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2016/06/21 21:17:47

thewebbmasterone

Briggs V-Twin valve tuning

I have a Briggs v-twin that is in a craftsman DLT2000. I have had issues with the exhaust valve guides backing out. From what I've read this is a pretty typical issue and is solved by replacing the head. I have had this issue on both heads. As of yet I have not replaced the heads because they are $125 a piece. When it starts acting up or it pops a rod I take the head off and I press the valve guide back in place and put everything back together. Usually I go about a year like this before I have to do it again. Normally I don't have a problem tuning the valves but this time it is giving me some trouble. Usually I only have to rebuild one side. so usually I can look at one side while I tune the other and make them just about match and it will run good. This time I had to rebuild both sides and I'm having trouble getting the valves right. I have the repair manual for this engine and it explains in detail how to do everything. It says at a 1/4 inch past top dead center on compression stroke both valves need to be set at 0.005" using a feeler gauge. I did this to both cylinders and it didn't want to run very good so I tried to set them a little tighter to 0.004". The way the engine ran changed but it would misfire and idled very high. SO, I tried to go the other way and set the valves to 0.006". The engine would idle lower but it would still misfire, It misfired quite a bit. So, in the end I put it back to what the manual said at 0.005". The engine doesn't like to idle until it heats up. If you turn it down to an idle it will just flat out die. It may sputter once or twice but it just dies. After it warms up it will idle but it will start surging and misfiring and progressively getting worse. If you turn the throttle up a little it will go away. I also noticed that After mowing my yard ( about 1 1/2 hours) it will start smoking and misfiring no matter what the throttle is at.

As an added note, this time I had to retrieve one of the rods from inside the block so I had to disassemble the engine. I have done this before with no issue. I made sure the timing mark on the cam is lined up with the timing mark on the crank shaft so I don't think that is an issue. After reassembling I re-set the governor to make sure it would function properly so I don't think that is an issue.

Can anyone give me any advice on this? Does it sound like a valve issue or is there something else that I am missing?

35 comments Leave a comment

Mikel1

What exactly do you mean when you say can't get valves right? Are you replacing head gaskets when taking heads off? What color smoke?

2016/06/22 11:34:27

thewebbmasterone

No, i didnt replace the head gaskets. When i took everything apart they came out in one piece and were still solid so i figured i could get away with reusing them. The smoke was darker but looked kind of blue to me. If i rev the engine up and kick in the mower deck it blows a puff of white smoke. When i say i cant get the valves right i'm assuming that my problem is with timing and i'm just simply not getting the valves adjusted right but no matter what i do with them i'm not getting anywhere.

2016/06/22 14:47:20

thewebbmasterone

Aaaaaa. Sorry for the extra posts. My browser was a little slow and i didnt realize so i submitted the same post 3 times before i noticed the browser was loading.

2016/06/22 14:52:16

Mikel1

Are both cylinders working? Have you tried changing spark plugs? A leak down tester would be ideal for this. Do you have a compression tester?

I took out the duplicate posts.

2016/06/22 22:38:45

thewebbmasterone

I do have a compression tester and a spark tester. I will check both on both cylinders and get back to you.

2016/06/23 03:17:23

thewebbmasterone

I checked for spark and I have good spark on both cylinders. I checked compression and I have 120 psi on cylinder #1 and 100 psi on cylinder #2. Checked my manual but I cant seem to find a compression spec. What is good compression for these engines?

I couldn't remember If I was supposed to check the compression with the engine warm or not, so I went back and I let the engine run at a higher RPM for about 5 minutes so it was warm. I checked the compression and now I'm getting 100 psi on cylinder #1 and 80 psi on cylinder #2.

2016/06/24 19:06:21

Mikel1

Yeah Briggs doesn't publish it because it varies, they suggest using leak down tester. Compression tester just gives a general idea on the cylinder(s). Yours look good to me.

What spark tester do you have, inline?
Just recapping but misfires, doesn't idle until warmed up, surges and misfires until throttle is increased. Then you can cut grass for 1hr 30 minutes with no problems before smoking and misfiring no matter throttle position. Is all this correct?

2016/06/24 23:34:08

thewebbmasterone

Yes, you are correct and yes, i have an inline tester. This time when i started the engine it was misfiring at high rpm right from the start. Even after it warmed up it didnt improve.

Is it possible its a carb issue? I've heard that there are a couple different carbs that come with this specific motor and some of them are junk.

2016/06/25 02:36:16

Mikel1

I was thinking about the carb with the surging. Easiest way to do this would be to give it some choke while running. If it makes no difference take off air filter(temporarily). If taking off air filter doesn't make any difference, then spray some carb cleaner thru carb.

If that doesn't make a difference, while running disconnect ignition coil on one cylinder, then turn off. Repeat on other cylinder.

2016/06/25 13:25:02

thewebbmasterone

Ok, so it seems like we are getting somewhere but I don't know what any of it means. I started the motor and turned the revs up a little but not really high, just enough so it would run smoothly. When I say smoothly I mean that it will run without almost dyeing. It still misfires. I gave it a little choke, about half with no change. If I give it full choke it starts sputtering and blowing black smoke. I turned the choke off and I removed the cover for the air filter so it was getting straight air without the filter and I got no change. I put the air filter cover back on and I removed the spark plug wire from the plug on cylinder #1 and the misfire went away and the engine ran smooth. I put that back on and the misfire came back. I removed the plug wire from cylinder #2 and the misfire went away and the engine ran smooth.

So, to sum it up the engine will run smooth on one cylinder or the other but will misfire with both cylinders running.

2016/06/25 18:01:05

Mikel1

Test the diodes, should be in the manual. There's one diode for each ignition coil.

2016/06/25 20:22:30

thewebbmasterone

Ok, so I think I may have found the issue. I tested from the armature connector to the wiring harness connector so I could test the whole circuit. If I test to the black wire so i am testing across the diodes I get nothing from either armature connector. The multimeter reads 0L. I noticed that by the wiring harness plug there was a bunch of electrical tape. I removed all the tape and it appears like the previous owner rewired the engine. All of the wires are cut and spliced back together. when I wiggled everything the grey ground wire that goes to the carb bowl and then to the block came apart. From what it looks like to me the diodes are open and need to be replaced. What I don't understand is how everything was functioning normally if this is the case. If I turn the key on the engine runs, If I turn the key off the engine shuts off. If the diodes were both gone wouldn't the engine either never run or never turn off? what am I missing?

Either way, considering the condition of the diodes and the rest of the wiring harness I am going to replace the whole harness. It's only $16.

Would the diode issue cause my engine to run like I was explaining, or is it possible there is another cause?

2016/06/27 16:37:23

Mikel1

If both diodes are open and the fuel solenoid is working then you will still be able to turn it off with the key.
I would just disconnect the kill wire from both ignition coils. If it still misfires then that's not the problem. I would do this temporarily only. Just in case fuel solenoid doesn't work, have seen rust hold plunger in its down position. Have a plan to cut the fuel flow or take coil boots off spark plugs.

2016/06/27 19:06:52

thewebbmasterone

I have run into a bit of an issue with getting a new wiring harness for my engine. My model number is 445777. I have the parts list for briggs 445700 series engines. There are several wiring harnesses to choose from. The one that looks to match the closest to what I have is 789C in the parts list or part #696576. I looked it up on several parts websites and it matches what I have almost exactly except for one exception. This harness shows two wires going to the diodes, a blue one and a black one. My wiring harness only has one black wire that goes to both diodes. The tractor side of the wiring harness has 4 wires, Gray, Blue, Black, Orange, and Red. The Harness I have now only has Gray, Black, Orange, and Red. Will this new harness work with my tractor and engine, or am I missing something?

It almost looks to me like the tractor is set up to handle one wire for each diode but since both diodes are on one wire on my engine, it still works. Could this be possible? It obviously has worked before since the blue wire from the tractor hasn't gone to anything and the engine still ran and shut off when it was supposed to.

2016/06/28 09:42:58

Mikel1

I see what your saying, several are listed. Jacks has the #698330 listed for models 445777 series however looking it up there are several harnesses, confusing. Might want to post up some pictures. Do you have the #'s on your craftsman, usually start with 917.?

2016/06/28 12:17:41

thewebbmasterone

It nasty and rainy here today. I'll see if i can get some pictures and numbers for you tomorrow. I looked up the harness you listed and it doesnt look anything like mine and i dont see how it would plug into my tractor. My tractor has one big 6 pin plug and thats it.

2016/06/28 12:57:31

Mikel1

So does the #696576 match up with yours other than the blue wire. Looks like if you had to you could just splice the blue wire with black wire or vice versa if you needed to.

2016/06/28 14:01:04

thewebbmasterone

Yeah. Everything looks the same except the blue wire. There is only one wire going to the diodes and not 2. Because i have found that someone was doing some crappy repair work it make me wonder what is supposed to be there and what is right. If i fix it i want to do it right and not just put a bandaid on the problem. I'll upload some pictures and give you some model numbers in the morning and see if you can make any sense of it.

2016/06/28 23:19:32

thewebbmasterone

OK, so here are some pictures and what I have for information. Hopefully this will clear things up some. Depending on file size I might have to do it in several posts.

2016/06/29 11:19:41

thewebbmasterone

another picture

2016/06/29 11:21:25

thewebbmasterone

I was going to upload the tractor manual and the parts list I have but It looks like both are too large to upload here. You can see my engine ID tag in the picture. My tractor model number is Craftsman 917.272261. The two wiring harness pictures, orange goes to orange, red goes to red, black goes to black, blue goes to grey, and the white (or faded yellow) goes to nothing.

Black goes to the diodes, Orange and Red go to the voltage regulator, and grey goes to the carb bowl.

From what I can see none of the wiring harnesses listed for my engine match my harness exactly. The closest one I could see has two wires going to the diodes. One for each diode. My harness has one wire going to both. I'm going to try cut out the old splice and clean everything up and do my own splice so I know it is good and retest everything to see if it was the splice in the wiring that made the diodes appear open.

2016/06/29 11:37:19

thewebbmasterone

Ok, so I repaired the splice in the harness and put everything together and It didn't make any difference. It's like you said, the connection to the solenoid in the carb cuts the engine out even if the diodes don't work. So even though I do need to replace the wiring harness, that is not the issue causing my engine to run rough.

2016/06/29 12:55:19

Mikel1

So did you unplug one coil kill wire or both coil kill wires? With both kill wires unattached and if it still runs rough, try a shot of carb cleaner into carb while running, any change?
Busy at work so I will relook at your info when I get off work.

2016/06/29 14:50:55

thewebbmasterone

Instead of removing the shroud from the motor I just disconnected the black wire from the wiring harness because I spliced all the wires with plugs. When the diodes are unplugged it does not change anything. I did notice that the engine will shut off but not like normal. It It would still run and started idling low and sputtering but did not die. I had to turn the throttle all the way down and that seemed to starve it enough that it died. I don't understand how the diodes appear to have an effect on the motor if they are both bad and measure open with a multimeter.

I plugged the diodes back in and with the engine running at a medium rpm I waited for it to heat up and start misfiring. My brake parts cleaner was empty so I used mass air flow sensor cleaner because it is very close and still very highly flammable. I thought I bought more but I couldn't find it. Hopefully it doesn't make a difference. If I gave it a shot it would smooth out and run good for a few seconds before it would start running rough again. So, I figured I would see if I could time it right and give it a shot every couple seconds and see what happened. The engine continued to run smooth. After a few minutes I stopped spraying anything into the intake and the engine continued to run smooth. I was even able to turn the throttle down and the engine would idle pretty low and idled smooth.

Does this point to a carb issue?

I figure I should add something that I noticed about how the engine runs to see if this helps. When I first start it, it doesn't really misfire. It almost seems like it skips. Once it has run for a minute or two and starts to warm up it turns into misfiring. It doesn't get bad enough to turn into backfiring. But, at first it sounds like the engine is skipping and then once warm you can clearly hear it firing when it shouldn't.

2016/06/29 19:58:07

Mikel1

I would give the carb a good cleaning. Also make sure you don't have an air leak at carb.
Yeah not sure what to think on the diodes.

2016/06/29 23:31:48

thewebbmasterone

I pulled the carb apart this weekend and I cleaned everything. I found several issues. I discovered a crack in the fuel line. I'm guessing that this might cause the fuel pump to suck a little air sometimes. I also found my fuel filter was pretty clogged with some dirt and bits of rubber. I replaced the fuel filter with a clear one so I can see what condition the filter is in. I also replaced the fuel line. I found one of the rubber intake manifold gaskets was cracked and a piece of it was missing. I replaced the gasket with a new one. After putting it all back together I performed the static governor adjustment and I also checked all my valves.

I am seeing quite an improvement. I now have only two issues and they are very distinct. At low RPM I am getting combustion on the intake stroke. I'm assuming this is a valve adjustment, I just don't know witch way to adjust them. I am also having trouble with the governor. I double checked the adjustment according to the manual and what I did was correct but it doesn't appear to me like the governor is working properly. I think I must be doing something wrong. When I start the engine it will run ok just a little above idle. When i turn the throttle up it will rev up just fine. when I turn the throttle back down the engine will slow down but then it will rev back up and I have no control over it. The only way I can get it to come back down is to engage the transmission and drive up a hill or engage the mower deck. This brings the RPM back down and when it hits an idle i shut it off before it can go back up. I assume this is a governor adjustment, I just don't understand what I did. I followed the manual and I double checked it after I had the issue and I don't see where I went wrong.

2016/07/06 09:23:57

Mikel1

On the first problem if you increase throttle does it go away?
On the second problem, does it seem to be binding?
If you let it idle in low throttle position until it has warmed up does it start reving up?

2016/07/06 17:34:39

thewebbmasterone

If you increase the throttle it appears like the intake combustion goes away. The engine doesnt idle very well because of the intake issue so i cant let it idle very long or it dies. If i turn the throttle up just a little it does not go away. It only appears to go away at high rpms.

As far as i can tell the engine does not appear to be binding at all. Everything seems to be moving like it should.

Yes, the engine revving on its own seems to happen after it warms up. When i first start it i can get it to idle at lower rpms it just has the intake combustion issue. Once it is warm i cant keep the rpms down unless i put a load on the engine. It will rev high even if the throttle is all the way down.

2016/07/06 22:44:12

Mikel1

I usually see popping/igniting out carb on low rpms when decompression release is on intake valves. If fuel is on the lean side then it's worse due to the lower idle. Full throttle it usually goes away.
When it is reving can you manually move throttle shaft at carb? Also make sure choke plate on carb is fully opening.

2016/07/07 14:29:04

thewebbmasterone

I dont think i have a compression release on this engine. I've had the heads off seversl times and there are just two valves and a spark plug. I dont see anything else there.

When it is revving i have checked and the throttle is fully closed. Or at least it is closed to the point where it is against the idle adjustment screw. I tried to adjust the idleto see what happened. It reacted the same as if i moved the throttle lever. When revving i bavkef the screw off slowly si i could see when the engine reacted. I hsd to back it off about 3 full turns before i got a response. What i got was it immediatly dropped rpms to almost nothing and then died. When i went to restart it i could not get it to run. It acted as if it had no gas. I assumed i turned the idle down too much. I was able to get it to start by giving it full choke. It was sputtering and almost dying. So i started going the other way with the idle screw. I turned it about 3 full turns before it responded at all. The engine revved up to full throttle like it was doing brfore. It seems like the engine is slow to respond. I figured by moving the adjuster screw i would hear the rpm change and i could more or less get it close by ear. It appears like it makes no change at all unless you move it a lot and then it goes to one extreme or the other.

2016/07/07 17:29:50

Mikel1

Compression release is a bump on the camshaft on the vtwin. It will lift one valve off its seat. You can see it if you turn engine while watching valves.

If the throttle is being closed while it is revving then the governor is working. Sounds like it's getting too much fuel.

2016/07/08 12:25:01

thewebbmasterone

So it seems like before i cleaned things up and put in a new fuel filter i wasnt getting enough fuel but now i'm getting too much. As far as i know there is no carb adjustment. How do i reduce the fuel flow?

2016/07/09 00:00:16

Mikel1

Take a look at the below links. Second link has 2 parts

https://www.google.com/ur...XEtMaWDJywhFP3BQLeHO5g

http://outdoorpowerinfo.c..._intek_v-twin_carb.asp

2016/07/09 10:18:53

thewebbmasterone

It looks like i'll have to take the carb apart again and check things out. Both links were very informative. I didnt realize the jets inside were 2 different sizes and one has to go on the left and one has to go on the right. I thought they were the same. I may have put them in wrong.

2016/07/10 11:27:45

thewebbmasterone

OK, so I pulled the carb apart and checked everything. The links helped. I checked the jets and they were in the right place. I checked my gaskets and none of them were squished and blocking any holes. I also checked to make sure none of them were leaking. I noticed that I forgot to plug crank case vent tube into the intake the last time I put everything together. I also noticed that the intake manifold seems to be flexing where it bolts to the carb. In the middle I can see a gap. I held it up to the light and I cant see any light through it so It can't be that bad but it doesn't seem right to me. I'm not sure how I would fix this though because the intake should be rigid enough that I can tighten it and it will fit squarely against the carb. If its flexing it makes me think maybe I am tightening the bolts too much so I backed off and it didn't seem to improve until I got to the point where the bolts were barely finger tight. When I put it all back I replaced the O-ring in the bottom of the bowl because I saw that it can cause issues when It goes bad. When I put things back together I checked the the adjustment for the throttle and choke and I adjusted them a little. I started the engine and it idled nice and smooth. It ran really good. no combustion in the intake at all. I'm not sure how but it seems like that was a carb problem since the only thing I have touched is the carb. It sat there and idled fine for about 5 minutes. At Idle it was surging a little. Nothing major, just a little. I adjusted the idle adjustment screw a little so the throttle lever would touch it when idling and the surging went away. I wanted to see how things would react when I turned the throttle up and that is where I ran into trouble. I moved the throttle lever a very tiny amount, maybe 1/2 an inch or less and the engine revved up out of control. The governor is definitely working because it hit its peak rpms and held there steady. I watched and you can see the governor holding the throttle closed. It is tight against the adjustment screw. I let it sit there for 3 or 4 minutes and it ran steady at high rpms and didn't come back down at all. I gave it some choke and it had no effect until I completely choked it out. When I opened the choke back up a little the rpms shot back up again. when it starts acting up I can have the choke at about 90% with no effect. its the last 10% that kills the engine. Before I started the engine I checked and when the choke lever is in the choke is wide open and when it is all the way out it is completely closed.

I did read somewhere that people have seen an issue with the carbs running rich if the main jets fit loose in the bottom of the supply tube. Mine seem to fit OK. They don't fall out or anything, but The o-rings that are on them are pretty flat. Is this a possibility, or wold they need to be falling out before it would cause this problem? If this could be the issue, where do I get new jets? my briggs parts list doesn't show them in the breakdown of the carb.

2016/07/13 10:55:59

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Briggs V-Twin valve tuning

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