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  1. N

    Exhaust Compatibility

    All carbs were matched to number two not too long ago. Should I bench sync, then see how off the other carbs are from number two, or if they are all affected the same?
  2. N

    Exhaust Compatibility

    Alright, readjusted the clearances and now they are all set. Compression didn't change, Still I'm with you, my gauge is wrong so I will get another and retest to see what the actual psi is. I would like to add, started the bike up and it was idling pretty funny and sounded like it was misfiring...
  3. N

    Exhaust Compatibility

    Okay I will do that, then give an update. Thank you!
  4. N

    Exhaust Compatibility

    So what should be my next approach from here? Adjust the valve clearance to make up for the valve face being beat and see how it responds?
  5. N

    Exhaust Compatibility

    Word, I didn’t think to cut the valve seats when doing the rebuild. And yep throttle was wide open while cranking.
  6. N

    Exhaust Compatibility

    Dirt digger, thank you very much for your response! The cylinders have been honed, but you nailed it right on the head. I put brand new valves in the old seats without lapping or cutting them across all four cylinders. I did do a leak test though, and nothing seaped through. But I guess all it...
  7. N

    Exhaust Compatibility

    Update: Just poured a little oil in the spark plug holes, and retested the compression. Nothing has changed, still within 5 psi of what they were before across the board
  8. N

    Exhaust Compatibility

    Now I’m planning on replacing the rings again, as well as new gaskets for the whole engine
  9. N

    Exhaust Compatibility

    I just replaced the valves, gaskets, and rings about two months ago. Thinking the rings are burnt from having no back pressure. But other people have driven around with a chopped exhaust, so I’m not sure why mine is so different.
  10. N

    Exhaust Compatibility

    Hmm possibly. I could drive it around when I first chopped it, then it slowly dwindled down to now it’s having a hard time pulling it’s own weight. Compression is at 80,85,90, and 70.
  11. N

    Exhaust Compatibility

    Hey there, I have a 1978 CB750k. I had the stock exhaust on mine but had a rust hole in it, so I chopped it right below the foot peg…. Bad idea and wish I never had. Haven’t ridden it much at all, barely had any torque after that, now the bike will barely pull its own weight. Thinking I burnt...
  12. N

    Choke not engaging

    Awesome, thank you very much!!!
  13. N

    No spark on 2-3, getting power from yellow wire until hooked up to coil

    Update: The two prongs at the points, one for condenser, and one to coil, were mixed up.
  14. N

    Choke not engaging

    After taking my 1978 cb750k carbs apart for a rebuild, taking plenty of pictures and videos, I put it all back together and now my choke is not engaging to close the butterfly valves. I did it just as I took videos of, so I know the springs are in the right position. The cable is moving and...
  15. N

    Carb Screws

    Alright guys, I’m totally new to the carbs on these. I have just left them stock for as long as I have had the bike, just did a deep cleaning and new gaskets. I have done a ton of reading, however I have not found much on the screw with a question mark. Pretty sure the a/f mixture screw is on...
  16. N

    No spark on 2-3, getting power from yellow wire until hooked up to coil

    Hey guys, this is a 1978 cb750k. I am getting spark on 1 and 4, but not 2 and 3. I am getting power in the yellow wire all the way up to the connection to the coil. The multimeter reads that it is getting power, then as soon as I plug it up to the wire that connects the coil it drops off. It has...
  17. N

    Bike Idling high with small throttle pull

    I have not synced the carbs, but the advance timing unit works and is free, timing is also all good at the points
  18. N

    Bike Idling high with small throttle pull

    Hey guys, I have a 78 cb750k. I have done a lot of work on the bike, starting with unseizing the engine, new pistons rings, new valves, valve adjustment, coil packs, spark plugs, carb rebuild, pods and chopping the exhaust just behind where your foot sits to ride. The bike will start, and I have...
  19. N

    Engine will not turn over right after replacing rings

    Update, took the engine back apart and the connecting rods for cyl 1 and 3 were tightened tighter than spec, causing the crankshaft not to move well at all. Headed to get new bearings tomorrow morning!
  20. N

    Engine will not turn over right after replacing rings

    I am going to go in depth to give as much info as possibly to help diagnose because I am totally stumped. Problem :Engine will turn all the way with screwdriver and about 50 lbs of force on the crank, but kickstart will not turn the engine over. Back story: This is a 1978 cb750 that was sitting...
  21. N

    Crank not wanting to turn over after replacing rings

    I am going to go in depth to give as much info as possibly to help diagnose because I am totally stumped. Problem: Engine will turn all the way with screwdriver and about 50 lbs of force on the crank, but kickstart will not turn the engine over. Back story: This is a 1978 cb750 that was sitting...
  22. N

    Valve Adjustment/ Cam installment

    Okay awesome, thank you! With the option of doing the cyl 1 and adjusting four of the valves, mine seem to be off and it has me very confused. I have cylinder 1 at top dead center, in between the exhaust stroke and compression stroke, and the cam sitting how it is positioned in the first place...
  23. N

    Valve Adjustment/ Cam installment

    I just completed my first rebuild, putting the engine all back together. I have installed the camshaft at top dead center on cyl 1, and to my understanding is also top dead center for cyl 4 (please correct me if I'm wrong because it makes sense in my head but I'm not 100%), now I am getting...
  24. N

    Tuning for no air box and chopped exhaust

    Okay, sweet thank you. It doesn’t look like the piston hit the valve. And I didn’t find anything that could’ve blown through it. I couldn’t upload my own picture but it looks almost identical to the valve in the link.
  25. N

    Tuning for no air box and chopped exhaust

    Took the engine out, the pistons look pretty rough but the cylinder walls look good so I don't think I need a bore. The valve on cylinder 2 was also cracked, so that explains such low compression on cyl 2. As well as the head gasket not completely sealing on almost all of the cylinders. When...
  26. N

    Tuning for no air box and chopped exhaust

    That would make sense, I'm debating having it bored to 836cc. Is it just as simple as take the block somewhere to get it bored, put the new pistons and rings in, put it all back together and ride? Or will I need to do a lot more if I'm planning on having it bored to that cc?
  27. N

    Tuning for no air box and chopped exhaust

    So I first got it and it had a locked up engine, got it freed, got spark again the it ran for about a week until I tore it down for paint and then chopped the exhaust. What do you suggest? New piston rings and head gasket to increase compression? Or a whole engine rebuild?
  28. N

    Tuning for no air box and chopped exhaust

    I would like to note: when I first got the bike, the engine was locked up from sitting for 15 years. Could have something to do with the rings not operating properly
  29. N

    Tuning for no air box and chopped exhaust

    Compression levels were 120psi at cyl 1, 20psi at cyl 2, 75psi at cyl 3, and 62psi at cyl 4
  30. N

    Tuning for no air box and chopped exhaust

    Could the chopped exhaust mess with the compression enough for it not to run?
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