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YB 8 not running
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YBista



Joined: 23 Jul 2019
Posts: 8
Location: UK

PostPosted: Wed Sep 11, 2019 6:03 pm    Post subject: Reply with quote

Sounds like you are making great progress!
In answer to your 2 questions :
Q1.the exup valve is located in the exhaust under rear of the engine.The valve is positioned on the left hand side ,with 2 cables running to it.There should be a chrome dust cover ,but these are often missing .If you can't see it obviously then you may have an aftermarket exhaust system, which will have eliminated the exup valve .If you still have the original Yamaha exhaust with the exup valve then you should definitely maintain it whilst the fairing is removed.These valves have a tendency to seize if they are not looked after,which will either ruin the mid range or the top end power ,depending upon the position that it stuck in.Maintainance merely involves removing, cleaning, lubing,reinstalling and re-calibrating .
The challenges are :seized fixing bolts ,seized valves (refusing to come out...),bent exup shaft, loosing the inner bush in the exhaust and knackered bushes.The design,removal and reassembly are very straightforward if the valve has been previously/recently serviced (I'd recommend annually or every 5k miles ,whichever comes 1st).The most important advise I can give is :use lots of penetrating fluid (plusgas formula A),be patient,don't snap any of the fixing bolts ,and if you have concerns that you are about to (or have already ...)snap a bolt then remove the exhaust and take it a local engineering shop .If the previous owner was decent then this is a 30 min job ,all in .However if they failed to show the necessary respect then you may face a challenge ....
As regards the actual task, take a look at the Haynes manual (code 2056).I know people slag off these manuals but I think they will provide you with excellent info for 90% of the tasks on your YB8. Just try to get a late edition that covers the later years as well, because you may wish to utilise some of the RU mods on your YB8 at a later date , so the extra info is useful.
The final tip is :don't lube the valve with copper grease, which is an anti seize grease and is therefore abrasive.....I use grease purely to hold everything in position when reassembling, but the valve generally runs dry, even if you use super high temp grease (such as ceramic etc).The location of the valve is just HOSTILE , so regular disassembly, removal of carbon build up and lightly polishing the moving surfaces is fhe bedt way to avoid problems IMHO.

Hopefully I have not scared you too much,but the motor will not RUN well unless the EXUP valve is working as Yamaha intended . It was , and still is ,a fantastic design. As soon as the 10 year patent expired the majority of other manufacturers (including sportscar makers)jumped on the band wagon, and a lot of big bikes still have them fitted today although, in truth, this has a lot to do with the secondary benefit of the valve which is noise reduction.
Q2.The easier one ..The Tourmax code is 229823. I am useless st links but take a look on eBay UK , item 303129854130 for the bargain price of 23.36.Just Google "Tourmax 229823" and I'm sure you'll find a convenient supplier . Note the price quoted is for all 4 rubbers . Don't even think about how much these are from Yamaha.

Finally, I thought it would also be helpful if I provided a list of other "fairing off "jobs that you might like to add to the list ...if you have time ...:in addition to the oil/filter change and exup service:
1. Change clutch fluid .
2. Check exhaust manifold nuts for tightness .
3. Fit Morgan carbtune inlet take off and carb balancing extension tubes (particularly as you already have the carbs off!).
4.change engine coolant.
Hope this helps.
GOOD LUCK!
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YBista



Joined: 23 Jul 2019
Posts: 8
Location: UK

PostPosted: Thu Sep 12, 2019 6:26 am    Post subject: Reply with quote

Just to avoid any confusion about the grease etc: I am saying don't use copper grease to lube the exup valve etc, but you MUST use it on all the fitting bolts to aid future removal.
Hope this makes some kind of sense ...
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Andrew034



Joined: 02 Apr 2017
Posts: 29
Location: Sydney

PostPosted: Thu Sep 12, 2019 7:33 am    Post subject: Reply with quote

When I bought my bike the EXUP was seized and in spite of soaking the cover bolts in penetrating oil overnight 2 of the 3 of the retaining bolts still sheared when I tried to undo them (the whole system was so dry, I suspect the EXUP had never been apart)

The original bolts were relatively soft so I managed to drill out most of the bolt material and then clean the threads with a hand tap.

The EXUP appeared to have seized due to carbon build up on the inner pinion. A quick clean with a wire brush and some high temperature grease had everything working again.

Once it was back together, I then adjusted the cables.

I can PM you an excellent guide from a Yamaha website if you want.

On the newer Yamaha motors, the EXUP servo goes through a cycle before starting the engine, unfortunately ours don't. Therefore, I just occasionally check to see if the EXUP valve moves when I rev the engine.

Don't forget the spark plugs too (access is very tight and I had to remove the ignition coils to get at 2 of the spark plugs however the job is possible).

Andrew...
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tenchu2x



Joined: 09 Sep 2015
Posts: 106

PostPosted: Sat Nov 02, 2019 12:46 pm    Post subject: Reply with quote

Some news here, I cleaned the carbs and put all back together

I had a hard time starting it having to idle a lot at first but now it starts easy and runs.

But : on 3 cylinders only. The most left cylinder in driving view is not running. I checked the pipes and the most left is cold.

Any easy tips to check before I get it to the workshop at last ?

Cheers Robert
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tenchu2x



Joined: 09 Sep 2015
Posts: 106

PostPosted: Sat Nov 02, 2019 12:46 pm    Post subject: Reply with quote

Some news here, I cleaned the carbs and put all back together

I had a hard time starting it having to idle a lot at first but now it starts easy and runs.

But : on 3 cylinders only. The most left cylinder in driving view is not running. I checked the pipes and the most left is cold.

Any easy tips to check before I get it to the workshop at last ?

Cheers Robert
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tenchu2x



Joined: 09 Sep 2015
Posts: 106

PostPosted: Mon Nov 25, 2019 12:44 pm    Post subject: Reply with quote

ok guys, its running again, i took it to Armin and he put the carbs right , changed the plugs and also some oterh stuff.
now i hope it will keep running.

although i did not mamange to do it myself i learnde a lot about the bike.

Thx guys and cheers Robert
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