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Help with Top End Rattle?
- dogman
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Replied by dogman on topic Help with Top End Rattle?
Today I'm going to get a measurement on the piston and the cylinder bore. I want to get a new piston (kit) in it and if that means getting it bored, I'm willing to do that. The rod ends are in spec as far as I can tell.
I know myself and if I think there is something wrong it will bother me. I want it to run as good as possible as I do plan on trail riding this thing. Too many fun places to go here in Idaho
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Thanks for the guidance RT325, it has been helpful.
I know myself and if I think there is something wrong it will bother me. I want it to run as good as possible as I do plan on trail riding this thing. Too many fun places to go here in Idaho
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Thanks for the guidance RT325, it has been helpful.
08 Dec 2024 07:49
#31
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- MarkT
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Replied by MarkT on topic Help with Top End Rattle?
A challenge is getting it bored correctly. Even back when these bikes were new, it wasn't easy to find a shop that knew how to bore and fit a new piston correctly. Many liked to "add a little clearance" because it was an air cooled engine and they thought it would help prevent seizing... it doesn't.
Ports need to be chamfered properly afterwards as well.
I'd consider shipping the cylinder to Bill Bune's shop as they have been around forever and know these engines.
Ports need to be chamfered properly afterwards as well.
I'd consider shipping the cylinder to Bill Bune's shop as they have been around forever and know these engines.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
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08 Dec 2024 12:52
#32
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
Thanks MarkT. I found the site and reached out to them.
08 Dec 2024 17:52
#33
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
I shipped the cylinder to Bill Bune's shop. I'll update when I have something to report.
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12 Dec 2024 20:00
#34
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- automan
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Replied by automan on topic Help with Top End Rattle?
I ordered 3x jugs to be bored/honed to .0004" of my spec. target with Ra 25 micro inch finish.
They came back within .0001" of target and a Ra of 20-30 uI
All at 75°F
Ports all chamfered .020"
Decks true to .001"
Bill Bune was/is the best.
I finished up to my target with a 400 rigid stone to 15 micro inch finish.
Added my secret coating and oiled.
cliff
They came back within .0001" of target and a Ra of 20-30 uI
All at 75°F
Ports all chamfered .020"
Decks true to .001"
Bill Bune was/is the best.
I finished up to my target with a 400 rigid stone to 15 micro inch finish.
Added my secret coating and oiled.
cliff
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
Hello all. I'm waiting for my cylinder to get back to me and in the mean time I'm trying to make sure everything is correct regarding parts.
Josh over at Bill Bune Ent. said I need a .25mm over, so I purchased and shipped him a 251-11635-00 yamaha piston.
I also purchased a set of 251-11601-10 rings and have those in hand.
What I'm trying to figure out now is which ring is the top ring. I have read quite a bit on the forum trying to uncover the info I need, and this was the most relevant post: yamaha-enduros.com/index.php/forums/1972...ston-ring-ct3#135177
My rings do have the 25 stamp, and I can easily see an "N" stamped on both rings. But I don't clearly see a 1 or a 2 (maybe a 1). This was an ebay purchase, the box was sealed by original tape as far as I could tell. It also came with 2 expander rings, but they are both the same shape (looks like the top expander in the service manual).
I'm looking for some insights here to keep me on the right path.
Ring A (click to zoom):
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Ring B (click to zoom):
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Expanders:
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Josh over at Bill Bune Ent. said I need a .25mm over, so I purchased and shipped him a 251-11635-00 yamaha piston.
I also purchased a set of 251-11601-10 rings and have those in hand.
What I'm trying to figure out now is which ring is the top ring. I have read quite a bit on the forum trying to uncover the info I need, and this was the most relevant post: yamaha-enduros.com/index.php/forums/1972...ston-ring-ct3#135177
My rings do have the 25 stamp, and I can easily see an "N" stamped on both rings. But I don't clearly see a 1 or a 2 (maybe a 1). This was an ebay purchase, the box was sealed by original tape as far as I could tell. It also came with 2 expander rings, but they are both the same shape (looks like the top expander in the service manual).
I'm looking for some insights here to keep me on the right path.
Ring A (click to zoom):
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Ring B (click to zoom):
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Expanders:
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
The more I look at the pictures, the more I see a "1" on both rings.
31 Dec 2024 12:26
#37
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- MarkT
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Replied by MarkT on topic Help with Top End Rattle?
From what I can tell from part number, rings are identical and both are supposed to both be "keystone".
I think post #6 in that other thread shows how ring won't go very far into keystone groove if inserted "backwards" due to slight taper in groove. That should be true for both grooves in your new piston.
I think post #6 in that other thread shows how ring won't go very far into keystone groove if inserted "backwards" due to slight taper in groove. That should be true for both grooves in your new piston.
1963 YG1-T, 1965 MG1-T, Allstate 250, 1970 CT1b, 1971 R5, 1973 AT3MX, 1974 TS400L, 1975 RD350, 1976 DT175C, 1976 Husqvarna 250CR, 1981 DT175G, 1988 DT50, 1990 "Super" DT50, 1991 RT180, 2017 XT250
31 Dec 2024 13:09
#38
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
Well that's good news. If both rings are the same, that would help me make sense of my old rings. I was very careful to keep the old rings marked as to which was the top/bottom. When checking those, the bottom ring has a "1 N" mark and the top ring has no markings (probably worn off after 8,500 miles).
The service manual had me confused because it says the top ring is the Keystone ring.
Before moving forward I will verify the grooves in the new piston once I have it in hand. The picture shows it stamped with a "K" at least.
@MARKT thanks for your post in that other thread, it was very helpful to me.
The service manual had me confused because it says the top ring is the Keystone ring.
Before moving forward I will verify the grooves in the new piston once I have it in hand. The picture shows it stamped with a "K" at least.
@MARKT thanks for your post in that other thread, it was very helpful to me.
31 Dec 2024 14:48
#39
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- dogman
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Replied by dogman on topic Help with Top End Rattle?
The service manual had me confused because it says the top ring is the Keystone ring.
I just wanted to add a note regarding my statement about the service manual. I was looking at the PDF copy which covers AT1 and CT1. My physical CT1-C service manual reads differently and makes more sense.
PDF Manual:
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CT1-C Manual:
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I just wanted to add a note regarding my statement about the service manual. I was looking at the PDF copy which covers AT1 and CT1. My physical CT1-C service manual reads differently and makes more sense.
PDF Manual:
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CT1-C Manual:
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