[dentalboy]

Has anyone any idea if its worth replacing the big end bearings on my 2001 400 burger or [ costing wise] if its better just to get a second hand engine?

 

[NormanB]

How can you be sure it is only the big ends that require replacing?

 

[Ralph M]

If it is the big end then there will likely be other damage and I may be cheaper to
get another second hand engine, thing is knowing if the one you are fitting is good.

 

[dentalboy]

All good points well made. I dont know it just the big ends, hense why a second hand motor. But as pointed out, how do you know how good that is untill you get it in and running. My motor is running at the moment but noisey under load. Oh what to do.??

 

[Ralph M]

A bad big end is usually noisy as you shut off the throttle as it then looses
the cushioning of the pressure around tbc I have never ridden a pre 2007
scoot but the later ones are quite harsh under acceleration, it is very rare
for one to do a big end.

 

[Quantum Mechanic]

Do bear in mind your engine had a roller bearing big end and cannot be replaced as an individual item. It means a new crankshaft (or secondhand if you can find a good one). It's unlikely to be cost effective to get an engineering firm to press out the crank pin and fit a new bearing. There can be problems doing that. However, you can test the play on your conrod with the head and cylinder barrel removed. This is a good indicator as to how good the big end bearing is. You will feel any play that is present. The workshop manual gives you the tolerances that are acceptable. There is always some tolerance on roller bearings but it must be within the guidlines laid down in the manual.

Like others, I wonder why you are thinking the big end bearing may be on it's way out, or gone? Are you confusing the Suzuki engine rumbling and rattling under acceleration with an engine problem? Come back with a more enhanced explanation if you can about the noise. These engines can be noisey under acceleration even when everything is fine.

 

[dentalboy]

Hi Quantum. The reason for saying the big end has gone is based on talking to my mechanic. The noise is akin to a mini anvil being struck with a hammer. It sounds the loudest on heavy acceleration, but not on overun. On tickover there is no sound. Any help?.

 

[Ralph M]

Try some super fuel in it see if that makes a difference, and if anyone as a similar scoot or a local dealer as one try to blag a test ride, the later ones are quite noisy on acceleration and at first I wondered if mine was pinking, but am now sure it's intake noise, wile it could be a big end it's very unlikely.

 

[Scootereno]

Hi Quantum. The reason for saying the big end has gone is based on talking to my mechanic. The noise is akin to a mini anvil being struck with a hammer. It sounds the loudest on heavy acceleration, but not on overun. On tickover there is no sound. Any help?.

That sounds just like FatJocks did (he let me ride it) before it came apart.
Piston and rod were shot and he posted pics here about 6 months ago.
Might try a search and check it out.

 

[Fatjock]

That sounds just like FatJocks did (he let me ride it) before it came apart.
Piston and rod were shot and he posted pics here about 6 months ago.
Might try a search and check it out.

Yup, Mine blew at around 60mph, around 30 miles from home.......when I got it apart, the bottom end and the rod were fine, piston was in "a million little pieces", and the sidewall of the cylinder ripped asunder. The exhaust valves were also bent.

Head was okay, and fortunately the valve seats were fine.
For the new valves, cylinder, piston kit, and gasket kit, was around $600 in parts. That's not counting the additional tools, and service manual, I had to buy to get it done.

Could have got another engine for around $750, and would have taken a lot less work to replace, but I wanted the experience.

I learned a lot from it, and enjoyed doing it, but it took a long time, and a lot of effort.

At the end of the day it's up to you which way to go, but a replacement engine is definitely the simplest.