facebook1   youtube1   twitter1   instagram   linkedin1   pinterest1

logosmallNOTICE:  If you are not a free registered member of the site, you will not see the photos in the forum, and you won't be able to access our premium member content. Please consider joining our community!

Yamaha Service Manuals

24 Mar 2020 11:45
jmagda
Novice
Novice
Posts: 40
More
Topic Author
Yamaha Service Manuals #1
I was under the impression that the service manuals are the be-all, end-all for working on these bikes, but I can't seem to find any mention of when to apply a sealant to gaskets, or to metal-to-metal areas. At best, it will just say "replace gasket if needed." How do you know when to apply sealant unless I come in here and ask for every little thing?

Please Log in or Create an account to join the conversation.

24 Mar 2020 18:53 24 Mar 2020 18:54 by MarkT.
MarkT
Site Supporter
Site Supporter
Posts: 6601
More
Yamaha Service Manuals #2
Very few service manuals are really "instructional"... they expect you to have basic general mechanical knowledge.

In the Tech Library is a 1969 Yamaha Shop Guide that covers a lot of theory and basic principles.

Without knowing which specific manual and which specific bike I'd venture to guess that the Yamaha manual DOES tell you every place to use sealer. You have to remember that many of the sealers we have today weren't available back when these bikes were new.

Even Loctite... while it was around... wasn't really used much back then.

In most cases, the only place Yamaha recommended a sealer was between the case halves. I don't remember ever seeing a Yamaha manual that missed that requirement...

As far as sealer anywhere else? A true purist wouldn't use any unless it was recommended in the manual. And you don't "need" to. Some of us do from experience or whatever... but not strictly required... just use the gaskets dry.... or an old mechanics trick is to coat the new paper gasket in oil and it usually won't stick and can often be reused.

:Buds

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
The following user(s) Liked this Post 2fishkev, Swoop56

Please Log in or Create an account to join the conversation.

25 Mar 2020 02:36
jmagda
Novice
Novice
Posts: 40
More
Topic Author
Yamaha Service Manuals #3
Thanks for the quick reply, MarkT. My bike is a DT3 250 and the manual I refer to is "71-73 DT & RT (250cc-360cc) Service Manual". (It does mention Yamabond when resealing the case halves.)

At this particular juncture, though, I am finished with my carb and have moved onto the reed valve assembly. It appears there was some sealant smeared onto the metal around the gaskets. And I think I read in these forums that this area is particularly susceptible to gas leaks. True? If so, seems like there would be a recommendation of Yamabond concerning both gaskets used for the reed valve assembly/carburetor joint. But if you think dry is best, that's the way I'll go.

Please Log in or Create an account to join the conversation.

25 Mar 2020 05:01
MarkT
Site Supporter
Site Supporter
Posts: 6601
More
Yamaha Service Manuals #4
I didn't say what was "best"... I personally use a thin coat of Yamabond on those gaskets. And don't overtighten as "too tight" might sound like a good idea but can warp the reed valve and make it leak.

Just FYI, Yamaha, even on newer bikes today, does not recommend or use sealer on the reed valve mounting surfaces...

I never use any sealer on carb parts... if you use a Mikuni gasket on the bowl and don't overtighten, they don't leak. There is a risk if you use sealer some could get into the bowl and clog jets. And if you're going to use sealer, you have to be smart about it... Like if you used some Permatex #1 on the reed valve it would seal great but you might never get it off again. Or the common "silicone sealers" often don't hold up well to gas and I don't use them on reed valves or intakes... these are things you learn from experience and by not following the factory specs.

P.S. What frustrates me more is the difficulty finding bolt torque specs in early manuals...

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

Please Log in or Create an account to join the conversation.

25 Mar 2020 08:24 25 Mar 2020 08:26 by mdscott. Reason: typo
mdscott
Site Supporter
Site Supporter
Posts: 2134
More
Yamaha Service Manuals #5
Hylomar Blue is what I use on most gasket or rubber to metal surface like on the reed block. Its non hardening.
YamahaBond always between case halves.


www.amazon.com/Hylomar-172-148-Universal...ealant/dp/B00J4Z7N9I

hylomar.com/hylomar-product-range/gasket...ounds/#universalblue

Thanks Mark
Roseville, Ca.

'76 Bultaco 143 Frontera
'06 GL1800
'01 KDX200
74 DT360
75 Norton
73 CB500K
63 C200
87 PW50
64 McClane Edger

Please Log in or Create an account to join the conversation.

Moderators: yamadminDmanEnduronutMakotosunDEETVinnieDevinJames Hart