1979 Tight Valves, Cam Damage, How Bad Is It?

[millsmobile]

Alright so I got the valve clearances sorted on the bike. Everything on the exhaust side is .005 or .006, and one .007, and on the intake same .005 or .006 with one .004. The #4 exhaust previously had several .003 and a .001 which coincided with the lowest compression reading at 90psi. Replaced the cracked cam cap "D", new valve cover gasket, new valve cover bolt rubber. Started right up with no leaks, but as it warmed idle started to drop, and if I gave it gas it would rev rough, and then die. Checking things out after warmup, the #2 exhaust was significantly less hot than the other 3. The carbs currently have pods on them, and I'm probably planning on moving to a different carb system.

I believe the #2 carb is the reference, so I'm curious if these could be that far off to cause misfiring on #2? That carb is leaking a small amount of gas out the drain tube, and it's also collecting a small amount on a plate a little higher than that and off to the side.

I'm going to recheck compression & spark on all cylinders next time I get over there to work on it, what else should I be looking at?

If everything else checks out I'm possibly looking to replace the carbs, these have pods on them and I don't really want to rebuild them to still not run right.

 

[brettp]

Alright so I got the valve clearances sorted on the bike. Everything on the exhaust side is .005 or .006, and one .007, and on the intake same .005 or .006 with one .004. The #4 exhaust previously had several .003 and a .001 which coincided with the lowest compression reading at 90psi. Replaced the cracked cam cap "D", new valve cover gasket, new valve cover bolt rubber. Started right up with no leaks, but as it warmed idle started to drop, and if I gave it gas it would rev rough, and then die. Checking things out after warmup, the #2 exhaust was significantly less hot than the other 3. The carbs currently have pods on them, and I'm probably planning on moving to a different carb system.

I believe the #2 carb is the reference, so I'm curious if these could be that far off to cause misfiring on #2? That carb is leaking a small amount of gas out the drain tube, and it's also collecting a small amount on a plate a little higher than that and off to the side.

I'm going to recheck compression & spark on all cylinders next time I get over there to work on it, what else should I be looking at?

If everything else checks out I'm possibly looking to replace the carbs, these have pods on them and I don't really want to rebuild them to still not run right.

Did #2 fire before the valve job? Have you messed with the ignition wires at the coil at all?
Your carb could be leaking from the fuel tube and not necessarily the bowl. And have you vacuum sync'd the carbs?

 

[millsmobile]

Did #2 fire before the valve job? Have you messed with the ignition wires at the coil at all?
Your carb could be leaking from the fuel tube and not necessarily the bowl. And have you vacuum sync'd the carbs?

Not 100% sure, before the valves I was more concerned about the smoke, burning smell, and oil streaming from the valve cover lol. It ran rough and compression testing was 150, 150, 120, and 90 so I was more intently looking at 3 & 4. I have not vacuum synced the carbs or done any work to them. Previous owner said they cleaned them but did not mess with any jetting. If these boards are correct then I'm kind of assuming it will run poorly even synced because of the pod situation.

 

[brettp]

I would definitely check my spark situation. After that is fixed, sync the carbs.
I just bet a guy today who is a member of this forum. He has an 80s c 850F that he turned into a cafe racer. It is super nice! He had pods on the stock CV carbs. He said it runs very well on them (and no tape!). I asked about his jetting but he didn't remember. Said he would keep me in the loop.

 

[millsmobile]

Definitely no fire on #2, and was not firing before the valve job either. The plug looks like it just came out of the bag. Reverse order in the pic.

 

[millsmobile]

Well I answered the question of this post lol, motor is a teardown for sure. Have spark on all cylinders, no fire on #2, and compression 150, 150, a jumpy 90, and 100. Pretty much pot committed on the bike now, might look for another motor to put in it in the meantime.

 

[dirtdigger]

So #2 has 90 psi? I am just making sure I am understanding correct. Cylinders are numbered from the left to right as you sit on the bike.

 

[brettp]

The same cylinder has low compression AND no spark?

 

[millsmobile]

No I laid the plugs down in order from the other side of the photo, so they're backwards 4 to 1 as pictured. #1 has 150psi, spark, and fire. #2 has 150psi, spark, but no fire. #3 & 4 have low compression, but spark, and fire. #4 was the tightest for valve clearances before adjustment, and the site of the cam damage. #3 was really jumpy on the compression test, it didn't jump up with every turnover like the other three cylinders. All 4 tested fine for spark, seems odd there would be ZERO ignition signs on the #2 plug. Not shockingly, it ran like absolute poo lol.

 

[brettp]

Then you have a fuel issue on carb #2. Float might be stuck up.

 

[dirtdigger]

Well I would also say number 2 is not getting fuel if it is dry. If there is fuel in the bowl its got a blocked passage or jet. 3 and 4 is a possible leaking head gasket between the two cylinders....they are close in compression numbers to say possibly leaking between the two.

 

[brettp]

I wouldn't go to full engine tear down just yet.

 

[millsmobile]

Well I would also say number 2 is not getting fuel if it is dry. If there is fuel in the bowl its got a blocked passage or jet. 3 and 4 is a possible leaking head gasket between the two cylinders....they are close in compression numbers to say possibly leaking between the two.

Yah there's definitely fuel in the bowl on 2, I drained it the first time, and it filled again and has a slow drip leak out the bottom. In any case I don't want to spend much time if any on these carbs.

 

[brettp]

On the positive side, the carbs are except for #2. You're going to have to open it up and make sure the jets are clear

 

[Bo82CB]

Yah there's definitely fuel in the bowl on 2, I drained it the first time, and it filled again and has a slow drip leak out the bottom. In any case I don't want to spend much time if any on these carbs.

…you have fuel delivery issue and you don’t want to spend much time on those carbs!?
I guess that bike will never run properly…

 

[millsmobile]

…you have fuel delivery issue and you don’t want to spend much time on those carbs!?
I guess that bike will never run properly…

Nah it will be awesome. My understanding from these forums and others is that even if I get those carbs dialed in, this bike will not run well. I've got low compression on two cylinders, it has pods (I don't have the original parts), and a pretty unrestricted 4 into 1 exhaust. Pretty sure that IS the recipe for never running properly. The not spending much time plan on these carbs is to avoid the headache you guys all talk about and swap carbs to something that's easier to tune on DOHC and can handle pods.

 

[millsmobile]

Well I've got the carbs off the bike and I think it's kind of a miracle it ran at all lol. #1 is missing the little rubber plug where the needle lives, and when I took the bowl off #4 the jets fell out. How did 4 have fire lol? Also I'm not 100% sure, but I think the gasket on the #2 bowl might have been out of the groove and interfering with the float, but it had fuel in it for sure. The engine side rubber boots were wet with fuel on all four and the overflow tube was kind of wrapped up not sure anything could escape that way.

 

[Bo82CB]

Well I've got the carbs off the bike and I think it's kind of a miracle it ran at all lol. #1 is missing the little rubber plug where the needle lives, and when I took the bowl off #4 the jets fell out. How did 4 have fire lol? Also I'm not 100% sure, but I think the gasket on the #2 bowl might have been out of the groove and interfering with the float, but it had fuel in it for sure. The engine side rubber boots were wet with fuel on all four and the overflow tube was kind of wrapped up not sure anything could escape that way.

You see a little time spend on those carbs can maybe save you from other extra work and possibly bigger expense. BTW you can get stock air-box on fleabay…!

 

[millsmobile]

Also after further inspection the primary jet and secondary jet on #2 are reversed, could that prevent fire? Normally I'd think yes but seeing 4 run with no jets not so sure lol.

 

[brettp]

Could absolutely prevent firing. The air travel pulling fuel up the pilot jet is very low. You need far more air to move fuel out of the main jet. Sounds like taking the carbs out was a smart move, nicely done!