Hello everyone! this is a timing issue I believe. I have a 1995 cbr 600 F3. It has started hard from the time I brought it home. Would have to crank it 30-60 min. The bike has 900 carbs & a fuel pump not normally on 600's. The bike ran fine after started, a bit rich though. Where are the timing marks on the crank? Does the the oil sensor stop the bike from starting if it is bad? The bike has fuel & spark. Any help would be helpful. Thank you.

 

Timing marks are on righthand side (on the trigger). It's not adjustable so shouldn't be your problem. Unless you mean the cam timing? I'm surprised the 900 carbs fit. I wouldn't have thought the spacing would be the same. The oil press. switch will not keep it from starting. How did you verify it was getting fuel? Try a lil shot of carb cleaner down carb throats while cranking. Plugs look good?

 

Plugs are good. plugs are wet spayed ethier down carbs, not even a hit! no life. back fires threw pipe & sometimes threw header, once in a while. cam marks are lined up , just no marks on crank or timing rotr

 

Probably an aftermarket advancer hence no timing marks on trigger. Has motor been tore down? It's been forever since I've been in an F3. If it's like the 900RR (and for the most part they are) it's possible to have cams 180 degrees out and still show it's lined up with the marks. On the 900, at TDC on #1 the intake and exhaust lobes on #1 cyl. are facing away from the center of the head. Not sure of the angle, probably in the 50 degree range.
What you need is a stock trigger with the timing marks on it to verify cam timing. Surely there are online F3 manuals available. I'll try and see if I can find one to verify that it's timed like the 900. I'm with you on the timing since you said it backfires loudly. I had cams in my 1000 Hurricane 180 out once and it sounded like a cannon going off.

 

It appears to be a foctory timing rotor.It only goes on one way. No adjustment.I have a cheap manual & it shows the mark on the timing cover to line up with timing rotor on crank. There is only a number 2 on the rotor. I have built one of these bikes beofre & I know what it sounds like when timing is off. The pullling thing is It ran the way it is timed know. Real strong topped out at 165mph on speedo. Will the oil switch stop the bike from starting if there is no oil in it?

 

If it was factory it would have a "T" with a line and an "F" with a line. The oil switch will NOT stop it from cranking.

 

Yeah, if it's been running good it's not 180 out.
Backfiring could also be from the plug wires in the wrong order. I know it happens sometimes if you've had your plugs out or wires off trying to figure something out. Just a thought.
Oh, and I moved your thread over here to the F3 section... maybe get some more help.

 

Thanks for moving my q's to the proper spot. Yeah I put in new plugs & it ran after that. I thought it might help the starting problem. It didn't. I know the oil swich wouldn't stop it from cranking but what about starting even though there is spark & fuel though? So you think it might be the timing rotor then? Should I by a adjustable timing rotor to adjust the timing?

 

I found a stock timing rotor on ebay I think I will purchse it 7 hopfuly that solves my problem. i already bought a used good CDI. No change with either unit. Or I might purchase the adjustable timing rotor. Thank you for your help. Thomas.

 

Personally I'm not a big fan of the adjustable timing rotors. If you're gonna spend that much, might as well add a lil more and get a Dyna 2000 for it. Much quicker starts, advance can still be adjusted, adjustable limiter, plug hotter spark.