Backfiring causes?

[Skateguy50]

real gasket sucked for me... tach is on the cover and messed up the worm drive connection, ate a cable or two... and by the time I torqued it down enough to work it crushed the real gasket. Oh and the one they sent for my specific model missed a bolt hole.

I hear that greasing the head lightly a bit and installing the oem gasket dry on the top will keep it from baking to both sides and hopefully get it to last a few times. (or so I hope)

I think your tach is up front so no big deal there.

[nutsandbolts]

I can get behind all of that Josh. Lemons and all :P.

Just out of curiosity, how long on average would the OE style gasket last before it's toast?

I've had my factory gasket (probably the original from the looks of it) off 4 times in a year and its sealed each time so far.

[1948man]

Are things any Vetter? Inquiring minds want to know.

[Skateguy50]

I got word via pm last week the 2.30 shim I sent her was actually tight in the offending cylinder, and might take a 2.25 to be in spec. However it got her compression back so it was way negative on what was in there causing the exhaust valve to not close.

I do not know if she got the others measured and if she has new shims coming via the shim swap club or what.

Also had another thread about one offending exhaust stud that broke, not sure if she ever got that out.

Hoping for some updates too.

[Allie]

Yes Mr. Sk8dood sent me a 2.30 and a 2.50 shim to aid in diagnosis. The 2.30 is 'just' tight on the .05 feeler gauge, so I think the valve on #2 exhaust valve is actually within spec on it but a 2.25 would be ideal. And yes a compression check, even cold, now reveals a fairly healthy #2 cylinder. Using the 2.30 shim I measured the real clearances on all the rest of the valves, and I just need to send the Valve Shim Club the fee and the deposit to get five shims sent to me. I hope they have an official Valve Shim Club cap to send me, I think a Mickey Mouse Club had with 2.55 and 2.60 etched onto the ears would be pretty snazzy.

When I measured all the shims, the #3 cylinder is of special note. It was the other cylinder with less than recommended compression (though it was more than ZERO at least...), and the tight exhaust valve called for a 2.50 shim, less than all the other healthy cylinders. I popped in Sk8's 2.50 shim and the clearance now measures .08, perfect, and the cylinder has healthy compression. INTERESTINGLY, the two 'bad' cylinders, 2 and 3, BOTH had 'good' intake valve clearances, in addition to the way tight exhaust valves. BOTH of the cylinders that had good compression, 1 and 4, had tight intake valves as well as tight exhaust valves. Interesting wear pattern.

So, long story long, I actually have one cylinder perfect, and the rest will be so after I put new shims in. I will definitely keep a log of compression checks from now on. I could honestly run the bike right now if I put the 2.30 shim in, but I wouldn't be riding much anyway, until school gets underway for my son... and there are many things I can still do to the bike while it's apart. I think I owe it to the bike to wait until all valves are ideal anyway after the close brush with the grim reaper I just treated it to. The exhaust stud is not out just yet, but it will be one way or the other. I'm planning to have someone weld a nut onto it to attempt removal.

[Skateguy50]

Has the shim club sent you shims yet?

Let us know how the battle goes and if it was just the shims after all.

[Allie]

Arg it's been crazy here, I haven't even sent the deposit out yet for the shims... Must do it tomorrow! I did get some Mapp gas today while I was toilet shopping, so I will give that a shot on that exhaust stud. I'm positive it was valve clearances but I will certainly keep y'all posted!

[Dave8338]

Arg it's been crazy here, I haven't even sent the deposit out yet for the shims... Must do it tomorrow! I did get some Mapp gas today while I was toilet shopping, so I will give that a shot on that exhaust stud. I'm positive it was valve clearances but I will certainly keep y'all posted!

Turn the petcock to ON, not half the way, in between!!!

[Allie]

I got my shims today, many thanks to the Shim Club. All the valves are in spec now, but I have a few things to do before I run the bike again.

1. Before I put the carbs back on I will test them for sticky floats using my home made auxiliary gas supply, I was having a little trouble with that.

2. I will buy some of that freezy stuff to try on the exhaust bolt, and also see if I can use MAPP gas on it. The design of the torch seems to rule out using MAPP alone, I must use oxygen to get a usable flame. I'm thinking the 'soldering/heat treating flame is the one to use.

3. A quick mod to my petcock so that it has a manual 'off' position, so I can at least run the bike for getting the carbs dialed in. I'll be replacing it soon with an aftermarket from Z-1.

4. I need to get a stainless steel stud kit and put the exhaust system back on.

6. Change the oil, and the plugs

5. All the other miscellaneous reassembly.

I've been kind of busy with the Fall semester, but things should even out now and I'll have a little time to work on it.

[Allie]

Quick update

Das Frankenbiken runs again. It's aliiiiiiiiiive! It also smokes more than a 1940's movie star, I think it's running a bit rich.... but it starts very easily now. What a beautiful sound!

By the way umm, when I first tried it I got another backfire. The first time around I never got to rechecking the ignition timing, which is always good advice, because I was so deep into the other stuff which obviously needed attention. After it backfired again I started prodding around the breaker plate and all the adjustments were loose so there was quite a bit of 'break dancing' going on. Did I mention ? Oh well that mental lapse got me to take care of a dire situation (valve lash), so it's all for the best. Oh and before I put the carbs on I did a quickie compression test, cold, just a few kicks on the kick starter. All the cylinders were fairly uniform at about 110-120 psi, and readings are typically higher when cranking the electric start. I think the engine is in a good state of health now, so it's time to start dialing those carbs in. I'll be rereading whatever tutorials there are on it, but it seems that turning the fuel screws on the bottom gradually in is the first thing to do, assuming it's rich. I hope to start on Monday.

[robaroni]

I just read this whole string from beginning to end. It's like a who done it with a happy ending! Even had a Princess Bride reference. Not every guy would catch that. Now I thing I'm going to go buy a pie at the local farm!

[tkent02]

Took me a long time, 1 1/2 times reading the thread to find the Princess Bride reference.
I liked the Star Trek reference better.

It feels like a TNG episode, and we finally ended up re-modulating the sub plasmic interphase matrix to accept a negative flow of phions to cause an inverse collapse in the secondary phase of the warp field. Scotty, of course, would have just shoved his wiener in the warp drive (but I canna hold it for long!!).

[Allie]

Took me a long time, 1 1/2 times reading the thread to find the Princess Bride reference.
I liked the Star Trek reference better.

It's true, I am the Lorelei Gilmore of motorcycling.

[1948man]

Good on 'ya Allie. I'm all valved up too and starting carb dip.

[Allie]

Good on 'ya Allie. I'm all valved up too and starting carb dip.

I'm glad, I was going to ask how that finally went for you. Here's to some nice crisp fall riding!