bob
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Posts: 4
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Post by bob on Sept 30, 2022 14:11:03 GMT
Hi all, I'm rebuilding my '81 cb250n superdream engine. I need some new crank and gearbox bearings.
Big end brgs- 2x Green
Crank journal brgs- 2x Black 1x blue.
Mainshaft and layshaft roller brgs and needle brgs.
Im also after the rubber boot which goes over the starter motor power cable where it bolts to the motor.(or an alternative).
Thanks.
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Post by johnfcbn44dx on Sept 30, 2022 17:47:53 GMT
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bob
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Post by bob on Oct 1, 2022 13:53:12 GMT
Thanks very much that's a great help. I'm rebuilding my engine using a donor engine. Mainly using donor internals, keeping my pistons/ conrods and engine cases. The donor engine would normally be brown crankshaft bearings, which I'm sure I've read are not available. The black code bearings are the two outer ones. I'll buy these big end brgs though. Although all my old bearings are not too bad, need new because I'm mixing and matching. |
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Post by buster on Oct 1, 2022 14:56:16 GMT
for the mains (three sets) blacks are difficult to find for the 250's and browns are difficult to find for the 400's.
in fact they are so scarce I now keep any secondhand 'users' that I can lay my hands on
just out of interest have you cleaned the gearbox bearings out and had a good check of them? if you've got a donor gearbox too then I'd think you could make up at least one decent set of bearings? I'm not saying they cant go but they dont often get that much stick, even on a badly abused 400 I had no issue with the gearbox bearings
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bob
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Posts: 4
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Post by bob on Oct 3, 2022 8:45:10 GMT
for the mains (three sets) blacks are difficult to find for the 250's and browns are difficult to find for the 400's. in fact they are so scarce I now keep any secondhand 'users' that I can lay my hands on just out of interest have you cleaned the gearbox bearings out and had a good check of them? if you've got a donor gearbox too then I'd think you could make up at least one decent set of bearings? I'm not saying they cant go but they dont often get that much stick, even on a badly abused 400 I had no issue with the gearbox bearings I could use a bearing out of each gearbox, but I'd prefer to use all new if possible. I'll look which one size down shells may do the job. |
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Post by buster on Oct 3, 2022 9:03:37 GMT
have you measured the shells with plastigauge?
I'v found that I'm happy enough to do the con rods by feel but the main journals feel like they have a preposterous amount of slop in them when they actually measure within tolerance.
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bob
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Posts: 4
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Post by bob on Oct 3, 2022 21:06:54 GMT
No, I haven't measured them. I was just hoping to fully replace. Looks like I may have to adjust my plans.
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