GP100 Full Engine Rebuild

[MattWadz]

Okay, i need to change the crankshaft bearings in my GP100, and whilst im there, i would like to do a full rebuild.

I was wondering if anyone on here could give me a list of things that would be really neccesary during the reubild. i havent got a flywheel puller, and could i use the old piston and new rings in the old barrel? the bike is running fine but i want to keep the costs down.

I was thinking

2 Crankshaft bearings
1 Full Gasket set

Is this a particularily difficult job?

And would anyone be able to write me up a step by step guide to doing it, i would say i have a fair mechanical knowledge.


Thankyou

Matt


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Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[Dr. Quack]

Crank bearings need to be placed in flush with a vice using an old bearing, along with the seals. NEVER BUY AFTER MARKET PARTS WHEN REBUILDING ENGINES UNLESS YOU KNOW WHO MANUFACTERS THE PARTS! SOME BEARINGS ARE OK BUT YOU NEED TO KNOW THE SCORE WITH THIS. YOUR AFTER MARKET GASKET SET WILL BE OK.
In the past when I’ve done full rebuilds I gave the crank case to a mechanic. The crank case also needs to be split and put back together using a special grease like substance. You will also struggle to loosen the flywheel without an air gun. Top ends are easy enough; check for cam and rocker wear? just make sure the barrel is within tolerance before buying new rings ECT. It may need 10th milli oversized re-hone or even a new chrome plate. Replace small end bearing too. Oh, if your gunna replace the crank bearings you might as well replace the big end bearing too, I made the mistake of not doing this once.

Next time I will give the whole engine to a mechanic and fling him £500, depending on the engine of course.

Source: Rebuilt a few engines then sold the bikes quick time!

[Blau Zedong]

[Dr. Quack]

As said above!

[27cows]

Would strongly advise you to try and find a whole GP motor. Full rebuild will work out relatively expensive. Considering how fragile they are, IMHO it's not worth the grief.

Get an RXS100

If you're intent on a rebuild, in theory it should be a very straightforward job. I built a GP125 from two old motors and it went fine. Reused everything, including gaskets and seals Not sure how long it would have lasted for but I did a couple of thousand miles, no bother, and the guy I sold it to never came back irate because the engine had carked it shortly after he got it.

The problem with simple jobs is that often you encounter one thing that turns out to be a complete bastard. Or discover other damage when in the process of rebuilding...or even do damage yourself. It's easily done.

I know what it's like to love something that everyone else thinks is crap But really, the GP is the kind of bike that needs constant work. Fix one thing, something else will go. I speak from experience.
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The RXS100: vehicle of choice for Chuck Norris