GPZ500 - building spare engine... (long!)

[StormCrow]

TL:DR:- What do I need to look out for when building GPZ500 engine?

Hi folks

While my bike seems to be running reasonably well, she's on 63,000 miles.

I have gained various parts to rebuild a spare engine - in order to swap out.

I have a good bottom end - bearings look fine, gears all look perfect, no scoring etc anywhere.

I have just bought an apparently good top end - pistons, barrels and head.

Most parts are from a Gen 1 engine - I will be swapping my Gen 2 CCT over (will put together with Gen 1 for setting timing etc) and will be swapping flywheels and stator (spare engine doesn't have them).

I have ordered a cam chain with 8,300 miles on it - which will be swapped.

Obviously I intend to pull the valves and lap in etc - alongside lapping the head as per FOG.

Now then - the gears...

I know that the Gen 2 gearset is preferable to the Gen 1 - usually because of slipping into a false neutral - yes? At present I only have a decent looking Gen 1 set - anything specific I should inspect? My current gearbox is whining in 4th so that's out. (Also Gen 1)

I intend to measure and hopefully reuse the piston rings - the whole thing is on a budget and they ain't cheap...

The primary drive chain from my bottom end set looks fine - I will remeasure the link lengths but if I remember correctly it was within spec.

So - consider this a sort of project thread - I can take some pictures throughout if the people so require it!

My first question (of likely many!) - is there anything else I should be specifically checking or looking for? Anything I've missed? Parts will be checked as they are installed - certainly the bottom end visually looks fine - no chipped teeth anywhere, bearing shells look fine, crank seems good etc. The top will be inspected after I pick it up - I know that camshafts etc aren't swappable due to machined surfaces etc - presumably lifters, valves etc are though?

What is the suggested course of action with valve stem seals / other gaskets? I know it's possible to rebuild and use existing gaskets, but, for example, would it be an idea to do the valve stem seals at least? A full gasket set is around £80 - or £60 if I order from the States


Cheers

[lihp]

Why go through all the effort of building an engine to re-use the piston rings that seal your cylinders and control oil?

With that much effort it would be a silly thing to do, may aswell save for a bit longer and do it right.

[sickpup]

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[Rogerborg]

I have to ask... why are you spending time and money on preparing to swap out a working engine?

It's not broke, don't fix it. If it does break, fix the broken bits.

Is this purely for the lulz?
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[stinkwheel]

Leave the gearbox alone. If you're in there, check the hooks on the primary gearshift mechanism (that catch and pull the selector drum round) aren't rounded off.

I confidently predict you are going to spend more on this than a good, working second hand engine would cost.

Remember the IC igniter goes with the ignition system. No point fitting a second generation stator to a first generation bike without the right black box.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[lihp]

I can understand doing this if you plan to keep the bike.

Rebuilding my R6 engine will probably cost similar to a replacement engine and will definately take many hours longer.

But I'm planning on keeping the bike quite a while so I may aswell rebuild it and get good life out of it and check and replace the condition of anything that is worn.

However, to do it on a "budget" is a bit silly tbh, and a major waste of cash.

[devojunior]

your 63,000 mile cam chain could well be in far bette rthan a 8,000 mile chain how do you know that the engine wasnt run low on oil at some point it mmay have been ragged within a inch of its life.

seem slike alot of waste of time tbh what have you gained from all this.

[jjdugen]

Most of that engine is extremely durable. Replace the primary drive chain with a NEW one, inspect the pistons carefully as they do take a battering, I would replace them and rings if the bores are good.
Check second gear dogs for rounding, replace with new.
I rebuilt one of these with the usual wear bits for less than £80. Most of this was, admittedly, from a crashed low mile bikes engine.
Always a good idea to swap the early rotor for the later more robust item, as mentioned, you will need the later ECU.
Just keep you eye on the costs, the early GPZ's are not worth spending any real money on, as I found out when selling the one I rebuilt.
____________________
The CBR900RR has been sold. Aprilia Falco worms its way into my heart.
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[StormCrow]

OK folks, point(s) taken!

I will change the rings and gaskets then. Will also be checking the bores, I've been told that they WILL be out of round, although I'm dubious.

Yes, its partly for the lulz, but the engine in there at the moment isn't exactly perfect, its a high miler with an irregular top end rattle, and gearbox whine. I want to take the bike on medium length tours next year so I need it as reliable as possible.

I may be a bit of a glutton for punishment, but I'd rather build it up and learn from mistakes than not do it at all, buy another engine (of unknown condition) or whatever.

[lihp]

Engines are as reliable as the person is competent at building them.

Not to say, don't do it, but take your time, keep everything organised and spotlessly clean.

No shortcuts, lube what the manual says to lube with the lubricants it recommends, don't take a "my friend said this" advice either, following the MANUFACTURERS WORKSHOP manual unless you're experienced and know what you're doing

[StormCrow]

Well I've built plenty of car engines - bottom end, top ends etc - just not tackled a full bike engine (yet!).

Cheers guys

Pictures to follow when I get started.

[StormCrow]

[Robby]

So you have a working engine, showing an appropriate level of wear for its age.

Because you don't trust it, you're planning building another engine using a collection of second hand items, including the high wear items, from other bikes.

A second hand camchain. Really?

If you it vaguely right you'll be spending £50 on gaskets, o-rings and seals alone.

The rest of your bike will give up before the engine does. A bit of noise from an engine doesn't mean failure is imminent.

[tsmith]

My 2002 GPZ500 has done just under 65,000 miles. The only major thing that was done to it was a new camchain at 40,000 miles. I do regular oil/filter changes every 5,000 and a valve check every 10,000. The old girl just keeps on going. The engines do rattle a bit, but some ear plugs soon cure that.