Clutch won't fully engage when hot

[Grant1Shepherd]

Hi guys

Some of you may or may not know that I am an admin for the UK Motorcycle Theft Protest  (UKMTP) and that this weekend we had our awareness ride in central London. I was leading a group of 80-100 bikers from Greenwich Park to Westminster Square. The ride was slow (10-20 mph) at all times (1st gear) lots of revving and horn beeping with lots of attention and eyes being given by the public.

However sadly as I was getting so close to Westminster my bike was incredibly hot, it was a hot busy Saturday in central London with no filtering and it got to a point that I could not shift the bike into natural, and then later on even with the clutch level fully pulled in and engaged, i still had to hold the brake lever otherwise the bike would start moving forward.

As soon as i turned my engine off though straight away it could go back into natural, and after the whole bike had a chance to cool down and i was on the way home (normal riding) the clutch and gearbox were fine with no problems.

It was annoying as i replaced the whole clutch less than 1000 miles ago so I can't seem to work out why it goes all messed up when its hot.

Hope you guys can help.
Thanks in advance.

[Graham53]

did your engine fan cut in when it started to warm up ? The oil is cooled at the oil cooler from engine coolant via the rad so the oil may have been getting too hot, further to that what's the level of your coolant and when was it last changed old coolant is less efficient , additionally how old is the oil? What's the oil level? Is it  low , spot on or high ? And is it of the correct grade, being a wet clutch I would say it's down to oil overheating somehow remember oil doesn't just lubricate it cools the engine as well and the older it is the less efficiently it does both,  I could be wrong but as you say it's fine when it cools down somethings causing the overheating.
BTW What's the UK motorcycle theft protest ???

[darrsi]

What is the "exact" brand and type of oil you are using?

[joebloggs]

If under normal circumstances its ok I'd leave it alone. No point throwing money at it trying to sort an issue unlikely to occur on a daily basis

[Fazerider]

Since Yamaha chose this bonkers method of using a long rod pushing through the entire engine to  disengage the clutch it is bound to happen. The body of the engine is aluminium which has a large thermal expansion compared to the steel of the pushrod, so effectively the rod becomes shorter.
You should be able to arrange the bottom adjuster on the clutch to give you enough range on the one at the handlebar to compensate while riding. Did you try it?


The cooling system concentrates on the cylinder head, if you’re crawling along slipping the clutch for long periods the bottom end will get much hotter than usual. It is very dependent on a decent flow of air to keep the bottom cool, if all it gets is what convects off a blazing hot exhaust collector it’s going to suffer.


That said, it’s worth checking the cooling system. if the fluid level has dropped, a hot engine won’t turn on the fan because the sensor is high and dry on the thermostat housing.

[unfazed]

  If the red light in the Tacho did not come on than check the coolant level to be safe, bike was not designed to work the way you were using.

[daviee]

it will be the clutch plates over heating and expanding they should go back to normal once they have cooled nothing to worry about

[Grant1Shepherd]

Hi guys


Just to answer a few of the points raised in comments:


1. oil and filter were changed the same time as the clutch (less than 1000 miles ago)
2. How do I check the coolant levels and if low what coolant would you all recommend I use?
3. Yes everything starting performing back to normal once the bike had cooled down

[Grant1Shepherd]

did your engine fan cut in when it started to warm up ? The oil is cooled at the oil cooler from engine coolant via the rad so the oil may have been getting too hot, further to that what's the level of your coolant and when was it last changed old coolant is less efficient , additionally how old is the oil? What's the oil level? Is it  low , spot on or high ? And is it of the correct grade, being a wet clutch I would say it's down to oil overheating somehow remember oil doesn't just lubricate it cools the engine as well and the older it is the less efficiently it does both,  I could be wrong but as you say it's fine when it cools down somethings causing the overheating.
BTW What's the UK motorcycle theft protest ???

Hi again Graham


We (UKMTP) are a motorcycle theft awareness group looking to reduce motorcycle theft in the UK. We are passionately pushing for changes in laws such as stricter sentences for major motorcycle thieves and gang members, we are fully behind police forces to be given more rights and protection to chase and knock off stolen bikes without fear of being prosecuted themselves for potentially injuring these thieves on stolen bikes. We also look to put pressure on councils and businesses for more attention and security put into motorcycle parking in order to make motorcycles harder to steal.


Please feel free to check us out and join us on Facebook, we have nearly 7000 members:
https://www.facebook.com/groups/ukmtp/?ref=br_tf


and Twitter:
https://twitter.com/UkTheft
   

[darrsi]

Check the white expansion tank for coolant levels, you're best off putting bike on centre stand and looking at it under the right side of seat.


If it's low, or empty, i would seriously consider doing a Radflush treatment, as you may have a clogged up system.
When it's all good the levels should remain the same when the bike cools down, and if the bike gets warm it should trigger the fan.
I would check that sooner rather than later.

[tommyardin]

One thing that might be worth doing is to draw the clutch push rod out of its location, just in front of the sprocket (After removing the sprocket cover) and wipe it over with some grease before pushing back, also make sure the clutch mechanism return spring is still in place as the are quite a fine wire gauge spring and can snap where the hook onto the mechanism.
Also make sure the ball bearing is in place in the clutch mechanism.