Pto clutch operation

[38racing]

I thought that I would post this while searching online. Can a pto clutch have a defect that could cause a binding load on the engine pto that would result in slow cranking. This would be with pto disengaged and belt to deck removed? Meanwhile I'm going to to also check all the reasons that could result in slow cranking. It's our church's mtd with 1998 briggs vtwin. Problem started last fall after 4 years of no problems. Initially it would turn slow but finally kick in and start. Finally it just turned a bit and no more start. Using a booster sometimes worked, sometimes not. After checking connections I took battery home to test only to find it was ok. I took it back and for a short while it started ok. Then it just got slow turning again so I brought it home for the winter. Just pulled it out and a freshly charged battery didn't have enough umph. Going make sure the battery used passes load test. Going to do some voltage drops. Wondering if valve clearance on the compression release will do this on a vtwin like the singles. Easy to swap the solenoid (can't remember if I did that last fall) . then the starter. Just had another thought. Maybe I should do my starting tests by jumping to small tab on solenoid just to make sure it's getting full juice. One safety is through pto switch which I had changed last year to get it engaging. I know those safety paths can be an issue. Had to add a solenoid to a jd 160.

[38racing]

Gee. I should have thought of this. With plugs pulled I should see if engine turns freely with a ratchet on the clutch holding bolt. I did try starter cranking with plugs out and my gut feeling was that it should have spun faster.

[bgsengine]

I would start with the simple stuff first - bypass the start system completely , key off (so engine won't start) no choke, throttle on idle/slow jumper cables from battery - terminal to bare engine block (not frame) and clip B+ jumper to battery + and touch to starter B+ terminal - if it cranks good, you know starter and battery are fine, then you can do voltage drops, etc .. if it don't crank good, you already know it's either starter itself, or mechanical engine issue.. and yes valve clearance will affect compression release on a Twin same as it will on a single.

[KE4AVB]

38, I actually got a brand new clutch that is binding an engine that should pick-up soon if I can get Stens to honor the warranty. They are not wanting to send a pick up tag so I might need to refile that the warranty and add a couple hours labor to the claim so I can drive 1-1/2 hours round trip to the UPS office.

The internal spacing is off and as I torque it down it jams against the field end of clutch so much that it pulls the engagement disc off the magnetic brake.

But answer your question yes clutch can bind because of internal problems like a bad bearing, warp rotor, warp engagement disc, or a damage field winding. If you suspect the clutch you simple remove it to test provide it not stuck on the crankshaft. I fought with one this week for several hours that was hanging on the key but it had to replaced due a half shorted winding. Getting the new one was just about as hard sanding, filing, even some grinding on the key.

[38racing]

I was reluctant to remove since torque on installing is so critical. If I disconnect the wire lead and remove anti rotation pin and then the coil housing rotates fine then is it safe to assume that bearing is good and rotor is not jammed.
On the starter end of things I had this issue on a friend's and it was play in the upper bushing so I jumped the gun and have pulled it. I'll replace it and start as bsengine suggested.

[38racing]

I have it starting now. Details to follow.

[38racing]

So details. Problem is that I often forget what order I did things in. Since I had the gear replaced on the donor starter I put it on. As suggested I used my genius booster directly on the starter. Thinking the plugs were out I thought that the cranking was slow. Then I realized that I had put one plug back in. Removing it increased speed a bit but putting either plug in slowed but that's expected but I felt still too slow. I had recharged the battery and it passed load test to 400 CA and I recharged after the test. Tried with battery and again it cranks slow and then slower to nothing. I check battery and it's 11.7 volts. So I decided to pull the battery from my snowblower unit with same engine that is starting fine. Guess what. It cranks fast enough to start. But kicker is later I recharge the other battery and put it in my blower unit and she cranks perfectly. Go figure.
So now I pull the valve covers to check valves. All 4 in double digits. On first cylinder I set both to .005. I just could not detect any compression release bump on the intake so I set it to .004. I still cannot see the bump. Did second cylinder to same specs and still can't see a bump.
But bottom line is that it's starting fine now and I cannot be 100% sure what fixed it . lol.
And while doing it Murphy paid a visit. It started on choke but died whenever I removed choke. In order to install one starter bolt I had to remove a piece of shroud. That included a small bolt underneath that had to be done by feel. Turns out that the ground wire for the carb solenoid had been on that bolt.

[KE4AVB]

Next time you have cranking problem you should not only check the battery voltage but the voltage across the starter itself and along electrical path if something is out of spec while cranking. It is called a voltage drop test. It helps to know if there is wiring issue getting current and voltage to the starter and returned. Things like bad terminals at switches and poor grounding will show during voltage drop tests. Or you could just try wiggling your ears.

If doing by yourself might need to be an octopus or squid; unless, you have clips for your meter leads. Here I use a Guinea pig sometimes. But I do like to see their eyes light up when touch the plug wires.

As for compression release bump it depends on the make, model, and spec of the engine. Not all have them.

[38racing]

As you said I would do voltage drop if i had 3 hands but I need to get alligator clips made up for tester. I used to have a squeeze switch until a neighbour fried it. Wondering if this twin needs the release when a cylinder is only 20 cubic inch and only one on compression at a time. But looked like intake rod was aluminum and exhaust was steel.

[bgsengine]

As you said I would do voltage drop if i had 3 hands but I need to get alligator clips made up for tester.

You need to find yourself a set of multi-tip tester leads - They have threads on the upper end of the needle probes to thread on different test probe tips, such as alligator clip (best ones have insulated outer sheath), and Needle Point (long slim probes, sharp like a needle), spade terminal (male & Female) and similar probe adapters. I can't find it now but I got a nice set from a ATV parts website., after noticing the probe set in a (I think Kawasaki or Yamaha) OEM ATV service manual.. and then researching on that, came across several versions, ranging anywhere from a few bucks (made in china insulated alligator clips) to a few hundred dollars (OEM Service tool set)

I used to have a squeeze switch until a neighbour fried it. Wondering if this twin needs the release when a cylinder is only 20 cubic inch and only one on compression at a time. But looked like intake rod was aluminum and exhaust was steel.

Yeah the starters are not really built for the torque needed for modern higher compression engines.. unless the engine has a gear reduction (usually a solenoid shift) starter So, knowing the compression specs for the engine you're working on is important.. too much compression, your starter is gonna struggle.. Often the first thing I will check since a compression test is quick and easy, as long as you can get starter to crank engine over at all.. (I keep a good, fully charged automotive 650 CCA battery around just for that reason- I can use it for jump starts) and pretty much all the briggs OHV Intek engines (single and twin) use the aluminum intake and steel exhaust pushrods