Topic: What's the worst that could happen?

[Artf0rm]

Over the last year I have put tons of time into rebuilding a cb750 from the ground up.  Tonight I installed the exhaust system and I think I have everything in place to try and start the bike tomorrow.  my question is this.  What is the worst thing that can happen when I try and start this thing tomorrow?  Could it explode, could it burn to the ground? 

Tonight I put a little starter fluid in one of the carbs with no gas in the bike and it blew flames out of the carbs??     I think I'm worrying to much but still with a year of work on the line I would rather be safe then sorry.

[phil71]

your first attempt at lighting it up and you used ether, and just in one carb?
Don't do that again, and double check your static timing.

[rklystron]

If this is a fresh build or the engine has been sitting around for awhile, I would recommend just turning the engine over and make sure you have oil pressure and oil is getting to the head. Easy to do and takes little time. Pull one of the exhaust tappet covers, flip the kill switch on and hit the starter button. You may have to cycle the starter a few times. Don't keep the starter spinning for to long. 10-15 sec should be good, 4 or 5 times. You should see oil pooling around the valve spring. If it is a high compression engine remove all the plugs that way the engine isn't fighting against itself and will allow the engine to spin freely. Good Luck I look forward to seeing how it all worked.

[chopped550]

I suppose you trying to start it could trigger an alien invasion of half unicorns and half wolves to come down from the mother ship and eat all the grass in the entire world.  Thus causing a shortage of oxygen and all of us dying.  Ya, good luck with that.

[OldSchool_IsCool]

I think Ryklstron means kill switch OFF. You don't want the bike to start when priming the oil galleries this first time. May wana use the kick start arm to save ur battery too.

Double check the 3k tuneup section of ur manual. Also read up on the 600-mile break in process. After you have run her down the road for a dozen or so miles, do a bolt check to make sure none are loose or missing.

[rklystron]

+1 on the kill switch OFF. Thanks OldSchool_isCool.

[Artf0rm]

alright, checked the exhaust tappets and there is oil in there.  So I added gas and after tightening the ring clamps to stop the leaks in the lines.  I turned the key and 1 and 3 got hot but nothing from 2 and 4.  I blew a couple of packing peanuts out of the tail pipe and a little smoke but nothing else.  Battery died so I am giving it a charge but if it doesn't start tonight where should I start looking for why 2 and 4 aren't getting hot?

[Tugboat]

Carbs. Clean 'em really good.

[Artf0rm]

Carbs should be clean.   New CR's.  Any other ideas?

[phil71]

it's still the carbs.

[Coyote13]

Could really only be the carbs, or you've already fouled the plugs because you had the gas on while you were cranking.  Finnicky little barstids.

[Artf0rm]

fire comes out of the back of carb 2?  still nothing from tube 4.

[phil71]

just out of curiousity, why can you SEE the back of carb #2?

[Artf0rm]

Can see the flash of something burning just for a split second through the K&N pod air filter.

[Artf0rm]

My worst fear here is messing up something internal to the engine.. This is my first rebuild and I swear I think I did everything by the book but there is always the "what if?".  I really don't want to mess this thing up.

[phil71]

are they actual CR carbs, with no idle circuits?

[Artf0rm]

CR-Specials The newer of the two versions as I understand it.

[phil71]

Kehin CR carbs are built without idle circuits. you can't tell very much about anything with those carbs until it's over 3k rpm, and it willl always require constant blipping of the throttle. Is this on stock engine internals?

[Artf0rm]

OK, here is the list of things I am considering:

1. Packing peanuts could be blocking on of the tubes? 
(I blew them out with compressed air but maybe I didn't get them all since some popped out of the back when I tried to start it)

2. Valve timing is somehow off? (I think I was pretty meticulous about the rebuild on the engine but everyone makes mistakes)

3. Compression is low on those 2 cylinders? (The engine has been sitting without being running for a few months after the rebuild.  Should I put a little oil in the cylinders through the spark plug holes?)

4. Carbs are F@#$ed somehow? (CR-Specials are completely clean but I understand they are temperamental by nature.  Perhaps I should take the whole bank ff and clean them them?) 

5. Ignition timing is off? (Not really sure how to time these things when they don't start?)

The other thing that I am considering is taking it to a guy that works on these bikes here locally and just letting him finish off the final details to make sure I didn't mess anything up.  Again, this whole thing makes me wonder what's the worst that I could do to it?  I did turn it over a number of times with the starter before installing all of the peripherals and compression tested it.  everything was around 110 (+/- 10%) so I'm not really sure how it would be compression issues.  I'm really at a loss.

[Artf0rm]

Yes, stock internals.

[phil71]

OK, here is the list of things I am considering:

1. Packing peanuts could be blocking on of the tubes? 
(I blew them out with compressed air but maybe I didn't get them all since some popped out of the back when I tried to start it)

NO WAY.

2. Valve timing is somehow off? (I think I was pretty meticulous about the rebuild on the engine but everyone makes mistakes)

MAYBE, but that would certainly effect all the cylinders, not just 2
3. Compression is low on those 2 cylinders? (The engine has been sitting without being running for a few months after the rebuild.  Should I put a little oil in the cylinders through the spark plug holes?)

Nah.

4. Carbs are F@#$ed somehow? (CR-Specials are completely clean but I understand they are temperamental by nature.  Perhaps I should take the whole bank ff and clean them them?) 

You're going to have a hard road making those carbs work on that bike.. period.

5. Ignition timing is off? (Not really sure how to time these things when they don't start?)

You need to read the shop manual section re: static timing, it's not really hard.

The other thing that I am considering is taking it to a guy that works on these bikes here locally and just letting him finish off the final details to make sure I didn't mess anything up.  Again, this whole thing makes me wonder what's the worst that I could do to it?  I did turn it over a number of times with the starter before installing all of the peripherals and compression tested it.  everything was around 110 (+/- 10%) so I'm not really sure how it would be compression issues.  I'm really at a loss.

Sounds like you have a number of issues here, and you should keep picking away at eliminating problems, because, honestly, if you brought something like this to me, it would probably be expensive.. it's VERY time consuming to forensically go backwards thru someone else's job, not knowing their workflow, or proficiency level. Rule out anything you can before you hand it over to someone for $

[Retro Rocket]

Can i ask, why are you using CR's with a stock engine. I would install a stock set with the airbox for the run in period...

[Artf0rm]

OK, so let's get the information straight so someone can help you for real.
1) The engine was in an unknown running state
2) you didn't check compression before the full or partial disassembly.
3) the ground up rebuild, is not a rebuild at all.
4) you took the cam out, and or removed the timing chain at some point (i'm confused on this point) and put it back in, but can't remember if you lined up the dots?
5) you never checked static ignition timing before attempting to start the bike
6) you're running race carbs on a street bike with no internal mods whatsoever

would you say this is pretty much accurate?

1) I did see the engine run before buying the bike.  The guy that sold it to me pulled off one of the carbs, shot a little starter fluid in it, and it started right up.  I should point out that I bought it for $350 so start is about all it did.

2)You are correct.  I did not compression test the bike before pulling the top of it apart.  I assumed because it started and ran it was ok in that department?

3)Your right, I removed the engine, took the frame to bare metal and modified it, replaced or upgraded all of the non-engine parts I could,  but I guess since I didn't completely rebuild the engine it's not a "ground up" rebuild.

4) Some of the fins were broken so I replaced the cylinder head and redid the valves.  I did not do the rings.  I followed the step by step procedure for this in the Honda manual and cross referenced this site when I needed help.  The outcome was good, or so I thought based on compression testing.

5) Simply put... No.  Does the Dynatek S require that?

6) Again, Simply put.  Yes.  The only modifications I have made are the Dyna coils, the Dyna S kit, Carpy's Yoshi knockoff 4-1 exhaust.

Any help would be appreciated.  Thanks in advance.

[OldSchool_IsCool]

Could the plug wire for #2 have been switched with #4 by mistake?  Might explain the carb backfire if #2 plug is firing while the intake valve is open.  Worth a check.  The coil with the blue wire should service cyl 1&4.  The yellow fires 2&3.

[Spanner 1]

Good one Old School... +1. or , if not stock plug and coil set, could #2 and 4 plug wires be reversed ?