valve clearances - xj650 (uk) differs from usa??

Hi all - just checking valves and the haynes manual - my `81 xj650 (uk) clearances are stated as 0.16-0.20mm for both intake and exhaust. This is the first time with shims for me, but I have never experienced the SAME clearances for intake and exhaust. It cant be a typo because it is mentioned in 3 separate sections. Any facts/theories?

 

It actually is a typo......if you look on the silver "tune-up data" sticker on the inside of the right side (I think) plastic frame panel, it will give the correct specs.

 

Chacal is correct. There are several errors in all of the service manuals, and that one is well documented. The errors will never be rectified, because there's no money in it.\
The DYI section has several threads that clear up the errors in the service manuals. Just look at the pinned articles for whatever system you are working on.

 

As per the Yamaha factory service manual, the intake and exhaust valve clearances are both the same at 0.16 ~ 0.20 mm.

 

See this thread for further details, UK 1980 XJ650 4K0 SHIMS | XJBikes - Yamaha XJ Motorcycle Forum

 

Why do you suppose the 1980 Euro/UK 650cc engine would be the only engine in the entire series that used larger intake valve clearances?

 

My UK XJ650 (4K0) was manufactured in June 1980, this was the first model run.
The genuine Yamaha service manual is the 1st edition, published in June 1980.
The information provided by a local Yamaha dealer was from two different service manuals, see page numbers.
My bike is now 43 years old and has covered over 62,000 miles without any valve clearance related problems.
From new, the intake valve clearances have been 0.16 ~ 0.20 mm and will remain the same.

 

thanks guys, 3 of my intakes were 0.15 so will match 4 to that - that is near enough for a tightwad yorkshire lad

 

Once again, I've spoken to a UK Yamaha dealer and they have confirmed that both the inlet and exhaust valve clearances for my model should be the same at 0.16 ~ 0.20 mm (0.006 ~ 0.008 in). The information they provided came from the same Yamaha service manual as I now have a copy of and as quoted in the Haynes manual for a UK model. If I took the bike to them for servicing, they would use the above valve clearances.

The Haynes manual covers models from 1980 to 1984.

Model, Frame number, Date
XJ650 (4KO), 4KO - 000101 on, 1980 to 1982
XJ650 (11N), 4KO - 055101 on, 1982 to 1984

I've seen a Yamaha supplementary service manual from 1983 with the different page numbering. Is it possible that for some reason (model year), Yamaha decided to change the inlet valve clearances. Could this be after the introduction of the YICS models.

 

The clearances were never changed. The error has existed since the first printing of the Yamaha manual (which was written by Haynes, and copied by Clymer).
This is a topic that has been cleared up on this site by a Yamaha factory Tech who worked on the bikes when they were brand-new, and confirmed by the data on the sidecovers of every model relevant to the error, my own machine included (the error exists in the Yamaha XJ750 service manual as well).
Is the data sheet missing from your sidecover?

And just why would Yamaha make the valve clearances different for just one nation on a machine that was sold worldwide?

https://www.xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/

 

.

 

The Yamaha manual says is was written by Yamaha Motor Company.

From new, my bike has never had a data sheet on the side cover. Does this mean that the error is not applicable to this model.

 

Found an example of the data sheet from another model.



My bike still has the battery vent pipe routing sticker on the RHS side cover but nothing on the LHS.

 

Why indeed - and why would they then specify an oil cooler for a model residing in potentially a cooler climate?
I confess I dunno?

 

This ^ tells me Yamaha decided there was nothing wrong with the manual. Suppliers are always updating technical data if needed, so why did they not, via uk suppliers, update the vc settings, if they were wrong?
My engineering head tells me the clearances should be different...

 

My theory is that they figured the US is more open-road riding than city riding, so the bean counters won and saved a few bucks on the oil coolers in the USA.

 

Hi David - any chance of a chat and a look at your bike? I am 4 miles from Whitby

 

The oil cooler thing was probably one of Yamaha USA's famous requests to cut costs and boost profits. There are a lot of Yamaha models of that era which had changes made to them just for the North American market (the crap version of the XV series starters being my least favorite)

 

Yep, Yamaha was in a financial pickle about this time ( see our " History of Yamaha" article at: https://www.xjbikes.com/forums/threads/tech-topic-the-history-of-yamaha.14576 ) and was right at the start of the infamous price wars between all the motorcycle manufacturers (that eventually led to the infamous tariff restrictions on bikes over 700cc's in the mid-80's a/k/a the Harley-Davidson Protection Act).....so a lot of things were dropped. XJ750 Seca models no longer had the oil cooler also. XJ900's were dropped from the North American continent. And probably lots of other things, too. A dark era.....but Yamaha did continue to soldier on.

 

Yes, I've started a "Conversation" with you.

 

Have emailed another UK Yamaha dealer and got this reply.

"We agree that the Yamaha service manual gives 0.16 ~ 0.20 mm (0.006 ~ 0.008 in) for both inlet and exhaust."

"Neither ourselves or Yamaha UK can give any guidance on why this is different in other manuals."

The point being, it is not different for a UK motorcycle in the Haynes manual.

 

Have had this email reply from Haynes too.

"We believe the views on the forum are correct. The original Yamaha service manual specified 0.16 to 0.20 mm for inlet and exhaust, although in later publications the inlet clearance was given as 0.11 to 0.15 mm. This figure is in line with the inlet clearances on other models such as the XJ600 and XJ900 fours. Please accept our apologies for any confusion caused. Details are on file for the clearances in the Haynes manual to be corrected when it is reprinted. Note that Yamaha service manuals are produced by the Yamaha factory."

Whilst Yamaha UK and Haynes cannot agree, I'm going to continue with having both the inlet and exhaust valve clearances the same. It's served me and the bike just fine for over 62,000 miles. If I took my bike to a UK Yamaha dealer, they would use the same valve clearances for inlet and exhaust.

I'm sure I'll get shot down but haven't been shy in sharing the information.

 

It's not enough different to make the bike not run. It is enough different to make the engine not produce as much peak power. Maybe that was the goal for Yamaha UK given the license categories. Maybe it had to do with different emissions requirements (before anyone second-guesses, the USA had emissions requirements for motorcycles at the time (see the plugs on the headers for sniffers), and was the dominant market for motorcycles over 400cc at the time. there's a profit incentive to making as few variations as possible in a product. I'm just guessing as to the motivation of the various Yamaha divisions at the time).

 

The Yamaha '82 XJ650 Supplementary Service Manual covers 11N UK models 1982 to 1984. Was this when the YICS models were introduced.

The first Yamaha '80 XJ650 Service Manual covers 4KO UK models 1980 to 1982.