kat motor timing?? problem or...

[sparki]

i posted this over on OSS too so please accept my apologies. just need a few opinions as to what i am likely missing

ok.. bear with me while i describe whats what

had a 1074 in my kat that was a little ill... so got a later black 1074 to go in it. while that motor was waiting to be fitted i did a few bits n pieces, the motor ran fine before being taken out of the other bike.

i stuck some efe cams and slotted sprockets in it.... all ok. worked out the timing thing and all should be fine. everything turned over no problem.

anyway, get the old one out and the new one in yesterday and it's farting and backfiring out of all orrifices... so check the coils and they're all on the right plugs... thought i'd fecked up the cam timing so pulled camcover and counted the teeth... still had 20 pins between #2 and #3 so that was ok. everything lined up ok. thought i'd double check on the old motor to see if i was a complete twat and all lobes etc are in pretty much the same place as the non slotted wheeled sprockets... as it was my first tme with slotted sprockets i stuck the std ones back on to be sure.... Now the only difference is the cams.... efe vs std 1074 cams. everything lined up, pin count all good, all back together...... still the feckin same.

coils are dyna and worked without issue before engine was removed. carbs haven't been touched and came off the running kat. ht leads are on the right coils.... but still farting and backfiring and blowing outta everywhere as though the timing is WAY out.

we did cut the plug off the pickups on the "new" engine as the connector was f$%^%$.... but we used the connector off the "old" engine. blue to blue and green to green... going into the std ignition box. other than that coils haven't been disconnected since god knows when. left to 1 n 4, right to 2 n 3. dyna green 3ohm

need some ideas cos i'm sure it's my fault but feck knows where.... seem to be going in circles atm so any pointers most appreciated...

cheers

[FBJ]

Hello sparki. Got Efe cams in one of my 1074 motors on stock sprocket. If u ain't degreed in the cams then swap the blotted sprocket back for the kat ones. Efe. Cams are normally dialed in at 110 110 degree I think.

[johnr]

check that the mechanical centrifugal advance retard on the ignition rotor is working. if the motor has been standing then they might have seized so you could either be trying to start it fully advanced or trying to run it fully retarded. take the cover off, with the engine off get hold of the ignition rotor and twist it, you should be able to move it about 1/8th of a turn without the crank turning, and when you let go it should spring back.

[sparki]

Hello sparki. Got Efe cams in one of my 1074 motors on stock sprocket. If u ain't degreed in the cams then swap the blotted sprocket back for the kat ones. Efe. Cams are normally dialed in at 110 110 degree I think.

Cheers John - swapped out the slotted sprockets yesterday afternoon when this began... It's back on the std sprockets now...

[sparki]

check that the mechanical centrifugal advance retard on the ignition rotor is working. if the motor has been standing then they might have seized so you could either be trying to start it fully advanced or trying to run it fully retarded. take the cover off, with the engine off get hold of the ignition rotor and twist it, you should be able to move it about 1/8th of a turn without the crank turning, and when you let go it should spring back.

Thanks John... I got all excited when i tried this as it was stuck at first... Few twists and its freee again... Tried starting and same as before.... Some good popping out of the pipe and ats it

Had the carbs off, and theres no rags in the inlets, exhaust has been off and that's clear too. 100% satisfied the cams and 20 pin spacing on the sprockets is correct. Only things left are coils, ignition, pickups and plugs. The knackered motor was started just before I pulled it out so I could drain the oil and get into the clutch as I needed a few bits. All was working fine then so the only difference is the pickups from the "new" motor... Even used the plugs out of the old motor. Gonna swap the pickups and see if that's it. The new motor was run maybe 3 months ago though.... Fired up easily with no strange characteristics... Revved nice so I'd be surprised if it were the pickups.... Still. Nothing ventured eh!

Thanks again...

[sparki]

Turns out it was the plug we'd changed between the pickups and the ignition box... The pickup wiring had the same colours going to the same cylinders so we matched the colours to the ignition box... As you would. Blue to blue and green to green.

As soon as I changed the wires around.... That's blue to green and green to blue it fired straight up.... Mechanical advance has since been stripped and cleaned up... Regreased and is now nice n smooth again too....

How does this make any sense?

[johnr]

makes sense to me.

[sparki]

thanks all for the suggestions.... Nutty thing