Author Topic: Still a miss mess. (Read 4425 times)

matt mattison · « **Reply #25 on:** June 15, 2012, 02:58:51 AM »

Quote from: twistedengineering on June 14, 2012, 07:03:48 PM

I suppose that's a possibility however I have new seals and guides in it.
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If your next compression test checks out good, maybe do a leak down test,or have a shop do one for you. If both of these test come back satisfactory, I would suspect a leaking seal or guide only if you are sure the carbs are right. There is no positive test to isolate guides or seals, just a process of elimination of what it is not (the problem). Does any adjustment on carb 4 change that sooty plug? If there isnt a change in the plug deposit, suspect an oil fouling condition.

Lostboy Steve · « **Reply #26 on:** June 17, 2012, 06:04:28 AM »

well, it looks as though I'm #$%*ed. Last night I did a hot compression test. I get 150-160 in all except numero uno. 80psi. Lovely. I'll have you know that I had the cylinders honed by a pro. The valves were all bench checked for leaks after the headwork was done by a very reputible machine shop. Now I'm thinking crack in cylinder? Out of round cylinder? Possibly a cracked ring? I was very carful when putting everything together so I just dont know. I'll tell you this though, if its coming apart again, its getting new sleeves and pistons. Probably to the tune of 600cc's. EVERYTHING NEW.

phil71 · « **Reply #27 on:** June 17, 2012, 08:32:30 AM »

Don't overreact.. Could be valve related. Re check clearances.
How many posts before the great "to hone, or not to hone" debate rears its head ?

dave500 · « **Reply #28 on:** June 17, 2012, 12:30:11 PM »

if you have an air compressor rig up a line into that #1 spark plug hole,set that cylinder on tdc compression and listen at the carb intake and exhaust for a hiss,if the cylinder was that bad to cause that amount of pressure loss youd have plenty of blow by out of the breather hose when its running and i think it would be a smoke machine if you had a broken ring?i call valves,slightly bent stem?

matt mattison · « **Reply #29 on:** June 17, 2012, 02:52:57 PM »

Im betting on a top end issue by your test results. Like Dave said, a broken ring would blow a lot of smoke or even pressurize the crankcase to some obvious degree. I guess a scored cylinder is also a possibility, but either way your head might be comming off again.

matt mattison · « **Reply #30 on:** June 17, 2012, 03:08:28 PM »

Also, When/if you pull the head , flip it over and pour kerosene in the bad compression chamber. If it holds, you got to give the cylinder a look. Obviously if you leak, it's a valve. Before pulling anything apart though double check the valve clearances. I would even do the test Dave suggested or a leak down test with the piston @ TDC . Even take it an extra step by backing off the adjuster nuts so you are certain the valves are fully closed.

Lostboy Steve · « **Reply #31 on:** June 18, 2012, 05:54:06 AM »

Quote from: dave500 on June 17, 2012, 12:30:11 PM

if you have an air compressor rig up a line into that #1 spark plug hole,set that cylinder on tdc compression and listen at the carb intake and exhaust for a hiss,if the cylinder was that bad to cause that amount of pressure loss youd have plenty of blow by out of the breather hose when its running and i think it would be a smoke machine if you had a broken ring?i call valves,slightly bent stem?

A cheap yet effective leak down tester. I have a good Matco tester that I'll bring home tonight and see what I get.

Lostboy Steve · « **Reply #32 on:** June 19, 2012, 09:37:37 AM »

So I re-tested the compression hot and got 150-160. (Must have been my lovely compression tester?) WTF?! Last night did the leak-down. Absolutely leak free! Pardon my terrible camera work.

Cb550k cylinder leakdown test

iron_worker · « **Reply #33 on:** June 19, 2012, 12:15:10 PM »

Try swapping plugs to see if the problem follows. I'm starting to think fouled plug or cracked insulator.

I'm glad your leak down test was good results though.

IW

Lostboy Steve · « **Reply #34 on:** June 19, 2012, 01:02:05 PM »

Yeah, me too. I already changed the resistor caps and plugs. Problem doesn't follow if I swap wires. I just bought a second set of carbs off ebay that I will clean without boiling and install. Then, I will go from there.

Brit550 · « **Reply #35 on:** June 20, 2012, 03:33:49 PM »

I have had very similar issues with cylinder 1, but I think I have sorted it tonight. Like you I tried carbs, cleaned at least 3 times, coil, plugs leads the lot. After looking long and hard at the carbs yet again I noticed that the top had been off carb 1 at some time as there were traces of old silicone around the gasket, i took the top off again replaced the gasket and fired it up, ticking over nicely on all four cylinders for the first time since I had the bike, havn't run it on the road yet, doing that tomorrow so hope all remains well.

I spent so much time focussing on clean jets etc. and I didn't check well enough for an air leak, but I read on this forum what a small leak can cause and it seems to be the case.

Lostboy Steve · « **Reply #36 on:** June 21, 2012, 07:23:32 AM »

This is why I bought another set. I can't guarantee that the bodies aren't leaking. I tried all the rest. I scored a MINT set of 78 carbs off ebay for 50.00. Going to do a cleaning without complete disassembley and will go from there.

iron_worker · « **Reply #37 on:** June 21, 2012, 08:14:19 AM »

Let us know what you find. I'm pretty curious about this one.

IW

TwoTired · « **Reply #38 on:** June 21, 2012, 09:15:52 AM »

Quote from: twistedengineering on June 19, 2012, 01:02:05 PM

I just bought a second set of carbs off ebay that I will clean without boiling and install.

You boiled your carbs in what?

phil71 · « **Reply #39 on:** June 21, 2012, 11:03:20 AM »

I've done it in lemon juice, in a pot, on a bbq. It dulls the finish a lot, but it gets the crap out. I suspect almost any semi-caustic liquid heated to a boil will do a good job in the circuits. I'v often wondered about a steam cleaning..

Lostboy Steve · « **Reply #40 on:** June 21, 2012, 01:20:46 PM »

vinegar, water mix.
Before all this, I did a simple rebuild, (jets, carb cleaner, and a good scrubbing.) Still misfired on 1. So then I COMPLETELY disassembled them, Soda Blasted the bodies. Then I hosed them off. Then I soaked them in simple green. Then I rinsed them again. Somewhere in the middle of all this I blew them out a few times with compressed air. Then I soaked them in paint thinner. Then I boiled them in water/vinegar mix. To ensure any debris or chemical was removed. Then I cleaned all the lose parts. Replaced all the felt gaskets and o-rings. Installed BRAND NEW jets, and called it a "week". After the last rebuild, I tore into the engine (mostly out of frustration). This is when I did a rebuild with new rings, standard pistons, full valve job and porting. Cut the head and powder-coated everything I could get my hands on. The valves turned out to be pretty bad. But still although the bikes runs awesome. Starts one kick, NO CHOKE, has plenty of "gittyup", but at idle I get un-burnt fuel and a miss on cylinder 1. Upon further inspection of my carb's after the FULL cleaning, I did have some corrosion damage to certain parts. Mostly where the pin goes through to hold the float. So maybe my bodies are junk. If I pull extra air it will in turn try to pull more fuel right? MAYBE THAT'S WHY CYLINDER 1 PLUG IS ALWAYS SOAKED! WE SHALL SEE! Its those #$%*ing mice that made a home out of my entire intake system. And the 21 years of sitting with the gas on.

Lostboy Steve · « **Reply #41 on:** June 21, 2012, 01:22:16 PM »

BTW these carbs I scored are literally mint. I mean REALLY. I cant wait to bolt them on. The zinc finish is still shiny!

lucky · « **Reply #42 on:** June 21, 2012, 01:40:38 PM »

Now I would like to get all the jetting information.

Compression check good, and electrical issues solved.

Lostboy Steve · « **Reply #43 on:** June 21, 2012, 01:59:53 PM »

Lucky we've been over this. It's a 42 idle (stock) 105 Main, Stock needle position. Had my needles turned 1.5 out. Went from UNI's to stock airbox with UNI filter, NO COVER. (Cuz I don't have one) I like the airbox much more. Felt way more powerful as well. Still have my 4 into 2 pipes (pretty LOUD) I'm assuming fairly free flowing. Plugs 2-4 are a dark coffee brown. Plug 1 is BLACK and if you chop it, at idle wet. I will install these new carbs with stock jets (90) to try to develop a more solid base line. Although the 105's with a open exhaust should be decent.

Lostboy Steve · « **Reply #44 on:** June 27, 2012, 06:59:19 AM »

GREAT NEWS! Got my new carbs, cleaned those, now my misfire is cylinder 2 to the point that the pipe stays cool. lol FML. Cylinder 1 is running awesome. I have been so thorough with these carbs and I just cant get them right.

News:

Author Topic: Still a miss mess. (Read 4425 times)