Possible electrical issue

[posplayr]

I have a new data point today. I started the bike and went up a long hill, was going fine until I crested, then got the same loss of power symptoms that I did before, did a U-turn and coasted in gear down the hill, and the bike was back to normal after it cooled off. (I now confirm this is a heat related issue now).

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I dont know what that the BOLD above means but because you seem to indicate the bike was warm that I will deduce you were going highway speeds.(4-5K rpm?). Before you said you had loss of power below 3000 RPM . Indicating a low RPM issue people are suggesting carberation.

Well I don't think a major loss of power at 4-5K RPM is due to lack of carb sync. It is probably igniton which is either a coil or ignitor. So you need to isolaate what it is between coils and ignitor. I would proceedd as below.

A.) make sure the voltage to the coils if above 11V with the key on.

B.) check which pipes are not as warm(unless you already know).

c.) Swap the 1-4 coil to the 2-3 coil and see if the is a change in symptoms )which pipe is getting cold)

D.) If the cold pipes more with the coils then it is coils else ignitor.

You should probably gets spares of both see if that solves it.

[tom203]

I'm having trouble with this . You are going up long hill ( this requires decent power output ) " going fine ", yet when you crest the hill ( and probably back off throttle ) you have a power loss ? Then, you let bike cool off- how long ?- and it's normal again ? After you glided downhill, but before cooldown, how did bike run ?

[posplayr]

I'm having trouble with this . You are going up long hill ( this requires decent power output ) " going fine ", yet when you crest the hill ( and probably back off throttle ) you have a power loss ? Then, you let bike cool off- how long ?- and it's normal again ? After you glided downhill, but before cooldown, how did bike run ?

for all the discussion of manometers what is missing are some of the basic details of power loss. This would be helpful and without would leave most just guessing.

[alnmike]

Thanks for the list of items to check. Gonna take me a couple days to do this.
As far as the power loss, it starts as a little jerking sensation (cylinder misses a beat, then again, ect) and then there is a smooth loss of speed, going 70, couple of seconds, now im going 50, few more seconds, now im going 30, all while the throttle is maxxed. The loss of power continues until I can hold about 10 mph in first gear around 5000 rpm, as long as im not going uphill (guesstimate, im too busy making sure theres no cars around trying to ruin my day).
When the bike cools down, all is right as rain again.

When I was going up the hill, I felt the surging at the top of the hill, I decided to turn around, put it in neutral, bike died, put it in first (still moving) and jumped it, held throttle wide open and used the clutch to come to a stop, turn the bike around and get going down hill, where I let engine braking control my speed (no throttle input) when I got to the bottom of the hill, the bike was back to normal, full power band, 5th gear going 50, twist the grip and get pushed back, ect.

Going 10 miles as 45-50 mph is fine, going 2 miles at 70mph gets problems. I assume the extra load is making the bike get to the temperature that is causing problems. My oil mark is exactly in between the full and add marks in the window.

almarconi

I don't know the maintenance history of your bike but there are certain maintenance items that must be done to an old bike if you ever hope to get it running reliably.

Here are the some of the steps

1. check and adjust your valves
2. properly disassemble, dip, replace o-rings, reassemble carbs, bench sync
3. install new carb boots and intake holder o-rings if your bike has them
4. install clean air filter, make sure air box is installed and sealed properly
5. install carbs, adjust throttle cable and choke linkage
6. set idle mixture screws using highest rpm method or use a colortune
7. vacuum sync the carbs

I have done 1, 2(except for mixture screws, and bench syncing, gonna read about that later),
3 (did the o-rings, fixed a high idle problem I had when I first got the bike), 4,
5 (How do I adjust these, I have the bike idling where I want it via the screw, and the choke linkage has dips where the screws go in),
6 (Need to read about colortunes and do this step),
7 (Need to do this step too)

[tom203]

Well , I don't think it's overheating since it recovers by the time you get to bottom of hill unless it's one long hill! It seems like fuel starvation, but going uphill would push more fuel to petcock area unless your tank was really low. I'd check my petcock/ filter, since it is weak point and should be done regardless - it's a quick job.

[alnmike]

Hah, I forgot; I checked my petcock and the screen was just pristine. I was told on here that the petcock might be my problem, but to go ahead and buy a new one anyway since the rebuild kits dont often work, so I have a brand new petcock on it. Oh, and the tank is also pristine.

My bike is generally pristine, theres no corroded bolts all over the place (the valve cover bolts were slightly rusted, nothing my impact driver didnt solve), very slight rust on the chassis (under the front seat mounting brackets). Its been driven around 8k miles when I bought it, and garaged since new it looks like. Only thing is its been dropped in the driveway (not me), ive screwed the paintjob on the tank taking it off so much (being an idiot and setting it upside down on concrete without cardboard), and there was an oil leak from the valve gasket (ive replaced with real gaskets), but havent cleaned up the oil, yet.

[tom203]

You used impact driver on cam cover bolts? I'm learning something new everyday! Anyways,your "pristine" new petcock means good fuel delivery down unkinked/unblocked fuel line- assuming tank cap vent is ok. Did you check to make sure carb vent lines ( between 1+2, also between 3+4 ) are clear and not blocked as they hang over airbox?

[alnmike]

Heh, well, I kinda used the carb vent hoses to empty my fuel tank when I took out my petcock, so they're clear. The main reason I got my impact driver was the carb screws were stripped. Now that I look back, I didnt use the driver on any valve cover bolts. I believe my tnak vent cap is venting since it leaks fuel when I turn the fuel tank upside down (accidently, got scratches on my tank, dammit).

Next week is get bike back to top shape goal time.

[tom203]

Wait a minute- I want to know how carb vent hoses can be used to empty fuel tank!