Suzuki Burgman USA Forum banner

1 - 20 of 21 Posts

·
Registered
Joined
·
4,083 Posts
Discussion Starter #1 (Edited)
The subject of the 2009 and above (inc. the 2008 retrofit) CVT redesign has caused some of us to have fits with it cooling. For example, in hot weather and on the highway for any length of time, if I would pull off and try to go through traffic, the clutch/bell would act like it's grabbing and the entire bike would start to literally shake.

I think I may have come up with a way to fix that and very little cost. I can't speak for other model year 400s, but on mine, there is an area on the left footboard area (below where you put your feet) that used to be open in earlier year models.

What I did was remove the cover piece (three screws), detach the hose from the CVT cover, tuck it out of the way and then cover that open area with some wire mesh. Since the CVT cover is tilted slightly upwards it shouldn't be a problem with stuff getting in there.

Here are a couple of pics. Ignore the missing bolt on the CVT cover - the mechanic forgot to put it back on (it's since been replaced).

I haven't had, and won't have, a chance to try this on eight to ten hour runs, but just around here in the 100+ degree heat, I haven't had any problems so far. Just be sure to save the parts you took off.
 

·
Registered
Joined
·
1,545 Posts
Hi happytech, interesting mod! I'm not too sure though it would work for folks who ride in all weathers. Don't forget the CVT cooling fan draws in air at some considerable force. Altering the point at which the air is inducted down to a relatively unshielded lower level like that will undoubtedly draw in very moist air in wet weather and probably allow water into the CVT area too from puddles and pools of water on the road. The bikes get a good drenching in rain and it doesn't bode well for the clutch, belt or variator if they get wet. It will certainly introduce more dirt into the filter too as well as the moisture, playing havoc with the rollers. In addition it is likely to cause the air filter to block quickly giving the reverse effect of what you actually want. The snorkel fitted as standard to these bikes is just that. It allows the bike to induct air to the CVT from higher up above the road, and keeps the inducted air much cleaner and very dry by intaking from a safe sheltered area behind the fuel tank. Suzuki designed it so the air is warmed by the radiator too helping to keep the CVT area clear of condensation and moisture generally. That's very important for CVT dry clutches, belts and variators. Sorry if I appear to be raining on your parade but it's my honest assessment of your mod. I designed and built engines and induction systems for a living until not too long ago. It's a nice idea but I think you may have some issues if you run with that for too long. In any case I don't think you will get anymore air through the system by removing the snorkel. If anything, removing the snorkel will reduce the amount of air overall as the snorkel provides a slightly pressure fed supply of air to the CVT. Let us all know how you get on with it and top marks for effort and experimentation. I admire that spirit. Good luck.
 

·
Registered
Joined
·
4,083 Posts
Discussion Starter #3
I'm not taking offense.

However, I know that during the summer, the CVT gets so hot from highway driving that it shudders, jerks and tries to shake the rear of the bike apart.

I never had that problem on the old K5 with the direct air intake. If there was another way to duct it I would.

I really wish there was another way to duct the air cleaner - all the road grime I pick up plays havoc with my air filter causing me to have to clean it twice a year or so, and that's not with a lot of miles on it.
 

·
Registered
Joined
·
3,396 Posts
Why does the cvt go so hot, tech? Is there anything that prevents its operation. Maybe change the lube type?
 

·
Registered
Joined
·
1,545 Posts
The clutch is designed to run hot without problems. If you are getting the judder and shake it's not a temperature problem primarily. It's a clutch problem. I reckon a proper deglaze and clean of the clutch will solve your problem. Unless your clutch has worn operating shoe arm pivots. This makes the shoes wiggle on their mounts and the clutch needs replacing. Maybe check out a recent post I made in the Newbies section on this: here's the link in case you haven't seen it.
http://burgmanusa.com/forums/23-newbie-questions/66730-clutch-shoe-de-glazing-5.html#post903450

Good luck happytech
 

·
Registered
Joined
·
3,396 Posts
I supposed tech knew already about glazing. Otherwise it's exactly where problem might lie. I had even HiT clutch glazed and very hot cvt area despite reading about proper maintenance until i realized i still was not doing it correctly.

After proper service the cvt is barely warm however long might the ride be.
 

·
Registered
Joined
·
4,083 Posts
Discussion Starter #7
The HiT clutch has its advantages, but for me, it's also been a thorn in my side. The OEM would shake sometimes when it got hot or when it rained (and that was with the OEM cooling hose hooked up), regardless of how I deglazed it. That's when I bought the HiT. Finding a spring combination that worked took, I don't recall how many months of test and refit - probably at least six if not twelve.

All I know is, when I used to tour with the HiT and the OEM hose, the clutch would be fine as long as I was on the highway. But, when I got in to town at the end of my ride, it would give me fits.

I don't foresee a moisture problem with my mod unless you're riding through water of any depth, and then in general, all bets are off.
 

·
Registered
Joined
·
3,396 Posts
Would be good to have a picture of your clutch, when possible.
 

·
Registered
Joined
·
3,475 Posts
Is it definitely the clutch heating?

The description in the first post mentions the problem is after riding on the "highway" (I'm a Brit so I'm reading that as motorway).
The clutch should be locked up and not creating any friction/heat.
 

·
Registered
Joined
·
3,396 Posts
The clutch should be locked up and not creating any friction/heat.
That is what i often read, but what isn't my experience really. I'm positive that clutch slips even at higher speeds on motorways, especially when climbing on a hill. Another proof is quite a significant difference in top speed between the OEM and HiT clutch, and even the latter slips to some extent.
 

·
Registered
Joined
·
2,089 Posts
I often experience judder following long periods of high-speed cruising. Although the bike cruises, accelerates and decelerates normally, the subsequent judder tells me the clutch is slipping/glazing. A day or two of blipping the throttle during in-town riding gets rid of the glaze, and all is well until my next high-speed cruise.
 

·
Registered
Joined
·
3,475 Posts
Do we actually know the clutch is slipping at high speed or is that an assumption?
I've never seen anything conclusive to support it.

I've put over 400HP through a centrifugal clutch with no slippage at all so it isn't something inherent to the design.

Could it be the extra centrifugal force is redistributing dust onto the clutch face in the spaces between the pads ?
Or is heat from the increased friction of the belt/pulley at high speeds being conducted to the clutch?
 

·
Registered
Joined
·
2,089 Posts
Bluebottle - you are correct, there could be other causes. I'm approaching 15k miles, so I'm sure I've collected quite a bit of dust that needs to be cleaned out. But something is happening within the clutch 'environment' where a non-juddering clutch + 20 minutes of high-speed riding = a juddering clutch.
 

·
Registered
Joined
·
1,545 Posts
Jeff, it's just the resin in the glazed shoes which mixes with the clutch dust when it's hot. The resin actually become sticky and becomes impregnated with small amounts of dust. This is what causes the judder when hot. The clutch is not actually slipping when you are riding, except at take off. If it did the clutch would wear out very very quickly.
 

·
Registered
Joined
·
3,475 Posts
Chears Jeff
I didn't know if you knew something about the clutch that I hadn't come across.
I will keep a close eye out to see if mine ever does it.

Going back to the original reason for your post I had a look at the snorkel too.
Note that the snorkel ends in a high pressure area within the body so the cooling flow is getting a bit if help from that extra pressure.

I have seen and heard people try to line up the end of the snorkel with the small vent grill under the seat front. This is a very bad thing to do (even though it looks like it should line up).
The small vent is an exhaust - not an inlet (a blower not a sucker). It vents from high pressure in the body cavity to the low pressure area behind the leg screens/shield.
Lining the snorkel up with this vent will make it harder for the cooling fan to draw air in.

I know you haven't done that but other readers might be thinking of trying it.
 

·
Registered
Joined
·
3,396 Posts
Why, Mech -- it may not slip all the time, but say for every 20 or 50 revolutions it slips. i.e. misses 1. Of course the lighter load and better clutch maintenance is, the less slippage occurs. But i generally agree to what Tech says -- this system does not work best for heavier loads.
 

·
Registered
Joined
·
1,545 Posts
I think unless the clutch is already well worn, it just wont' slip when on the move above it's minimum engagement point no matter what the load. These centrifugal clutches are pretty much bullet proof on the go even if there is lots of dust in the bell. They won't normally slip. The scenario you describe Bolzen would really be a clutch that is wearing out anyway. The main issue seems to be all down to the resin getting heated up on the move and becoming quite sticky. It's the normal pattern for clutches like these. When cold, they can be fine. As the bike warms up just a little judder can start, then when really hot, a bit more judder. When cold it goes back to normal. That's one scenario. The other is that it judders like crazy at startup from cold, then as the engine heats up, the clutch gets smooth. I've seen it happening both ways on these Burgmans and on a Silverwing 600. Same as the clutch bell blueing. That really only seems to happen due to owners doing a clutch 'burn out' to excess. Not because the clutch is heating up too much in normal riding. Obviously if the clutch is worn and is allowed to slip then that will produce excess heat and maybe some blueing. But most of us will know when it gets to that stage as you can smell the clutch burning when slowing to a stop and at junctions etc. Just my take on it.
 

·
Registered
Joined
·
1,545 Posts
Oh guys, Bluebottle is a wind expert here in the UK. He's quite well known in various circles and his science is aerodynamics and some other stuff that I don't understand. He ascertained long ago that the area the snorkel breaths from is mildly pressurised. It's a useful place to take the air for the tranny from and as he says, this pressure helps with the cooling. Moving the snorkel from there is not such a good thing to do. If you put your hand in front of the grill under the front of the seat you can feel air being expelled from the compartment under and around there. It's only slight but it's there. Just give you an idea of how well Suzuki designed their baby. It's not perfect but very near I'd say.
 

·
Registered
Joined
·
2,089 Posts
VERY interesting discussion. If I've learned anything, it's that I need to step up my clutch hygiene - must clean and deglaze!

Forgive my tiny, non-mechanic liberal-arts trained brain, but if the clutch is not slipping during a sustained run and thus not heating up the bell due to friction, is it simply 'normal' ambient temperature that heats the resin? If so, it seems the cure would be 1) don't get resin, or 2) if you do, keep it cool.
 

·
Registered
Joined
·
4,083 Posts
Discussion Starter #20
At one time I considered running an old carb pre-heat tube from the CVT cover to that (now opened) vent in the lower left floor board. That would, I would think, force more air in to the CVT.

Going back to the original reason for your post I had a look at the snorkel too.
Note that the snorkel ends in a high pressure area within the body so the cooling flow is getting a bit if help from that extra pressure.

I have seen and heard people try to line up the end of the snorkel with the small vent grill under the seat front. This is a very bad thing to do (even though it looks like it should line up).
The small vent is an exhaust - not an inlet (a blower not a sucker). It vents from high pressure in the body cavity to the low pressure area behind the leg screens/shield.
Lining the snorkel up with this vent will make it harder for the cooling fan to draw air in.

I know you haven't done that but other readers might be thinking of trying it.
 
1 - 20 of 21 Posts
Top