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Rebuilding my Dt 360a motor

  • treeves
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Rebuilding my Dt 360a motor was created by treeves

The crank bearings are bad so I need to split the case.  I am in need of crankcase splitter and crank puller.  What about the tusk brand?  I am going to have the crankshaft rebuilt but need a rod kit, looking on line the only one I see is Bike Buzzard.  Has anybody used his rod kit or is there someone else?
26 Feb 2021 15:47 #1

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Replied by MarkT on topic Rebuilding my Dt 360a motor

I'd check with DEET on the crank puller.

For splitter, a two bolt puller you can probably borrow for free from auto parts store will work fine... 
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
26 Feb 2021 16:29 #2

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Replied by Jack on topic Rebuilding my Dt 360a motor

I bought the 360 rod kit from Bike Buzzard. In case you're not aware of it he sells two rod kits for the old Yamaha's so make sure you order the correct  one. The 360 rod is a bit longer than the 250 rod. Everything in the kit was correct.
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26 Feb 2021 16:50 #3

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Replied by treeves on topic Rebuilding my Dt 360a motor

Mark I sent Deet a message about his puller. Jack thanks for the info, I will make sure I get the longer rod.
Thanks for the quick reply
26 Feb 2021 17:53 #4

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Replied by msavitt on topic Rebuilding my Dt 360a motor

hey there
i just did mine
to split i used a two bolt puller and the tapped holes
to reassemble I used the Tusk, it is a very high quality tool
on the stator side it was a snap as the Tusk comes with an adaptor that fits the threads on the flywheel side
on the primary drive side, despite some comments that this side is slip on (it is not), I had to make an adaptor to fit primary side of crank threads.  After some head scratching I determined that if I bought an extra primary gear nut and rounded off the hex with a file that it would perfectly fit the Tusk took and the primary side threads.  I was concerned that if the draw force was as high as tit was on the stator side that the slot that drives the pump pinion might flex a bit and the nut adaptor slip off and damge the treads so I filed the gap with 1/4" keyway stock plus a couple of feeler gage sections that added up to the width of the slot.  This worked perfectly.
I also used the Tusk crank install tool to press the crank seals in, using a perfectly fitting PVC fitting between the tool and the seal.  I posted pictures of this on the "life after meltdown" that documents all the mistakes I made leading to the unfortunate meltdown and all the questions  I had that this amazing group answered.  Just today I got my DEET pump back so prject is offically done (I hope!) and i am searching for another cool yamaha to restore!
26 Feb 2021 19:48 #5

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Replied by MarkT on topic Rebuilding my Dt 360a motor

That's the thing about DEET's tool.  It reportedly comes with the adapters that fit all the different crank threads..

His email is Yamaha @ nc.rr.com

(Take out the extra spaces)
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
26 Feb 2021 19:53 #6

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Replied by treeves on topic Rebuilding my Dt 360a motor

  I have split the case and used the splitter to get both sides of the crank out of the crankcase.  When I did get the crankshaft out I was surprised that both bearings were still on the crankshaft.  I have sent the crank off for rebuilding and the cylinder off for boring but am wondering why the bearings did not stay in case?  
27 Mar 2021 07:07 #7

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Replied by msavitt on topic Rebuilding my Dt 360a motor

looks like the crank/bearing interference force exceeded the force beteween bearings and cases.
when i rebuilt mine there was definitely interference between both, on both sides too.
do your new bearings have an interference with the cases?  If so, then i think you are good; if not then you have an issue.
I installed mine by putting cases in oven at 250 and bearings dropped right in and when cool were really tight.  Then I used crank tool to draw crank into both sides.  I also used crank tool to nicely pull main seals in too.
27 Mar 2021 08:59 #8

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Replied by RT325 on topic Rebuilding my Dt 360a motor

Right side bearing is a slide fit on every model from 50 to 360--or sc500 if you like.. If its not sliding then someone has loctited it or has rusted or just crud, but loctite if its truly stuck. Left side is a press fit on the shaft & in the case as right side is a press into the case. Right isn't tight on the shaft because its bolted up solid to that side by the crank nut. That way it's easy to pull the right side case away leaving the crank in the left. If its as it should be you could tap the right side away with no tools, but have to be careful doing it to keep it even or it'll try to hang up on something in the trans. Still the problem of removing crank from the left though. & for assembly you 'could fit the left bearing & pull the crank in then assemble the rest from the right & slide the case on with the new bearing already in the case. Mind you after that when right side is on the crank nut would need to pull the crank over to the right a mm to snug it up to the bearing leaving a mm estimate gap between left bearing & crank web, which is how it should be--left being tight on shaft & case. But a light tap might be needed on the left to release the pulling from the right, just de-stressing it or might feel slight binding to turn.
After all 'that', better do it your way to avoid my confusion. Wish i knew how to use smiley's lol.
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Last edit: 27 Mar 2021 18:10 by RT325.
27 Mar 2021 18:08 #9

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Replied by treeves on topic Rebuilding my Dt 360a motor

I have ordered the new bearings but have not received yet.  I was thinking something was wrong with my case when the bearings came out on the crank.  Thanks msavitt for letting me know it happened to you.
28 Mar 2021 17:33 #10

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