seizure?
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
seizure?
hi folks
Im hoping someone can give me some advise and tell me where im going wrong.
Ive just finished building myslef an afc with a 89 motor. The problem ive got is ive only done about 10 miles on the bike and it has seized twice.
the first time i put it down to the guy i bought the engine off supplying me the wrong size piston, so i had the barrel rebored and fitted a new piston the correct size, bought some new oil (castrol a747) and mixed it at 30ml per litre.
2 miles up the road same thing happened?????
i check carb (39mm pwk) and all is fine, check jetting and thats fine too.
i dont know why it keeps seizing and cant afford to put a piston in it every 10 miles
could it be that i didnt drill holes in the piston for lubrication of the exhaust port bridge?
thanks in advance
Im hoping someone can give me some advise and tell me where im going wrong.
Ive just finished building myslef an afc with a 89 motor. The problem ive got is ive only done about 10 miles on the bike and it has seized twice.
the first time i put it down to the guy i bought the engine off supplying me the wrong size piston, so i had the barrel rebored and fitted a new piston the correct size, bought some new oil (castrol a747) and mixed it at 30ml per litre.
2 miles up the road same thing happened?????
i check carb (39mm pwk) and all is fine, check jetting and thats fine too.
i dont know why it keeps seizing and cant afford to put a piston in it every 10 miles
could it be that i didnt drill holes in the piston for lubrication of the exhaust port bridge?
thanks in advance
- NightBiker07
- Posts: 1942
- Joined: April 16th, 2008, 8:59 pm
- Location: USA
Too lean of jetting probably. overheating and seizing is my guess. My 3 wheeler used to do that.
2000 CR250, pipe, filter, Vforce
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
ok, so had a chance to spend time time looking at the bike this evening.
checked the jetting again and in my pwk im running a 55 pilot 178 main and 1.5 turns out on the air screw. Its set a bit rich at the mo until its run in.
checked the coolant thats fine too, so im thinking its got an air leak somwhere.
im guessing the leak would need to be around the crankcases rather than carb or reeds? is that right.
the motor has some damaged to the cases but i didnt think much of it as thought it was on the gearbox side.
there is also a small hole in the join in the cases at the bottom not far from the drain plug, it looks like its supposed to be there tho
checked the jetting again and in my pwk im running a 55 pilot 178 main and 1.5 turns out on the air screw. Its set a bit rich at the mo until its run in.
checked the coolant thats fine too, so im thinking its got an air leak somwhere.
im guessing the leak would need to be around the crankcases rather than carb or reeds? is that right.
the motor has some damaged to the cases but i didnt think much of it as thought it was on the gearbox side.
there is also a small hole in the join in the cases at the bottom not far from the drain plug, it looks like its supposed to be there tho
- Roostius_Maximus
- Site Admin
- Posts: 4641
- Joined: November 16th, 2007, 3:24 pm
- Location: Mt Nebo, Manitoba, Canada
- Contact:
you're right about the small hole. its for draining the ignition side case.
That bolt too long?
i'd pressureize things and see if the case is also leaking to the trans
That bolt too long?
i'd pressureize things and see if the case is also leaking to the trans
http://www.youtube.com/user/500bigbore
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
- NightBiker07
- Posts: 1942
- Joined: April 16th, 2008, 8:59 pm
- Location: USA
start the bike, and while it is idling, start spraying any gasketed areas with starting fluid. if it is leaking, the starting fluid being introduced into the leak will change the engine's RPM. easy, cheap, dirty way of air-leak hunting.
2000 CR250, pipe, filter, Vforce
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
1980 XL80s
1969 Broncco TX-6
Natural selection favors Smart people, so nature selects morons to be slow and dumb for tigers and stuff too eat. But in our modern world there just aren't enough tigers.
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
- jbsleddin
- PVT. 1st Class
- Posts: 251
- Joined: June 12th, 2011, 10:48 am
- Location: Wheatley, Ontario, Canada
The best thing you could do right now is invest in a leak down testing kit, or if you're super ambitious (and a cheap ass like me ) you could opt to make one yourself. I, myself, don't have the ambition or time to dick around trying to put a kit together myself. Bought the Motion Pro kit several months ago. I have to say, I don't know how I got by as long as I did without it! It's already paid off with many hours saved from chasing my tail unneccessarily!
Make a joke and I will sigh, and you will laugh, and I will cry.
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
this is what i came up with to leak test my motor.
and this
i got to about 20psi on the gauge and found that it had a leak from where the rubber boot joins the reed block. I have a spare and tried that but it was leaking in the same place,
The gaskets were new when the motor was built and the metal plate on the boot looks like its in good condition and not distorted.
Ive put some silicone gasket sealer between the joints but not sure if its a good idea leaving it like that, just in case the silicon blows out and it seizes again.
and this
i got to about 20psi on the gauge and found that it had a leak from where the rubber boot joins the reed block. I have a spare and tried that but it was leaking in the same place,
The gaskets were new when the motor was built and the metal plate on the boot looks like its in good condition and not distorted.
Ive put some silicone gasket sealer between the joints but not sure if its a good idea leaving it like that, just in case the silicon blows out and it seizes again.
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
- jbsleddin
- PVT. 1st Class
- Posts: 251
- Joined: June 12th, 2011, 10:48 am
- Location: Wheatley, Ontario, Canada
Yeah, 20 psi is enough to push seals out too, The kit I have recommends 8psi max, allowable to lose 1 psi per minute, more than that and start looking for problem areas. I'd go out on a limb and say you've already found your problem though, unless more leaks are apparent too.
Make a joke and I will sigh, and you will laugh, and I will cry.
- Roostius_Maximus
- Site Admin
- Posts: 4641
- Joined: November 16th, 2007, 3:24 pm
- Location: Mt Nebo, Manitoba, Canada
- Contact:
did the bridge have relief to spec?
what was your ring endgap?
actually, it was probably right, by looking at the pin we can tell it has seen some heat also.
so...
it didnt sink the dome in from lean wfo
it didnt start to blow chunks out of the piston from lean or too hot of a plug
it didnt 4 corner sieze from running hard cold
so you didnt ride it wfo, and it probably idled fine, it will have got to big rpm, then closed the throttle a bit and squeaked it right?
It did close the gap on the ring
It did stick at the bridge
bridge clearence isnt there or enough
the ring took the heat, got long and butted the endgap
it likely needs more fuel on the needle, more bridge relief and more end gap on the ring
what was your ring endgap?
actually, it was probably right, by looking at the pin we can tell it has seen some heat also.
so...
it didnt sink the dome in from lean wfo
it didnt start to blow chunks out of the piston from lean or too hot of a plug
it didnt 4 corner sieze from running hard cold
so you didnt ride it wfo, and it probably idled fine, it will have got to big rpm, then closed the throttle a bit and squeaked it right?
It did close the gap on the ring
It did stick at the bridge
bridge clearence isnt there or enough
the ring took the heat, got long and butted the endgap
it likely needs more fuel on the needle, more bridge relief and more end gap on the ring
http://www.youtube.com/user/500bigbore
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
- Roostius_Maximus
- Site Admin
- Posts: 4641
- Joined: November 16th, 2007, 3:24 pm
- Location: Mt Nebo, Manitoba, Canada
- Contact:
sorry, its been hella busy, took me like 2 hours to compose that post
http://www.youtube.com/user/500bigbore
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
My CR500 Tech Reference... http://sdrv.ms/1a0CIiz
MRE Components... http://sdrv.ms/1bs2zhd
I don't see any lube holes in the piston?
IDK but, no holes and IF the bridge wasn't relieved.....
Those 2 together would seem to be a perfect storm.
Since I'm not an engineer by any stretch, I try to take the best advice I can get.
On the 500, it's here and everyone preaches about those 2 things
Got any pics of the cylinder?
IDK but, no holes and IF the bridge wasn't relieved.....
Those 2 together would seem to be a perfect storm.
Since I'm not an engineer by any stretch, I try to take the best advice I can get.
On the 500, it's here and everyone preaches about those 2 things
Got any pics of the cylinder?
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am
ill take some photos of the barrel/bridge when i get home. When the barrel was bored there was still some relief on the bridge? should i relief it some more?
so i dont need any holes drilled in the piston, is this right?
i not sure im following all the lingo your chatting, wfo? wide f+{}king open?
how do i measure the end ring gap?
both times when the bike seized it was in the same spot on the same road which is strange, anyway I was being careful with it and as soon as i opened the throttle to about a 3rd it seized. Exactly the same both times
ive checked the jetting 3 times, so cant be that, should i raise the needle?
thank for all the help folks, really appreiciate it
so i dont need any holes drilled in the piston, is this right?
i not sure im following all the lingo your chatting, wfo? wide f+{}king open?
how do i measure the end ring gap?
both times when the bike seized it was in the same spot on the same road which is strange, anyway I was being careful with it and as soon as i opened the throttle to about a 3rd it seized. Exactly the same both times
ive checked the jetting 3 times, so cant be that, should i raise the needle?
thank for all the help folks, really appreiciate it
-
- Posts: 10
- Joined: November 6th, 2011, 10:28 am