Resistor Spark Plugs and Spark Caps 1971 CB450

[WYOjoe]

UPDATE. There are two versions of the BR8ES. One has the removable top the other does not. I went on line hoping there were photos of the packaging. There was and it was not what I saw in the store yesterday. I thought I was in the twilight Zone. I knew the 4 digit number had a 22 in it. The worker at Advanced Auto did not realize there were two versions. Now for gapping and see if the bike runs better.


Hi, I just joined. I picked up riding in 2018 after 40 years off bikes. My other bikes are more modern, so I am struggling with my current CB450 which is stock. While going thru the bike which at first did not run, I attempted a continuity check on the spark plug caps. I got no reading for ohms or continuity. A friend who works on Hondas (lives 300 miles away) checked his Honda and found the same, and equally surprised. I watched Motorcycle MD checking a variety of ignition parts and he too was surprised by same.

I know there are resistor plugs and caps but to get no reading on the highest ohm setting was a surprise. Also no continuity.

More to the point, since NGK now only sells the BR8ES (resistor plug) with the top no longer able to be removed (according to NAPA guy on the phone) to make non-resistor type, 1) do we stick with a resistor cap on the spark plug wire, and use the BR8ES? 2) If resistor plug can/should be used with a resistor cap, does the original Honda cap need to be replaced with a resistor cap that can accept the larger tip of the spark plug?

I have set the timing, valves, checked carbs, fresh gas with no ethanol and the bike breaks ups. Starts easy, idles, but any more than 1/4 throttle boogs down. In short the only two things remaining are replacing the E3 plugs the previous owner installed, and finding smaller jets for the carbs. The bike had been set up for 2,000 Ft elevation. I live at 7,200 Ft. elevation, a mile higher.

Thanks,
Any other comments and suggestions welcome.

Joe

 

[ancientdad]

I know there are resistor plugs and caps but to get no reading on the highest ohm setting was a surprise. Also no continuity.

Might be a silly question, but did you disconnect the plug caps from the wires to check them?

More to the point, since NGK now only sells the BR8ES (resistor plug) with the top no longer able to be removed (according to NAPA guy on the phone)

NAPA guy is wrong, there are BR8ES plugs that the top unscrews from, many here are running them.

1) do we stick with a resistor cap on the spark plug wire, and use the BR8ES? 2) If resistor plug can/should be used with a resistor cap, does the original Honda cap need to be replaced with a resistor cap that can accept the larger tip of the spark plug?

Most of these caps can be taken apart, the older ones allowed you to unscrew the inner brass part that attaches to the threaded top of the plug but those are mostly gone now. Most if not all of the newer ones that do not have a screwdriver slot in the area where it fits on the plug can still be disassembled, take a look at this.

Remove the resistor from 5K ohm plug caps

Since the DOHC450 and 500T use 120° plug caps, finding non-resistor caps to work with the BR8ES resistor plugs is more difficult (and expensive) than other models since NGK stopped selling them in the US. The older resistor caps had a threaded connector for the terminal stud on the plugs and...

www.vintagehondatwins.com

I have set the timing, valves, checked carbs, fresh gas with no ethanol and the bike breaks ups. Starts easy, idles, but any more than 1/4 throttle boogs down. In short the only two things remaining are replacing the E3 plugs the previous owner installed, and finding smaller jets for the carbs. The bike had been set up for 2,000 Ft elevation. I live at 7,200 Ft. elevation, a mile higher.

Are you using the stock air filters, or pods? And not that it would cause your problems, but what did you set the valves at? And are the index marks pointing away from the spark plug?

 

[WintrSol]

The NAPA guy is probably right about changing a resistor plug to non-resistor by unscrewing the top - I've never had one that could be so changed. But, if he meant removing the nipple to expose the threads, yes, they are available.

 

[WYOjoe]

Might be a silly question, but did you disconnect the plug caps from the wires to check them?

NAPA guy is wrong, there are BR8ES plugs that the top unscrews from, many here are running them.

Most of these caps can be taken apart, the older ones allowed you to unscrew the inner brass part that attaches to the threaded top of the plug but those are mostly gone now. Most if not all of the newer ones that do not have a screwdriver slot in the area where it fits on the plug can still be disassembled, take a look at this.

Remove the resistor from 5K ohm plug caps

Since the DOHC450 and 500T use 120° plug caps, finding non-resistor caps to work with the BR8ES resistor plugs is more difficult (and expensive) than other models since NGK stopped selling them in the US. The older resistor caps had a threaded connector for the terminal stud on the plugs and...

www.vintagehondatwins.com

Are you using the stock air filters, or pods? And not that it would cause your problems, but what did you set the valves at? And are the index marks pointing away from the spark plug?

Yes caps removed from coil wire
I mentioned NAPA because I got the reply over the phone. I tried to remove the top on a Champion (NGK equivalent, no NGK in stock at the time) and destroyed the plug. I recall unscrewing the tops decades ago, but a lot has changed in the 40 years I was off bikes.
Stock air filters. There were pods on the bike when I picked it up, but dead battery and it would not start. The seller had the original filters I put back on the bike. I drove 300 miles one way to get it so I was not going to leave empty handed.
The video on those guys in Houston said the original OEM was too tight at .0012", but .003" made more sense. I used 0.003" go, 0.004" no-go.

I found the above link on how to remove the resistor. Is this required or suggested when using a resistor plug? The cap will fit the plug tip with the resistor on?

Thanks

 

[WYOjoe]

The NAPA guy is probably right about changing a resistor plug to non-resistor by unscrewing the top - I've never had one that could be so changed. But, if he meant removing the nipple to expose the threads, yes, they are available.

The NAPA guy said the resistor tip does not unscrew.

 

[ancientdad]

The video on those guys in Houston said the original OEM was too tight at .0012", but .003" made more sense. I used 0.003" go, 0.004" no-go.

those guys in Houston's videos are not what you should be watching, they disagree with the very FSMs (factory service manuals) they offer for download. Honda was a lot smarter than those guys in Houston and actually employed engineers when they designed and built this engine almost 60 years ago. Yes, .0012" is tight and it's partly because of where you measure it between the follower and cam lobe, the geometry works out to a larger number at the actual valve tip - but maybe those guys in Houston doesn't think that far. I like to set them at .002", .003" is okay but will make more noise than necessary.

 

[ancientdad]

The NAPA guy said the resistor tip does not unscrew.

The thing is, the tip that unscrews is NOT the resistor, it's inside the plug. The little threaded cap is so the plug can be used in other applications where more automotive-style caps are used.

 

[EzPete]

Yes caps removed from coil wire
I mentioned NAPA because I got the reply over the phone. I tried to remove the top on a Champion (NGK equivalent, no NGK in stock at the time) and destroyed the plug. I recall unscrewing the tops decades ago, but a lot has changed in the 40 years I was off bikes.
Stock air filters. There were pods on the bike when I picked it up, but dead battery and it would not start. The seller had the original filters I put back on the bike. I drove 300 miles one way to get it so I was not going to leave empty handed.
The video on those guys in Houston said the original OEM was too tight at .0012", but .003" made more sense. I used 0.003" go, 0.004" no-go.

I found the above link on how to remove the resistor. Is this required or suggested when using a resistor plug? The cap will fit the plug tip with the resistor on?

Thanks

This line in bold is bull... that's close to 3X spec and I'm pretty sure that the actual engineers had a way better concept of that engine than dudes that take a mallet and a paint scraper to gasket surfaces do.. While the .0012 gauges can be tough to find/use. .002 is very simple to use.

If you have to, order the NGK's on Amazon or find them locally, and just buy a 4-pack. (unless you find the non-resistor plugs, then buy them ALL)

 

[WintrSol]

I have a couple sets of feelers, SAE and metric. Smallest SAE is .0015, but the metric has the correct .03mm.

 

[WYOjoe]

The thing is, the tip that unscrews is NOT the resistor, it's inside the plug. The little threaded cap is so the plug can be used in other applications where more automotive-style caps are used.

This line in bold is bull... that's close to 3X spec and I'm pretty sure that the actual engineers had a way better concept of that engine than dudes that take a mallet and a paint scraper to gasket surfaces do.. While the .0012 gauges can be tough to find/use. .002 is very simple to use.

If you have to, order the NGK's on Amazon or find them locally, and just buy a 4-pack. (unless you find the non-resistor plugs, then buy them ALL)

I have feelers that get below .002" but not as thin as .0012". As far as plugs, there are two types with the same BR8ES. Explains why some say the top comes off and other said they don't come off. The last 4 digits are needed. I bought a box of 4. I will return and get a few more. I was surprised by the .003" vs the OEM spec. But I have a 1959 Royal Enfield Project. Over the years many user mods have been developed. Better venting to prevent leaking. The most surprising is a radical rerouting of the external oil likes. The RE vintage supplier in UK sells the kit. The Brits know these bikes like the back of their hands so if it was a gimmick they would know and warn others on the site. The Japanese do do a very good job of refining designs. Thanks