Running Rough!

[viclioce]

OK. I’ve been working with Alan. He is having problems with his Ace 100 B+.

After a complete bottom end rebuild, the bike was running great! In fact he says it was his best running bike of the 5!

Then all of a sudden, it started having a high idle. Here’s what was done:

1. Bike ran normally
2. Then bike started having high idle issues
3. Idle screw was adjusted with no effect
4. Took apart carbs cleaned throughly
5. swapped carbs same thing on both bikes
6. Tested for clogged pipe by running w/o pipe briefly.

The bike is now responding with no ability to idle and full throttle does not provide high rev’ing. Instead it barely runs and the rpms only increase to just above idle with it bogging down. Releasing the throttle the engine goes straight to a stall.

The carb is jetted properly to stock. A 95 main jet, a 25 pilot, a 4F6 jet needle, 2.0 slide, in the factory original VM20 carb.

I’m not with Alan ad he lives in British Columbia. Looking for advice on what to look for, how to proceed. Thanks in advance for any assistance provided.

[thrownchain]

Sounds like an air leak, check the left side crank seal.

[JPark]

Head torque? Seems like an air leak somewhere. Base gasket blown. Mag side seal popped out or installed too far in - should be flush with the case surface. These are the things you can check with the motor in place. My 100B+ that I just got running again had a pretty serious mismatch between the cases at the base gasket which I solved by taking the studs out and levelling. It used to drool. A bit tricky to do in the frame with the block assembled. The manifold to cylinder gasket is another possibility.

I'm assuming the carb o ring is good. But that would only give a high idle and become less relevant as the revs go up.

[viclioce]

Well, we might have it figured out. It may be that the float needle & seat are Worn and it’s overflowing the bowl. The spark plug has kept coming out wet. So Alan is going to order new float needle & seat for the carb. We will see if this stops the overflow & changes the way it runs! I’ll report back. Victor

[thrownchain]

You have the tools to do a leak down test ?

[viclioce]

No. Alan does not. I suggested he make the tools though.

I’m going to have him recheck the left crank seal to make sure it’s in correctly and also the counter shaft seal. But, the bike is running more like it’s getting too much gas to idle down. The float needle & seat appear worn. If it’s leaking fuel into the bowl, slowly overfilling it, that excess fuel could be raising the idle. And if it’s bogging down when opening the throttle, that to be is like when the main jet is too big and it’s flooding the motor. It’s also leaving the plug wet, but not fouling the plug black. The plug is new & is staying white, but coming out very wet.

Like I said, I’m not there with him. He’s 5 hours North of Athena in B.C. Just 15 minutes North of Sumas, Washington. So we’re trying to trouble shoot this remotely, using Facebook Messenger, videos & photos. Victor

[Dale]

Excess fuel does not raise the idle. Lean condition does. Air leak as mentioned is the primary suspect.

[viclioce]

OK Dale. So if it was running lean, why would the spark plug be wet with fuel? Just asking. Victor

[Dale]

The bike was running normal. First symptom was high idle. That is a lean condition. Carb was cleaned then swapped. Now it is rich and plug is wet.
Are you trouble shooting the high idle or the carb overflow? Seems to have multiple symptoms now.
That is how.
So I would address the air leak first. Either find and fix or confirm that there is no leak. Then the carb issue can be addressed.

[viclioce]

OK. Biggest problem is I’m not hands on. The bike is 1500 miles away. Alan is still green at carb working. Sometimes I have to restate what to do more than once or twice.

I’ve asked him to remove the float needle & seat. The photo shows the condition of the needle. I figure the seat is worn just as badly but he didn’t remove the seat.

He’s going to order a couple more float needle & seat assemblies from Terry in Monday.

I’ve also asked him to remove the stator and chancing the left crank seal to see if it was inserted high, glush with the case or pushed in to low. Alan bought a bottom end kit but he took it to a machine shop to have them install the bearings & seals. So he’s hesitant to even inspect the crank or countershaft seals. I’m not there so I can’t check, nor can I get him to inspect them, yet.

I had him pull the carb back off, and clean the main jet, the pilot jet, and confirm they are the OEM stock sizes, consistent with the a Model B specs. Slide, needle and jets are all OEM original. So the float needle and seat will be replaced as soon as they arrive.

More to come in a few days. Victor

[Bullfrog]

Spark plug wetness and fuel over-flow were not mentioned in the opening message. Did those symptoms show up after the carb was opened, cleaned and re-assembled?
Ed

[thrownchain]

Plug gas wet or oil wet? Makes a difference on where to look.

[dirty_rat]

You said that you (or he) swapped carbs and both bikes ran the same with the first carb? He has two Ace 100's? Both ran a high idle with the one carb? Did he put the carb from the other bike of the first bike to see if the problem persisted?

[viclioce]

Captain, in answer to your question, “I don’t know.” I asked him to check if the plug was fouled. He pulled it and showed it to me in a pic. It was a brand new plug, unfouled but extremely gas wet. This lead me to have him pull the float needle because the bike was overflowing out the carb overflow tube.

As an Also Found Out, he pulled the stator to check the left crank seal, and the seal was sitting higher than the case. He’s adjusted it now. That should address the lean running high idle issue.

So we now we will wait for the new float needle & seat to see if that cures what is an apparent bowl overflow issue. Victor

[Bullfrog]

Dang! Sorry I was busy all day today. It was designated as a "burn day" by the county, the winds were low, it rained a bit last night so the neighbor's field of dry grass wasn't a tinder-box AND my burn permit came in the mail on Friday . . . so the day was spent taking care of a LARGE burn pile.

. . . and dagnabit, who knew the one factually erroneous bit of information posted in this thread would be one which was acted on. The magneto side seal should NOT be pressed flush with the cases.

So now, in addition to the distinct possibility of an air leak - which almost certainly was not cured by pressing the seal flush with the cases - the path for pre-mix oil to get to the main bearing may have been inadvertently closed off. Failure of the mag side main bearing is now a possibility too.

A pressure test is in order. If there is indeed an air leak, rapid and catastrophic seizure is a distinct possibility.

Sorry to be the bearer of bad news.

Ed
PS: Did I mention that a pressure test should be completed?
PPS: Slow down. You'll go faster.

[ossa95d]

All is not lost by pushing the seal flush with the case. It needs to be fixed but is relatively easy to remedy, however the next step is definitely a pressure test. If all the information in the earlier posts is correct, it still could be a carburetor issue. We know that the conditions changed drastically after the carburetor was disassembled. Here is how I would approach it. (This is only my opinion and should be approved or modified by others before being accepted as proper protocol and taking action.)

1. Do a leakdown pressure test before doing anything else.
2. If the engine fails the test, locate the source of the leak.
3. If fixing the leak requires the engine to be torn down, replace all bearings and seals and gaskets in the process.
4. If fixing the leak doesn't require a complete teardown, do the necessary repair, then remove the seal that has been pushed in too far and carefully replace it. It can be done without splitting the cases.
5. If the engine passes the pressure test and there is no leak, the magneto side seal still needs to be removed and replaced. Again this can be done without disassembling engine. I would only take this approach if there is no leak.
6. Once we are sure that there are no leaks and the seal has been replaced, attention can be directed toward the source of the problem.

This is only offered as a starting point for conversation. Good luck!

[Bullfrog]

Ivan's note is spot on. There is one thing I would add - it is important that a pressure test be completed AFTER all engine work is done. Pressure test may be useful multiple times - at the start to identify what and where the leakage is . . . at the end to confirm that all the work . . . worked. The pressure test is the diagnostic procedure which says, "OK. This engine is now proven to be ready to run in terms of air-tightness." Lack of a pressure test is just going with a "gut feeling" that it is ready.

Ed

[viclioce]

I agree. A pressure test WOULD BE GREAT, if Alan had what’s necessary to do a pressure test. However he doesn’t have what’s needed & he is 1500 miles away from me.

Alan used someone else, a machinist, to install his bearings & seals, as he didn’t feel he could do the work himself. I advised him that this is why he’s now having a problem. He gave the work to someone else who didn’t know what the specifics of the installation were and Alan himself didn’t find out there were some specifics for the installation which needed to be adhered to. Now the problem has been exacerbated by trying to trouble shoot the problem without proper testing abilities or knowing for what to look.

I am going to recommend that he get on the forum and learn what’s needed to build leak down testing equipment. But, I can’t force him to do it. He has to want to do it. With 5 bikes in his shop and another on its way, it’s something he needs to learn to use.

There is a separate issue with the carbs. Both have worn float needle assemblies and so both are causing too much fuel to enter the motor and habitually flooding the motor. It becomes especially evident by the fact that the carb, with the motor off, continues to flow out the overflow tube, even though I have guided him through leveling the floats and that has appeared to have been done correctly.

Also, with the Ace 90 & the Ace 100, the bearings & seals were installed by the same machinist, so, chances are the same mistakes were made twice and Alan didn’t know what to look for before re-assembling the motor.

So he has now tackled leveling the left crank seal and will be calling Terry tomorrow morning to order the float needle & seat assembly for both carbs.

I take some responsibility for the float issue with the carb for the 90. This was a carb body which Maxie sent me to build for him and I failed to inspect the float needle & seat for wear, or it was close and the bit of use he’s given the bike has caused it to wear to the point of leakage. So now the needle & seat will be replaced on both. The only other difference is the 90 carb has a 100 main jet instead of a 95 because I didn’t have a 95 on hand. Victor

[Bullfrog]

Leveling the mag side seal?

"So he has now tackled leveling the left crank seal and will be calling Terry tomorrow morning to order the float needle & seat assembly for both carbs."

Do NOT "level" the seal. See previous post with Hodaka Service Bulletin.

Ed

[viclioce]

What’s been explained to me is the seal needs to be level with the case surface into which it is installed. If the seal is higher than the case surface, or below the case surface, this can cause an air leak.

Where do I find said service bulletin???

Ahh. I see it a few posts back! Thx! Victor

[viclioce]

What’s the best tool to use to pull the seal back a bit without damaging the seal? Victor

[thrownchain]

If he’s ordering carb parts, get a couple of new crank seals.

[taber hodaka]

Victor read what Ed sent you look again at the picture and reread the script. Sometimes these things remind me of Mission Impossible. All of my last seals I purchased are taller than the origional. Without the leak down we don't even know if the seal failed. A air leak will let a engine over rev, then the needle seat leaking could mess up everything. I would blame me, before I would the machine shop. Does Alan have a ace 90 shop manual?? if not he needs one. I was looking forward to your Oregon visit this spring, stay positive and keep an open mind. ---------------- Clarence

[JPark]

Seals that I have pulled back tend to have kinked springs. It may be best to just pull it entirely out and then assess the spring and lip damage. If you have a spring from a previously removed seal it may be okay to use that. Straightening the spring is difficult to do without weakening it.

I've fashioned tools from coat hanger wire [ground thinner post bending] that loop around the back of the lip and pull on the seal case, but it's still unlikely to get it out without damaging the spring and you'll never know if you did or not unless you pull it all the way. If you have an old seal it helps when forming the tool.

Good luck.

[viclioce]

JPark. Would a pick with a 90* bend work? Victor