Yamaha Star Bolt Motorcycle Forum

Yamaha Star Bolt Categories => Technical Discussion => Topic started by: Sdaniels on December 29, 2020, 02:02:05 pm

Title: Belt slack different for a C spec?
Post by: Sdaniels on December 29, 2020, 02:02:05 pm
Need guidance on this because the service manual makes no sense.  It says to have the bike on the side-stand or a stand to get the rear wheel elevated....the wheel cannot be elevated if it's on it's side-stand.  So which is it?  The other question I have is does the C-spec have different slack measurements?  Rear shocks on a C spec are slightly longer than Bolt/R spec...does that have any effect on it?  I don't know & all I have is the Bolt/R spec service manual to go by.  Manual states 7-9mm deflection with 10lbs applied with the special tool.  I've read elsewhere 6-8mm.
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on December 30, 2020, 05:36:47 am
I have about 10mm or so of free sag that goes away when on the sidestand. Lifting the frame doesn't drop the swingarm any further. How much free sag do you have?
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on December 30, 2020, 07:19:05 am
By free sag, do you mean how much slack there is when the 10lb is applied with the tool? 

EDIT:

Okay, put the bike on a stand, rear wheel elevated, got 12mm slack using the tool.  Got exactly the same measurement with bike on the side stand so that question is answered.  Adjusted to 10mm of slack.  Also noticed the right side tick mark was off a bit.  Way to go Yamaha  ::)  This was the first adjustment in 4K miles.
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on December 30, 2020, 11:30:21 am
Free sag is how much the rear end sags without rider on board. Pull up on the bike while vertical to top out the suspension and see how much it sags when you let go. Too much and it'll sag when resting on the sidestand. The shocks should be fully topped out on the sidestand if the preload is set correctly so it won't be any different than lifting the rear. Watch some Dave Moss videos if you haven't already. He recommends 5 to 10mm free sag.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on December 30, 2020, 12:21:31 pm
Not sure why you're asking about suspension sag.  I'm asking what the belt tension is for a C spec if it is, in fact, different from the Bolt or R spec.  But, since you asked, I got 6mm sag with shocks on the second setting from soft. 
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on December 30, 2020, 06:21:07 pm
You basically set the belt tension with zero suspension sag. If you had way too much free sag for some reason, you might not be able to adjust the belt on the sidestand and would have to use a lift to get the swingarm to go all the way down.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on December 31, 2020, 07:29:41 am
Ahhh, got it.  So what about the belt?  How much slack should I have?
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on December 31, 2020, 05:06:29 pm
I would use the recommended setting because it has to be set so it'll never go too loose. I've heard of teeth being stripped off a Zero FX belt from being too loose but never a problem with the factory (overtightened) settings. One FX owner insisted the dealership made the belt too tight so he loosened it. The belt lost teeth and the shop put another on. Again, he thought it too tight and again, he loosened it. Dealership installed another belt and the owner finally left it alone.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on December 31, 2020, 05:48:28 pm
So 7-9mm?
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on January 01, 2021, 06:18:13 pm
Yes, or for us Americans, about the thickness of a cigarette. You're only likely to have problems under certain conditions if looser. Low gear, high HP, good traction, irregular road surface, supension topped out all contribute. For high speed and mileage with only soft take offs, you can run a little loose but the Bolt isn't meant to be ridden that way ;D. Some bikes can run up to 2" but probably use a different swingarm angle and a thick, old style belt.

I have the Progressive shocks that make the bike lean a lot more on the sidestand than the stock C-Spec so I know the swingarm arc is causing the belt to get tighter than Yamaha orginally intended. I set it to stock specs and now it's almost at 1/2". I won't make it any less if it doesn't increase much more soon or cause a problem.

My MP tension gauge seems to be assembled wrong with the o-ring installed inside so the spring can't do it's job. I lubed it with silicone to make it move freely but I'd like to rebuild it. Thought I'd mention that in case others got one that felt like it sticks.

I couldn't find a video of how slack a belt gets under load but here's a chain:

https://m.youtube.com/watch?v=-t3QLWMse00
Title: Re: Belt slack different for a C spec?
Post by: legion95928 on January 03, 2021, 08:13:38 am
Not sure why you're asking about suspension sag.  I'm asking what the belt tension is for a C spec if it is, in fact, different from the Bolt or R spec.  But, since you asked, I got 6mm sag with shocks on the second setting from soft.

To actually answer your question: The C Spec "specs" are the same as all the other Bolts...
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on January 03, 2021, 01:18:51 pm
Sorry, I overlooked that question. The C-Spec SM isn't freely distributed but the OM is if you didn't get one. Belt tension specs can be found in both.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on January 03, 2021, 01:23:34 pm
I wouldn't mind paying for a service manual but it's ridiculous what they're asking for a C spec-specific. 
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on January 03, 2021, 02:52:13 pm
Every year, I would organize our shop manuals and when a previous year got superceded by the next, I would throw it out. That's how I got my 2014 Bolt manual and all the manuals for my older bikes. Unfortunately, paper manuals were replaced with digital around the time the C-Spec came out so I had to buy mine. I haven't had to organized them in years since we haven't needed the space for more but I'll take a look in case someone ordered one since then. On the bright side, we've never had to do any repairs on a Bolt other than general maintenance and accessorizing.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on January 03, 2021, 05:03:36 pm
Yeah, most of the stuff applies to both bikes & the stuff that doesn't isn't rocket science.
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on January 04, 2021, 05:32:26 pm
Didn't you install emulators in your forks? What fluid capacity did you use? I don't have the C-Spec SM handy so I don't know if they both use the same amount.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on January 05, 2021, 10:01:13 am
Race Tech said to put fluid level at 140mm from the top of the fork to the surface of the fluid, no spring & fork tube all the way down.  They don't specify differences between the C spec & R spec.  R spec stock level is 116mm, or 4 1/2" compared to 5 1/2" for RT recommended level.  C spec forks are only 9mm longer so I seriously doubt fluid level difference would matter for extra length.
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on January 05, 2021, 11:12:51 am
I know this is getting away from the topic of the thread but decided to measure some things since the bike was on a stand.  My forks compress 40mm going from no load, front wheel off the ground, to bike weight only & upright.  They compress another 12mm with me on it.  I have progressive springs in it, .35/.90 kg.  I imagine they wouldn't compress as much if it was a straight .90 kg spring.  My front/rear weight bias is not the stock 60/40, but 52/48.  Race Tech said to put preload at 15mm but that is going with a straight-rate spring.  Might play around, throw in a longer spacer & get a bit more preload on the spring.
Title: Re: Belt slack different for a C spec?
Post by: lunkhead on January 05, 2021, 12:52:11 pm
Racetech calls for a lower level than stock. As long as the forks don't bottom out over the biggest bumps, you can run as low as you want. You'll find that you have to run over a certain amount. OTOH, too much and you won't get full travel. My XV750 bottomed easily until I added a smidge more. You won't notice a little too much fluid but you will notice not enough. Racetech's recommended level sounds about right if it's not bottoming ;).
Title: Re: Belt slack different for a C spec?
Post by: Sdaniels on January 05, 2021, 01:53:02 pm
I'm pretty sure I'd know if they were bottoming without putting a zip tie around the fork & actually measuring...I'll do it anyway just to know though.  I can remember thinking in my earlier years with less preload I would have more travel & would work out to a better ride.  Those were some of the harshest rides...the only way the fork would come close to using full travel was hitting a square-edged shape you could feel in your teeth & sometimes resulted in a bent rim.  Yeah, I'll take that advice & leave well enough alone.