xj900/650 motor swap

i've fitted a 900 motor and carbs into my 650 chassis and though it starts straight away and will tickover all day long it will not rev without popping and banging like hell. backfires, spitting etc. the spark is strong, valve clearances/timing is spot on, the battery is new and fully charged, the fuel is new and there are no air leaks anywhere around the inlets. my question is do i have to use the 900 tci/cdi?

 

This is not my expertise at all but I would think that you would have to use the tci from the 900. It only makes sense to me. Sounds like an awesome toy you will have when you're finished.

 

You should use the whole "900" ignition.

The 900 swingarm is longer than the 650's - - prepare for wheelies !!

 

yes, use the 900 electrics
dave

 

thanx for replies. as far as i can tell it's not an easy plug and play tci swap but more like a connector swap around in the tci. the 6 and 4 pin connector blocks are the opposite way round on the 900 to the 650. as i've only got the 650 loom i'll just reconfigure the tci blocks and go from there. there's just one wire different from the 900 tci and that is for rev limiter which i wont need.

 

can someone help me out here tho....why would the engine start so easily and tickover fine if the connector blocks were opposite way round on both bikes? according to the info i've gleaned, the 650 pick up wires go into the coil wiring block on the 900 tci......so in affect i've turned the tci inside out/back to front or whatever!!!! i've since tested the 650 tci on another bike and it works so i've not blown any internal components in it....

 

Sorry. I can't help you on this. But have thought about the mod. Can you drop a picture so we can see how well the engine fits? Would be great!

 

You have no idea if the TCI's are the same unless you look at the schematics of each and compare. Switching the wires around might work, might not and will do damage. 900 engine needs 900 wiring harness and ignition components or you'll fry something eventually. Any job worth doing, is worth doing right the first time.

 

well my xj650 with xj900 motor running thru the 650 loom and re-wired 900 tci runs spot on. pod filters, open pipe, carbs set/balanced, strobed up and ignition is perfect......screams like a banshee and goes like a scalded cat on steroids......if it can be done, it will be done

 

Any pix or vids?

 

Hopefully you haven't fried things and are actually running on raw unregulated electric surging through everything ..... Til it all blows...... Lol
Dave

 

Get a book for the 900 seca electrics. And between that & your 650 book electrics it is actually fairly easy. I have the 650 maxim with the 900 motor on it. It runs like a scalded cat. I probably now have about 50,000 miles with this setup. I had to use some of the 650 parts to swap on the motor. Had to also make some brackets. But what a fun rider it is.

 

Why is it people talk, talk but never post photos ?
You can't be that antiquated....
And I bet that i am the oldest retired guy in here

 

Indeed, pictures or a how-to would be greatly appreciated!