help my race bike wont start

[ratbag56]

i have spent the whole bloody day going over the wiring trying to find y there is no spark? i have just refitted my engine after a timing chain change, i have checked the timing it correct 4 times but still have no spark, i have fitted the coil mod as i wanted to see wot it felt like but no spark, i refitted the old coils and still nothing! i have a signal for the pick up and i have voltage at the plugs to the coils but nothing can any1 send me in the right direction?

[Davw]

have you modified the loom?

[ratbag56]

in wot way it has a race loom in it?

[Davw]

On the assupltion that the bike was running with this loom and electrics (coils, CDI etc) before the cam chain repacement there are a number of options

1) Both coils u/s - very very unlikely
2) Pick up rotor not the right one (who changed the cam chaiin?) - unlikely - but possible
3) CDI u/s - possible but you have voltage to the coils
4) Are the HT leads made up correctly? - unlikely to be a probelm if you didnt disassemble them


If the bike hasnt ever run with this loom there could be any number of other issues but i wont go into that unless this is a new loom.

Id try it with a known good CDI

[ratbag56]

thanks for the help i have played with it nite i plugged my laptop into the ecu and it said that it was not picking up the pick up (if that sounds right lol) so i checked the conections again and it flashed up it connected, i then found that the connector has broken at the plug so i cut it out put some new connectors in and a spark wo ho now just gotta recharge the battary and get it started now thanks again

[ratbag56]

still wont start i have a great spark now, i checked the timing and its spot on, there is no fuel now i am going to test the fuel pump, just wanted to know if the pump should be working all the time?

[Davw]

Take fuel line off the carbs and see if it pumps when you hit the starter. If it does then pump is ok. if pump is ok then try a quick squirt of easy start in each of the carb intakes and use the jump leads of a car. - Sometimes the first start can be a bit painful. If that still doesnt do it then there must be some blockage in the carbs / carb intakes. Is fuel getting to the plugs?

[ratbag56]

it does pump but not continuously it sort of does a few short bursts, i will try the easy start, i have cleaned the carbs out and put them back to standard as i thought it may have been the different jets i was runnng but still nothing. the plugs are damp but not wet like it was flooding? that's wot made me think it was the pump?plus is the only thing left now! i mite try it with out the fuel filter may be a little blocked?

[Davw]

Pump is faulty or the filter is blocked (sounds likely)- there should be petrol pissing out of the hose when you turn the engine - not a few short bursts.

[ratbag56]

yeah wot i will do 2mrw is by pass the filter and see wot happens i have a new fuel pump rely coming so can try that? thanks i will let u know wot happens

[ratbag56]

it still wont have it i have had it running then it will just die and wont start again! i have put every thing back to how it was b4 i rebuilt the engine, the only thing that is now different is i have some over size pistons in it and they have been under cut, has any1 had trouble starting after these are fitted?

[rover220]

have you done a compression test?

[Davw]

it still wont have it i have had it running then it will just die and wont start again! i have put every thing back to how it was b4 i rebuilt the engine, the only thing that is now different is i have some over size pistons in it and they have been under cut, has any1 had trouble starting after these are fitted?

give us more info -

1) What did you do to get it running?

2) After it stalls does the engine turn over on the starter or not?

3) Have you got the idle set

4) Have you cleaned the carbs and checked the float level

Oversize pistons shouldnt make any differnece

[ratbag56]

i have cleaned the carbs out and reset the float hieght as per the manual, to get it started i had to jump it off the car run the choke on full and keep cranking it then it would jump into life, then die after 5 mins and not start for an other half an hour? i have done another compression test 2day and found the centre 2 pistons down on compression (used a different tester) took the engine apart and found oil on top of pistons and head of valves? thought it mite have been as when it was running there were exhaust gases coming out of the engine breather! i have 2 optoins now:
1. refit my orginal set of barrels with new rings or
2. get holed of a set of rings for the over size pistons (dont know were i can get them though)!