Clutch Problem?

[Mattster]

I have a 2020 C650 GT that I bought last month with 347 miles on it, so pretty much a new bike without a warranty. Most mornings when I set out for the first time in a day the bike thumps and jumps instead of just smoothly engaging the drive train. After about the first five minutes and for the rest of the day it is fine and smooth as expected. Until the next morning. I've gotten some limited relief from this by holding the brakes and running up the RPMs briefly before riding away for the first time in a day. So this appears to be an issue with the clutch, feels like it is grabbing and releasing. Has anyone else seen this behavior? How big of a deal is it to open up the cover and inspect the clutch?
Thanks.

 

[Pappy13]

It's not a big deal, but there are special tools required, at less than a thousand miles, it may just be surface glazing on the clutch materials or on the engagement surface. Holding the brake and turning up the throttle allows the clutch to slip over the surface and helps to engage once it's all warmed up. If it doesn't correct itself doing that for a few mornings then do a forum search and see what is needed to do a drive belt replacement for a list of the tools you'll need, pull the clutch and using fine sand paper de-glaze the clutch surfaces and the engagement drum, there could be areas between the clutch faces that slightly corroded while the scoot wasn't being ridden, holding the brake and getting the clutch to slip is a good way to use the clutch to re-surface the drum if it's just a matter of de-glazing. Then, if you do decide to tear it all down, a good mod is Dr Pulley sliders. From 2016 on the scooters were improved and work better than the original runs of scooters, but there is still and improvement in takeoff and mid-range to be had form the Dr Pulley, again, an archive search will answer most questions about that.

 

[Delray]

Had exactly the same situation with my 2019. Bought it this year with 1,192 miles. It basically sat in the seller's garage for five years.

I'm not sure what "thumps and jumps" is; I'd describe my issue as a lag when I turned the throttle. It was so pronounced that for the first several minutes of riding, I was careful to stay away from situations where I might need to hit the throttle suddenly -- I knew instant response probably wouldn't be there.

My solution was to let the bike warm up for a minute along with the same brake/throttle manuever. With regular riding, the problem has now disappeared entirely at 2,150 miles (around 1,000 since I bought the bike).

 

[Mattster]

It's not a big deal, but there ... questions about that.

Thanks for the insights Pappy13, when I asked the same question on a very large (mostly international) Fecebook group everyone who replied said, "Nah, not a problem because mine does that too." Hardly a rational answer when a bike is not working correctly. My hypothesis matches yours that it could be glazing on the clutch pads or contact surface, that's kinda what it feels like when it grabs and releases. Normally I would just jump right in and open it up and take a look for myself but I'm hesitating because the shop manual DVD is no longer available for study. I did find a dealer website in California that hosts all of the exploded diagrams for parts orders so that seems to be the best available resource.

You mentioned Dr. Pulley, I've seen them mentioned a lot in the forums and FB groups so yesterday I looked at their website and I have to confess that I don't quite understand what the rollers do and how to know what size I should want. Seems to me that changing the roller size might be like using a holeshot torque convertor in a race car?

 

[Mattster]

Had exactly the same situation with my 2019. Bought it this year with 1,192 miles. It basically sat in the seller's garage for five years.

I'm not sure what "thumps and jumps" is; I'd describe my issue as a lag when I turned the throttle. It was so pronounced that for the first several minutes of riding, I was careful to stay away from situations where I might need to hit the throttle suddenly -- I knew instant response probably wouldn't be there.

My solution was to let the bike warm up for a minute along with the same brake/throttle manuever. With regular riding, the problem has now disappeared entirely at 2,150 miles (around 1,000 since I bought the bike).

Thanks Mike, I re-read your post on clutch and belt servicing yesterday and am about to order the toolset from Easyboost. The symptom that I describe as "thumps and jumps" seems like a clutch suddenly grabbing and then suddenly releasing - the front fork goes up and down by inches with each one of them. Hardly a normal scooter behavior. The other thought that I had was that maybe the belt got a hard bend in it from sitting in a garage in Miami for four years. So I will also be ordering a belt from Carpimoto for when I go in to look at it.

Question for you about the rollers are they a part of the clutch or part of the variator? And how would I know what size I wanted if I replaced the rollers? I'm guessing from you rphotos that they are in the variator. I guess it's time for me to go look at those exploded parts diagrams online so I can get a working model in my head.

Thanks

 

[Ceesie76]

Let me suggest you do the 'manual deglazing' hack more forcefully/longer/stronger.
I noticed the same on my 2016 Sport but only since I started riding long (120 mile plus) fast highway stretches. Next mornings, the clutch would do what you describe: thumps and jumps/catching/slipping. I applied the advice I had read here: applying throttle while staying on the brake. It did work/help but not entirely. So I decided to just overcome my concern about breaking something, or wearing out the clutch prematurely, and I just did the hack a lot longer/harder. Lo and behold, the clutch went back to its normal, smooth self that I had experienced for the years I only rode the bike around LA on surface streets.
Then, very recently, I took the whole drivtrain apart using the Easyboost toolkit and in the process inspected the clutch, weary of seeing a lot of wear. It looked brand new, lots of meat on the shoes, to my relief.
So, I would try this first before taking it all apart or looking into aftermarket non-original parts.
I also have a Honda S300-i scooter that I installed a Dr Pulley clutch in. After some time I decided to swap the orignal Honda clutch back in. That's not to say Dr Pulley clutches aren't good or anything, but on that particular bike I found I prefer original. My 650 Sport rides perfectly smooth as far as clutch, drivebelt, transmission etc is concerned, all with stock BMW parts, I don't see any need to try and improve on that set-up.
I hope this will also be your experience and solution to this I agree very annoying issue.
I think Delray's problem was really different, sounds a lot more like dirty injectors or similar, not like the glazed clutch problem. Mine takes a few seconds before I can take off with a lot of throttle, also, in the mornings.

 

[Delray]

I think Delray's problem was really different, sounds a lot more like dirty injectors or similar

I think you are right (per usual ;o). Forgot to mention when I had my lag issue I used Seafoam for three consecutive tankfuls of gas. Haven't had the problem since.

Question for you about the rollers are they a part of the clutch or part of the variator? And how would I know what size I wanted if I replaced the rollers?

Variator. OEM rollers are 43-gram each for 2019 and '20. I installed 38-gram Dr. Pulley sliders. Basically, lighter sliders make the bike quicker, and sliders make it quicker than rollers. My bike was faster off the line and much more energetic in the mid-range with 38-gram. If I was going to do it again, I'd probably go with 36-gram. The sliders are cheap, around $60. Dr. Pulley has an excellent site with great explanations of sliders and rollers. They are also very responsive to questions via email. https://drpulley.co/sliding-roller-weight/

If you send me your email address via DM, I will send you a pdf of the belt/roller process from the BMW Workshop Manual. I can't post it here, tried and failed.

Workshop manual, also a bargain: https://www.ebay.com/itm/1653716172...S2LgMeOCFxbaZgi00epAIXM1wz32BkuYaAg2JEALw_wcB

Of note on the Workshop Manual: it's on DVD and only works on Windows PC's. I'm an Apple guy for life so I had to buy a cheap laptop on Facebook. Definitely worth it though. The DVD includes the manual for ALL BMW bikes.

If you're working on this and get stuck at some point or want a second opinion, give me a holler. I'm local.

 

[Mattster]

Let me suggest you do the 'manual deglazing' hack more forcefully/longer/stronger.

Thanks, I'll stay on it a bit longer in the mornings and report back with the results. I'm looking forward to opening things up and getting acquainted with the clutch and variator. But on a new bike I'm in no rush without a shop manual. I've been taking engines apart for nearly fifty years, including working part-time for a year at Portsmouth Yamaha as a side hustle while running the Clinical Chemistry Lab at night at the Portsmouth Naval Hospital in 1979 while I was on active duty. As an engineer, I always read the manuals. It's my competitive advantage because most of the engineers that I work with have egos that won't let them do that.

 

[Mattster]

I think you are {snip} give me a holler. I'm local.

Thanks again, I sent you my email in a PM.

That manual you linked (just bought it), is it a book or is it a copy of the DVD? Oh, never mind, I see you already said it's a DVD. I'm also a Mac guy so I will be running it in a Windows 10 Virtual Machine.

You mention that the lighter rollers/sliders make the bike accelerate faster, doesn't the ASC prevent it from really doing that?

 

[Delray]

Thanks again, I sent you my email in a PM.

Just emailed you two pdf's from the BMW Workshop Manual for CVT work and oil + filter change.

Beyond my paygrade to explain why ASC does or doesn't act as a governor; I only know the bike was quicker with lighter weight sliders.

 

[Ceesie76]

The ASC in my experience only kicks in when the rear tire slips, which it so far has only done on wet surfaces. So in my experience, if you are on dry roads, you can accelerate all-out without ASC interfering.
The shop manual I bought is a DVD, not aware of hardcopies being available.

 

[leslie]

I have a 2020 C650 GT that I bought last month with 347 miles on it, so pretty much a new bike without a warranty. Most mornings when I set out for the first time in a day the bike thumps and jumps instead of just smoothly engaging the drive train. After about the first five minutes and for the rest of the day it is fine and smooth as expected. Until the next morning. I've gotten some limited relief from this by holding the brakes and running up the RPMs briefly before riding away for the first time in a day. So this appears to be an issue with the clutch, feels like it is grabbing and releasing. Has anyone else seen this behavior? How big of a deal is it to open up the cover and inspect the clutch?
Thanks.

I have a 2019 with 9k on the clock and my bike does the same. It's first thing in the am but there is condensation all over my bike and guess there is some on the clutch too so maybe that's why the slipping is occurring

 

[lorcan]

I have a 2020 C650 GT that I bought last month with 347 miles on it, so pretty much a new bike without a warranty. Most mornings when I set out for the first time in a day the bike thumps and jumps instead of just smoothly engaging the drive train. After about the first five minutes and for the rest of the day it is fine and smooth as expected. Until the next morning. I've gotten some limited relief from this by holding the brakes and running up the RPMs briefly before riding away for the first time in a day. So this appears to be an issue with the clutch, feels like it is grabbing and releasing. Has anyone else seen this behavior? How big of a deal is it to open up the cover and inspect the clutch?
Thanks.

Hi, I have a 2018 bike that I bought 2 yrs ago from a BMW dealer in the UK with 300 mls on it and it started doing the very same thing… BMW changed the clutch 6 times….. yep… 6 and each time it would start creeping back in… they eventually did a deal with me on a GS1250 and I still have the C650. Interesting that they both had the same milage and laid up for similar time… after seeing BMW repeatedly change the clutch, it’s clear it has nothing to do with that… I read in This thread the possibility of squared drive belt.. that seems to make sense. A question to all… I have a 2012 C650 GT as well as the 2018… could I change over the whole back end? Are they compatible and would it be an easy swap? Thanks!

 

[RollaCosta]

Yep, clutch is major design flaw of the C650, so far from the perfect wet multi-plate on T-Max...
I've replaced mine with Dr.Pulleys, but it ships with too tight spring sets (all of them) so engages at higher RPMs which is a nuisance in the slow jammed traffic when I want to crawl quietly without periodic "uproars". I have written to manufacturer and they shipped me other (less tense) springs with my variation slider order. Yet to install. But the HiT clutch itself is perfect, though pricey.

 

[Ceesie76]

@lorcan try the de-glazing hack, forcefully and several times, the next time your GT's clutch 'shudders'.

 

[Mattster]

I have a 2019 with 9k on the clock and my bike does the same. It's first thing in the am but there is condensation all over my bike and guess there is some on the clutch too so maybe that's why the slipping is occurring

Yeah, my theory is that it is "flash rust" that forms on the surface when sitting/cooling. The bits of rusty probably get knocked loose and cause that grabby behavior.