So your saying a Thinner oil will help prevent clutch slippage?

[Gunz]

One of the biggest jobs of oil is to cool the engine components. The most critical being pistons and valve springs. Thinner oil dissipates heat more quickly, doesn't have as much tendency to cling to the hot parts, which can cause it to "coke". The resulting coked oil is abrasive, causing more harm than good. Anyone that has seen a seized (or well used) piston pin from a Raptor motor can attest to this. One of the oddities that Randy can attest to is the effects of film strength. When he was at the absolute limits of a factory style clutch, synthetic oil woul cause it to slip, then he could change out to dino oil and it would get better. This was not because synthetics are slicker(they aren't)..... it is because the oil wedge was so much stronger that it would not force the synthetic from between the clutch plates.

I have a brand new clutch in my bike and yesterday on its maiden voyage the clutch started slipping later in the day. I was riding it hard and the temp was 101* outside when I noticed the first slip. I'm running 10w-40 yamalube. This was the reason I replaced the clutch in the first place, because it was slipping. I wonder now if it's because of the oil I have been running. Anybody? Kenny? Randy?

[wobble]

IMO you are running too much TQ/HP for a stock clutch and need some kind of lockup.

[RaptorRandy]

 I don't think it has anything to do with the non synth Yamalube your running.  Do you have heavy duty clutch springs in it or are they just the stockers?   With shimmed heavy duty springs and fresh sanded steels and a good quality set of frictions you should be able to get some life out of the clutch on dirt..If you head for the sand or drag on pavement then you are going to need a lockup or your going to go thru clutches.....been there done that.




Randy

[Alkire193]

Good question Gunz, I needed to know that as well! 

[Gunz]

It's the "NEW" Barnett clutch w/hd springs. Jason at TeamRocketFactory told me he would put his name on it, over a stock clutch w/hd springs. So I went for it. I better call him and make sure he actually changed it.

[unclesharty]

Sounds to me like the hot temps and your riding style may be at fault. U said u were "riding hard". Does that mean u were drag racing? Drag racers tend to slip the clutch to get a nice hard launch. If this is what u like to do, then u need to get a clutch that is meant for that style of riding. Burnt clutches are a normal thing to serious drag racers with modded machines.

[Kenny]

Here is the fix to the problem......... You are gonna find that the clutch plate nearest the engine is a very narrow friction with 2 anti-rattle spring washers retained by a very thin piece of wire. This clutch plate is not only has very little surface area, there is an added problem of the spring spacers holding pressure away from it.



Here is a closeup of how little surface area there is. I have seen a hundred clutches replaced by reputable dealers when this is the only plate burned up in the whole set



Here is the fix; Get one new standard friction, throw out the washers (spacers, original narrow plate and retainer wire) and put in the standard size friction. You will see a HUGE improvement in clutch strength. I don't like heavy clutches, so I use stock springs with carefully selected washers so it will increase clutch seat pressure without raising overall spring rate.

Pay special attention to the area I have marked in red. If you take .010-.020" off the tab on the side that contacts the flywheel, you will have an even longer lasting clutch with more bite. Stock replacements work awesome

[Alkire193]

Its time for me to replace my clutch so ill try out this method with my big 6!

[tonyrt44]

I have a brand new clutch in my bike and yesterday on its maiden voyage the clutch started slipping later in the day. I was riding it hard and the temp was 101* outside when I noticed the first slip. I'm running 10w-40 yamalube. This was the reason I replaced the clutch in the first place, because it was slipping. I wonder now if it's because of the oil I have been running. Anybody? Kenny? Randy?

I had the same engine setup you have, barnett lasted only ONE DAY at the dunes, replaced it with KG Factory HD clutch and it held up almost TWO MONTHS till it was fried.
at the level of the power you have in your Raptor, a lock-up clutch seems to be necessary.

so quit wasting you money on clutch kits and get the lock-up, once and for all

Sounds to me like the hot temps and your riding style may be at fault. U said u were "riding hard". Does that mean u were drag racing? Drag racers tend to slip the clutch to get a nice hard launch. If this is what u like to do, then u need to get a clutch that is meant for that style of riding. Burnt clutches are a normal thing to serious drag racers with modded machines.

hot climate temps has no effects on the engine temps as it is controlled by the cooling systems, and it is limited to ~205* till the fan kicks in. also the hotter the oil, less slippery it will become.......
my riding style is to use the all the power my engine can make, so you may blame it on the rappy's power plant,  but not the riding style.
there could be another factor that can effect a clutch performance, that is installation procedure

[tonyrt44]

Here is the fix to the problem......... You are gonna find that the clutch plate nearest the engine is a very narrow friction with 2 anti-rattle spring washers retained by a very thin piece of wire. This clutch plate is not only has very little surface area, there is an added problem of the spring spacers holding pressure away from it.

Here is a closeup of how little surface area there is. I have seen a hundred clutches replaced by reputable dealers when this is the only plate burned up in the whole set

Here is the fix; Get one new standard friction, throw out the washers (spacers, original narrow plate and retainer wire) and put in the standard size friction. You will see a HUGE improvement in clutch strength. I don't like heavy clutches, so I use stock springs with carefully selected washers so it will increase clutch seat pressure without raising overall spring rate.

Pay special attention to the area I have marked in red. If you take .010-.020" off the tab on the side that contacts the flywheel, you will have an even longer lasting clutch with more bite. Stock replacements work awesome

Kenny, what you have said has been applied in the YFZ engines, and it works awesome.
I did this mod to the Raptor's clutch as I did to my YFZ long back.

the only problem now is trying not to blow up 2nd gear of the transmission 

info you have provided in this picture, what does it have to do with the flywheel side. it is not contacting anything.......thanks

[Kenny]

Ooops! Forget get that picture and instructions on machining the tabs....... different mod, different setup.....

[unclesharty]

I have a brand new clutch in my bike and yesterday on its maiden voyage the clutch started slipping later in the day. I was riding it hard and the temp was 101* outside when I noticed the first slip. I'm running 10w-40 yamalube. This was the reason I replaced the clutch in the first place, because it was slipping. I wonder now if it's because of the oil I have been running. Anybody? Kenny? Randy?

I had the same engine setup you have, barnett lasted only ONE DAY at the dunes, replaced it with KG Factory HD clutch and it held up almost TWO MONTHS till it was fried.
at the level of the power you have in your Raptor, a lock-up clutch seems to be necessary.

so quit wasting you money on clutch kits and get the lock-up, once and for all

Sounds to me like the hot temps and your riding style may be at fault. U said u were "riding hard". Does that mean u were drag racing? Drag racers tend to slip the clutch to get a nice hard launch. If this is what u like to do, then u need to get a clutch that is meant for that style of riding. Burnt clutches are a normal thing to serious drag racers with modded machines.

hot climate temps has no effects on the engine temps as it is controlled by the cooling systems, and it is limited to ~205* till the fan kicks in. also the hotter the oil, less slippery it will become.......
my riding style is to use the all the power my engine can make, so you may blame it on the rappy's power plant,  but not the riding style.
there could be another factor that can effect a clutch performance, that is installation procedure

I dont doubt you are a wise man, but clutch plates get MUCH hotter at a MUCH faster rate than the cooling system of an engine, which doesnt even directly cool the clutch.  They call them burt clutches, because excessive HEAT made them fail. The clutch plates are always a common weak link when drag racers play with modded engines. If you left the motor stock and just rode around like an everage joe, you wouldnt have as many clutch issues. The extra abuse isnt the clutch's fault, its the RIDER'S!

Sure, you can buy expensive, heavy duty parts to make your setup last longer and take more ABUSE, but it means just that.

[tonyrt44]

I dont doubt you are a wise man, but clutch plates get MUCH hotter at a MUCH faster rate than the cooling system of an engine, which doesnt even directly cool the clutch.  They call them burt clutches, because excessive HEAT made them fail. The clutch plates are always a common weak link when drag racers play with modded engines. If you left the motor stock and just rode around like an everage joe, you wouldnt have as many clutch issues. The extra abuse isnt the clutch's fault, its the RIDER'S!

Sure, you can buy expensive, heavy duty parts to make your setup last longer and take more ABUSE, but it means just that.

Sure, excessive HEAT will fry the clutch, yet that HEAT you are talking about isn't caused by the engine or oil temps.
It is generated during the slippage of friction plates against steel plates
and if you look at the picture Kenny posted, you would see that the little fiber plate was burnt due to it was slipping the most.
otherwise all fibers will show burn symptoms if it is related to oil temps

here is a picture to show you a steel plate hi temp signs generated by slippage of the little fiber plate.
look closely as you find the full size fibers don't show any burns



clutch Lock-up function is to limit, if not to eliminate, clutch slippage. which is the main cause of clutch failures

For a STOCK Raptor, you can abuse it like a $ hoe, and the clutch will hold up.
so it is not the jokey we should blame, it is "torque and hp" tearing it up

[DL700]

Thanks for posting up my clutch  pics KENNY 

guess i didnt post that topic here a while back.....




OIL TEMP can be different the COOLANT TEMP and it DOES affect clutch life and slip...

If the clutch steels and fibers can not disperse the heat into oil fast enough then they will swell the fibers and glaze as well as discolor the steels...

Heat transfer and clutch life  is directly related to oil temp...... so YES, it is important

[Kenny]

Everyone is on the right page here...... The oil temp is critical when you are on the edge. Coolant temps don't do much to change oil temps, but high coolant temps do indicate that the engine is hot, and oil is usually hotter than the coolant. We have plenty of good testing to show that clutch life suffers above 190°F. This is a double edged sword; When the small cone spring is left in place, the full size plates are partially loaded and the only plate totally disengaged is the small one. This allows the clutch to have a nice clean release because you haven't built a heavy oil wedge between the clutches, at the same time, they are soaking in heat that is much a much higher temp than the oil. If you remove the cone spring and replace it with a full size friction, you will spread the load more evenly amongst the plates instead of loading one small plate, and the ability for the clutches to allow more cooling oil between the plates. The problem is that we have built an oil wedge between the plates that cause us not to have a clean release. Synthetics and heavy oils have a higher film strength that makes the problem worse. So then we have to move to higher rate springs to improve the release.

I prefer shimmed springs over higher overall rate and I hope to explain this in a digestible way. This is only an example, and does not use actual spring pressure that is used in the clutch. Let's say you have a spring that is 50 lbs/inch and you want to increase seat pressure by 50%. There are two ways to do it. You can put a 75 lb/inch spring in OR you can combine a 1/2" spacer with the 50 lb spring to get the same 75 lb seat pressure, or you could use a longer(or shimmed) 25 lb lighter than stock spring. It gets very interesting through the range of travel........ Keep in mind that seat pressure is all we are after here.

travel   50lb/in   shimmed 25lbin  shimmed 50lb/in    75lb/in
seat         50               75                    75                     75
1"           100              100                  125                   150
2"           150              125                  175                   225
3"           200              150                  225                   300
4"           250              175                  275                   375

Obviously the clutch spring doesn't move 4", but this illustrates the difference between shimming a light spring or using a heavy spring to increase seat pressure. Notice in the example that there is 200 lbs less pull with the lightest spring, even though they have the same seat pressure. You can actually increase the seat pressure substantially over the heavy spring while having lighter than stock feel. We have experimented using longer lighter than stock springs shimmed to get the right seat pressure and came away with a very "silky" light clutch feel with plenty of seat pressure to hold the HP. Combine this with steels that have been ball milled to help relieve the oil wedge pressure, and lighter oil, you end up with a very rider friendly clutch with good bite. The shimmed, or longer light spring is the better answer. Add a lockup and you will end up with all the seat pressure you need while maintaining a reasonable clutch feel at high RPM.

Thanks for posting up my clutch  pics KENNY  

You are welcome to use them