G'Day Hogsnot........

A couple of questions

1. is it a main bearing (crank), big end (conrod) or little end/gudgeon (piston) bearing that is gone?

Deeper rumbles suggest bottom end (crank), lighter taps, gudgeon which tend to quiet down on acceleration?

2. How handy are you with spanners?

Any of the problems listed above are not for the faint of heart.

If it was me, I'd be pulling the motor and replacing all the bearings - but I'm a pedant.

Cheers, SB

 

First off...without questions there wouldn't be forums, and all questions are valid, especially here my brother.

How did you find it?

To answer you question up front, yes the engine comes out and gets turned up-side-down and bottom comes off.

If truly new to this and a bearing is bad, you will need a good mechanic with a micrometer that knows what he/she is doing to mic up the crank journals. If you have shavings (I remember this thread because there was a bet LINK ) the bearing may have been beaten to death and the metal to metal contact of the rod to journal may have dinged up the journal. If that happened you may not see or feel it but it would be just enough to have the bearing fail again.

The problem with crank bearings is that they are matched to the journal dia. When the factory machined the journal surfaces, they set tolerances and matched connecting rods to them with appropriate bearings. These tolerances are listed in the shop manual. There are I.D. markings on your crank, connecting rods and crankcase to depict what bearing set is needed for your engine. You will need to know what bearing thickness you need before purchasing them, providing your crank is still good.

The shop manual also has engine remove step by step procedure.

Best of luck to you.

 

Excellent post, TBT.

Hogsnot, I'm also wondering why you think it's rod bearings/wrist pin bearings, etc.
There are a lot of noises that can make you think it's rod knock, and to be honest.... if it truly was....I would probably just part the bike out and buy another one.
But that's just me.

 

I'd just buy a second hand engine off e-bay and fit that. Wouldn't be more than a few hours work, if that. Then you could ride again and sell the original engine off as parts, or keep it for spares in the future.

Cost of an engine here in the UK is £150 - £300 about $250 - $500.

So $500 minus whatever you sell your old engine for. No brainer to me

 

^^^
+1


Hawks idea - makes most sense - sell of bits of old engine to pay for a "new" used one

 

Because of this.

Running it even that long in the clip below, I'd say the crank is trash. I wouldn't spend the time trying to fix it. The journals would need to be turned and have matched bearings. Quicker and best to replace engine.

However, I'm stubborn and would at least mic it up when the engines comes out.
Honda Hurricane Motorcycle Noise - YouTube