honda305 Home honda305 Auctions honda305 Gallery honda305 Forum


honda305.com Forum

Login
□ Search
□ FAQ 
□ 
Vintage Honda Owners,
Restorers, Riders and
Admirers

Spark plug fouling

Points Based Ignition | Electronic Ignition Upgrade
mustanger
honda305.com Member
Posts: 36
Joined: Tue May 30, 2006 8:31 am

Spark plug fouling

Post by mustanger » Tue May 30, 2006 8:51 am

Hi FellowDreamers

I'm having trouble with spark plug fouling in 2 (yes 2!) Honda Dreams form 1966 and 1968. After about a half an hour of riding, the bikes stop and what gets them started again is a new set of plugs. A web site described a dry fouling phenomenon which coats the insulation that separtes the positive pole of the plug from the base of the plug as getting coated with carbon (graphite) which is conductive and therefore grounds out the spark. A dirty plug either won't spark at all or sometimes will spark if I hold it a couple of millimeters from the engine, in which case the spark goes from the curly part of the plug on the bottom (the ground part) to the engine. So obviously the current is leaking across the positve pole to the base of the plug thus shorting out the spark. So the web site explains that plugs are supposed to be hot enough to burn off any deposits that accumulate before they ground out the plug. The site also indicates that too hot plug will either burn itself up or get hot enough to predetonate the fuel before the spark has a chance to---the engine will knock and ping. The Honda dealer looked up the recomended plug which was a D(R)8HS. I recently noticed the Owners manual recomended a D6HW under normal conditions and a D8H for stressful conditions. Stressful conditions isn't me, so I guess I need a 6. I don't know what the significance of the W or the S is in the plug number. Does anybody have any guess as to why a recommended plug would foul so quickly in TWO bikes? and does anybody have any feel for how hot a plug (how low a numbered plug) I could go. Are spark plug ratings the same as they were 40 years ago? I don't think I'm running too rich, but even if I were, is it reasonable for any plug no matter how cold it is to foul up in 30 minutes? Do you know what would happen if the plug were to hot, that is is the web site right would I just start knocking and pinging, in which case I could stop before I did any damage?

joeweir1
honda305.com Member
Posts: 761
Joined: Wed Mar 08, 2006 9:35 am
Location: middletown,pa

fouled plugs

Post by joeweir1 » Thu Jun 01, 2006 6:48 am

When I first started to get into these bikes I had same problem with plugs fouling. I thought I had a coil issue since there's new plugs in bike right! But do to inexperience I did not realize I was running too rich and the plugs were indeed fouling and it took only a few minutes to do so.The new plugs looked black after I took them out! They should be a light cocoa or tan color when running correct. Mine looked like that after adjusting my main needle and plugs stopped fouling.Did you rebuild your carbs or clean them?I had rebuilt my carb with a Keyster carb kit and it had different jets than the originals and thats what caused my running too rich.The main needle jet was bigger and I not thinking put the clip on the needle in the same palce as the original and it was letting too much fuel in and causing me my problems. I moved needle up one notch and it fixed the problem and no more fouled plugs.Hope that helps. Joe

mustanger
honda305.com Member
Posts: 36
Joined: Tue May 30, 2006 8:31 am

Post by mustanger » Thu Jun 01, 2006 8:16 am

Thanks so much for your advice. I did indeed work on both carbs. I had no choice. The kits came from ebay and I don't remember the manufacturer. I also don't remember the clip on the needle having any adjustment. I remember it's held into the barrel by a clip, but I don't remember any notches.

At any rate, I guess you're saying either the needle has to go in lower or the hole (the jet) it goes into has to be smaller. Right?

It's peculiar that the bike is running fine as long as the plugs are new. I would think that there would be black smoke coming out the back or rough running.

If I'm not able to find an ajustment or the right carb kit or jets, do you think lowering the float levels would help? Also do you have any feel for what a hotter plug (DR4HS) would do?

joeweir1
honda305.com Member
Posts: 761
Joined: Wed Mar 08, 2006 9:35 am
Location: middletown,pa

plugs

Post by joeweir1 » Thu Jun 01, 2006 4:15 pm

I would check float level, but as long as it is pretty close to the 26.5mm it should be ok and the float needle is sealing when the float rises it should be ok. As far as plugs go I just got the D8's at Advance Auto parts and they work fine.Advance actually list the CA77 on their computer and the plugs.Yes there are notches on the main needle and if you indeed got the Keyster kit you probably got the same as I did and like I stated earlier the main jet was bigger and the clip needed moved up one notch so the needle would go down in further.I think it should be in the second notch from the top if you have the 130 main that came in the rebuild kit.Old main was 120.Also, make sure you are not get any fuel into the pistons while it is sitting.I had this also and it will wash out the pistons(you will here a loud screech from the cylinders when this happens)and foul plugs right away sometimes. This would be a float issue.Hope this helps.Joe

mustanger
honda305.com Member
Posts: 36
Joined: Tue May 30, 2006 8:31 am

Post by mustanger » Fri Jun 02, 2006 7:55 am

This is helping a lot. I've been going to cars shows picking as many brains as possible to try and get a sensible explanation to this. I never knew there were so many people who didn't know squat about spark plugs! I went home and looked at another keihin carb I happen to have and it does indeed have notches on the needle. They're small notches and I have bad eyes and my memory isn't too good either. (The eyes and memory are the 2nd and 3rd things to go!). Anyway, I can't wait until the weekend when I can get those carbs apart and look at the needle.

Thanks again, this discussion group is just what I needed!

rbaselt
honda305.com Member
Posts: 209
Joined: Sat Apr 08, 2006 7:24 pm
Location: Seal Beach, CA

Post by rbaselt » Sat Jun 03, 2006 8:25 pm

I don't understand why those rebuild kits contain 130 main jets, they're way too rich for a stock engine. Maybe if you were running open megaphones, your bike could handle it. Ohio Cycle and possibly Sirius Consolidated should be able to supply 120s.
--Randall

mustanger
honda305.com Member
Posts: 36
Joined: Tue May 30, 2006 8:31 am

Post by mustanger » Tue Jun 06, 2006 7:57 am

I lowered the needle one notch over the weekend. At first I lowered the needle 2 notches and like a dumbass I did it in both bikes without even testing them. Neither would start, so I lowered them back to one notch above where it was when it was fouling. I rode one bike around for 10 miles--that's 5 miles farther than I ususally get and when I took out the plugs to compare how badly they had fouled, they looked better than when I put them in!!!! What a difference a notch makes! I would have never figured this out by myself.

Thank you, joeweir1. Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you Thank you!!!!!!!!!!!

Post Reply




 

CB-77 | CYP-77 | Road Test | Riding Log | Literature | Zen | Marketplace | VJ Survey | Links | Home