RO78IN Posted January 23, 2012 Report Posted January 23, 2012 PLEASE HELP. The engine is missing and farting like a son of a bitch! at low rpm when its cold, its a total pig, open the throtle and it straight dies, low throtle will SLOWLy rev up, no throtle = straight dies. It backfires and shoots flames out the inlet LOL! I have looked for vac leaks and really couldn't anything... the vac line to the rocker cover had the valve a bit crappy and leakage. so i left the valve open, blocked the line and it makes no difference. Had the carby apart twice now and everything looks ok including the float levels, Jets all seem within reason. its all pretty clean, but in all honesty, i really don't know a great deal about carbies in general. so any input is appriciated. I looked into the ignition system, it all looks OK, i replaced most of it anyway, and double checked first cylinder timing and it looked ok. Then put the timing light on all other cylinders and looked at the RPM on the tacho and the light and everything marries up. Is it possible that the timing chain slipped? Anyway, all help is appriciated. I've owned this thing for two days! Quote
altezzaclub Posted January 23, 2012 Report Posted January 23, 2012 What was it running like when you test-drove it?? Did the guy selling it mention a problem? Does it run like that cold and hot, or does it change. What else has been done to the motor? Extractors? Cam grind? What have you done to it since you bought it apart from what you mentioned? It does sound like the timing is wrong, but it could be the carb just as easily if it is very lean. Quote
RO78IN Posted January 23, 2012 Author Report Posted January 23, 2012 Hi guys, Thanks for the reply. Yep the guy selling was very honest about it all :y: Ok, so last night i had a mate come over and start / throtle the thing, what we found was that we almost ended up advanced about 90-100 degrees and then the thing runs half decent (not perfect, but pretty good). So i think they were timing it off the wrong notch in the crank. That being said, I'm taking a Dial indicator home, finding TDC and will time it off the piston. As for other work, its got the 32/36 weber on it, a nice set of extractors and not much else as far as i can tell. THe engine had just had the head done VERY recently, i just changed all the spark leads, dizy cap and so on. At this stage, to me at least, i think its somewhere in the ignition. Please let me know if anything else might cause this! Quote
altezzaclub Posted January 23, 2012 Report Posted January 23, 2012 Sounds like the dizzy is wrong somewhere... wrong mark as you say would be likely, pull it out and start again. Has the cam been out?? or just the head off? Cam timing would be a possibility, or an inlet manifold leak. Quote
Twinky Posted January 23, 2012 Report Posted January 23, 2012 Could very well be the dizzy! only takes a few teeth to be out completely. Quote
Evan G Posted January 24, 2012 Report Posted January 24, 2012 1 tooth is 20 degrees. more than enough to cause it to run like shit. a good trick of mine is when trying to get the oil pump slot lined up with the dissy. get some one to crank the engine while pushing the dissy down. works a TREAT. recheck timing and repeat. make sure you put the bolt that holds the dissy down before revving the engine. Quote
altezzaclub Posted January 24, 2012 Report Posted January 24, 2012 make sure you put the bolt that holds the dissy down before revving the engine. haha! THAT sounds like a story Evan! Quote
bAKER Posted January 24, 2012 Report Posted January 24, 2012 haha! THAT sounds like a story Evan! HAHA, he always learns the hard way. :laff: Quote
RO78IN Posted January 24, 2012 Author Report Posted January 24, 2012 Ok, some progress tonight. Checked TDC and found the only place it would actually run is 80-100 degrees BTDC. freaking surprising hey! Then we decided to have a look at the condensor and points. The points actually had a hole blown out and the other side looked very badly pitted. So we're planning to change them both and see what happens. Do you guys thing that the points and condensor could actually cause this? I mean this is the actual timing based on timing light and defined crank position... Also to note, the timing chain cover looks awefully clean, maybe this was done with the head and the chain tensioner wasn't done correctly allowing it to slip. Is this a likely scenario? Tomorrow I'm also planning to take the rocker cover off, ensure all valves are closed and pressurise the inlet to see leaks. I'm 99% there's none, but worth checking. Thanks again for your help and input. Quote
altezzaclub Posted January 24, 2012 Report Posted January 24, 2012 Do you guys thing that the points and condensor could actually cause this? Yes, but it doesn't cause it to run at 80deg BTDC! The condensor could load the points like that, so replace both. It would cause a very weak spark, but shouldn't affect the timing. Just start from the beginning & go over all of it. Cam timing, compression, tappet gap, points gap, direction of rotation, plug lead order then ignition timing... Check all the basic stuff and make sure its all sweet then hunt leaks and carb problems. Cam timing is pretty suspicious if the cover is cleaned up. Did they take a hot cam out of there and put a stock one back in one tooth out? You should be able to measure the degrees BTDC or ATDC when a valve opens and get the cam timing. Anyway, check it all first. Quote
Evan G Posted January 24, 2012 Report Posted January 24, 2012 haha! THAT sounds like a story Evan! nah it just pops up just enough not to spin the oil pump. Quote
RO78IN Posted January 26, 2012 Author Report Posted January 26, 2012 WEll so far, i still have nothing! Camshaft timing = OK Ignition timing = 90ish BDTC to make it run, back at normal it hardly runs Dwell angle = Perfect (new) Condensor = New Dizzy cap = new Plug Leads = New Spark Plugs = new fuel pump = good Carby = Just rebuilt (twice)!!! Inlet leaks = Cannot find any. tomorrow i'll check compression, but I'm not expecting any issues there. Rotation is something i'll have to look at, but I'm pretty sure it would be ok hey! i've checked plugs being to the right cylinders, but it must be ok given that i can make it run fine. This 90 degrees out is totally got me stumped. if it was 180, i'd say the leads were one cylinder, but its 90. I'm going to double check the timing light tomorrow, but again, I'm fairly sure its all good. Is there anything basic that i've missed? Quote
altezzaclub Posted January 26, 2012 Report Posted January 26, 2012 The rotor looks like this on mine. I marked the flywheel out to 50deg when I was doing the advance curve, so it has a lot of white paint on, but it is sitting on 8deg BTDC in the photo, that's what the yellow lines show. Number one firing means rotor points to the engine block, and is swinging clockwise towards number 3. Quote
WA_TRD_83 Posted February 23, 2012 Report Posted February 23, 2012 hey mate, your problem sounds a lot like my problems!! and I've still yet to pin point the fix its friggin frustrating!! :bash: http://www.rollaclub.com/board/topic/56069-lack-of-power-ke70-4k-motor/ I'll keep an eye on your thread and you can keep an eye on mine in case it turns out being the same problem! Damo Quote
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