Bore seize why?
Moderator: Moderator
Bore seize why?
So I have been building scooters for five years now. First seize. Here are the specs my setup.
48mm big bore
Dio derestricted exhaust 26mm.
Nyc variator stock roller weight
Temp gauge 14mm cht.
78 main
Stock airbox.
On my way to work today after running 260f came to a stop and it turned off. Oil mix is 40:1 cant be a heat seize.
48mm big bore
Dio derestricted exhaust 26mm.
Nyc variator stock roller weight
Temp gauge 14mm cht.
78 main
Stock airbox.
On my way to work today after running 260f came to a stop and it turned off. Oil mix is 40:1 cant be a heat seize.
Last edited by Limp1144 on Tue May 22, 2012 9:44 am, edited 1 time in total.
Re: Bore seize why?
the only way to know is open it up and see.
Nothing like getting stroked!
Thanks to my sponsors
Nos Energy Drinks,themopedcompany.com,nwautoevents.com,Cycle Gear
90 honda dio sp 72cc
87 elite 50 s with 86cc watercooled mini stroke
87 elite 50 race bike mhr 72cc
91 yamaha tzr 250r
Thanks to my sponsors
Nos Energy Drinks,themopedcompany.com,nwautoevents.com,Cycle Gear
90 honda dio sp 72cc
87 elite 50 s with 86cc watercooled mini stroke
87 elite 50 race bike mhr 72cc
91 yamaha tzr 250r
Re: Bore seize why?
LOL cant be seized? hehe
but baka is correct open it up and study the piston, it will tell you pretty much exactly if it was a heat/cold sieze, misalignment..
78 jet seems pretty small
dont worry limp it happens to all of us!
but baka is correct open it up and study the piston, it will tell you pretty much exactly if it was a heat/cold sieze, misalignment..
78 jet seems pretty small
dont worry limp it happens to all of us!
Re: Bore seize why?
It runs super cold with that 78 main jet. I did not modify the airbox bore never seen over 300f. It was a cheap taiwan bore not ruima. When it locked up it idle down then when I went togive it gas it made a baaaa noise then turned off. The electric start fired it back up. Could it be the stock gears doing about 50mph so I am sure it was high in the rpms
- Downsouthdio
- CB900F
- Posts: 1205
- Joined: Wed Dec 21, 2011 11:00 am
- Location: Key west
Re: Bore seize why?
Just curious.. Did you ever look at the plug? And if so how'd it look
Honda super dio
Corsa
26mm
Sparrow
Corsa
26mm
Sparrow
Re: Bore seize why?
Havent pulled out the plug but the temp gauge elminates that. I drove it around all day to and at 35mph 195f-205F. Top end run almost at 50mph 225F so it is getting cooler on the temps. I will pull the plug out but i would bet it is black from richness
- tazland001
- Board Supporter
- Posts: 1333
- Joined: Thu Apr 30, 2009 11:46 pm
Re: Bore seize why?
That 78 sounds way to lean for that set up. If your running your stock carb you need at least a 100 main in my opinion.
Also did you break the kit in????
Taz
Also did you break the kit in????
Taz
Re: Bore seize why?
Where is everyone getting these jet sizes. No bore had 25miles on it. 4 heat cool cycles. Wot temp doesnt go over 260f now. Most bores can go to 375-400 before the seize. 100 jet my temps would be in the low 100f lol
Re: Bore seize why?
It can seize even at 200, just pop the head off and look at the top at least or the exhaust and look through the port to see at least exhaust side. Or better yet compression test it.
Re: Bore seize why?
Actually the heat spike that seizes an engine happens so fast that a gauge will never respond that quickly. If you are lucky it will show up afterwards but not always.
Bear 45/70
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
Re: Bore seize why?
wow. you sure about that "temp gauge eliminates that"? More like the opposite. you can run and tune a bike with looking at the plug. Just relying on the temp gauge isnt a good idea. There are a few variables , bad gauge or bad sender.. Also im hoping when you read your plug you dont just go by the color. That way of reading a plug is not really the true way of reading plugs. Mopeds with a stock carb will look nice and clean. try using a fat pilot most times a good tune will still look oily and black over a time. All plugs look tan in color if pulled at the right time. The real way is to cut open a plug and look at the base for the fire ring. I usually know what im looking for so a good bright light source can see down the plug if its new.Limp1144 wrote:Havent pulled out the plug but the temp gauge elminates that. I drove it around all day to and at 35mph 195f-205F. Top end run almost at 50mph 225F so it is getting cooler on the temps. I will pull the plug out but i would bet it is black from richness
Re: Bore seize why?
Or use one of these to see without destroying your plug.
http://www.ebay.com/itm/140755408539?ss ... _823wt_931
http://www.ebay.com/itm/140755408539?ss ... _823wt_931
Bear 45/70
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
'83 Aero 80 X 3
'84 Aero 80 X 3
'85 Aero 80
'84 Aero 125 X 2
'84 Aero 125
'84 Aero 125 X 2
'85 Aero 50
'85 Spree
Re: Bore seize why?
Weds off work will check it out. Gonna I thought the cht gauge would give me the insight on the true temps. do a plug chop since it turned off put about 40 miles so far no issues. Thought the cht was pretty accurate. Getting better gas mileage to 68mpg now
- Downsouthdio
- CB900F
- Posts: 1205
- Joined: Wed Dec 21, 2011 11:00 am
- Location: Key west
Re: Bore seize why?
Somethings not right somewhere.. Cht is good but cant jus rely on that..good luck man , its frustrating i know
Honda super dio
Corsa
26mm
Sparrow
Corsa
26mm
Sparrow
- Wheelman-111
- Moderator
- Posts: 11321
- Joined: Wed Oct 22, 2008 5:09 pm
- Location: Deepinnaharta, Texas
Re: Bore seize why?
Greetings:
Jetting and apparent temps aren't the only things that can kill a bore.
A bad tank of fuel - either too-low Octane or shrapnel blocking a jet - will cause sudden failure. Chunks-O Hot Metal can cause pre-ignition and the Detonation Death Spiral faster than any gauge could register. Often the Temp That Really Matters happens off-throttle - if the Pilot jet is too small. Bad or insufficient oil can do it too. So can sufficient oil, if it's not where it needs to be.
I'm surprised Baka hasn't mentioned chamfering the edges of the ports and piston skirts - he has many times. The more affordable bore kits have knife-edges that scrape too much of the oil off the cylinder walls and basically the piston/bore interface runs dry of lubricant. It's a short time indeed at 200 strokes/second before the piston goes red-hot. Poof!
Jetting and apparent temps aren't the only things that can kill a bore.
A bad tank of fuel - either too-low Octane or shrapnel blocking a jet - will cause sudden failure. Chunks-O Hot Metal can cause pre-ignition and the Detonation Death Spiral faster than any gauge could register. Often the Temp That Really Matters happens off-throttle - if the Pilot jet is too small. Bad or insufficient oil can do it too. So can sufficient oil, if it's not where it needs to be.
I'm surprised Baka hasn't mentioned chamfering the edges of the ports and piston skirts - he has many times. The more affordable bore kits have knife-edges that scrape too much of the oil off the cylinder walls and basically the piston/bore interface runs dry of lubricant. It's a short time indeed at 200 strokes/second before the piston goes red-hot. Poof!
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH