Alright, this is my first CBR but I'm by no means new to bikes or hondas, so I'm trying to get a feel for if this is a common(ish) issue, or if anybody has any ideas.

Got the bike (94 F2) with a used engine (crank locked up in original) that the guy had put in turned over, but had never started. I pulled the carbs which were clean, cleaned the air filter (K&N), put the radiator back on with new coolant, changed the oil filter and put in new 10w40 oil. The bike will start up without a problem (though seems to be very cold natured) and idle fine. it starts to pull fine and seems to run without problems up until about 5k RPM, then kind of stutters and sometimes a slight knock until about 8k RPM, then BAM it wants to jump out of its skin like a two stroke hitting the powerband.

It really feels and acts like dirty carbs, but I know they're clean. I didn't pull the needle jets, but there is NO indication that they'd be dirty because every other jet was squeaky clean. And the oil light... I know it's got the right amount of oil in it. The wiring seems a little wonky (side stand light worked at one point... now it doesn't?) so I'm thinking maybe it's just wired wrong.

Anything to watch out for? I haven't heard or seen any indication of a low oil pressure situation. Just that the light stays on at all times. Where is the sensor? Could it be bad?

Any thoughts or ideas, experience or stories welcome!

 

I'd guess bad sensor on the oil light issue - although a weird wiring issue could be an issue.

After I wash my bike, every time, the Neutral light will stay dimly illuminated when the key is on even when the bike is in gear. After a day or 2, whatever it is dries up and all is normal.

The honda manual I have on my PC doesn't mention any specific troubleshooting for the oil pressure sensor. When I get home, I'll check my Clymer manual and see if there is any static testing you can do to see if it is working or not.

 

I'd say the stuttering might be an air leak, or carbs that need to be synched. after 8K maybe everything is getting completely off the low speed jets and is running only on the highs? Just a guess.

 

hey,thanks for the replies. I notice you're in west monroe... That's actually where I picked the bike up last week. I was down there for the graphics shutdown! Small world, huh?

Really good idea about the slow jets... Makes sense, but I doubt it because they were squeaky clean. I'm not TOO worried about the oil light because it seems to be getting plenty of oil. I'll look for open vacuum hoses and see if I have a leak somewhere. Does your clymer have a vacuum line routing diagram?

 

Ahh - did you get the one off craigslist? JNSRacing here on the forum was thinking about getting that bike. Unfortunately even in this small town, I had never laid eyes on it.

Where's home for you? Were you working a shutdown @ the Riverwood plant? That papermill makes the whole town smell like a wet fart from time to time.

I can check the Clymer when I get home for you. You can download the Honda F2 manual from here:

http://www.stephygee.com/F2manual.zip

 

I did get the one off craigslist. Ended up giving the guy a grand, but it was a bit of an ordeal. The bike's engine locked up and he decided to rebuild the bike instead of selling it, so he got another engine and new plastics, etc. Wanted 1500 and I offered 1k. So far it was a really good deal but there still appear to be a few gremlins. I'm thinking of bypassing the sidestand switch because it was causing me problems earlier today on a ride.

Just the usual basket case junk to deal with, y'know? No spacer on the front axle, and I didn't realize that 'til I tried to pull the axle and swap the speedo drive to the CORRECT side.

Anyway, today I was riding and my tach slowly (as in a matter of hours and miles) stopped reading. it got lower and lower, reading about 3k when I knew I was running more like 8k.

ALSO, the stutter is all through the power range, I just hadn't ridden it enough to notice it when I created this post. It acts like a spark issue, because it runs but not super well. It doesn't smell rich (but I haven't pulled any plugs to look yet). I'm kind of thinking the sidestand switch has a short and could be causing weak/constantly intermittent spark. The switch just kills power to the coils if it's "down" , right?


Hmmmm. I need a new set of clip ons too.

 

A bit more info as I'm researching in the manual... It REALLY seems like a spark issue. Side stand switch line (b) is connected to frame ground when switch is in the "up" position.. So theoretically you could bypass the switch by connecting that to constant ground.

I've got some things to test but so far I'm really liking how that manual is laid out. Thanks for that. Do you happen to have a copy/link to the clymer manual? I'm a big fan of clymer.

Basically... I think it's really boiling down to a gremlin in the ignition. hopefully the little magical black box is good, but who knows until I pull everything back apart and test it.

Oh - and I never answered your questions RE: papermill. I don't know if it was the one you were talking about, but it was the one right on Thomas road, "graphics" was the name of the company. I hear ya about the papermill smell. It's cause of the black and white liquor (chemicals) they use. That mill is REALLY not bad compared to the one in Crossette, AR (home to me is north central AR). That mill will make you sick at your stomach just being in there.

 

My Brother in law works for that Georgia Pacific plant in Crossett, he drives in from Monroe though - he says he can smell when he's @ work, and smell when he gets home, lol.

I haven't found a link to the Clymer manual online. If I had a decent flatbed scanner, I'd probably have started on creating one. I picked mine up on fleabay cheap (like $10 iirc), but I got lucky - looks like the cheapest on there are about $22 shipped.

Yes - looks like the sidestand switch throws ground to the Ignition control box when the stand is in the Up position, and the clutch is pulled in. Otherwise the ignition box gets a ground signal through the same wire when the gearbox is in neutral. Tthat ground signal is routed through the main chassis diode though - so there might be another point of failure to research.

Luckily, it sounds like you are pretty understanding of chassis electrical - on a motorcycle at least, there's a lot less chassis and hidden wiring to troubleshoot.

 

you might want to put eyeballs on the coils and the connectors going to them. there's been more than one rider on here that have found issues there. Even including improper coils in place of what should be OEM, and plug wires that didn't have endcaps on them.

when I tore my bike down, one of the coils wasn't bolted down, and one of the signal wires had rubbed bare against the frame.

 

Been there, done that. I actually had the bike quit on me (symptoms of a coil going bad... sputtering and coughing, "felt" very spark related vs. fuel) and I checked the plugs to the coils right then and there on the side of the road. When the coils had cooled it started back up. Seems to do worse and want to quit on me if I really get on it and hit up towards the redline.

I looked at the wiring diagram and it appears the tachometer is fed through the yel/grn wire coming from the ICU box... uh oh. That has me a little worried why the tach would be failing if it were unrelated to the black box.

Like I said, I'm new to the CBR world but by no means new to bikes. I've got 4 other bikes that I'm always wrenching on so a new project is just fine by me .

I'll bypass the sidestand and see if that helps anything... I'll report back