2008 Brute Force 650, clutch is slow to engage

[Coyote251]

I'm trying to help a buddy out with his bike (he's not really on the internet or familiar with these forums) and I'll admit that I am not super familiar with the transmission and clutches in these bikes. I owned a Brute a few years ago, but never had an issue like this that I had to troubleshoot.

So basically my buddy bought a group lot of 650's to build one good bike out of. He got it all put together and has it running but when he pushes on the throttle the clutch doesn't engage till the RPM's are quite high and even when its moving it doesn't really speed up, almost seems like its in "limp mode". He's tried 2 different transmissions so I don't think that's the problem. 

Is there any adjustment on the clutch engagement? Anything else I can tell him to look at? Let me know if you need anymore information if you think you can help.  

[Gwbarm]

I would try a clutch adjustment centrifical clutch is probably worn a little. 

[Mech]

I had a quick look at some parts diagrams and it doesn't appear to have a clutch. The three models I looked at were all belt drive. I also have the 2008 750 manual so looked in there and it looked like the same engine/trans setup, and it has no clutch. It seems the belt and pulleys are the only "clutch"..

I would suspect that the variable ratio system of the belt drive is playing up. That's the variable width belt pulleys I'm talking about. One of them is possibly moving apart at too lower revs, or one of them isn't moving apart when it should.

He should get a manual. They can be downloaded for free, from right here in quadcrazy quite likely..

 

[spock58]

It sounds like the drive (primary) clutch is getting hung up somehow and can't move properly. I've seen bits from a broken belt get into the sliding sheave bushing making this happen. You'd likely need the proper clutch puller to get it off to clean & inspect.

[Coyote251]

Thanks for the replies guys. We've gone through the clutches and everything looks okay and is in spec. I am pretty sure that his issue is that the bike is in "limp mode" from the belt failure switch. The problem with this is that the person he bought the bike from replaced 2 of the connectors that would be used to reset the belt failure and take the bike out of "limp mode" with trailer plugs that now can't be crossed over because the other connectors are the factory plugs. Can anyone tell me what wires are being crossed over when the plugs are switched during the reset process? I feel like I should be able to jump these out to get it out of "limp mode" to see if that's what is causing his issue. If that solves his problem we can look at getting the proper connectors. I've looked through the service manual but can't clearly figure out what is taking place during the reset, and I don't want to burn something up or make the problem worse.  

[Mech]

Hi. I looked through the 650 manual and it didn't mention any Limp mode. It shows the switch as being connected to the wiring by two wires only. The manual is in the manuals section..

Is it still needing high revs to get moving, as you mention in your first post ? That doesn't really sound like Limp mode.. Those variable ratio belt drives can be quite temperamental.. They need everything just right on the front and rear pulleys, and the distance between pulleys, or they cause problems.

[Coyote251]

On 5/14/2025 at 11:41 PM, Mech said:

Hi. I looked through the 650 manual and it didn't mention any Limp mode. It shows the switch as being connected to the wiring by two wires only. The manual is in the manuals section..

Is it still needing high revs to get moving, as you mention in your first post ? That doesn't really sound like Limp mode.. Those variable ratio belt drives can be quite temperamental.. They need everything just right on the front and rear pulleys, and the distance between pulleys, or they cause problems.

Just getting back to look at this issue now. My friend ended up pulling the bike apart further and decided to replace the full wiring harness as there was lots rigged up wiring on the bike and he wanted to make sure his issues weren't stemming from an electrical problem. We finally found a harness and got it installed last weekend and now have the bike back up and running. The issue is still there though with the rpms having to be quite high before the belt starts to engage and move the bike. With the electrical all back to stock, it is definitely in the converter system. Like I mentioned in my original post I'm not super familiar with this system and what should be taking place when he pushes on the throttle. We have the manual, which is great for assembly and disassembly, but lacks any explanation on how this is supposed to work and what I should be looking for to be taking place.  Any chance you could give me a bit of a rundown on what I should be seeing? Maybe some common issues that I could investigate? He's telling me that the throttle is almost 3/4 of the way before the belt is starting to engage. Is there a way to measure the RPM's or to know at what RPM the belt should be engaging?

We're trying to get his bike ready for hunting season this fall, so any help would be greatly appreciated.

[Gwbarm]

The belt reset switch is under the belt cover just push it back if it has tripped. This video might help there are many things that need servicing including adding or removing shims for belt adjustment.

 

 

[Coyote251]

That will certainly help, I will have a watch of it tonight. Thanks.

[spock58]

How'd you make out, working better yet? Just consider that the belt itself can be to blame, try another one & see if that helps.