96 xvz13ah multiple questions - backfire - coolant leak - carb sync/vacuume guages

[Berdman]

Finally got the bike all back together, had some issues starting it but finally adjusted the idle speed and it fired right up! Had issues getting into gear. I had to cut the screws off the switch to remove it. Once I removed the side stand switch it worked fine.....Now need to replace it because of the grinding 😒. Does anyone know the size of the kick stand switch bolts?

It idles nice, but backfires on start and when dropping back to idle.

I had the carbs rebuilt over winter, would the backfire be caused by any adjustments or synchronization? I can not get the motor running if I use choke. Would lead me to believe it is running too rich?

How does one read dial vacuum gauges? The needle was moving so fast I had no idea what the reading was. One of the gauges eventually broke. Are there any different kind that are easier to read?

I seem to have coolant weeping from the cylinder head gasket(front left cylinder). I do not notice any oil though. When I replace the gasket, is draining the radiator enough. Or will I need to also pull the cylinder plugs.

I will check the valve clearances when I replace the gaskets. could that be causing the backfire?

 

Thank you in advance! Every time I fix one issue I find 2 more . If the coolant leak and side stand were the only issues I would be ecstatic. But the "musket" going off every 30 seconds is not good. I am sure my neighbors are not too happy at 930 at night! 🤪 Not to thrilled to have to pull the carb off again. It took me about 2 hours to get it back on this last time.

[Berdman]

I should clarify its the valve cover gasket that is leaking. Not the head gasket.

[luvmy40]

If you have coolant leaking from the valve cover gasket, you have major problems. 

[Berdman]

38 minutes ago, luvmy40 said:

If you have coolant leaking from the valve cover gasket, you have major problems. 

I was worried about that! I just replaced the coolant. I wonder if maybe it was residual overflow from letting the air out of system. I really hope that is the case. It's on low side of engine. So if it burped up and ran under the crome cover. I really hope that is the case 😖

[frankd]

To read the intake manifold vacuum, you need to restrict the hose to the gauge so that the vacuum at the gauge can average out.     I've tied knots in the hose near the engine and then just adjusted the knot tightness to restrict the vacuum signal.   I've also taken a 1/2" bolt, and drilled a hole in the bolt big enough to pass the gauge hose through.   Then you thread a nut onto the 1/2" bolt adjusting it to restrict the vacuum signal.   You could also use a needle valve to restrict the vacuum signal.      Whichever method you use, when you have the engine running, you should see the gauge moving a tiny bit.    When you shut the motor off, the gauge should slowly move to zero.

[frankd]

One thing I should have said is that the reason the vacuum gauges are moving so violently is that the only time there is flow through the carb is when that cylinder is on an intake stroke.    Then the vacuum is high.    When that cylinder is on a compression, ignition or exhaust stroke, there is zero flow through the carb and the vacuum is zero.   I seem to remember that the gauges will indicate about 9.5" of vacuum when all the carbs are synchronized properly.     This reading is on my First Gen, but Second Gen should be close.

[Berdman]

4 hours ago, frankd said:

To read the intake manifold vacuum, you need to restrict the hose to the gauge so that the vacuum at the gauge can average out.     I've tied knots in the hose near the engine and then just adjusted the knot tightness to restrict the vacuum signal.   I've also taken a 1/2" bolt, and drilled a hole in the bolt big enough to pass the gauge hose through.   Then you thread a nut onto the 1/2" bolt adjusting it to restrict the vacuum signal.   You could also use a needle valve to restrict the vacuum signal.      Whichever method you use, when you have the engine running, you should see the gauge moving a tiny bit.    When you shut the motor off, the gauge should slowly move to zero.

Thank you for the info! At the moment one of the guages is broken. So looks as I will be buying a new set. That must be what the extra pieces were for in the kit. 

 

[Berdman]

So I have the valve covers pulled. I checked the valve clearances. I cant get the smallest .008 feeler in any. So I am going with I have no clearance at all on any shim. Ordered the tool today. bike has 42k on it. Unsure if the valves have ever been checked before. A little surprised that all of them were so tight.

[BlueChips84]

.008 is a pretty large shim and at the top of the tolerance for the exhaust if I remember right. You will want to get a feeler gauge that goes down to at least .0015" and check with that, make sure the timing is in the right position to get proper measurements. 

 

[RDawson]

If I remember correctly intake clearance is .004-.006 and exhaust is .006-.008. Set them toward the higher limits as clearance shrinks with wear. 

[BlueChips84]

I can confirm, .004 to .006 for intake and .006 to .006 for exhaust, as per my manual.  

[Berdman]

8 hours ago, BlueChips84 said:

.008 is a pretty large shim and at the top of the tolerance for the exhaust if I remember right. You will want to get a feeler gauge that goes down to at least .0015" and check with that, make sure the timing is in the right position to get proper measurements. 

 

I thought my clymers manual stated intake was .011 to .15. And exhaust was .021 to .025. Is that metric maybe? I will have to look again. 

[BlueChips84]

Definitely those are metric numbers but you have the decimal in the wrong place. I grabbed the above values from my Clymer manual.

 

Divide the your numbers by 25.4 and you will get the imperial equivalents. 

 

Edited March 26, 2021 by BlueChips84
Spelling

[Berdman]

On 3/25/2021 at 8:31 PM, BlueChips84 said:

Definitely those are metric numbers but you have the decimal in the wrong place. I grabbed the above values from my Clymer manual.

 

Divide the your numbers by 25.4 and you will get the imperial equivalents. 

 

Okay, that makes a huge difference! I got a master feeler gauge set goes down to .0015.

 

                                   Front

Ex    .005 | .006     ||  .005/6 | .005

IN  .0025 | .004     ||  .003 | .003

 

IN    .004 | .003     ||  .003 |  .003

Ex    .005 | .005     ||  .005  |  .005

 

Cylinder one is TDC when lobes face inwards to each other. Cylinder 2 &4 seem to face outwards? or am I positioning the crank wrong.  The 3 that are at minimum. Should I bother adjusting them? Or just leave as is. I am waiting on the valve tool to check the shims still.

 

I was able to pull the covers with out removing the carb! Thank god!

[BlueChips84]

I honestly cannot recall the exact facing of the lobes but as long as the intake and exhaust lobes for the cylinder you are checking are either facing toward or away from each other, you should get a good measurement.

 

I shimmed all of mine that were questionable to the top(larger) end of the tolerance as they can generally only get tighter as they seat themselves. If they are in tolerance, I would not bother unless they are right at the bottom of spec. 

[saddlebum]

If the lower size goes in freely and the upper size does not go in at all, I am happy. Keep in mind, though its true clearance decreases with, age this usually occurs mainly during the break in period 1st 60,000 miles after that they really don't change all that much and IMHO too loose means more engine noise and reduced valve opening.

Edited March 28, 2021 by saddlebum

[Berdman]

Okay I have the new valve shims in, new cover gaskets. All is back together. I synced the carbs. It is hard to get started cold. The backfire is not as bad now. I only get it when I twist throttle too fast. At first I saw flame out of the exhaust, I have turned the pilot screws out one turn. No more flame, just black smoke on backfire. 

 

According to the vacuum guages I should be getting higher vacuum. I read somewhere that the only way to adjust the "timing" is to adjust the TPS on the carb. Should I worry about the low vacuum or leave it as is as long as carbs are synced. 

Should I turn the pilot screws out any more? 

The bike idles like a champ. It's so close to be ridden. I'm just worried about this backfire to take it out on the road. 

[Marcarl]

Nice to have those gauges. You can use them to adjust your needle valves as well. It's just takes a pair of glasses sometimes, well at least for me anyways. Set your idle at 900, then turn the needle in or out and find the spot that shows highest idle and then the lowest idle, set point is right in-between the high idle point and the low idle point. No need to blip the throttle or anything like that for this has nothing to do with linkage. Each carb will be set at different amount of turns seeing as one carb is never totally identical to another. Keep in mind that the circuit you are dealing with only has full use when the throttle is closed, as the throttle opens this circuit has less and less effect on the overall carb system.

[Berdman]

12 hours ago, Marcarl said:

Nice to have those gauges. You can use them to adjust your needle valves as well. It's just takes a pair of glasses sometimes, well at least for me anyways. Set your idle at 900, then turn the needle in or out and find the spot that shows highest idle and then the lowest idle, set point is right in-between the high idle point and the low idle point. No need to blip the throttle or anything like that for this has nothing to do with linkage. Each carb will be set at different amount of turns seeing as one carb is never totally identical to another. Keep in mind that the circuit you are dealing with only has full use when the throttle is closed, as the throttle opens this circuit has less and less effect on the overall carb system.

Thanks for the info. I was tinkering around tonight on it. Didnt notice any change in rpm when I adjusted the screws. I did open the pilots up pretty far, seemed to calm the bang in neutral. 

Thought I was ready to ride. But as soon as I try to start moving the rpm drops and just bang bang bang. So what i have noticed, it only backfired at low rpm(below 1100 according to my guage), I only notice it on cylinders 1&3. There is a small leak at the front and rear of the mufflers. I thought for sure the rear was a drain for water. But the front one looks to be a weld. So next I am going to pull them off and reweld and inspect them. I wouldnt think a pinhole would cause such a bad bang. 

I'm starting to debate if I might just part this bike out. I'm baffled as to why they would have designed a bike with this issue. Think I am realizing why this bike was abandoned. 

[Marcarl]

11 hours ago, Berdman said:

Thanks for the info. I was tinkering around tonight on it. Didnt notice any change in rpm when I adjusted the screws. I did open the pilots up pretty far, seemed to calm the bang in neutral. 

Thought I was ready to ride. But as soon as I try to start moving the rpm drops and just bang bang bang. So what i have noticed, it only backfired at low rpm(below 1100 according to my guage), I only notice it on cylinders 1&3. There is a small leak at the front and rear of the mufflers. I thought for sure the rear was a drain for water. But the front one looks to be a weld. So next I am going to pull them off and reweld and inspect them. I wouldnt think a pinhole would cause such a bad bang. 

I'm starting to debate if I might just part this bike out. I'm baffled as to why they would have designed a bike with this issue. Think I am realizing why this bike was abandoned. 

You won't likely see much change in the RPM. You need to hook up the vacuum gauges and check the vacuum at idle, 900  rpm.

[Berdman]

9 hours ago, Marcarl said:

You won't likely see much change in the RPM. You need to hook up the vacuum gauges and check the vacuum at idle, 900  rpm.

Okay for giggles I turned the pilot screws in. They are fully seated and the bike is idling fine..... I was able to see a vacuum change on cylinder 4 from fully seated to about 1/4 turn. The other cylinders had no change in vacuum. 

I'm thinking the bike is running way too rich, I forgot the vacuum caps after I pulled guages off and the bike was still idling fine. It was a slight boggy and when I cracked throttle it died a couple times. 

Is there anyone on here that specializes in these carbs? I already spent 400 to get them rebuilt. I dont think they need a full rebuild again. But I'm just curious if something was rebuilt wrong. 

[Marcarl]

Yep, I would say that your rebuilt carbs were not so  rebuilt as one would have thought you to believe. If me was closer, then we'd get 'er done. Now if you move to Ontario and enjoy life..............

[Berdman]

39 minutes ago, Marcarl said:

Yep, I would say that your rebuilt carbs were not so  rebuilt as one would have thought you to believe. If me was closer, then we'd get 'er done. Now if you move to Ontario and enjoy life..............

Great 😖. Tomorrow I will try riding it again. Hopfully its lean enough now to be ride able. I will try replacing the pilot jet myself. I'm familiar with carbs. It's just the 4 bank is a little intimidating. 

[Marcarl]

32 minutes ago, Berdman said:

Great 😖. Tomorrow I will try riding it again. Hopfully its lean enough now to be ride able. I will try replacing the pilot jet myself. I'm familiar with carbs. It's just the 4 bank is a little intimidating. 

What's neat about the 4 carb setup is that you take one apart and then you can put it back together as you 'destroy' the next one. Before you do though, maybe get some carb cleaner, remove the needles and inject the cleaner into the now open port. Keep in mind that there are 2 openings in that port, one goes directly into the throat and is fed by one opening off the side of  the port, Somehow both need to be cleaned. Inject the cleaner, wait a while and then shoot again and again. Give it about 2 hrs to complete. Then shoot it with a shot of air to complete. Put the needles back in til they gently stop, back out 2 turns and then reset at 900 rpm to highest vacuum. Each needle has a teeny tiny washer next tot eh spring and an even smaller o-ring. Don't loose them.

[Berdman]

On 4/24/2021 at 9:15 PM, Marcarl said:

What's neat about the 4 carb setup is that you take one apart and then you can put it back together as you 'destroy' the next one. Before you do though, maybe get some carb cleaner, remove the needles and inject the cleaner into the now open port. Keep in mind that there are 2 openings in that port, one goes directly into the throat and is fed by one opening off the side of  the port, Somehow both need to be cleaned. Inject the cleaner, wait a while and then shoot again and again. Give it about 2 hrs to complete. Then shoot it with a shot of air to complete. Put the needles back in til they gently stop, back out 2 turns and then reset at 900 rpm to highest vacuum. Each needle has a teeny tiny washer next tot eh spring and an even smaller o-ring. Don't loose them.

I'm quite ecstatic! I rode the bike tonight. Had only 3 booms go off and they were minor! Two of them I pushed the start a lil hard, the 3rd was going up a hill in 3rd gear 30/25mph. 

I ran the carbs dry because I still plan to re jet the pilot. I dont like living on the "edge" of the bang. I hope finding smaller jets wont be too hard to do. Going down one size should be adequate I hope. I will post update as i get to it. Hopfully my findings will help some others also! I noticed the consensus with most is it's running lean, but I found mine running way to rich causing it.