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Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Mon Aug 01, 2016 11:00 am
by racerclam
where is your sense of adventure

Rich

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Mon Aug 01, 2016 12:51 pm
by viclioce
The bike was used. If a dealer couldn't have a bike for sale ready to ride, why would I consider it? I was 18 at the time!

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 6:09 am
by viclioce
Max, or someone. Can you point me to the published "How To" for doing this? I don't want to damage another cylinder and would like to have something published I can read and follow. Is it stored on the forum somewhere? Or in a back issue of the Resinator? Please let me know. I'm off to find a stone today. Would like to read the publication and have it handy. I also need to find feeler gauge with .003 gauge in it. What's a good location to try to find one? I have an AutoZone & O'Rileys close by to my house. ; D Victor

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 6:48 am
by hodakamax
Victor, there's a service bulletin part of which I posted on page one. There's also a picture of the type of stone you're looking for. I got mine in the fishing tackle department. Be careful out there!

Max

PS--I did the clearance measuring by pushing a ring (using a piston to keep it square) to the center of the bridge and measuring it with a feeler gauge.

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 7:13 am
by Bullfrog
Um, place rounded end of whetstone on exhaust bridge. Rub stone back and forth. Check progress. Repeat as needed.
Ed

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 9:27 am
by viclioce
Yeah, Ed. Nice technical info. Thanks. ; D Victor

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 11:36 am
by Bullfrog
That's how technical the job is. Do it all in a craftsmanlike manner and you'll be good to go.
Ed

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Tue Aug 02, 2016 3:41 pm
by viclioce
Well I got a good .001-.020 feeler gauge today. Man. Talking about removing material no thicker than a sheet of aluminum foil! This should be Interesting now that I have a gauge! ; D Victor

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 4:07 am
by Bullfrog
OK. Yup, you are not removing much material. Just to clarify - in my previous technical advice post, the phrase "back and forth" means to rub the stone on the bridge with movements in the same directions the piston moves (parallel to the center-line of the bore, not sideways across the face of the bridge).
Ed

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 7:34 am
by DGardner
This is what a exhaust port bridge should look like after you use a stone to relieve the bridge
fine_cratex2.jpg
This is what a piston looks like that has started to stick.
P9260015Large.jpg
This is what I do with every bike I have that has a bridge. Put the piston on the rod without the rings, put the cylinder on and mark the bridge outline on the piston and then drill two small oiling holes in the piston.
images.jpg
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images (1).jpg
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This should help from sticking a piston on the bridge again.

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 7:39 am
by admin
Very nice Doug!

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 10:34 am
by spudman
I like the idea of the "cooling holes" Doug! For some reason though, I'm able to click on and enlarge the first two images in your post, but not the bottom two. I tried different browsers and nothing seems to work. I'm just trying to get a better view of the image with the two yellow arrows so I can read the text (hole size?) to the left of them. Thanks!

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 1:10 pm
by dcooke007
Spudman,
Doug cant respond at the moment...at work. Said to relay to you 1/16th inch.

Danny Cooke

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 1:55 pm
by spudman
Thank you Danny. When Doug has time to respond, maybe he can give us an idea of how far down from the top or up from the bottom the holes are drilled as well. Also, can we safely assume that there is no weakening of the piston that would occur here with the two small holes? I would think not, but just wanted to be sure.

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 2:23 pm
by dirtsquirt80
would you still drill these holes if you had a savage port?

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Wed Aug 03, 2016 7:02 pm
by Bullfrog
? ". . . savage port"? I don't know what that is.

Ed

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Thu Aug 04, 2016 4:09 am
by DGardner
spudman wrote:Thank you Danny. When Doug has time to respond, maybe he can give us an idea of how far down from the top or up from the bottom the holes are drilled as well. Also, can we safely assume that there is no weakening of the piston that would occur here with the two small holes? I would think not, but just wanted to be sure.
I would put the first hole about 1/2 to 3/4 of a inch from the top of the piston and the next one about 1/2 from the first hole. I've never seen a problem putting holes in the piston.

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Thu Aug 04, 2016 4:18 am
by DGardner
The only problem I have ever seen with putting the oiling holes in a piston was the time a friend thought he could judge the center of the piston! He put the cylinder on and when we looked in the exhaust port and there was two small holes right next to the bridge.
Like Maxwell smart on the get smart TV show would say "missed it by that much"

Re: Relieving the exhaust port bridge - a 41 year old mystery SOLVED?

Posted: Thu Aug 04, 2016 1:55 pm
by spudman
Thanks for the info Doug!