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Makotosun

Any help on how to separate the reed cage?

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Well I think I found out why the engine was sucking air. The fellow I used to build the engine has used two gaskets in an attempt to seal the reed cage. There is oil between these two gaskets. Not a good sign.

Any tips on how to separate the rubber intake from the reed cage? There has been grey RTV sealant used and despite trying with a utility blade, I'm making no progress. Would submersion in hot water help? I don't want to damage the reed cage.
I have a new repro rubber intake on the way so I don't care if it gets damaged. Are the reed cages still available?
25 Jan 2020 12:35 #1

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  • MarkT
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Replied by MarkT on topic Any help on how to separate the reed cage?

I use single edge razor blades and Xacto knives and a lot of patience.

Very common source of leaks... I use a thin coat of non-hardening Yamabond or Permatex Motoseal when assembling.
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
25 Jan 2020 15:22 #2

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Replied by Toxic on topic Any help on how to separate the reed cage?

Thanks, I might be over thinking this as my rubber intake is still very pliable and shows no cracking and the reed cage is better than most that I see on Ebay. I can't see it leaking air from around the rubber intake to reed cage joint. The double gaskets at the mount to the barrel had no sealant and was very easy to remove. There was a thin coating of oil between them. I think the engine builder used two aftermarket gaskets at this joint to create a better seal because the OEM gasket is substantially thicker than the aftermarket ones. I think I will clean everything up and reassemble with some of the sealant you suggest.
I had a local gasket maker provide me with some Nitrile gasket material that looks to be the same thickness of the original Yamaha gasket. I'm told the Nitrile is fuel and temperature safe for this application.
Once the bike was running for about 3-4 miles I could tell it was running lean. At idle the revs were bouncing around like crazy and when I sprayed it down with WD the idle evened out.
25 Jan 2020 16:37 #3

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Replied by FrankC on topic Any help on how to separate the reed cage?

I have been looking up gasket materials of late and I think you are correct nitrile is good for fuel.
25 Jan 2020 16:59 #4

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Replied by RT325 on topic Any help on how to separate the reed cage?

If it all looks good i'd bolt it up & try again to prove or dis-prove if its leaking. I've had some pretty dodgy ones i've made or adapted but never had a leak or a problem [that i know of]. i think i've seen two gaskets supplied in sets on ebay so maybe he though ok two so may as well use then up. Actually the two in a set would be for RT2 generation motors with Alloy carb flange--but anyway!!--Is yours a DT400 or similar.
27 Jan 2020 03:49 #5

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Replied by Toxic on topic Any help on how to separate the reed cage?


Mine is a 1975 DT400B and the manual shows just one gasket between the reed cage and the cly. The fact that there was oil between them and no sealant seems to indicate it was not sealed well and this was the source of my air leak.
The aftermarket gasket is 0.91mm thick and the Nitrile one I have made is 1.73mm thick and is a lot more pliable. I'm going to put a thin coat of Yamahbond and put it back together
27 Jan 2020 05:55 #6

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Replied by MarkT on topic Any help on how to separate the reed cage?

Side note... if air leak isn't fixed in my opinion it's extremely worthwhile to build or buy a pressure test setup. Otherwise you're just "guessing". Something that will work can be put together for not much $... I made my first one by cutting the cuff off an old manual blood pressure cuff... a couple block off plates out of scrap bar stock, and a fitting. Cost was $0. Even new you could probably rig something up for about $20.

I didn't pressure test for years... until I blew a rebuilt engine that had a defective new crank seal. Honda gave me a new seal... but lost a race and engine. Since then I've found seal leaks, gasket leaks, and even porous castings on newly rebuilt and used engines. All easy to find with 5 psi pressure and soapy water. No more guessing.
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
27 Jan 2020 06:46 #7

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Replied by Toxic on topic Any help on how to separate the reed cage?

Thanks, I have seen some pretty neat set ups to do this. I will do so if this doesn't cure the issue.

I have had the engine professionally rebuild by a two stroke specialist. I am rather surprised by the current situation as it seems to be a rather a simple error on his part. Every seal, rubber part, bearing has been replaced.
I would tell you the cost but I fear I would be kicked off of the internet for being so stupid.
I might have gotten carried away with this project.... oh wait... I always to that.
Once I start, I have to see it completed even when the smart move is to abandon the project

Gary
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27 Jan 2020 08:05 #8

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Replied by FrankC on topic Any help on how to separate the reed cage?

I had a professional do my motor and it did not turn out well. Between lacing up my rims, I bought the spokes, and an engine rebuild, I bought all the parts, it was 1100 bucks. I admit it, doh!
27 Jan 2020 14:34 #9

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Replied by Toxic on topic Any help on how to separate the reed cage?

This was a local guy that has building these bikes for decades, I easy have $1000 in engine parts.
Hopefully this will fix it
27 Jan 2020 14:46 #10

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