Tach problems, + backfiring
 

Hey all, first post here but avid reader. This site is a godsend.
Questions...
'90 CBR600f
I just bought it used, a few days ago, and had it running once, for a bit, but it was blowing some major smoke out of the back. Now, it wont start at all, just those damn gunshot backfires.
I wanted to check the spark plugs, and from the clymer manual it makes it sound like its a breeze, just twist em and they're off. However, from what I can see (I'm a car guy, not a bike guy) I need to remove the whole top portion of the engine to get to the plugs. Is there some special tool to get to them? Even throwing a finger down the hole, i can only barely reach the top of them. Am I missing something blatantly obvious?
Anyway, next on the list.
The Tachometer. When the engine was running, it didnt do a thing. No twitching, nothing. Any diagnostic hints on that, as from what I can tell, all the wires are intact. Do they just go bad over time?

Finally, rewiring the bike. It seems like some of the wires arent in such good shape, and i'd like to get the whole harness redone. what, in michigan, do you think id pay for this?

Thanks!!!!!

Of course, the day i get the bike, we get a nasty snowfall -.-

RE: Tach problems, + backfiring
 

first off, welcome to the site and congrats on your buy!

now, do you know the condition of the bike prior to you buying it? was it sitting, had it been ridden....stuff like that. sounds like you are having issues from gunked fuel or unsynced carbs. first you should realize that backfiring is caused by too much fuel being injected and it burning up in the exhaust is the backfire. so evaluate all the options of a rich fuel mixture and one of them should be your problem.. you could have one of many or all types of problems from gunked carbs, flooded carbs, fouled plugs, or it could just be running too rich.

the plugs are not the easiest thing to remove but it is possible to get a socket in there without removing anything. some people remove the radiator to give more room.

im not so sure about the tach unless the wires are bad. it is not uncommon for wires on an F1 to be corroded and bad. when they are on there, you can get a decent wiring harness off ebay for anywhere from $10-$100. new from honda they are $180. you can get one for $132.84 from Service Honda or Mr Cycles.

http://www.servicehonda.com/parts.ph...etprice=Submit

or

http://www.mrcycles.com/fiche_sectio...1990&fveh=3039

select 'Wire Harness' from the drop down, #10 on the list.

both of those places take a bit to ship, 7-10 days.

RE: Tach problems, + backfiring
 

plugs aren't too bad to remove. i unbolt the rad and move it up and out of the way, get a socket to undo the plugs, and then a telescoping magnet to pull it out. while out you might as well check cylinder compression.

i agree with rrasco on carbs. more than likely it is a rich condition. maybe the spark isn't hot enough and you are not getting a complete fuel burn. if plugs look okay, you may have to look at the coils. as for smoke, you didn't say what color, but could be oil getting into the cylinder. as i said above, check cylinder compression.

is there any damage to the instrument cluster? if so, the tach could have taken a hit if everything else looks okay.

as for the wire harness, i would take a look at the salvage yards and ebay.

RE: Tach problems, + backfiring
 

Check the fuse panel and make sure you don't have any toasted fuses. I think their is a fuse for the tach if I recall correctly.

If thats not it, I would bet the tach wire has come loose from the wire main harness under the fuel tank and air box.. I think it's the yellow / blue wire (simple bullet typeplug).

here is a link to rrasco's wiring diagram for the hurricane.
https://cbrforum.com/m_186735/tm.htm

Before you go andtear the bike down to get to thespark plugsuse rrasco's wiring diagram and check to make sure you have the plug wire correct, this would make it run bad if you had the wires mixed up.

goodluckon getting her running!

RE: Tach problems, + backfiring
 

Spent the last two hours with the carbs spread out over the kitchen table (it's too damn cold outside), and wow, were things messed up in there... it was almost like someone just spread grease over all the jets, stuck it in the dirt, and threw it in the bike. I'm confused how I ever had it running in the first place. Nice and shiny now though.
Speaking of which, when i first pulled her out of my truck, i fiddled around a bit and managed to get her started up, but what i noticed was, the only times that she started, the fan kicked on as soon as I turned the key to the On position. Any guesses? I'm gonna make my way over to the clymer and look through the wiring diagrams, i guess. How interconnected are the fan and the parts related to ignition? I hope I dont have some, improptu, juryrigged wiring harness to go wading through -.-

RE: Tach problems, + backfiring
 

then you are lucky to not have a wiring harness like mine. i have been wanting to replace mine since the day i bought it.

RE: Tach problems, + backfiring
 

Nothing. -.-
I cleaned the carbs, checked the spark plugs and the wires. I can feel the fuel pump kicking on when i crank it if i lay a finger on it, so i'm assuming theres gas. My petcock leaks horribly when its just standing still, but when gas is sucking through it it doesnt, and it stops leaking when i crank it. I know theres spark- I zapped myself, forgetting i had to ground the spark plug when i was checking it. When i throw some starting fluid in, it backfires, but then it seems to catch, four or five times, but faintly. It's teasing me now -.-
*repeats the mantra "you don't need the dealer, you don't need the dealer"*

RE: Tach problems, + backfiring
 

do you get spark from all the spark plugs. if the spark is weak, may want to check the coils, there are 2. one for each pair of plugs.

check cylinder compression if you can.

RE: Tach problems, + backfiring
 

Fuel, air, and spark (and compression and timing) are required for the engine to run.

I doubt air is a problem, especially if you've got the filter off to spray the starting fluid in. I assume you've been playing around with the choke.

As a previous poster mentioned, check all of the spark plugs for spark and condition of plug. If they're fouled or damaged or gapped incorrectly, fix 'em. new plugs are cheap, and can have a huge effect on an engine.

Timing - Shouldn't be an issue

Compression: Test it, but if there's alot of air coming out of the pipe when it cranks, it's probably not too bad.

Fuel - I haven't gotten into the fuel system on my hurricane, but I wouldn't assume that it's working properly. Is there a way to disconnect the fuel line at the carburetor and then turn on the bike to see if fuel sprays out of the line?

Do these bikes need valve adjustments?

RE: Tach problems, + backfiring
 

yeah, they do need valve adjustments every so many thousand miles or else they will get "tight". bad for the head.

there is a main feed to the carb rail which in turn feeds each individual carb. it's a pretty fat line compared to all the others on the carb stack. just disconnect that or disconnect from fuel pump and turn key to "ON" and then press the start button. have bucket ready.