Project The Dying FZ

They should be the same as 2KR pistons, which are taller in comparison to 3LN pistons, there is also a 2mm change in rod length between 2KR -> 3LN because of this change in compression height of the pistons.

A lot of this info is in the bucket motor thread

http://2fiftycc.com/index.php?threads/fzr150-bucket-race-motor.8949/

Sounds like you need to measure bores and ring end gaps and I don't think it's safe to assume that the ring end gaps will be correct if the bore diameters are identical between them.

See if AHL can give you the specs on 2KR ring sets to compare with 3LN ring sets that should clarify some things.

 

When I bought 1HX rings off AHL, the oil control rings and spring were too large for the 3LN piston. The top compression rings were fine.

Take a piston off and clean it up, the underside should have the model code cast into the piston. My original pistons and new chinese ones had the same webbing and "3LN" on the underside.

If in doubt, measure the piston you have and see if you can find new matching ones with rings on aliexpress. It's a cheap exercise.

 

that's the major issue it seems with the stuff from Aliexpress - I can't vouch for their quality but they also list parts for several models of machines which from research I know to be incompatible because of changes.

One the upside you will find FZR250 models engine parts differentiated by 1HX and 3LN codes in the descriptions, for some vendors who do realise the differences between models.

Hopefully the AHL rings are of comparable quality to OEM, because there has to be some possibility that they're producing OEM components for some company.

I'd be willing to venture that both the specs and tooling for many of these parts has been acquired by these new companies who've seen a market for parts where OEM replacements were just a huge exercise in exploitation $$ wise.

I seem to recall having read some years ago that ART pistons was the major OEM supplier of pistons to the big four in Japan, located in Taiwan for memory.
The underutilised tooling for low demand pistons may very well have migrated to Chinese mainland production facilities, it's just a shame that there isn't the faith in quality control at present to be able to trust their components.

Spending some time on Asian (Thailand, Malaysia, Singapore and Indonesia) bike parts sites you start to realise that the cost of parts here has nothing to do with the cost of production and everything to do with charging what any one given market will bear. The Asian bikes and their parts can't be complete rubbish because otherwise broken bikes would be lining the sides of the roads like shopping trollies do here in some suburbs. The big four all have production facilities throughout Asia to reduce costs I can't envisage them sacrificing their reputations for quality in such enormous markets.

 

art pistons in the 1960,s were prone to cracking.

 

On the subject; here's an interesting thread I bumped across recently regarding brake rotors, note this is an FJ1300 owners forum, those things are damned heavy, and even Busa owners are using them. Arashi wave rotors that is.

http://www.fjowners.com/index.php?topic=13290.0

Not defending metalgear, however their discs seem comparable in price to good used OEM parts from wreckers here, and wreckers always charge a good % of new OEM replacements, so we're basically seeing high OEM parts prices latched onto much cheaper Chinese produced products. Their business model is profitable given the buy and sell prices, actual retail margins for a lot of goods are actually quite low, I suspect their gross margins are very healthy indeed.

Not too long ago, Taiwanese goods were poorly thought of, nowadays Taiwanese goods are very high quality equivalents which occupy upper market segments previously occupied by Japanese produced goods, which have now become unaffordable.

The same transition is occurring in China, albeit at an accelerated rate with the entire world enthusiastic to take advantage of lower labour costs and therefore keen to export know how for short term profit increases.

Curiously even Lufthansa (Yes pedantic Germans) have aircraft serviced in China, saw one Chinese engineer interviewed and he moaned a little about his pedantic German supervisor who made sure everything was done absolutely perfectly.

I just wish it was easier to discern the good from the bad , its like homebrand vs name brand at the supermarket, some things are equivalent, some things are not.

BTW Mike Norman rebuilt the MC22 from his thread here with Chinese pistons which he mentioned on the 400greybike forum thread here - he says they were indistinguishable from OEM except for a few machining differences

 

Just an FYI - the 1HX is across the entire range from FZ250 -> FZR250 (2KR) -> FZR250R (3LN) and Zeal. The Zeal however lists a 2 elsewhere in the part number though I've yet to see one which has that stamping difference.

Seems AHL are helpful, I wish I could trust their valves because that is one component which if it breaks catastrophically, wreaks total havoc on a lot of other parts and can trash an entire motor

 

now if only we could get the chinese to make us some needles and emulsion tubes for cheap!!

 

OK so I just double checked, I didn't purchase the valves from AHL - so they may supply good quality valves as they don't list FZR250 valves on aliexpress in their store.

I did purchase a pair of 2KR valves to check quality, the stems measured up correctly as did the heads however the friction welding of the stem to the head hadn't been done concentrically and the face is uneven around the circumference.

Perhaps I will contact AHL about CBR400 NC23 valves for my 310cc overbore project, the others I ordered from another supplier never arrived unfortunately.

 

OK so the plot thickens - there's the store above AHL -> https://www.aliexpress.com/store/1292494 - they list FZR250 valves obviously

There's also an official AHL store -> https://ahlmotorparts.aliexpress.com/store/1315288 - no FZR250 Valves