Author Topic: Engine overheat? (Read 1775 times)

TurtleSnifferII · « **on:** November 02, 2018, 08:20:18 pm »

So my CB650 engine died and quit while going down a hill. This had happened a couple times before the past couple of years but was also having electrical problems so I blamed it on that. Ive always been running 20w50 oil and added a new (RR that DOES charge my new AGM battery) so I could avoid overheating. I warmed up the bike today for a minute and a half and took off from driveway, power was good once it was warm and scaled the local hills easily and made a quick trip less than 6 or 7 miles. On the way back, Im going down a hill and the bike stuttered and started to bog then died once I reached level ground. The bike started a couple times but it was weak. The compression was low in the end pipes and sounded really blubbery and was misfiring. If I revved it a little it would kill the bike. You could hear the engine working and a valve that might have been clicking. The best way to describe it was that it felt hollow or empty. There was a noticable lag when throttling because it was slow to respond to throttle and acting lethargic. The petcock was indeed on and I just filled up with gas and battery was reading 12.78v after it died so nothing there. This time it wasn't battery related since it could still spin the starter and the engine would would turn and die. I was able to run start it in second gear a coule times but would die immediately after. Its confirmed that there is oil and its nearly on the max fill line on the dipstick. Spark plugs are also new and the only mod is the GM hei ignition modules. Ive gone on longer trips with the engine hotter than this before in warmer weather and still lived, what gives?

PS I was little more revvy than usual but still reasonable.
Need some leads to follow here plz $:-\$

TurtleSnifferII · « **Reply #1 on:** November 03, 2018, 11:09:38 am »

calj737 · « **Reply #2 on:** November 03, 2018, 11:27:00 am »

Your electronic ignition mod is the culprit.

TurtleSnifferII · « **Reply #3 on:** November 03, 2018, 12:34:33 pm »

How do I test this? I just barely put that on recently and was having this problem way before this mod. The old CDIs were no good and was still experiencing the overheating back then.

calj737 · « **Reply #4 on:** November 03, 2018, 12:53:21 pm »

What’s “overheating”? The engine? The electronics?

The engine is air cooled. Air flow and oil cover most of the “cooling” reuiquirements unless you’re motor is running super lean and you’re beating the snot out of it.

TurtleSnifferII · « **Reply #5 on:** November 03, 2018, 01:03:30 pm »

Okay I just discovered that the flabby sounds were cylinders one and four not firing so I suspect coils. Two and three have spark while others do not, this would explain the air whooshing sound I was hearing. The cb650s from what I could find use 2.5ohm coils and are battery hogs (even before the GM hei) could this be the problem? Maybe I should use different ohm coils? Pinhead never reported any problems with the gm mod and if dont have to then I dont want to dump 200 bucks for old CDIs. Not worth it at this point. The battery drain is slightly less than the old CDIs.

When I got the bike the old coils were split and were no good so I replaced them with new emgo 2.5ohm coils to keep it stock. My current setup is new 5k resistance caps and DR8ES-L plugs all new. Ill swap coils once I remove the stuff to get to them.

EDIT:My apologies, I was typing and didnt see your reply. It looks like 2 cylinders died and thats what I felt happened and mistook it as overheating. This is my first bike and dont really know how "hot" is too hot. But this has happened twice before except now a coil died.

flatlander · « **Reply #6 on:** November 03, 2018, 01:11:39 pm »

LOL i was just going to ask: what makes you think it's overheating, do you see it glowing when you look down?

if you have any parts that say "emgo" on them, toss them in the bin and replace them with something that will not die when you just look at it from a distance. that brand has a reputation of being notoriously unreliable. cheap crap.

TurtleSnifferII · « **Reply #7 on:** November 03, 2018, 01:16:37 pm »

Quote from: flatlander on November 03, 2018, 01:11:39 pm

LOL i was just going to ask: what makes you think it's overheating, do you see it glowing when you look down?

Dont joke about that. When I first had it it would get so hot you could see whitish smoke rising from the engine that will get the gas hot.

flatlander · « **Reply #8 on:** November 03, 2018, 01:24:30 pm »

it was a genuine question:
you stated that you thought the engine cut out because of overheating - yet you did not say how you diagnosed the "overheating". it's really hard to overheat these engines unless you stand still with engine running, or ride at walking speed for long periods - meaning when the aircooling does not work. therefore, overheating as a cause for your problem sounded a bit fishy.

but now that you found a defective coil, i think we can put the heat theory to rest

flatlander · « **Reply #9 on:** November 03, 2018, 01:31:18 pm »

p.s.
i re-read your post - so it's not sure yet the coil is defective. it could also be any of the connections. i'd check those first before swapping coils.
i suppose you checked for spark by removing the plugs from the engine and seeing if they actually produced a visible spark?

TurtleSnifferII · « **Reply #10 on:** November 03, 2018, 01:41:49 pm »

Yes, i removed them and grounded them against the engine and got blue spark for 2,3 and nothing on 1,4. I also used a fresh plug just to make sure. The 1&4 plugs also light gas residue on them and the other two were fine.

flatlander · « **Reply #11 on:** November 03, 2018, 01:57:50 pm »

ok clear. so what you know at this point is that the plugs don't produce spark - the reason for it is unknown. you assume it's the coil which may be right but did you verify that somehow, and did you exclude other possible causes?

sorry if i'm asking obvious things, just trying to understand if you followed a systematic approach and don't jump to conclusions.

calj737 · « **Reply #12 on:** November 03, 2018, 02:35:13 pm »

Swap the coils to the other plugs and try again. That will help determine if the problem is the coils.

Don R · « **Reply #13 on:** November 03, 2018, 07:25:21 pm »

If you have an inline fuel filter change it or remove it and see if it's better. Or water in the fuel that gets to the petcock on a hill? The little filters will gell up and look clean but not flow.

TurtleSnifferII · « **Reply #14 on:** November 03, 2018, 11:30:51 pm »

Okay so after having fun fishing one of the mounting bolts out of the #2 cylinder I was able to conclude that the coil died. I swapped coils and it sparked just fine on the 1/4 side and 2/3 were dead. Just to be extra sure I dug out one of the old original OEM coils and replaced it with the bad coil using the same spark plug leads and got spark despite its kinda rusty. I guess I need to figure out why the coil died but I doubt its just because emgo sucks. I replaced my oil filter bolt with their brand and it works great and no stripped head. Their restrictive air filter was perfect for my bike which was running a tad lean. The coils costed more than other ones online and ebay and I thought 4into1.com was a reputable source for parts.

The problem I encountered when I installed these earlier in the year was the polarity. The coils are not mounted in the same direction on the bike so on one side the positive was up and on the right hand side it was facing down. I figured its a 50/50 shot so maybe that would explain why only one of them died unless polarity doesnt matter. One side has the power black w white stripe and blue wire while the right side has the same black and a yellow wire.

Also to Don, yes I have a filter its this one to be specific. I didnt notice any change in the fuel flow and was still able too flood my carbs pretty quickly back when they were giving me trouble. Ill remove just to see if theres any difference although I would like to keep it.
https://www.ebay.com/itm/1-4-6mm-Universal-Motorcycle-Pit-Dirt-Bike-ATV-Quad-Inline-Gas-Fuel-Filter-Red/113232114583?hash=item1a5d28f397:g:C94AAOSwvIFbjYlk:rk:3:pf:1&frcectupt=true

flatlander · « **Reply #15 on:** November 04, 2018, 12:33:59 am »

the + should be connected to power from the battery but i think chances are good that it died just because it says emgo on it

you may be able to get a warranty replacement but i think ultimately you'd be better off getting OEM coils or a higher quality replacement.

there should be a fuel strainer inside the tank, covering the intake tube of the petcock. if that's present, then no additional filter is needed, as long as you've cleaned the entire fuel system thoroughly. and that original setup is the best for flow, have a look at the parts diagram.
i've noticed this myself when i had an inline filter installed temporarily. especially after switching to reserve, it regularly disrupted the flow and starved the engine of fuel. since i get rid of it and went back to the original in-tank filter, it's all good. also make sure your fuel lines are the correct length and diamater so that their routing allows fuel to flow with minimal restriction, and helped by gravity.

TurtleSnifferII · « **Reply #16 on:** November 04, 2018, 12:57:45 am »

I just checked and the black stripe power cable feeds to the positive on both sides even though their mounted differently so that looks good. There's also a little bit of rust that built up where they are grounded with that green loop in the picture below so I'm going to sand it a little a bring out fresh metal. So does this mean my other emgo will die on me too? Most other coils on the internet looked cheap and they were only 15-20 bucks, these ones were 30 bucks a piece. I dont want to go with oem since the store said they were 180 bucks EACH!! and it would take 2 weeks. Is there another brand you guys recommend and I assume they need to be replaced as a set.

flatlander · « **Reply #17 on:** November 04, 2018, 04:19:03 am »

i'm not familiar with the 650 specifically so hope somebody else can chime in. if you know their electrical specs you can find something suitable but i'm sure someone's been there before you and can advise, or do a site search. dyna may have some?

use dielectric grease on the contacts to protect them from corrosion.

flatlander · « **Reply #18 on:** November 04, 2018, 04:44:12 am »

by the way, on only 2 cylinders your bike will sound like a tractor and power will be miserable - but it will still run. so you might also have something else at play there. but one thing at a time... make it run on all 4 again, then we'll see.

TurtleSnifferII · « **Reply #19 on:** November 04, 2018, 03:29:29 pm »

I just measured the resistance in the coils and found the numbers differ quite a bit maybe this would help to diagnose why their going bad. The previous 2 oem honda ones were both split open before I got the bike and fixed the ignition and now the one of the new ones died so maybe its not a coincidence. I've put less than 400 miles on this sucker since ive owned it.

Original LHS coil 1/4 : 3.8 ohms
Original RHS coil 2/3 : 3.9 ohms
New LHS coil 1/4: 2:4 ohms (the only proper spec resistance that quit)
New RHS coil 2/3: 3.7 ohms

The proper spec ohms is supposed to be 2.5 for the 650s but I find it strange that that the 2.4-5 new one died and the others still work and why the resistance would be so high. They were supposed to be 2.5 ohms for both the new ones but I never measured them when I got em so cant say for sure. Would the higher resistance cause more draw from the battery cause now my new agm looks to be dying as well since the voltage fluctuates when igntion is used but the bike is confirmed charging.

flatlander · « **Reply #20 on:** November 05, 2018, 03:50:54 am »

apparently, you made some mods to your ignition. does that have any effect on the required coils?

TurtleSnifferII · « **Reply #21 on:** November 05, 2018, 01:49:36 pm »

If I remember with Pinhead he had no problems with coils and he had even lower ohm coils.
http://www.geocities.ws/loudgpz/CBheiMod.html
This site shows it on a cb750 which uses 2.3 ohm coils and Pinhead also has a cb650 which works best with this mod. The 650 has 2.5ohm stocks coils with the CDI ignintion. Ive seen some posts on other 650 sites that used their stock coils and they worked out just fine. I think its possible I may have had a finicky rusty ground where the green loop connects to the mounting bolt for the left coil. I''ll buy a new set of coils since I assume they should be matching resistance. Should I also sand off the rust and some paint on ALL four mounting bolts to the coils? There a bit crusty so maybe clean metal will help dissipate the heat since the coils have metal mountings plates where the bolts go. My guess is it may have gotten cooked and died while other was too which increased its resistance. I installed these coils when I first got the bike and was still a noob not caring much for electrics.

If I somehow kill another coil then I'll blame the HEI modules.

kerryb · « **Reply #22 on:** November 06, 2018, 06:50:46 am »

I'm chiming in here because I struggled with an '82 cb650sc with same symptoms you described. It would run down the road just fine for a while and then wither and die. After looking at a lot of the components you are checking, we solved the problem by bypassing the vacuum petcock valve and pitching the pods in favor of the stock airbox. Ran perfect then. What's your air intake system look like? What carbs are you running?

flatlander · « **Reply #23 on:** November 06, 2018, 07:28:03 am »

ok so the page you refer to uses the standard coils. that's good as long as it's a reliable source. not trying to sound negative but you make a mod to a part of the ignition system - then you should be sure that the other parts are compatible, either by cross-checking more sources or by having enough electrical knowledge yourself.

anyway, if you're sure these are the right coils then i'd replace them both at the same time, with good quality ones.
i would not be worried about slightly rusty/crusty mounting bolts. if you really need those in order to lose heat then your problems are elsewhere.

TurtleSnifferII · « **Reply #24 on:** November 06, 2018, 02:13:08 pm »

I'm trying to figure out which coils would be best in terms of quality. Should I just get the regular coils just a different brand or maybe try these magna coils. BTW I called the store yesterday and the oem coils now cost 220 bucks and will take 3 weeks, yikes.

https://4into1.com/dual-output-ignition-coil-honda-cb550sc-650-700sc-750-900-1000-1100f-vf700c-750c-1100c-cbr1000f-cbx-gl1100-1200/#ProductReviews

https://4into1.com/magna-dual-output-coil-3-ohms-honda-cb550sc-650-700sc-750-900-1000-1100f-vf700c-750c-1100c-cbr1000f-cbx-gl1100-1200/

to kerryb thanks for the response. My 650 is all stock with airbox and no pods. My fuel line came routed like this when I got it but guess I should change it to a shorter hose and scrap the filter just to be extra safe this time. It is gravity fed and not vacuum since its only on hose. This one has the PD50B mechanical carbs with elusive parts.

flatlander · « **Reply #25 on:** November 06, 2018, 11:11:49 pm »

220 may be a bit much but i see some around the 150 mark, for example here:
https://www.z1enterprises.com/motorcycles/honda/cb650/electrical-parts/ignition-systems.html
these are from dynatek which is a reputable brand.

of course, you can search the web further. 20 or 30 dollares are at the low end... i have personally no experience with those cheap ones but most of the time, you get what you pay for.

jgger · « **Reply #26 on:** November 06, 2018, 11:33:59 pm »

I haven't gone back and checked, but I thought that the articles from the 650 forum listed a different coil. Maybe go back and check the links I gave you in your other thread, I could have sworn the coils were changed because there was talk of mounting issues.

But then again maybe I'm wrong.

flatlander · « **Reply #27 on:** November 07, 2018, 02:56:38 am »

turtle has concerns that the current coils may overheat - which also is an indication that they may not be the right ones.
i really can't give direct advice here on what is right or wrong as i'm not familiar with the 650 and this specific mod but it does sound like some more research is needed.

TurtleSnifferII · « **Reply #28 on:** November 08, 2018, 10:53:41 am »

Thanks for the link flatlander, I ended up buying the gray 2.2ohm coils you linked. They look like space savers too.

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Author Topic: Engine overheat? (Read 1775 times)