plugs and caps

[fishermanferg]

hi I'm refurbishing some things on my xv535 ,now need some advice ,ive heard that it if you have resistor type I have bpr7es ,its better to have non resistor spark plug caps and advice on this ,ive heard its better to take the resistors out of the caps and replace with a bit of wire or a nail is this correct

[Grumpy Old Git]

You need to consult your workshop manual - If the caps are resistor type as standard, then these are 'matched' to your coils - There is a real danger of burning out the coils if you do not use the resistor type caps (and the correct type of Plugs).

[fishermanferg]

the original caps are resistor type ,but the original spark plugs were not ,now the only plugs I can get ,are resistor type plugs have been told ,not to run bike with resistor plugs and resistor caps ,if you have resistor spark plugs then you don't need resistor spark plug caps ,this is what I'm trying to find out ,if its true or not

[JRH]

Taken from the NGK plug cap listings.

All motorcycle manufacturers now comply with current legislation which demands a standard of noise

suppression on every vehicle. This is achieved usually by fitting NGK resistor covers though in many cases a

combination of NGK resistor covers and NGK resistor spark plugs (R type) is necessary to satisfy the ministry

tests. It is emphasized that despite the use of both resistor covers and spark plugs in such engines, due to the

unique and superior construction of NGK products there is no loss of performance or shortening of service life.

so for some bikes you need both.

see what the resistance value of the cap is and check if the plugs offer the same resistance.

Other web pages suggest the higher the resistance in the circuit the "longer" the spark time for clean burn but the plug is more prone to fouling.

So sorry no real help here.

[fishermanferg]

thanks for reply ,you hear so many conflicting theories the caps I believe are 5ohms but no idea about plugs I will take one out and attempt to test it should the plug have THE SAME VALUES As the cap ,I know you saisd some engines are fine with resistor plugs and caps ,I'm just wondering if mine is ,as I said the original plugs were non resistor type ,but te capas were

[Mr Fro]

So why can't you get non-resistor plugs?

BP7ES throws up loads of results on Google...

[fishermanferg]

ok I may try google ,maybe this will help ,the owners manual states the plugs to be bpr7es ,the resiostor type and I believe the original caps to be resistor type also ,the Haynes manual states the plugs to be bp7es non resistor type plugs ,its puzzling ,perhaps you were right in saying that some engines run ok with resistor type plugs and caps ,although ive heard that running resiasteot plugs and caps may damage the tci unit

[Mr Fro]

If you know the plug caps to be original then go by the owners manual - Haynes are not always correct.

[JRH]

if you google resistor plugs and resistor caps they were introduced to stop electrical interference for radios and other electronics, eg ICU.

The NGK caps document list several values of resistance. 1 , 5 & 10Kohm.

[fishermanferg]

thanks jrh you are right ive seen bp7es on ebay ,that might solve what I'm looking for ,its strange but my 1982 Honda cm400 had resistor plugs and caps and it run well ,but if it was a wee bit hard to start the plugs fouled quite quickly ,ive took the resistors out of the old caps and put a small piece of metal in the bike started ok ,but I think since ive bought brand new ngk resistor type plug caps I may as well use them and try the non resistor type plugs from ebay

[fishermanferg]

thanks challenge 100 have sent away for original plugs bp7es and will use ngk caps 5k-ohms

[fishermanferg]

i take the ngk caps that are listed for my model has 5k-ohms resistance will that be ok as I'm planning to use non resistor plugs bp7es

[JRH]

If you google no plug caps one of the results is a data sheet which lists all the caps along with the resistance.

[fishermanferg]

thankjs jrh I know the resistance of the ngk ones to be 5-kohms the original ones I'm led to believe are 10.000 ohms

[fishermanferg]

weel the original plugs arrived bp7es now should I use the original caps or the new ngk ones the caps are both resistor type whereas the plugs are not

[Grumpy Old Git]

You will be OK to use both the original plugs and original caps as specified in your owner's manual. As previously said, Haynes are not always correct.