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TOPIC: Yamaha DT1 1968 - big end bearing size

Yamaha DT1 1968 - big end bearing size 24 Jan 2017 15:52 #1

  • David Mortimer
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I need a crank rebuild and need to buy some replacement parts before I take it to my local engineering shop for refurbishment. I would be really pleased if someone could tell me the size of the needle roller cage bearing (big end) which is at the bottom of the con rod. It is part no 93310-524k4-00 on the crank shaft page of my parts book. I would like to buy one direct from a bearing supplier rather than pay a fortune for a nos one on fleabay or via cmnsl in holland. I know the internal diameter is 24mm - that is the size of the crank pin. However what is the external diameter and the width? I'm sure someone has one around that can be measured or has the sizes. I'd also be interested to know the size and type of washers which are either side. I've already bought the KOYO manufactured 6306 main bearings for half the price of exactly the same bearing but with a yamaha part no on it. Thanks in anticipation.
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Yamaha DT1 1968 - big end bearing size 29 Jan 2017 00:59 #2

  • alostdt
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Hi David.

Ive just rebuilt my 71 dt engine including a crank rebuild. I ended up sending my crank to grampian motors in liverpool. They did a really good service and had my crank back to me in 3 days. They also fitted a new rod from a gt750 as its exactly the same length etc. Total cost was less than 100 quid but it did get it done through a friends trade account. Eitherway id highly recommend them.
By the way. If you ask them for crank seals they will most likely send you later model ones 73 onwards. These do ot fit. They also could not source a piston when i tried (december 2016) but did say they were out of stock rather than a flat out no. May be worth trying again.
Good luck!
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Yamaha DT1 1968 - big end bearing size 31 Jan 2017 12:04 #3

  • David Mortimer
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thanks for the response - I'll try them. Did they supply the crank bearing (big end)? On the seals - If you look at simply bearings they do all the seals you need. All you need to know is the size of seal - which you can find out online or written on the original seals. They also do the Koyo bearings.

thanks again

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Yamaha DT1 1968 - big end bearing size 17 May 2019 08:32 #4

  • bart.ives
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93310-52478-00
BEARING 24-31-19.8

90209-24073-00
WASHER, CRANK PIN 24.2-38-1 152-11685-00

214-11681-00-00
PIN, CRANK 240

431-11651-00-00
ROD, CONNECTING

Outer Crank bearings
93306-30610-00
BEARING 6306


Piston
93310-21874-00
BEARING 18-22-22

214-11633-00-00
PIN, PISTON

93450-20026-00
CLIP 604-11634-00
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Yamaha DT1 1968 - big end bearing size 17 May 2019 16:56 #5

  • RT325
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Just reading the question wondering if they run C3 clearance so google it & i see i've been here before & thought the '30' after the 6306 in the middle number probably means C3 clearance. Food for thought?. C3 allows for the crank tight fit on mag side expanding the inside. On the RH side the bearing just slides on the crank & held tight by the crank gear. Anyway, sorry to ruin your day. ps, C3 helps with less than perfect alignment of the crank too. Same number both sides i see so maybe that's blown my theory away or they just like extra clearance both sides except tight fit on the mag side takes away the extra clearance--clearance of the balls in the race that is, not clearance of fit on the shaft or in the case.
yamaha-enduros.com/index.php/forum/1968-...43-rt1-crank-bearing

www.partzilla.com/product/yamaha/93306-3...07133ae735d8e9c4f468
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Yamaha DT1 1968 - big end bearing size 17 May 2019 18:25 #6

  • MarkT
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Unfortunately I've had new superseded part number Yamaha bearings not match the original "internal clearance"...

For the crank I use new bearings that have the increased internal clearance like C3... I think sometimes C5?... so very good point. :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

Yamaha DT1 1968 - big end bearing size 20 Aug 2019 05:13 #7

  • bart.ives
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93310-524K4-00 Big in Crank Rod Bearing size is by my measurements: 24mmx32mmx19.68mm.

My New Rod, from HotRods is stamped 8106-1, 130mm in length, measures 19.85mm wide at the crank end, including two 1mm x 24mm shims and is using the above bearing and my original 24mmx60mm crank pin. This setup uses the original 18mm piston pin and cage bearing 18mmx22mmx22mm.
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Yamaha DT1 1968 - big end bearing size 20 Aug 2019 06:17 #8

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My heads spinning reading that at sleep time. But working it out in my head the bearing is about just under 7 thou or approx 0.17mm narrower than the rod which won't matter . Are you worried about mismatching things or is she all set to go. If it's just info your giving us then that's great knowing what non original numbers can work thanks. Main thing is that the width of the rod with thrust washers is the same as original or the crank overall with will be too wide & cases won't go together. Well you might get away with a little, but if for instance if the thrust washers were 1.5mm wide instead of 1mm, ending up 1mm wider overall then might have trouble. Then again maybe not as the mag side bearing has a bit of gap as the crank is bolted to the right side.
Maybe i'm way wrong lol [tell me] but not going to start again.
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Yamaha DT1 1968 - big end bearing size 20 Aug 2019 08:23 #9

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I ordered from bikebuzzard on ebay. Initially I ordered his setup for the 24mm Crank pin and 125mm rod length. When I spilt the cases found out that my rod length was 130mm so emailed Chuck at Bikebuzzard and we exchanged rods, kept bearings and new 24mm pin. Now, my next step is to reassemble. If there is an issue I will post back here.

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Yamaha DT1 1968 - big end bearing size 20 Aug 2019 08:32 #10

  • Pillsbury
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I used bikebuzzards rod with OEM Yamaha bearing, thrust washers & lower pin. I did not like the look of their pin under a loop. It looks like he is using oem bearing & thrust washers. I've done two with no problems. One of them turns 10,000 rpm.
The bearing & pin are not expensive nor hard to get.
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1970 DT1-C Grand Prix race bike
1970 DT1-C Street tracker
1968 Honda CL90
1971 Honda Sl 125
1973 Honda CR250
1974 Honda MR-50
1966 Triumph Tiger Cub
1967 Moto Guzzi V700
1970 Suzuki TC90
1947 Mustang
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