But top end kills my new BBK's everytime.. |
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Post by rockynv on Aug 5, 2013 4:26:59 GMT -5
Too much oil and they will either carbon up the exhaust ports or lean out and overheat. Not good either way.
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Post by skuttadawg on Aug 6, 2013 2:27:13 GMT -5
Glenn airbox and stock exhaust ? How many RPMs do you ride at ? Did you do a plug chop ?
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Post by carasdad on Aug 6, 2013 16:39:30 GMT -5
Glenn airbox and stock exhaust ? How many RPMs do you ride at ? Did you do a plug chop ? Kevin...yes stock airbox...stock gears. I run 9.5k at 55mph. But 9-9.5K is where it soft seizes. Plug chop looks great...no oil or black partially burned oil marks on it. Just a sooty light brown coating. |
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Post by nassauequipment on Aug 6, 2013 18:41:53 GMT -5
long time 2 cycle power equipment dealer here.
Its a common mistake made on two cycle engines to run too rich on oil mix.
Not only can it cause the exhaust port to build up carbon which can break loose and score the piston and cylinder.
Think of it this way. Oil is a GREAT insulator. That's why its in big electrical transformers.
An excess oil gas mix will put excess oil on the skirt of the piston. Heat MUST transfer from the piston to the cylinder wall and dissipate on the cylinder's fins ( we're talking air cooled here). Guess what happens when the extra oil is on the piston and "insulates" it from transferring the heat to the cylinder.
When you see dark brown on a piston skirt its "cooked" oil from heat.
The thought if some is good mORE is better just doesn't apply here.
Use the premix or the oiling system but not both.
main thing use an oil for an AIRCOOLED 2 stroke.
I run my 2004 AlphaSports/eTon on RedMax 2 cycle oil that is a good blend of synthetic.dino oil. Made for air cooled two cycle engines I have low to no smoke and approaching 2k miles. Other than running premium fuel, changed to NGK Iridium about a year ago and keeping a good fuel filter its had nothing done since 2004.
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Post by carasdad on Aug 6, 2013 19:45:00 GMT -5
long time 2 cycle power equipment dealer here. Its a common mistake made on two cycle engines to run too rich on oil mix. Not only can it cause the exhaust port to build up carbon which can break loose and score the piston and cylinder. Think of it this way. Oil is a GREAT insulator. That's why its in big electrical transformers. An excess oil gas mix will put excess oil on the skirt of the piston. Heat MUST transfer from the piston to the cylinder wall and dissipate on the cylinder's fins ( we're talking air cooled here). Guess what happens when the extra oil is on the piston and "insulates" it from transferring the heat to the cylinder. When you see dark brown on a piston skirt its "cooked" oil from heat. The thought if some is good mORE is better just doesn't apply here. Use the premix or the oiling system but not both. main thing use an oil for an AIRCOOLED 2 stroke. I run my 2004 AlphaSports/eTon on RedMax 2 cycle oil that is a good blend of synthetic.dino oil. Made for air cooled two cycle engines I have low to no smoke and approaching 2k miles. Other than running premium fuel, changed to NGK Iridium about a year ago and keeping a good fuel filter its had nothing done since 2004. Thanks..your experience and expertise in the field confirms my soft seizes. Engine top end is now shot...but drained the premix and run on oil pump only. Usually 50-75 yards WOT at about 9k-9.5k and 55 mph...soft seize! Ran it today many miles on the oil pump only. Feeling brave..the last 2 miles home I ran it WOT...figuring ?... I gotta replace the top end anyway since the compression is about 90psi. NOT EVEN a hint of soft seize! Its final soft seize was so bad I actually heard the piston squeal and whistle in the cylinder before it locked up. Piston and cylinder are scored extremely deep and cannot be saved.Power is so low it takes a mile to hit 9k or so. Once I hit that I kept going 2 miles WOT...not single glitch. Sooo...new BBK will be oil pump only. Also I always use air cooled 2T oil. Bel Ray or Yamalube...never a drop of TC-W3 designated boat or jet ski liquid cooled oil. Even though most of it says 'Multi-Purpose' and has a motorcycle pic on the label. A guy I know the next town over fried his new Aprilla Sr50 on the 3rd tank using that stuff.  Glenn |
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Post by CopperDeer on Aug 6, 2013 21:22:01 GMT -5
Interesting, good stuff to know. I am in the process of putting a BBK on my 2T Derbi and was going to run some pre-mix in addition to the oil injection because I thought the extra oil would help her break-in. Bad idea.
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Post by carasdad on Aug 7, 2013 10:09:28 GMT -5
Interesting, good stuff to know. I am in the process of putting a BBK on my 2T Derbi and was going to run some pre-mix in addition to the oil injection because I thought the extra oil would help her break-in. Bad idea. CopperDeer..learn from my mistake and the professional 2t small engine folks posts up there. Today I Install my 3rd BBK due to excess oil. Each one was dead in less than 100 miles. According to a certified Yamaha Mechanic at the local dealership..my 32:1 premix with what the oil pump puts out at 3/4 to WOT...it becomes a 12:1 ratio! He was surprised it even ran..as many have done the same with their Zuma's or Vino's..which would barely run when he got them in the shop....after several soft seizes the piston..rings and cylinder were shot. Gouges so deep he said that even a .020 over bore could not remove! Which got me to thinking..with Yamaha and Honda Scoots..you can bore out .010, .020 and .030 and they make over bore piston kits for them...yet our Chinese or Taiwanese Scoots...we buy a new BBK. But he did say a new BBK is cheaper that what they charge to overbore a Yamaha or Honda..but then they are only allowed to use OEM parts. So the customer pays out the butt...while we can get off lots cheaper. Let us know how your BBK comes out. The extra 22cc does not seem like much...but as all will tell ya here...it a WORLD of difference in power...wow.  |
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