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General Category >> Rubber Side Down! >> Engine bogs down and knocks when clutch is pulled
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Message started by robb+ on 07/28/22 at 13:20:47

Title: Engine bogs down and knocks when clutch is pulled
Post by robb+ on 07/28/22 at 13:20:47

Hey everyone, I had another troubleshooting thread that turned into an entire rebuild, but this feels like maybe a separate thing. My apologies if the mods rather me keep this in my other thread.

Relevant mods thus far include:
Raptor Petcock
Wiseco Piston stock size
Versy head plug
Modified Cam Chain Tensioner
Mikuni VM36 carb from Murray's Carbs
Barnett Clutch

I understand the clutch has no bearing on the carburetor, but the engine seems to be bogging down and knocking when I pull the lever in. The motorcycle otherwise runs good, but when I pull in the clutch it will bog down or even stall once it's been running. Here are some video examples:

Pulling clutch in just neutral:
https://imgur.com/a/XhXVVwg

Clutch pulled and shift into first:
https://imgur.com/a/143mdbn

I've replaced the clutch pack with a Barnett kit. The original basket, inner hub, and pressure plate were also replaced due to pitting and me hoping it was clutch drag. I also ordered all 3 sizes for the pushrods and installed the middle sized one so maybe I should try the larger one? Maybe I put it together wrong? Seems weird that it would happen the same way twice, but I could just be consistently mistaken.

Any ideas are welcome and appreciated.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by Ruttly on 07/28/22 at 14:47:32

Hmmm , Check warranty and/or bank balance

Title: Re: Engine bogs down and knocks when clutch is pul
Post by justin_o_guy2 on 07/28/22 at 16:27:25

I sure don't have a clue.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by verslagen1 on 07/28/22 at 21:23:36

let's look on the bright side(cue monty python)... it's running!

Now, what could it be?
you let out the clutch and it picks up
there's a switch connected to the clutch lever
so maybe it's electrical
this wire runs to the side stand relay and the relay also looks at the neutral switch. this relay provides power to the TCI.
And seems to get worse when it's in gear.

Since you broke off the old thread you'll have to answer a few questions...
now open wide(cue marathon man)... did you f with any of the wires.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by robb+ on 07/29/22 at 06:45:07

Well, that's the best reason I've heard yet. I didn't really mess with any wiring besides moving where the ground was connected.

The wires from the clutch switch going into the control housing has definitely been pinched hard. I started the bike, disconnected the clutch switch, and tested the clutch again with the same symptoms. Does that mean it's mechanical?

I'm going to ride it over to a friend's place who's better at chasing voltage than I am this afternoon. He'd like to know why you think it's a TCI thing because spark is more of a binary thing right?

Title: Re: Engine bogs down and knocks when clutch is pul
Post by Gary_in_NJ on 07/29/22 at 10:15:45

Put the original clutch pack back in and see if the problem goes away.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by buster6315 on 07/29/22 at 13:57:43

That's my suggestion also. (Try the original clutch pack)

Title: Re: Engine bogs down and knocks when clutch is pul
Post by verslagen1 on 07/29/22 at 19:52:43

4D505D5D143F0 wrote:

The TCI is sensitive to voltage, if it gets below 10v it won't start.
But there should be other clues if the voltage is dropping out, like backfiring.
Turn on the turn signals, if it pops in time with the blinker it's about to drop out.
And if you have bad connectors it will do it too.

But, you changed the clutch and you have an issue with the clutch operation... here's your sign.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by DragBikeMike on 07/30/22 at 18:58:57

Robb, I observe two things when I view your vids.

1. That is one noisy motor. You have a helluva lot of cacophony goin on. You might wanna check valve clearance and your cam chain tensioner. Possibly even the flywheel nut.

2. It's hard to tell for sure, but it looks like there is "zero" free play in your clutch lever.

If you have your clutch cable adjustment grossly over tight, you may be bottoming out your clutch pressure disk or coil binding your clutch springs when you squeeze the lever on the handlebars. What happens if you only pull the lever half-way in? Does the engine still slow down?

How about if you only pull it one-quarter of the way in? Does the engine slow down as soon as you start to pull the lever in, or do you have to put some heavy squeeze on the lever before the engine starts to slow down?

Did you verify that the clutch release pushrod was the correct length when you assembled the clutch? Was the release lever on the clutch cover (on the engine) between the two marks on the engine case when you took out all the free play?

These would be the marks in question.

Title: Re: Engine bogs down and knocks when clutch is pul
Post by robb+ on 08/07/22 at 11:34:33

I should have tried the other clutch pushrods before posting. I put in the shorter pushrod, adjusted for the right amount of freeplay, and it works flawlessly. No difference in RPMs in neutral vs 1st (or any gear) with the clutch pulled. Thanks for the help everyone.

Mike, I agree it sounds noisy. I had just done the valves before this video after I noticed the noise, so I'm hesitant to say it's that. Wrenching is just my hobby though. It sounds a lot more normal now that the clutch isn't making the engine lug. I have installed the Versy modified cam chain tensioner. You definitely could be right on the loose flywheel nut, so I'll reach out to Dave about getting that figured out.

Here's my death, discovery, and rebirth thread if you're interested:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1498073682/0