XJ 900R (aka: XJ 900 SECA): Engine Rebuild/Replacement

I live in Tasmania, Australia and am on the hunt for parts to perform a full engine rebuild on my 1983 Yamaha XJ 900R (aka: XJ 900 SECA).

Currently my XJ is in a professional garage awaiting a full engine rebuild, but they have apparently been unable to source the appropriate parts. I find this pretty surprising as did my father (who used to ride one back in the day) as they were very popular and prolific during their time. Among other things, they can't even find over-sized pistons (the engine block will need to be rebored) and a new head gasket.

I was wondering if anyone out there knew of a supplier, person, specialist, etc. that could help me keep this beautiful beast going.

ALTERNATIVELY, if the appropriate parts for a rebuild cannot be sourced then I'd be interested in contacting anyone who has a secondhand motor that has done less than the (very) high amount of kms that my bike has done.

Hoping someone can point me in the right direction!

 

Upper right corner of this page click on xj4ever he should have about everything you need to order from him start an IM message with him he will give you a code to order he service is fantastic. Shipping down under may be high but trust me his parts are correct and if your new to this site welcome aboard you will find a lot of helpful advise on this site.

 

Thanks for the suggestion Jetfixer. I've actually contacted Len at xj4ever as well. He has been very helpful and stated that all necessary parts are available EXCEPT replacement pistons which he hasn't had in stock for the 1983 XJ 900 for five years. The problem being that the original 1983 model was a 853cc engine. This was changed very soon by the end of 1984 and thus parts for the original model have resulted in a lack of pistons available in the long run.

So I guess my next stage is a shout out to anyone who may randomly have the appropriate pistons (original or second hand) that would be of usable quality.

 

You might locate them in the UK motorcycle mechanics magazine has numerous vendors advertising in there . eBay in Germany might also be a source. Not sure about Australia if you have any cycle salvage you might be able to source some used pistons .

 

I just checked eBay UK looked like several xj900 used engine for sale sorry I still don't know how much pounds to dollars to Aus dollars translates to but if you could buy a used engine you might have usable pistons. Or a rebuildable engine just a few thoughts sure you've considered the same thing

 

Thanks for looking the great suggestions mate. Getting a second hand engine is definitely my plan B. The difference in cost is generally 2 dollars to every pound. I'll have a good squiz on the ebay UK and Germany depending on how things go on this end. Thanks again!

 

Matti made me aware of these kits in a previous thread:
https://www.speedmotoco.com/product-p/bbk015.htm
https://www.japbikespares.com/yamaha-xj750-81-84-820cc-forseti-big-bore-kit-65mm-piston-rings-gasket

Although specified for the 750 I see no reason why they won't work with your 853.
OEM bore = 67mm
these are 68 mm so you would need to bore the cylinders a mm and also check the resultant compression ratio. This will give you 878 cc's.
I think the head gasket shown is for a non-YICS so that won't work. Still the price is pretty good.

 

I think the pin height is different on the 750 vs. 900 pistons, and may mess with the compression ratio in an unacceptable manner......

 

I wonder if they made the pin height lower so the piston skirts clear the larger crank throw? I just assumed the rods were longer. Hmm, I wish I had time to get back to my project bike. I've got a 900 lump waiting to be dissected.

 

Pin height lower to make up for the shorter stroke surely? Put those in and youre likely to smack the head?
Hmmm, block spacer and longer timing chain perhaps?

 

Stroke is the same on 853cc and 891cc versions. Difference in bore 67.0 vs. 68.5mm.

 

Hi everyone, thanks for the brainstorming. I got a reply from Weemoto stating the following:

"I have seen somwhere that the TW 200 pistons are the same - but who know for sure?"

Can anyone confirm whether that would be accurate and compatible?

 

Are the pin sizes the same? If so you may well get away with it. Maybe get a dural plate made to raise the jugs a few mm?