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16 Jan 2019
Tonight we were hit with a spammer which was caught by Enduronut. The user has been banned, hopefully we will be able to nip this in the bud. Please if you notice spam being posted, shoot an email to me at makotosun1@gmail.com so I can act quickly. Sorry for the inconvenience. apparently our defenses are not perfect. MAKO

TOPIC: Whoa what happened here

Whoa what happened here 05 Jan 2019 11:07 #1

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Decided to throw s set of rings in my 71 dt today. So I slide the jug off and it comes off easier than expected like no resistance. I’m looking at the bore and heck there’s still hash marks from the last hone job and stock bore. Good there so I take the base gasket off and wtf? There’s two of them on there. That’s not right. So whatever they both come off easily. So I take the rings off the piston and hmmm where’s the inner rings. There’s just compression rings on it no inner rings. This can’t be right. No wonder I only had 105 psi compression
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Whoa what happened here 05 Jan 2019 12:58 #2

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Look on the bright side .. you now have a spare gasket !
I recently took the cylinder of my rt2 to find no gasket ,PO thought base gaskets came in a tube.
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Last Edit: by Wheel mad.

Whoa what happened here 05 Jan 2019 13:02 #3

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Lol glad I took this thing apart
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Whoa what happened here 05 Jan 2019 14:44 #4

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Prinzy wrote: Lol glad I took this thing apart


Yep, 8 days ago you were about ready to sell the GYT head and call it good..

a
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YAMA-LAND RESTORATIONS
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MINIBIKESERVICE@AOL.COM CUSTOM MINIBIKE (RALPH) 2002 110cc XR PAX RACING 1971 125cc AT1-C (DOROTHEA) 1971 175cc CT1-C (BRANDY) 1970 250cc DT1-C (MONICA) 1973 100cc Hodaka Combat Rat (ABBY NORMAL) 1969 125cc AT1-M MX (DELILAH)

Whoa what happened here 05 Jan 2019 17:02 #5

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A lot of people (including me) leave out the "ring expanders" (inner rings)... they can break. And if they do the result can be seizure. They seem to break more often with ported engines but I've seen them fail in a stock engine.

No harm at all in leaving them out and your compression will not change at all.

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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

Whoa what happened here 06 Jan 2019 11:46 #6

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Ok good to know should I just leave them out then?

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Whoa what happened here 06 Jan 2019 11:48 #7

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Gyt head isn’t going on. It needs a good home I don’t want to start jacking around with the timing and mess up a good bike. Should have done more research I guess live and learn

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Whoa what happened here 06 Jan 2019 12:33 #8

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I'm not smarter than the Yamaha engineers by any means! The expanders are only used on the second (lower) ring and I've seen claims that they keep the piston from rocking (not sure I buy that theory) to they help prevent the second ring from vibrating or fluttering in the groove (that theory sounds more likely).

I'm sure there are many opinions as to using them or not. I don't use them after finding them broken and getting advice not to from an experienced Yamaha engine builder much smarter than me. I'm not advocating that you don't use them. I'm only saying that "low compression" is not caused by leaving out the expander.

Maybe PM Enduronut and DEET and see what they recommend?

Since I'm on my soapbox I'll say that the presence of hone marks does not always mean the bore is good... having the piston and cylinder inspected by an expert like Enduronut is always prudent in my experience. ....at the very least have the cylinder honed to remove the glaze before installing new rings. (And of course the ports chamfers need to be checked/redone and the cylinder meticulously cleaned to remove all grit after honing.)

:Buds

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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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Whoa what happened here 06 Jan 2019 12:41 #9

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Forgot to mention that not all pistons had the expanders... Any markings on the piston? That can help identify which rings you need.

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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

Whoa what happened here 06 Jan 2019 14:29 #10

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I didn’t really clean the carbon off of the piston to check for markings but I measured both bore and piston so I know it’s standard bore. Rings should be here tomorrow. I would have preferred to go first over n start fresh but with holidays and snowmobiling trips can’t spend too much. I’m gunna throw rings at it new wrist pin n bearing and see what happens. At least I’ll have peace of mind that base gasket head gasket and rings are new. I have another engine that’s stock bore I’ll probably just buy a 1st over piston n have it bored accordingly sometime n slap it on there

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