450 Rebel Spark Plug Boots......

[GearJammer]

New thread as per Snorey's suggestion....

Snorey wrote: "Removed Cap Assy. (boot) from the wire and just tested the wire.....good (both of them). (Hmmmmm) So I took the innards out of the boot. (unscrewed the "nut" in the spark plug end) and out came the "nut" and a spring and a.......fuse? (Hmmmm?) I tested the "fuse" and.....nothing (both boots.) Everything else looks and tests good for continuity. There are no markings on the "fuse". I have never heard of a fuse in a plug wire. GJ, can you look in your Honda Service Manual to see if there is anything about that? It is not shown in the exploded parts view, it just shows the boot."

GearJammer wrote: "Checking coils: Disconnect coil leads.

For Primary: When touching each spade connector with the leads of your tester at the same time, measured resistance should be 0.1-.03 ohms

For Secondary: Remove spark plug boots & insert tester leads into the spark plug boots at the same time, measured resistance should be 7.4-11 k ohms (going from Honda Service Manual, hope this "k ohms" stuff makes sense to you, I'm no electrical genius, LOL!)

If measurement is out of standard resistance, remove ignition coil from bracket. Remove spark plug wires from coil & measure the secondary coil resistance between their terminals, measurement should be 3.7-4.5 k ohms

If measurement does not fall within standard resistance, replace coil & re-test. If measurement is within standard resistance, check spark plug wires for open circuit."


Snorey wrote: "The open circuit is in the boot. If you decide to check and your wires are stock, look into the boot and you will see a slotted "connector" (what the stem of the spark plug goes into). Remove the small outer cover. Take a flat screwdriver and unscrew the "connector". Remove the connector and you will also have a spring and fuse come out also. Check the ohms on the fuse. My meter makes a beep when there is continuity (no open breaks). When I check this fuse there is no continuity (open circuit) and it does not beep. The readout show OL (open line). That is where I think my problem lies. When you put it back together, the spring goes first and then the fuse."

[Snorebaby]

Thanks for making a new thread GJ!!! Here is what I have done today.

Went to a friends house and did a little "horse trading". He checked my coil and I worked on his computer :) .

Decided that the "fuse" was a spark arrester or something to reduce EMI, noise or something to that affect. One tested at 5.4k ohm and the other at 4.3k ohm (just tested them by themselves). But when testing the Secondary coil with them in place, there was no reading. Removed the boot and tested Secondary coil through the wires and it was 8.5k ohm (within the 7.4 - 11k ohm specs). Figured it probably would be a little more with the boots in place and everything was good. His test leads were a little short to check the Secondary coil at the coil itself.

So we devised a plan. I brought the coil home and stuck a small nail in the wire end without the boot. Held it close to the engine block and hit start to check for spark. (Made sure the kill switch was in the right position!! :wink: ) They both sparked. Put boot on and inserted spark plug and repeated test. They both did spark, but the suspected "bad" (left) side was kinda weak and irregular. Swapped plugs. Checked again and the same thing happened.

Found something to take the place of the spark arrester. What I did was take a spare gun cleaning rod (solid aluminum) and cut to length of the arrester and replaced the arrester with it. Re-checked and got a better spark. Both spark plugs probably need to be replaced and I will do that this weekend. But my coil and wires are fine. WHEW!!! The arrester apparently is weak. I cut another replacement for the other side. Will install it when I replace the spark plugs.

Now, all I have to do is reinstall the gas tank and try it again. Should get it fired back up. I plan on doing it tomorrow before I go to work (nights) if I don't sleep all day LOL!! I usually stay up late the night before so I won't be a walking zombie at work. Of course, I will post the results.

[GearJammer]

Ubetcha, Snorey!

Not being computer literate, if I horse-traded that way, my bud would kick over my chop & I'd kick over his computer.....hehehe....

Sorry, didn't get into the shop today, but it sounds like you & your Bro were busy taking care of business! I like the way you improvised using the nail in the plug wire & used the aluminum rod to fab a spark arrester. Very cool!

Curious about this spark arrester. So it's some kind of "suppressor" or whatever ? These "new" electrical systems with pulse generators & such are something I've still got to learn. (By "new", meaning that this 1986 Rebel is the newest vehicle I've ever owned, LMAO!)

Bottom line, your day went well & glad to hear that the coil & plug wires checked out O.K.

Oh man, I hear ya about working the night shift. Worked midnights for 8 1/2 yrs. Nooooo fun...except on weekends when we got to make up for lost time, LMAO!

[GearJammer]

Yo Snorey, (We may be posting at the same time....hehehe)

Did some quick research on the spark plug boots. What we've been referring to as a "fuse" is apparently a "resistor", with a spring behind it, as you've discovered, to suppress RFI (Radio Frequency Interference) so that components such as the CDI don't pick up false impulses to disturb normal performance.

[Snorebaby]

(Edit: I work 12hr rotating shifts, so in a 28 day period I only work 14 days. It is ok but this part of the rotation is kinda rough. Worked Friday through Sunday on days and I work Tuesday through Thursday on nights with this coming weekend off. So I don't have much time off in a 7 day stretch, only 1 day.)


That is great GJ. Where did you find this info and can I get one by itself? That was our conclusion yesterday (or something close to it). Even though we didn't know the exact reason, it was a EWAG (Educated Wild Ass Guess). Will the 450 run ok without it? I will need to break down and buy new boots, but won't have the extra money for a couple of weeks. Of course I will have to order it online (will get it from crotchrocket). I am trying to wake up enough to go out and re-install the gas tank and try to fire it up again.

[GearJammer]

Knew that you & your Bro had a pretty good sense of what you were dealing with yesterday, Snorey, just wanted to check it out to educate myself a bit, LOL!

Found it on some auto site after typing in "spark plug boot", "spark plug boot spark arrester", "spark plug boot suppressor" on www.google.com. Sorry, but don't have the exact site written down, but it was an informational explaination saying that there are essentially 2 types of spark plug boots: non-resistor & resistor type, (the Rebel's being the resistor type). Not sure if the resistor part itself can be ordered seperately or not, but for the fairly inexpensive price of new spark plug boots, it's probably better to go that way anyways & also have the peace of mind that there's no cracking of boots, etc.

Snorey wrote: "Will the 450 run ok without it?"...Not sure I'd want to chance that, but I'm certainly no expert. But these Rebels, both the 250 & 450 seem to have a minimal electrical replacement system, unlike electrical systems in the past, so it might be wise to stick with the OEM parts when using the existing ignition system ?

Rotating shifts ? Good grief! Straight graveyard shift was bad enough, wouldn't want to go thru the rigors of rotating shifts...*ouch*

[Snorebaby]

Well I did some more testing....got it to crank up but it is acting like it did before. There is good compression and the exhaust is heating up on the right side and the left side remained cool. Removed spark plugs and compared...the left side looked like it was "wet". Swapped plugs and refired. Same thing. The plugs upon inspection showed the same difference. Leaning toward the left coil being weak. It will spark but not have enough juice properly burn the fuel. They are seperate coils even though they are housed in the same housing. Will also have to check the electricals going back to the rectifier. May also be flooding the cylinder on the left side also. I will have to make the initial adjustments to the carbs to make sure.

If it does turn out to be the coil, I will replace it and the wires at the same time.

(On a side note....I replaced the gasket for the petcock connection to the tank with an O-ring and it is not leaking as of yet. I thought the lever was leaking as posted before. It is dry now that I replaced the old gasket. May have been leaking by it as the original was old and dry. Keep the magic dust handy for this one!!LOL)

[GearJammer]

The variance of pipe temps would normally point to timing, but I don't believe you've been doing anything to change the initial timing, so I'd be leaning towards either carb or coil.

Basics for combustion:

Proper air/fuel mixture
Compression
Spark
Resulting in Combustion

There's a very good chance that the carbs are not dialed in/synchronized close enough to provide the proper mixture, so even with good compression, the mix could be bad & not be allowing for normal combustion.

The coils/spark would be my 2nd guess in order of trouble-shooting, since the carbs have been an unknown here since the carb rebuild. Just to try to eliminate bad spark as a possibility, if you remove both plugs, put them back in the spark plug boots, then hold the firing ends of the plugs to the motor for ground, when you hit the starter button, are both plugs offerring the same degree of spark ?

If you're getting fairly uniform spark from both plugs, I'd wait until you get the manual (it's coming soon ?) & concentrate on the carb issue.

You may have nailed down the leaking petcock, Snorey. But absolutely, will keep some magic dust off to one side just in case, LOL!

[Snorebaby]

The manual is coming soon.....I didn't order it yesterday like I thought I would. I am going to concentrate on the carb situation. I really think it is the culprit as it is the "unknown" as you said. I think I am getting too much on the left and flooding the cylinder.

I believe I am getting about the same degree of spark from both plugs. Will have to do that test again and pay little more attention to the amount of spark.

How do you change the timing? I did'nt think you could do that on this bike. Just a straight forward regulator, CDI and coil.

I really appreciate all your help GJ!!!!

[GearJammer]

I haven't dove into this Rebel very deeply yet myself, Snorey, but am willing to help as best I can.

You're probably doing the right thing in concentrating on the carb situation first so's not to spread yourself too thin & possibly working on things are may actually be O.K. If you find that the plugs seem to be offerring the same amount of spark, you're probably fine in that area.

You're right about the timing being "pre-set" from the factory, I found that out with the 250. The pipe temps was mentioned from my experience with even older dinosaurs...I mean bikes, LOL!

You've got compression
You may very well have adequate spark
That helps to narrow it down to the air/fuel mixture (carbs)

Once you get her fired up again, you can lightly & carefully feel both pipes & see if they feel uniform heatwise. I usually do the light "pat-pat" type of thing to keep from welding my hand to the pipe, LMAO! If they feel too far off from each other, then I'd be thinking about valve adjustments, but would still concentrate on the carbs for now so's not to get ahead of oneself.