Thoughts on partially seized motor.

[ford_guy]

I rebuilt my motor recently. I rode it with the stock pipe for a few weekend and was minimally beating on it. I went ahead and put a toomey on it rejetted and plug chop so it was properly tuned. I was cruising down a trail and she seized on me. Kicked her over to hear scraping noises. I have two hypothesis. The new pipes powerband forced me to to stay in high rpms constantly. or the oil injection system failed. These are my thoughts. Lemme know what you guys think. I will tear her down this weekend!

 

[ford_guy]

I would to add that I had only rode it for about 2 hours before this seize occurred. Would an airleak cause this at cruising speed? Additionally I had new gaskets all around so I didn't even consider an airleak.

 

[Awk08]

Air leaks are the #1 cause of seizures.
I'd bet if you leakdown test before teardown you find one ?

What main jet did you end up with for the Toomey ?

Did you do proper hear cycles and retorque the head and base nuts afterwards ?

Warm it up properly before every ride ?

It would be nice to figure out why it fried before tearing it down, so it doesn't happen again.

Build one or buy a leakdown tester ASAP.
http://www.blasterforum.com/threads/leakdown-testers.55015/

 

[ford_guy]

Air leaks are the #1 cause of seizures.
I'd bet if you leakdown test before teardown you find one ?

What main jet did you end up with for the Toomey ?

Did you do proper hear cycles and retorque the head and base nuts afterwards ?

Warm it up properly before every ride ?

It would be nice to figure out why it fried before tearing it down, so it doesn't happen again.

Build one or buy a leakdown tester ASAP.
http://www.blasterforum.com/threads/leakdown-testers.55015/

the 310 main that they reccomended.
I did three heat cycles and had the proper torque on all bolts
I always warm it before rides.
And I agree I will buy one and leak test before I tear it down.
Also I don't know if this is related but one of the nuts on my exhaust came loose I noticed this after it seized.

 

[Awk08]

Also I don't know if this is related but one of the nuts on my exhaust came loose I noticed this after it seized.

that could also cause an airleak by sucking air back in as it scavenges the hot gases from the pipe

 

[ford_guy]

that could also cause an airleak by sucking air back in as it scavenges the hot gases from the pipe

So the only way to truley tell is to do a leak down test. Would there be a way to make it so those bolts do not come loose? Metal crimp nuts?

 

[Awk08]

So the only way to truley tell is to do a leak down test. Would there be a way to make it so those bolts do not come loose? Metal crimp nuts?

leakdown tester is the only way, message replied to for purchase.

lock washers under the nuts, or red/green loctite maybe, which ever is rated for highest temps

 

[joeak47]

The oil injection system is solid. Its not your issue.
Engine went lean.

 

[nick20555]

Lock washers are a lie. Professor beat that into our brains. He went full on crazy when someone suggested lock washers and had a very long and scientific explanation why. I don't remember exactly but it made sense at the time. Best to just use nylon nuts with a regular washer underneath or he will probably hunt me down and beat me for not suggesting that lol

 

[ford_guy]

The oil injection system is solid. Its not your issue.
Engine went lean.

I made sure I was running a little bit rich after a plug chop. The airleak would artifically lean it out? also could a bad crank seal cause this?

 

[ford_guy]

Lock washers are a lie. Professor beat that into our brains. He went full on crazy when someone suggested lock washers and had a very long and scientific explanation why. I don't remember exactly but it made sense at the time. Best to just use nylon nuts with a regular washer underneath or he will probably hunt me down and beat me for not suggesting that lol

The nylon wont catch on fire from exhaust heat?

 

[nick20555]

The nylon wont catch on fire from exhaust heat?

Good catch. I didn't think about that on an exhaust application. I just looked it up and they rate them for up to 140 Celsius which is about 284 Fahrenheit. Not idea what the temp of that bolt would see but from my understanding nylon melts not burns so worst case would be the nylon melts off and then it just acts as a regular nut. Loctite can handle up to 450 Fahrenheit from what I'm seeing.

 

[ford_guy]

Good catch. I didn't think about that on an exhaust application. I just looked it up and they rate them for up to 140 Celsius which is about 284 Fahrenheit. Not idea what the temp of that bolt would see but from my understanding nylon melts not burns so worst case would be the nylon melts off and then it just acts as a regular nut. Loctite can handle up to 450 Fahrenheit from what I'm seeing.

I will most likely use a metal crimp nut. I Better be happy with the expansion pipe I choose haha

 

[ford_guy]

Additionally, a running hypothesis is the crank seals are bad. Would this require a full rebuild? Should I just go ahead and do it to ensure that there are no repeats of engine seizing?

 

[MURPH]

you can remove the crank seals without splitting the cases by drilling a screw into the old seal to grab it and pull it out...if it was your stator side seal leaking that would give you a air leak but if your clutch side seal is leaking it would be burning transmission oil and you would see a lot of white smoke

 

[Larry's Shee]

Additionally, a running hypothesis is the crank seals are bad. Would this require a full rebuild? Should I just go ahead and do it to ensure that there are no repeats of engine seizing?

Seals are cheap and easy to replace. Think of it this way, nothing lasts forever. Natural heat of the engine will dry out the rubber eventually.
Even if leakdown doesn't reveal them as a problem, peace of mind is priceless.

 

[ford_guy]

you can remove the crank seals without splitting the cases by drilling a screw into the old seal to grab it and pull it out...if it was your stator side seal leaking that would give you a air leak but if your clutch side seal is leaking it would be burning transmission oil and you would see a lot of white smoke

Seals are cheap and easy to replace. Think of it this way, nothing lasts forever. Natural heat of the engine will dry out the rubber eventually.
Even if leakdown doesn't reveal them as a problem, peace of mind is priceless.

So I should go ahead and replace them and no go through with an entire rebuild? Chances are that I will be able to get away just replacing the seals? Or should I do it completely and rebuild the whole thing with all wiseco parts? I am not looking forward to spending 310 on it but I would spend 310 if it means I will not blow up mid ride again and spend another 110 to resurrect it.

 

[ford_guy]

Also I was burning white and not blue like I should have been. My transmission oil looked scarce as well.

 

[nick20555]

Also I was burning white and not blue like I should have been. My transmission oil looked scarce as well.

Sounds like crank seal. If your motor siezed, I'd be looking to rebuild

 

[ford_guy]

Sounds like crank seal. If your motor siezed, I'd be looking to rebuild

well its partially seized. I can still kick it over and she grinds. I even got it to start up but it ran like sh*t so I didn't touch it again.