Puzzled.

[Limeyrider]

Thanks for the heads up Fire-medic ... pretty sure that the jets were clear.... but " pretty sure " may not be good enough !. May be worth another check .... BEFORE everything is put back in place on the bike. In the meantime ... i will be looking for missing sparks at the plugs ... turning the engine over with the plugs out ... not seeing any sparks ..... just another hoop to jump through I guess ! . . Thanks again.

 

[02GF74]

If the carbs are still off, it would make loads of sense to remove the jets from the block to see if holes are clear.

Now the starter is turning the engine, did you reconnect the ignition/turn signal relay? It's disconnection may be preventing a spark - from the wiring diagram it appears not.

Re. Chasing the spark, start by measuring the voltage in the coils.

BTW how come the starter motor lead was disconnected? The engine turned over when you viewed and the only electrical job you did was replace the battery - wad it done then? (I replaced my battery but can't remember if the solenoid leads had to be disconnected)

 

[Limeyrider]

The carbs are back on ... but maybe worth taking off again " just for peace of mind " ...I'm second guessing myself now. I will begin spark chasing at the coils, hopefully the trip will be short !.
As for how the starter motor lead was disconnected .... not a clue !...
Thanks for your input .... I'll be working slowly to find the elusive sparks .... BTW ....,my son saw one plug give a weak spark ... nothing after that ???.

 

[Fire-medic]

Yeah, if they're still off, I'd pull the jet blocks and look at the two brass jets, you should be able to see through both of 'em.

Sorry, I wrote this hours-ago but didn't post it until now, I see your fellow countryman is looking out for you.

In all these pages, I forget if this was posted before: one way to check proper/improper operation, is to switch the coils from one location to another, and see if the omission of fire 'follows' the switch to the new location. Since the front ones are difficult to reach, use the one from the rear which seems to work, on whichever one in the front doesn't seem to fire.

 

[Limeyrider]

Hey Fire - medic, the carbs are back on, but as I said previously, I'm second guessing myself now, looking at the manual it shows two rubber plugs in the jet block .... I don't recall removing those . I DO recall seeing a note somewhere to NOT remove the plugs ???. I have had some experience with chasing sparks ... and your advice on switching coils around is what I have done in the past .... but only on Brit twin cylinder engines .... principal is the same though. Thanks for your input.

 

[Fire-medic]

To remove the two jet block brass jets, the rubber plugs have to be removed. Note they are different, and make a diagram of which goes where. This is where I like to use a zip-lock bag and a piece of masking tape to label things, and maybe a camera phone pic or two. Use as close a tight-fitting slot head screwdriver as you can fit to each jet head. You probably don't need much force, assuming no one has been there before to butcher the brass jet slotted heads. Choose the tightest-fitting screwdriver you can fit to each jet, and give the end of the screwdriver fitted into the brass jet's slot, a couple of good raps with a small hammer. NOT hard! You just want to break loose any bonding of the jet to the jet block body. They should easily back-out.

 

[MaxMidnight]

If you have battery voltage at the fuse then assuming all of the connections are good including the stop switch you should have the same (or near) at the coils.
A measurement there will identify any voltage drop.
Don't ignore the HT connections as these too can be subject to corrosion.
Also chech the connector from the pick-up coils under the motor and those at the ignition unit.

 

[Limeyrider]

To remove the two jet block brass jets, the rubber plugs have to be removed. Note they are different, and make a diagram of which goes where. This is where I like to use a zip-lock bag and a piece of masking tape to label things, and maybe a camera phone pic or two. Use as close a tight-fitting slot head screwdriver as you can fit to each jet head. You probably don't need much force, assuming no one has been there before to butcher the brass jet slotted heads. Choose the tightest-fitting screwdriver you can fit to each jet, and give the end of the screwdriver fitted into the brass jet's slot, a couple of good raps with a small hammer. NOT hard! You just want to break loose any bonding of the jet to the jet block body. They should easily back-out.

Hey Fire-medic ..... I will get around to cleaning the jet block when I have tracked down the ignition spark issue, thanks for the cautionary notes ... much appreciated .

 

[Limeyrider]

Hey Fire-medic ..... I will get around to cleaning the jet block when I have tracked down the ignition spark issue, thanks for the cautionary notes ... much appreciated .

If you have battery voltage at the fuse then assuming all of the connections are good including the stop switch you should have the same (or near) at the coils.
A measurement there will identify any voltage drop.
Don't ignore the HT connections as these too can be subject to corrosion.
Also chech the connector from the pick-up coils under the motor and those at the ignition unit.

Hey Maxmidnight .... I checked / cleaned the connections during the starter motor issue, I'll start at the ignition coils and work out from there ... I should probably replace the H/T leads and spark plugs ... just as a precaution, the plugs actually look brand new ... no carbon on the electrodes.... we have no clue as to when the motor last ran ... the seller couldn't remember either. Thanks for the advice .... much appreciated.

 

[MaxMidnight]

If you replace the leads go for bog standard copper cored lead bought by the foot from your local factor - no need for anything fancy.
Perhaps also change the HT caps as well?

 

[Fire-medic]

go for bog standard copper cored lead bought by the foot from your local factor - no need for anything fancy.
Perhaps also change the HT caps as well?

I suggest following this advice. You can try new spark plug caps, but unless you need replacements, you probably won't notice a difference. The NGK leads are available with and without resistors. Resistors allow you to run a radio, without interference from the ignition spark plug caps. How many of us run radios?

 

[Limeyrider]

I suggest following this advice. You can try new spark plug caps, but unless you need replacements, you probably won't notice a difference. The NGK leads are available with and without resistors. Resistors allow you to run a radio, without interference from the ignition spark plug caps. How many of us run radios?

If you replace the leads go for bog standard copper cored lead bought by the foot from your local factor - no need for anything fancy.
Perhaps also change the HT caps as well?

Hey MaxMidnight ... I began checking voltages today ... started at the coils and followed the direction of the Yamaha manual, I'm not inspired by the findings !. Battery voltage at 13.3 volts. The voltage at the R / W wires at the coils is : coil #1 10.86 v, coil #3 10.05 v, coil #2 10.79, coil #4 10.77. Checking voltage at the coils ... coil #1 8.7 v , coil # 3 8.6 v. .... I could not remove the coils as the screws are rusted solid, so placement of my multi tester probe onto the " spike " contact was " iffy ". The manula mentioned testing at the TCI unit ???. My son had bought a new plug cap as one of the caps was crushed and in bad shape, he bought according to the part number ...but my testing shows the new cap has resistance of 4,800 ohms, the three remaining caps are 10,000 ohms .... which is correct ?, will the new .. 4,800 ohm cap make a difference . New H/T leads will be made up ... and probably new plug caps.

 

[Limeyrider]

Hey Fire-medic .... no radio on this bike

 

[Fire-medic]

Yes, I expect the majority of VMax bikes don't have a radio either. My point is that in searching for the spark plug caps, you are likely going to find listings for either with or without resistors.

 

[Limeyrider]

Hey Fire-medic .....how much difference is there ( ohms ) between resistor and non resistor plug caps ? ...

 

[MaxMidnight]

Resistor plugs/ caps/ leads (you choose) are there to suppress radio frequency interference (RFI). As they have no detriment to the running of the bike and reduce any annoyance your bike may give to others why not fit them?

 

[Fire-medic]

Various values are available, see the chart.

https://www.ngksparkplugs.co.za/products/ngk-resistor-caps/

 

[Limeyrider]

Resistor plugs/ caps/ leads (you choose) are there to suppress radio frequency interference (RFI). As they have no detriment to the running of the bike and reduce any annoyance your bike may give to others why not fit them?

Hey MaxMidnight .... I have no problem in using resistor plug caps ... just wondering how much ... if any ... the difference in resistance MAY affect running of the engine .... one plug cap measures 4,800 Ohms, the remaining three caps measure 10,000 0hms.

 

[Limeyrider]

Various values are available, see the chart.

https://www.ngksparkplugs.co.za/products/ngk-resistor-caps/

Hey Fire-medic .... thanks for the chart .... good to have in the " library ". See my question to MM .... does different resistance affect plug performance ?.

 

[02GF74]

Hey Fire-medic .... thanks for the chart .... good to have in the " library ". See my question to MM .... does different resistance affect plug performance ?.

In theory yes. Putting resistance into the circuit results in a spark of lower voltage, which can get to the point it is no longer reliably igniting the mixture - nobody wants that = reduce performance. (ohms law states you are sapping the spark of power)

The caps should be 10 K ohm
The plugs have resistor in them too. (DPR8EA)
Plug leads I believe are copper wire, low resistance.

is the 5k ohm cap same number as the others? If it is, a lower resistor is indicating a fault.

Having lower resistance means a larger voltage than designed is flying around. One consequence is if the leads insulation is starting to fail, extra voltage may breakdown.

I doubt there'll be a problem but I suggest you fit the lower ohm cap at one of the rear cylinders in case you need to replace the coils or leads.