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Servicar melting piston at full throttle

Post Thu May 12, 2016 7:49 pm

Posts: 8
My 1951 servicar melted the rear piston while riding to work at full throttle. It's about 15 to 20 minutes of highway at one point of commute. I am at full throttle for this part at about 60 mph.. . This is my first servicar and I know you guys have seen this before, I'm thinking it just can't handle it , but my 1942 wl can run at 60 but not be at full throttle

Pa Site Admin

Posts: 6045
Location: Ohio USA

The gearing is different between the Servicar and the WL. That is why you can run higher speeds on one and not the other. When I say gearing, I am referring to the engine sprocket teeth number. As far as melting the piston goes. That should not occur. It sounds like you have a manifold leak.


Posts: 8
I thought that also but seals looked great. I was wondering if because m51 linkert had no fixed jet. (Blocked off) that maybe it was leaning out to much at 60 mph[img][img][/img][/img]


Posts: 8
how do you add pics, or how do you downsize pics so you can attach them


Posts: 377
could be too lean mixture too, or timing was off. Both cause overheating of engine. Especially on hot days and high speed traffic. It ran too hot, and that means normally either too little fuel, or timing not properly set ( too late causes heating of the engine too)

Too little fuel can be either a manifold leak like Pa suggested, it could be wrong setting of carburetor, it could be leaking through the throttlelever, via a headgasket, or a valve that doesnt ( or didnt) close properly.

Pa Site Admin

Posts: 6045
Location: Ohio USA

jwbull01 wrote:
how do you add pics, or how do you downsize pics so you can attach them


When you hit reply to a topic, there is an upload provision for posting pics via the forum software. Most use a Photoshop program to reduce picture size or they get a Photobucket account which will reduce the pics for you. 700 wide works well at Photoshop and you copy the Photoshop link and paste it in your reply.


Posts: 8
Try pic again not sure but trying
Attachments
image.jpeg


Posts: 8
I will check timing and carb,, I'm hoping that bike can handle full throttle riding, because I live in Smithfield and work in Newport News and the only way to get there is to cross the james river and if u r not doing 60 mph, people will run u over


Posts: 377
It should normally be no problem to go full throttle, but on a servicar I must say you will be pushing it pretty far.. WLA has a 60MPH limit warning on the tag.. Servicar being heavier and using higher gearing would not make it better I think


Posts: 2717
Location: Los Angeles, CA
jwbull01 wrote:
how do you add pics, or how do you downsize pics so you can attach them



Open a free account at http://www.photobucket.com
Upload your pictures to photobucket.
After uploading copy the IMG code and paste it here. No re sizing necessary.Image

Pa Site Admin

Posts: 6045
Location: Ohio USA

I have to resize many of my photos at Photobucket to post here Chris. 700 wide works. Any larger and the forum will not accept the link code.


Posts: 2717
Location: Los Angeles, CA
Pa wrote:
I have to resize many of my photos at Photobucket to post here Chris. 700 wide works. Any larger and the forum will not accept the link code.



I have uploaded over 2,000 pictures to photobucket and I have never had to re size a single one. Many have been posted here.

Pa Site Admin

Posts: 6045
Location: Ohio USA

Chris Haynes wrote:
Pa wrote:
I have to resize many of my photos at Photobucket to post here Chris. 700 wide works. Any larger and the forum will not accept the link code.



I have uploaded over 2,000 pictures to photobucket and I have never had to re size a single one. Many have been posted here.


This is true, however, pic size limits were much larger years back here. At one time one would have to scroll sideways just to view a large pic here. Folks complained about the scrolling and the time it took to load the pics on their PC screens, so the size of pic posting was reduced.


Posts: 8
Rear piston. Damage on intake side, what ya think
Attachments
image.jpeg
image.jpeg (92.91 KiB) Viewed 3314 times


Posts: 377
I have seen something similar during my roadtrip to Italy. 1 guy had a jammed engine, piston came out in exactly the same state as yours.

We never figured out what went wrong, the valves were all good, the spacing was good. It was also on the intake side, but his engine was running rich, not lean, so overheating seemed unlikely. However, with an intake leak somewhere its still possible!

Was your engine still relatively fresh? ( less than 1000 miles) Could be that you just went to fast for a new engine..


Posts: 8
On the mark,,,,,
It was a rebuild,


Posts: 377
Then my best figure is you went to fast too soon :(


Posts: 3316
Location: Central Illinois, USA
Can't believe Folks still punish themselves with vacuum leaks!

http://virtualindian.org/11techleaktest.html

.....Cotten
PS: "Running rich" is a red flag for a leak, because it won't run any other way!


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