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Makotosun

Hoping to bring my old DT 360 back from the dead

  • Jack
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Finished up with the glazing putty yesterday and it came out pretty good. Painted it this morning and that was going well too until I noticed a hair had found it's way into the wet paint. I'll have to let it dry throuroughly and then some very light sanding followed with one final coat. Otherwise I'm pretty happy with it.
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25 Jan 2021 09:21 #181

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Well, life got in the way for awhile but I'm finally able to get back to working on the 360 again, at least for while.
 
I was able to get the top end back together a couple days ago and it all went well with no problems as near as I can tell. I did a leak down test and the bad news is I have a leak but the good news is it's not one of the crank seals. It's leaking from the reed valve, it's a very small leak but may be difficult to stop.

 As it is right now it takes about three minutes to bleed down from 5lbs to 0. I had already replaced the gasket that goes between base of valve and cylinder and it's not leaking there. The leak is coming from between the aluminum plate that appears to be bonded to the rubber base and I don't think it's removable without damaging it further.  

Otherwise I'd just put some sealant between the two pieces. But I'm afraid to take them apart. Right now I have it bolted down as tight as I dare, already beyond torque specs, hoping that it may eventually seal itself up again but if that doesn't happen, any ideas?

 Since it's been awhile since I first looked into clutch parts layout I've been studying the parts breakdown on clutch disc arrangement and washer placement again and think I have that all figured out except that I noticed I don't have a second bellview washer which I had been thinking I would need 2, one for both the clutch and one for the primary gear.

 After realizing i only had one I rechecked the parts diagrams again and found that on the Japanese list, it doesn't list it for the 360, for the 250 yes but for the 360 no. In fact it doesn't show any washer at all for the 360, just the nut and that's it. This doesn't seem right to me but that's what it shows and I don't seem to have a washer that fits it, although that could have been been lost over the years. Anybody remember off hand if their primary gear is held on with just a nut and no washer, lock, flat or bellview of any kind? 

Made a handy little tool to hold my flywheel snug. Little funky looking but  it works fine.
 
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25 May 2021 20:26 #182

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Nice work!  Love the tools you've made.

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I use a thin coat of semi-hardening Yamabond on those manifolds. (Same stuff used on the center cases)  And don't over tighten.  Very common place to leak.  Even my all brand new YZ85 engine I built for my super DT50 had a leak there.
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 May 2021 20:35 #183

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Thanks Mark. I'm not understanding what you mean about fixing the manifold leak. It's leaking from between the aluminum plate and the rubber part of the whole assembly. I don't know for sure but it appears that the plate is bonded in someway to the rubber part. If it is then I don't seen how I can put any sealant between them. I haven't tried to pry them apart as I'm afraid I may do further damage and end up with a much worse leak than I have. I have some Yamabond left over from the case halves but how do I get it between the plate and the rubber?
25 May 2021 20:54 #184

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You have a rubber manifold and the aluminum plate you're talking about is the reed valve.  Two separate parts.  Look at the parts diagram. 

www.partzilla.com/catalog/yamaha/motorcycle/1974/dt360a/intake

Originally the rubber manifold had ribs and is supposed to seal to the reed valve plate without a gasket but like I said even brand new they don't always seal well... and yes, manifold might be stuck to reed valve but should come off.


 
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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25 May 2021 21:04 #185

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Thank you! I don't know why I jumped to the conclusion that the parts were bonded together. Didn't even occur to me to check the parts diagram. My brain gets stuck in reverse sometimes. Believe it or not I'm not always this dense... Anyway, thanks for straightening me out ,(for the umteenth time I think....)

I'll try to get it apart tomorrow and if successful will apply a thin layer of Yamabond and torque to specs and will retest for leaks. 
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25 May 2021 21:21 #186

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The rubber manifold did separate from the reed valve just as you said Mark. I just had to tap it with a plastic hammer a couple times and it came right apart. I put a thin layer of Yamabond between the two parts per your suggestion and no leaks! Thanks so much for the information.

Put the clutch back together today. Installed everything per the Japanese parts breakdown minus the last toothed steel plate, which I didn't have and you told me some time back was only used on the 250 if I remember right. Anyway, everything fit and looks right. Had a heck of a time torqueing the nut down, needed an extra hand or two but after strapping the engine down to the work bench and wrapping a belt around the center hub I was able to hold everything still while tightening to torque specs.  Just about ready to put the engine back on the bike!




 
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Last edit: 26 May 2021 18:55 by Jack. Reason: Edited to add pics
26 May 2021 18:53 #187

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Well, decided to snug down pressure plate screws just a bit more, big mistake. I managed to twist off one right off. Then to make things worse I screwed up the threads in the boss while attempting to remove what was left of the screw. Wasted more time trying to come up with some way to fix things, several possibilities came to mind but none that I felt were sound. Now my head hurts........

 The only good news is I got lucky and found a complete clutch assembly for cheap on ebay with everything I need plus I'll be able to make a clutch holding tool out of the extra plates. Parts should be here in a few days. In the meantime I'm going to clean the carb again, just to be sure I didn't miss something the first time around and get it back on the bike. 
01 Jun 2021 04:56 #188

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Replied by Mothersbaugh on topic Hoping to bring my old DT 360 back from the dead

What was it The Dead Boys sang? "You ain't done nothing that ain't been done before."
01 Jun 2021 11:30 #189

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Replied by Gr8uncleal on topic Hoping to bring my old DT 360 back from the dead

Happened to play a Dead Boys cd the other night!!

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Not sure I heard many violins on it though!

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I guess that DEET or Enduronut might have a Sonic Reducer in their stash!

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01 Jun 2021 12:27 #190

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