DirtyToes

you can SKIP the first half of this post as it's mostly bullshit

i'm pretty sure this has never happened to anyone so I didn't bother searching...

rebuilt motor...put everything back together...tip-over mod...kleen air mod.
(ex: http://cbrforum.com/forum/showthread.php?t=62786 )

I fully assemble the bike, and try to crank it for the first time...cranked very slowly for a 1-2 secs then picked up. (eheh....ehh....ehehehehehehee)...cumbustion!

revs kind of slow....i let it warm up....i rev it up to 10k np....i hit the rev-limiter....the bike shuts off! and is seized...won't start again.

as pissed as I am at this point, I start taking off the bolts for the clutch cover....as i take off the last bolt, the entire cover, shoots/pops out....and alot of smoke starts coming down the side of the head (through the cam chain port)...without touching anything else, i put the cover back on, and wallah, the bike starts again...hit the rev-limiter...seized, again....this time i just take out the oil-fill plug...and it goes psssstttt identical to a deflating tire...

i remove the cap completely and started the bike, hit rev limiter, it did not seize but smoke was shooting out of the hole.

I undo the KLEEN air mod and put the PAIR valve back in, and the motor no longer builds pressure or seizes.

WHAT THE ****??!!

[SKIP TO HERE]

...anyway, for some reason the Kleen air mod, caused excessive pressure to get built up in the motor, thus making it seize and shut off...until the pressure is reduced or somehow escapes.

I've done the kleen air mod on 5 other f4is before so I know i'm doing it right and it's a problem with this motor...

is this a problem with my head, valves, ports...anyone know?

old man roger

didnt go to your link i just read the post and it sounds like if you did in fact do the clean air mod right maybe the reed valves might be stuck or some one installed block off plates where the reed valve are supposed to be

DirtyToes

thanks for your input...but that's a negative

i gutt and checked the reed valves....they are clean and they open just fine (negative pressure)

...i also tried sticking a small metal wire through each of the 4 holes and none of them were plugged. i could get it pretty deep in there. the wire stops at the exact same distance on all holes.

whats at the bottom of those 4 holes? ...in the middle of the head somewhere.

i think whatever is down there isn't opening...(i've never gutt a head so idk the internals)

fyi...i used this head off a blown motor...only problem with it was 1 bent valve which i replaced.

old man roger

those holes are supposed to go all the way into the exhaust port , some racers do plug them if they get port and polish work done to the head ..

if they are blocked then even if your reed valves are working they wont create any scavenging effect , start the bike with the center hose from the valve disconnected and see if you get suction there , you should and if you dont then you need to find out whats causing the blockage ..

old man roger

unplug the valve so it stays in the open position while testing

old man roger

the exhaust creates pressure and suction but the reed valves only allow suction so the exhaust basically pulls a small vacuum through those holes , if those holes are closed off the blow by from the combustion chamber will create pressure in the crank case and it wont have any where to escape ..

it can escape through the air box into the throttle bodies and out the exhaust when you have it all hooked up like stock but if they are blocked off and not creating a small vacuum and with the clean air mod done you will just build pressure in the crank case .

if they arent blocked off the clean air mod creates a small amount of vacuum in the crank case which is good .

DirtyToes

I see...once again wise words, from the wise one...now with nearly 80k posts...holy shitt.

lol

anyway, that xplains it and makes complete sense. i'll try what you said tomo, but I'm already pretty sure there won't be any suction on either of the valves....I can't figure out WHY tho. :-x

old man roger

if there is no suction with the bike running and the valve unplugged then the ports going to the exhaust chamber are either plugged or the reed valves are in wrong , they need to be installed so they can get sucked open from the bottom ..

DirtyToes

yepp, just checked it...ZERO suction.

I replaced the entire head cover with another one I had laying around (with 2 other reed valves)

.,..so that proved the the reed vales are not the problem

so the order is:
pair-valve > hoses > head-cover > pair ports > reed valves > hollow dowels > ???

whats is the "?" ? ....is it just open to the exhaust or is there something that opens that?

old man roger

the holes go into the exhaust port , if you were to take off your header and look in the port you would be able to see the hole unless like i mentioned before some one had that head ported and polished in which case they may have just filled the hole .

if this is the case just plug the two hoses and leave the crankcase vent tube vented to the air with a filter on the end of the hose .

DirtyToes

ohhhh...i see what you mean now.

thanks dude