My Megabusa - trials and tribulations [update end p2]

Need help from a fellow owner, something to air - discuss away!

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ChrisL
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Re: My Megabusa - trials and tribulations

Postby ChrisL » Tue Jul 02, 2019 6:55 pm

Love the technical aspects of this, have you thought of working for Haynes?
That welding looks professional in my book but then you've seen my welding.
On the stator front I have replacing things on the basis they should cure a problem when it's an engine out job, like my clutch!!
Good luck and may the bolt shearing gods look favourably on you.
Yes I've been drinking, what of it!!

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SteveRST
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Re: My Megabusa - trials and tribulations

Postby SteveRST » Tue Jul 02, 2019 7:40 pm

Thanks guys, I enjoy learning about this stuff and would rather not pay someone else because I'm tight :lol:


I've created a video for the gearbox fault finding bit. I found it interesting seeing how the bike transmission works, so thought others may do too.
But bear in mind this is the first bike gearbox I've seen! So please point out anything I've missed.

Busa gearbox fault finding - part 1
https://youtu.be/FC33cOP1oc8

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SJLB
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Re: My Megabusa - trials and tribulations

Postby SJLB » Tue Jul 02, 2019 7:42 pm

Good work Steve. The stators usually look obviously burnt out but you are right to replace it. Hopefully the gearbox is just a selector fork problem or something.
Steve
Westfield Megabusa, Bromley, Kent.

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greenwoo
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Re: My Megabusa - trials and tribulations

Postby greenwoo » Wed Jul 03, 2019 7:27 am

loved the video, was really interesting to see the innards.....

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b33fy
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Re: My Megabusa - trials and tribulations

Postby b33fy » Wed Jul 03, 2019 12:05 pm

Great video Steve, stripped one back in the day after blowing it up (GT250) needless to say it didn’t ever go back together, ended up weighing it in. :lol:
Power.. small nail, fast hammer, Torque.. small nail, big hammer.. I got a big hammer :P

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Weathers
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Re: My Megabusa - trials and tribulations

Postby Weathers » Thu Jul 04, 2019 9:48 am

I know nothing about bikes but this is really interesting. Especially seeing how the fork thingys move the gears about.

Did you find the end of the circlip?

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Re: My Megabusa - trials and tribulations

Postby Wingco » Thu Jul 04, 2019 8:26 pm

Wow Steve great video ;loads of information in that. As others have said, I know nothing about bikes but you certainly have made it very interesting. Hope you get it sorted soon.
Did you find the ends of the circlip ?
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SteveRST
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Re: My Megabusa - trials and tribulations

Postby SteveRST » Thu Jul 04, 2019 9:56 pm

Thanks for the kind words guys.
I've not ordered the new parts yet so this might take some time unfortunately.

Re: the circlip and missing ends. Well it turns out that that circlip doesn't have the traditional 'eyes' at each end like you'd expect. It has to be low profile. I'd made a mistake and assumed it was a regular one.
So in fact there were no missing ends to find. :)

The circlip had failed though and was not seated in its groove.

Diff next...
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Tony B
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Re: My Megabusa - trials and tribulations

Postby Tony B » Sat Jul 06, 2019 7:20 am

Crikey, just catching up on this - fantastic video Steve and thanks for posting. I have a nasty felling I’ll be following your footsteps to find out what’s going on with 2nd gear, maybe I should pop up to yours to have a look at one in bits first!

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Re: My Megabusa - trials and tribulations

Postby SteveRST » Thu Aug 15, 2019 10:30 am

UPDATE
This has somehow managed to drag on for 2 months, but the engine is finally back in the car and appears to be working with 6 forward gears and no oil leaks!

Shortish video update... I say 'shortish' because I got bored doing the video blog and gave up part way through :roll:
Busa gearbox fault finding - part 2
https://www.youtube.com/watch?v=IfW6O39Jf20

(watch Part 1 here if you haven't done so yet: https://www.youtube.com/watch?v=FC33cOP1oc8)


Now for some details (and costs) -

I replaced the two gears that were failing to engage properly, as the 'gear dogs' looked worn. I also replaced the worn gear selector fork which moves one of these gears. While I was at it, I also replaced the standard oil pump drive gear with a 'hi-pressure' aftermarket item that simply drives the oil pump faster.
Picture below of these 4 items... and the cost - £500. These gears are not cheap!
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Old Vs New...
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Ready to fit...
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I also bought a new stator (generator) which I picked up from M&P shop on eBay with a 20% code for a pretty reasonable £78. Let's hope it lasts!
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Other costs...
- bottom end Cometic gasket set £65.
- Threebond 1215 case sealant paste £12 + a few sundries.

So total cost around £675.


The lower/upper crankcases are not sealed with a gasket, just a thinnish layer of the case sealant paste. So getting the mating surfaces super clean is important.
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Engine hoisted up on to the car, so that I can then attach the engine mounting cradle in place before lowering the whole lot in to the chassis. I must admit it came in/out reasonably easily... I didn't need a second pair of hands. No pesky clutch alignment dramas like you get with a regular car engine/gearbox.
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- - - - - - - - - -

So next job was to sort the differential oil leak.

Fuel hoses removed to create some space...
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Drive shafts unbolted... I was missing 1 bolt from one of the shafts!
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Unbolting propshaft from diff...
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Pain in the bum getting the diff out on your own, and even more of a drama getting it back in! Needed to use the engine crane to help me lower it back in to the chassis, .
This is the 7.5" diff which does seem heavier and leaves less 'wiggle room' for fitting obviously than the 7" diff in my other Westfield.
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When I took the flange off the end of the diff nose, it was clear that my oil leak was not due to oil leaking past the oil seal, but oil travelling down the splines in the shaft and then leaking out at the nut at the end of that shaft.
20190714_120836.jpg


I used some silicone gasket sealant on the splines and on the far end of the flange so that it should create a nice seal when reassembled and all seems ok.


So, working car again finally. :)
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