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Barn find 97' Bayou 220 - Double Intake from Exhaust and Carb - I'm Stumped

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Was given a 1997 Bayou 220 for free that had sat in the back of a barn for almost 9 years. Owner had parked it because his kids got too big for it, and they have other bigger bikes, said when it was parked it ran fine. He gave it to me as a trade from some networking I did in his home.  

First steps: 

*Marvels Mystery Oil bath down the cylinder to free up the piston rings (I let sit for 24hrs) 

*New battery as old one was shot from not having a charge for 8 years. I took my multimeter to the entire wiring harness and cleaned EVERY contact possible, as not even the headlights were working. After a few hours, everything electrical is now working. Headlights, green dash light, red reverse light (goes on and off with changing from reverse to neutral), and starter spinning strong (after a conversation with my mallet).   

*Drained old oil (no glitter!) 2qts fresh oil with new filter. 

*CDI was shot-- had zero spark and using a multimeter up the wiring harness everything was good up to the CDI—replaced with new one along with new plug wire and new plug now have excellent spark 

The original carb was a total loss. I'm assuming it was parked full of fuel with the fuel switch on. It looked like they found it buried in the sand and put it on, it was so eaten and corroded my thumb went through it trying to get it apart—so new carb. I did also inspect the intake and none of what was in the carb made it into the engine, thankfully. 

After oil bath, compression was still low—threw some brake cleaner down the intake and noticed smoke escaping from the head gasket—took the head off and saw the original head gasket was completely shot. Replaced that, and now compression is up to 90 from 50. I'm assuming, it'll need to go through a few heat cycles for the compression to really build back up (had the same issue with my 2000 Kodiak 400 from siting for 5yrs after a few heat cycles went to 180) 

While the head was off, I did a leak test on the valves and liquid stayed, so no signs of gaps in the valves sealing. Also took a look at the piston and wall and both are in excellent shape, very clean conditions. 

At this point, the bike should fire off or at least pop… but now that compression is back it's sucking air in though both the carb AND the exhaust pipe. Putting my hand on the pipe (no muffler) I can feel it sucking air in, doing the same with the back of the carb, I can feel it sucking air there as well. It isn't pushing air out anywhere.

I've checked timing and it's correct. The TDC mark on the flywheel is lined up with the spot on inspection hole. The mark on the timing gear in the head is lined up with the mark on the casting there as well, so timing is spot on. I don't believe it has a leak from the exhaust valve due to the leak test I did. I also don't believe a valve is sticking, I can see them both moving just fine when looking through the inspection holes. 

In the past, I've had a bike have intake from exhaust and exhaust going out carb, but that was the timing being off, which doesn't seem to be the issue here. 

Any advice on this would a big help as I'm stumped on what could be causing double air intake. Chances are it might be something simple that I'm not even thinking of. 

At this point, I'm about to order a box of hair from Amazon Prime from all the head scratching going on.

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You have been very thorough with your diagnosis, but if you are getting suction from the exhaust there has to be something not right with the valves, I would work with it a little more to see if exhaust valve is sticking before I take the head off.

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I jut re read your post and missed the part where you had already pulled the head and leak tested your valves, check to see if your getting any weird suction feeling at the spark plug hole with your finger it just won't feel right, the only thing I can think of that could cause this is valve timing, when you check the timing make sure you are on the compression stroke, not likely, but you could be 180 off and marks still line up.

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Checked the covers today they are the exact same size, I don't think that they could cause an issue if swapped. Went ahead and ordered new rings. Should be in by Friday. I'm going to inspect the valves to make sure nothing is bent and if all is good I'm going to go ahead and lap them. Might be a sealing issue and the leak test might have just not been enough to show that. Also going to really make sure that when I go and set timing I'm setting it on the compression stroke. I'm 100% sure I did when I set the timing last time, but I could just be an idiot... 

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I think I've finally found the issue. Taking the exhaust completely off and putting my hand over the hole and spinning the flywheel with a socket I can feel air coming OUT of the exhaust. But when I use the electric start air goes IN. Putting bike at TDC and blew smoke into the the cylinder through the spark plug hole. I can see that some of the smoke was escaping through the exhaust valve. I'm guessing that using the electric start causes a higher compression which is why when using the socket I didn't feel it sucking any air in. My guess is that it's slightly not sealing on that down stroke, it's sucking in so much air through the slight gap in the valve, It's making that loud suction noise. Going to order a new valve set and install those when I go to install the new rings. Hopefully by this weekend she'll be smoking pretty! 

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2 hours ago, HuckaDuck said:

spinning the flywheel with a socket I can feel air coming OUT of the exhaust. But when I use the electric start air goes IN.

That suggests a loose timing chain.  I used to have one of those quads and I had to weld a couple nuts to the tensioner to take up the slack.  Yep, two nuts stacked on top of each other to make the pusher long enough.  I may have done some milling on the jug to increase compression which would have made the chain too long, but I think it was pretty long to begin with.

When you set the valve timing be sure the chain is tight or your setting will be off.  Assuming a valve isn't sticking and you have the lash set correctly then the only other likely possibility is the valve timing is wrong, which could be caused by a loose chain.  Or maybe you're lining up the wrong marks or your lash setting isn't letting the valve close.  A more unlikely possibility is the cam is wrong or the sprocket isn't attached to the cam properly which is throwing off your timing.

Also, I wouldn't lap the valves because it wears the hardness off and then your valve won't be able to hold a lash setting for long.  The right thing to do (in light of all the work you're putting into it) is to cut new seats and install new valves made in Japan.  Your seats already have the wrong angle because they wore along with the valves so if you just slap in new valves the angles won't match and your valves will wear out quickly.  There is really no way around cutting new seats if you want to do it right.

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You should take Gw's advice and lap the new valves in. You should fit new valve seals too.

I'd have tried lapping the old valves in if it was me. They clean up mostly if it's only a bit of rust on there. If a motor's burnt a valve or distorted one then they might need cutting, but mostly we can get even those valves to lap in. Valves these days are tough ! And some valves cost a lot more than a seat and/or valve cut.

If the seats won't lap to a nice even line, that's not too thin, without rust marks across them, then the seats will need cutting.

And after cutting.. you lap them in.. always.

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Valve heads are carefully machined to a precise angle and hardened.  If you grind on them in any way you are altering the carefully machined angle and you are removing a layer of hardness.  Once the hardness is gone the valve wears down quickly in my experience.  I'd only recommend a very very light lapping in very rare circumstances.

The idea of a valve job is to make the angle of the seat match the angle of the new valve, that way both angles will be 45 degrees exactly.  If you lap a new valve to an old seat then neither angle will be 45 degrees.

Lap your valves if you want them to look like these down the road:





Also, Neway Manufacturing who makes the seat cutters does not recommend lapping after cutting.  https://www.newaymfg.com/cutters 

This page provides the rationale for why not: https://motorcycleproject.com/text/valve_jobs_done_right.html


Valve Lapping
First, valve lapping. Valve lapping, despite a few manufacturers' adherence to the procedure, is bad practice. It actually comes from the very early automotive mechanic's world, the turn-of-the-century period in which cars had much in common technologically with tractors. Lapping is related to interference valve angles. Interference valve angles means the valve faces were, for example, at 46 degrees and the seats (in the cylinder head) at 45, for example, the thinking being the difference ensured instant valve sealing. Of course this did not ensure sealing by itself -- a proper valve job did -- unless the valve job was sloppily performed. In that case, interference angles forced a knife-like edge on the valve seat. Unfortunately, this produced a built-in valve *recession* situation, so much so that Harley-Davidson, one of the practitioners of this technique, warned in early Sportster manuals about the loss of valve clearance merely miles after "valve jobs" are done in this fashion. Valve recession is a subject all by itself, but as one of the worst things that happen to a powersports valve, it isn't something you want to create on purpose! This knife edge is not a good way to do things. A half millimeter to one millimeter is standard spec in multicylinder powersports engines today. The interference angle method produced an effective valve seat that was far narrower than proper, and much narrower than mere numbers suggest, taking into consideration that today's valves are roughly half the size of their predecessors. Here's where valve lapping comes in. What valve lapping did was, as a final step, it broadened the interference angle's knife-edge contact point, by prematurely wearing part of it away, i.e., by rounding it off. Strangely, lapping has remained the final step in a few manufacturers' recommended technique long after interference angles have disappeared from powersports, mainly through inertia. That is, these manufacturers see little reason to abandon it, especially since it "covers a multitude" of cylinder head reconditioning sins at the dealer level. Lapping also smoothes the rough finishes, sort of, resulting from poor choices in valve seat cutters. So that is probably its claim to fame today. But best practice it is not. Best practice is to recondition the seats perfectly, at the correct angles and finishes, not using interference angles but the right, matching ones, and then not having to rely on any artificial "wearing in," by lapping or whatever. This also means using good valve seat cutting methods in the first place.

You don't want round edges on your valves because it impedes flow.  A 3-angle job is supposed to be angles, not curves.

So, there is rarely ever a situation where lapping is a good idea.  Rounded corners, loss of hardness, grit impregnated in the valve metal are always bad ideas.

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Mike Nixon  makes a lot of noise about Neway  cutters in his motorcycle babble. I'd listen to the manufacturers  and  mechanics  that recommend  valve lapping as a part of a "valve  job"..  Just the opinion of another that spent his working life in the mechanical trades  . Listen to  GW and Mech.

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Well good news everybody! She runs! Woke up early this morning to get started. Took the whole top end off. Went to swap out the rings and found out that the middle ring was basically married to the piston and took a hot minute to get it off. The piston was in immaculate shape all around. Did the new rings and the valve lap, tested it with no spark and the suction issue was gone and now she starts on first push! I attached the video. It is smoking white, probably from the brake clean I used as starter fluid and some of the Marvel's mystery oil I put in the cylinder so the rings wouldn't dry up on the first couple spins and she is loud because the muffler is non existent. Probably just going to pick up a cheap tractor muffler from tractor supply.

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4 hours ago, davefrombc said:

Mike Nixon  makes a lot of noise about Neway  cutters in his motorcycle babble. I'd listen to the manufacturers  and  mechanics  that recommend  valve lapping as a part of a "valve  job"..  Just the opinion of another that spent his working life in the mechanical trades  . Listen to  GW and Mech.

Yep, I did that.  I listened to those guys and I habitually lapped valves before finally realizing that 100% of the valves I lapped needed replaced within 2 years.  There was never once that lapping successfully replaced a seat cutting.  For a while I chalked it up to bad air cleaners, but after switching to the best air filters and still needing to replace valves I eventually narrowed it down to lapping new valves to old seats.

If you lap a valve to a seat that has just been cut then you might get away with it without catastrophic consequences.  It's still a bad idea, but you might not have to replace the valve.

If you lap a new valve to an old seat there is 100% chance the valve will need replaced in a couple years.  I have a whole box of bad valves I could show as examples, some from the 220 bayou.

Valve lapping is specious: it sounds good, but doesn't work in practice.  I lived it.

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Yeah it's funny how you have so much problems with things Randy, doing them your original self taught way.. 

Valves I lap last for years and years and thousands upon thousands of miles.. Carbs I work on  come right and stay good for years. The repairs I do are economical because I do and replace everything needed, and nothing that isn't.. But then... I'm trained and know what I'm doing.. 

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1 hour ago, Mech said:

Yeah it's funny how you have so much problems with things Randy, doing them your original self taught way.. 

Only when following the advice that you recommend.

And I followed it diligently for years.  I always found excuses to explain the failures rather than blaming what you and others recommend.

Problems that occur years down the road can always be explained some other way.  Maybe it's just a fluke.  Maybe I did something wrong.  Maybe the valve was faulty,  Maybe the air filter didn't do a good job.  Yada yada.

One thing I can guarantee: if you lap a new valve into an old seat it will fail.  I've done it dozens of times and each time I had to replace the valve again within 2 years.  Only when I started cutting seats did I get any longevity.

Disregarding your advice is the only thing that worked for me.  That's becoming a consistent trend on here.

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