[arc]

On my third Gen4 (the previous two lasted ~100,000 km before being taken out in accidents) and after 206,000+ km (128,000 miles) yep, one of the outlet valves snapped on #1 cylinder, snapped the spring retainer, bent another exhaust valve, bent an intake valve then embedded itself in the top of the piston, smashing into, splaying, and destroying the spark plug. Several parts of the failed valve went through into the headers (made a lovely rattling sound when I removed them!)

After much work, the engine is out of the bike and the crankcase split. I don't have the gear needed to check the trueness of the crank and the head will need machining (valve seats). So, what are my options?

1. Sell the bike for scrap
2. Part out the bike (easy to do as it's already in many parts!)
3. Replace with a second-hand engine - none so far found in Australia (or the world)
4. Get the crank checked for trueness
5. Replace crank bearings + big end bearings
6. Replace 4 cylinders (?) + rings + replace 8 con rod bolts (designed to stretch)
7. Get the head machined and
   1. Replace 16 valves
   2. Replace 16 valve guides
   3. Replace 16 sets of collets
   4. Replace 16 valve springs
   5. Replace 16 valve spring retainers
   6. Helicoil the spark plug thread
8. Replace the entire head with a second-hand unit
9. Sob quietly to myself

Who has rebuilt a motor like this, what tips, tricks, traps, and advice can you give? I'm happy to invest the time myself (it's kind of Zen working on a motor like this). Is there anything else I should look at, are there other options? I can get parts at wholesale prices (a rough estimate for the retail parts above is ~US$4,000). The #1 cylinder wall looks A-OK, still showing signs of honing. Cams and upper head are in an almost pristine condition with no visible signs of aging, scoring etc. Bike has been going through a very small amount of oil between regular 6k services (but I've been playing with first gear a lot: very high revs).

Rest of the bike is in mint condition - gearbox replaced ~15,000 km ago, clutch replaced ~20,000 km ago, new radiator, new gas tank, new fuel pump, new stator, new head stem and wheel bearings, panels in pristine condition. I also have three sets of stock exhausts with two cats, three sets of OEM levers, two sets of OEM pegs, a spare front and rear with new bearings.

Sure, I've been looking at a brand new '21/'22 ZX-10R too. The MY22 model is awaiting homologation - should be available in late January.

Thanks for your advice,
Arc.

 

[badassjake]

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[michael4012]

FFS mate, that's sad to see. We can get incredible mileage out of these but at the end of the day its a motor built for racing and there are compromises with that. Certainly not the first iv seen like that and not the first iv re-built. Considering the mileage of the bike i would be looking at getting repaired correctly but as cheap as possible and then trade her in for your MY22. The cylinder heads alone are becoming more common as the G4 ages and reaches the breakers so i am +1 with badassjake on buying a guaranteed low mileage head preferably complete with cams, yours have done incredible mileage. There is a good chance that the conrod is now out of round and possibly deformed small end! So i would be looking at getting a set of 4 second hand pistons and rods with guarantees, you can use G4 11-15 and G5 upto and including 19. If the price is comparable buy 2016+ as the pistons are a tatge better! But whatever set you buy in spend the cash on 4x ring set. The cylinders can be cleaned well with hot soapy water and scotch brite. The danger is the crank on the G4, with the higher mileage they are known to spin bearings. For the cost of sending it out for inspection you could buy yourself a dial gauge and 2 V blocks, a decent micrometer (not vernier) will be needed to check the journals. If your lucky just replacing the main bearings will do. If its FUBAR then you will be hard pushed to find a good replacement so repair will probably be the cheapest option. You have an immense clean up on your hands now, little bits of that shite are everywhere so meticulous cleaning of all parts is essential as is a new oil pump and strainer!! Even if your going to trade this in, be meticulous and replace the rod bolts and nuts, all the crank main and big end bearings, with a good second hand head and good rods and pistons with new piston ring sets you will notice a stronger sweater running motor but above all you will sleep at night knowing whoever takes it on is safe.

 

[RBZ10R]

honestly I'd just sell the parts (said with self interest) and get a 21/22, there have actually been a lot of changes from 2011 till 2021 they are subtle but there are many, as someone that has studied the parts diagrams extensively they are fairly different from 2021 onwards. Also importing an engine would be crazy pricing atm due to supply chain demands.

The time spent and cost prob wouldnt be worth it unless thats an area of interest... building engines i mean.

If you do part let me know about wire harness and ecu + keys

 

[Czano]

Jesus christ if my math is right you have about 400.000km worth of gen 4 riding. You sure do love that bike
I think you can save a few bucks fixing the engine yourself but if you want the easy way out you can get this engine with 17k km.

https://allegro.pl/oferta/kawasaki-zx-10r-11-15-silnik-gwarancja-rozruchowa-11295624337

It's from a Polish ebay-like site. I live in italy and have bought many times from this site and from this seller in particular. The site also has a buyer protection system if you pay with mastercard/visa. Had trouble with an akra pipe that was damaged during shipping last year so I appealed to the site and got all my money back and got to keep the akra pipe which I then fixed by replacing the carbon cap for 70€ lol.
12k PLN is roughly 2900 USD. Suppose it would cost you several hundreds extra to ship it to AUS. I'm half polish so I could help you contact the seller to organize the shipping.

 

[arc]

Thanks everyone for your suggestions. I will get pricing for checking the crank later this month when folks return to work in Australia. So tempting to rebuild the engine myself. A replacement head though will be a big $ saver. I'm surprised how pristine my buckets and cam are vs zooming in on photos I've seen on eBay of heavily scuffed buckets.

 

[arc]

...Even if your going to trade this in, be meticulous and replace the rod bolts and nuts, all the crank main and big end bearings, with a good second hand head and good rods and pistons with new piston ring sets...

Many thanks for your reply. I'm torn between repairing and parting her out and have until the 17 of Jan until head/engine specialists reopen. Even as a repaired engine I think I'll get next to nothing for her with such high mileage, I have Ohlins carts and their mechatronic rear too. If the crank is true I'm inclined to repair and defo replace the con rod bolts, all bearings and oil seals. If it's not true then I guess parting her out is more of an option.

Structurally the #1 rod is potentially suspect so I'd also replace that and defo replace all rings and #1 piston, but do you think I should also replace the other three pistons and rods while she's open?

I've been meticulous with oil & filter changes every 6k KMs with Motul 7100 and only did an oil change the night before the valve failed, there's no visible wear on the cams/buckets. Replace the cam chain while she's open too?

I read that the metal head gaskets should they be replaced as they're designed to crush through tightening and shouldn't be reused (and wow are they expensive!)..

The more I think about it the more parting her out seems to make the best financial sense :/

 

[RBZ10R]

You'd prob want to do all 4 pistons and rings rods etc, otherwise you have 1 brand new that isn't worn VS 3 others that are. Kind of like changing only the rear sprocket and using the front and chain from original yes you can do it but your mileage may vary as they make a complete system. The clearances should be quite different between the old and new especially given the 100k km unless you just coasting everywhere like less than 8k rpm.

 

[scout]

yes, g4's run solid right up to the valve failure; indeed, right before failure bike hits peak experience as in totally jumping to command. So, where am I going here? '11 10r valve failure (not confirmed, but still have the bike, but I'll get to why that was a valve) at 50k miles. NOT under warranty. I NEVER needed an extended until this bike; Thought it a fluke, so bought the '13 10r. 70k, valve blow out and same racket as the '11 problem. Dealer fixes, under extended, then valve blows out AGIAN, just past 80k miles or a bit more. if I recall. Under warranty. So, this time dealer did what you're thinking, just rebuild everything that Kawa wants to rebuild. When I got the bike back, service manager said 'this is basically a new bike.' Bike now has close to 110,000 miles; would be far far far more but wife took ill so can't ride until she can get around the house on her own. Bike's been sitting since May, 2020; I just warm it up every couple days.

So, yes, if you have the tech skills, buy the parts from Kawa. They don't sell complete engines but simply have their techs replace any worn parts. I respect all tech people!

 

[arc]

Update 2023-01-29, engine still in pieces, bike and all parts under dust sheets. Somehow I didn't get around to rebuilding the engine, I blame my new G6 from eating up all my spare time

 

[Czano]

Glad to see you found out a way to get back on the road. How does the gen 6 compare to the gen 4?

 

[arc]

Glad to see you found out a way to get back on the road. How does the gen 6 compare to the gen 4?

Night and day. Noticeably more power, much shorter gearbox (took time to get used to, but I like it now), more savage acceleration, 1/4 turn throttle requires a lot of finesse (or it is twitchy), QS is fabulous, hated the Kawi engine braking control (left disabled), headlights (seriously) are simply amazing, mirrors still too close in (I get a view of my arms, not right behind me). Stock pipe, no tune, flat spot until around plus 5k rpm (until EXUP valve opens/Euro5?). 45,000 road km ridden (yes, in a year, maybe 100 km commuting in total). Suspension fantastic but stiff off the showroom floor, am tuning this now using stock parts.OEM heated grips aren't anywhere near hot enough for an Australian winter (it does get really cold here!) - Oxfords much, much warmer. Takes the same rear rim as the G4 but not the front :/, reused G4 LSL frame sliders , cruise control has saved me from infractions, running engine temp much higher than the G4 at +5 to +10c (both with Motul Inugel expert ultra at 50% + radguard and flywire). Dash display great. More torque down low/more balanced than G4 which wasn't savage until high in the rpms.

Love my G6 steed

 

[Czano]

Nice, you're making me want one, only thing is I can't afford it without financing at least 30 % of it 😪 and you can't get a black one here in italy (not a fan of the white belly pan on the green version).
I'm in the market for a more recent liter bike coming from a gen 1 and so far my most realistic options are a 2016-2017 gen5 zx10r or a 2017 gsxr1000r. I also really like the sound of the r1 but I would only want a 2019+ because of the tranny recall they have on prev models.
I would fancy a brand new bike for the experience of being the first owner and taking proper care of it.

 

[arc]

Agreed, the black is a better colour option IMHO. Test ride one if you can and once it heats up in the northern hemisphere...also we don't need two kidneys

 

[Czano]

One thing I hate about all the online reviews I've read/watched is they don't give relatable numbers. For instance my gen 1 with +1 on the rear, full system+tune made no power below 4k rpm, had a noticeable sudden hit of good usable power at 4k and a second strong hit at 7k. How was the power band on your gen 4 and how is it on your gen 6? Did you also have the chance to try a gen 5?

I can get a gen 5 2016 with about 8k miles for 12k € and there are no used gen 6 on the market and a new one goes for about 21k €. If they have a similar power band I'd get the gen 5 and live without having the TFT dash and cruise control.

 

[arc]

...For instance my gen 1 with +1 on the rear, full system+tune made no power below 4k rpm, had a noticeable sudden hit of good usable power at 4k and a second strong hit at 7k. How was the power band on your gen 4 and how is it on your gen 6? Did you also have the chance to try a gen 5?...I'd get the gen 5 and live without having the TFT dash and cruise control.

My three G4s with ~400,000 kms ridden and several track days didn't become rabid until very high in the revs, then it was brutal and fantastic. The G6 is totally and completely different, lots and lots more peak power down low in the rpms. I do love the dash and the CC is a godsend for commute stretches to the "fun" roads.

 

[Czano]

Were they stock? You said the gen 6 starts making power at 5k rpm: at what rpm does a gen 4 start making power?

 

[arc]

Were they stock? You said the gen 6 starts making power at 5k rpm: at what rpm does a gen 4 start making power?

1st was stock save acra slip on, 2nd had a map, PCV and akra w link pipe, 3rd was datalogged and fully self-tuned with WRT and 100+ flashes (seriously) + akra and link pipe. Various iterations of bung in/out. On my G6 I had an EXUP error twice which disabled the servo, then there was no noticeable gap in power delivery, the EXUP errors cleared and I again feel a surge of power coming on from 4-5-5k upwards. It's well over a year since the last G4 but from memory at 10K plus I really felt it coming on. Flashed was completely different. Still rabid at the top end but far more linear and much smoother - set to 13.2 to 13.8 across the range in all gears with a +/- variance of 3%, that took a very long time to perfect but it was also the first bike I'd self-tuned. I wrote several articles published on my personal, non ad sponsored website from april 2017 about how I went about it, see

• So you want your bike tuned?
• Autotune for dummies – what makes good data?
• Autotune for dummies
• Autotune settings

Arc.

 

[Porschenut]

Interesting reading Arc! Most of it was waaaaay over my head but interesting nonetheless. I think I need an article called Autotune for dummies that are considered dummies by other dummies.

 

[Czano]

1st was stock save acra slip on, 2nd had a map, PCV and akra w link pipe, 3rd was datalogged and fully self-tuned with WRT and 100+ flashes (seriously) + akra and link pipe. Various iterations of bung in/out. On my G6 I had an EXUP error twice which disabled the servo, then there was no noticeable gap in power delivery, the EXUP errors cleared and I again feel a surge of power coming on from 4-5-5k upwards. It's well over a year since the last G4 but from memory at 10K plus I really felt it coming on. Flashed was completely different. Still rabid at the top end but far more linear and much smoother - set to 13.2 to 13.8 across the range in all gears with a +/- variance of 3%, that took a very long time to perfect but it was also the first bike I'd self-tuned. I wrote several articles published on my personal, non ad sponsored website from april 2017 about how I went about it, see

• So you want your bike tuned?
• Autotune for dummies – what makes good data?
• Autotune for dummies
• Autotune settings

Arc.

Thanks, I'll check it out.