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Sputtering, stalling and random rpms


jhawk

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Had a horrible ride into work today. There was a stopped train on the tracks I have to cross and my bike acted up and has been doing so since.

 

I noticed something odd almost like it was out of gas kind of lurching. Once stopped at the train, I decided to go another route and all thru 3rd gear it lurched and sporadically lunged untill finally dying after a mile. It wouldn't start at all. I was able to get it started and get to the office a few miles away, but had to practically pin the throttle just to keep it idling. Nor did it sound right while riding. Another thing that happened is the tach would bounce all over the place in RPMs, no matter what the engine was doing. Tach read 0 at some points while sitting at a light in idle and would jump all the way up to past 8000 and all over the place.

 

Bike is a 1988 Honda Hawk. What I can find online states battery, rectifier, coil contacts, carb cleaning, so not really sure where to start. Anyone got suggestions?

 

Thanks!

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test the battery first. If it's dead I'd charge it and then test the alternator output by running the motor at around 4k rpm and looking for 14 volts at the battery. If you don't see a significant increase in voltage from idle to 4k rpm then your rectifyer/voltage regulator could be cashed or it could be your stator. I would have said carbs right off but if your tach was acting strangely and it's electric (vs a cable that runs off the camshaft) then I'd say you have an electrical issue.

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Not familiar with the Hawk model, but I'm guessing from the year that it's carb and not FI.  If it sounds like fuel delivery, check for a dirty/plugged fuel filter, either in-line or in the bottom of the tank?  However, is there a fuel pump?  Disconnect the outlet side of the fuel pump and check flow rate; check for a plugged filter at the fuel pump intake.  If it appears to be electrical, first thing I'd check (after the battery ritual you performed already) is corroded ground connections (at the frame), fuse and fuse box connection integrity, and then go on to trace the wiring circuits for breaks, worn/cracked wiring insulation, melted connectors, oxidized pin junctions.  Lastly, are the plug wires original?  You can lose a lot of high-voltage charge thru cracked/dry-rotted plug wires/caps by jumping to ground.  Replace as necessary.

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It's got a pump, could have failed but that still doesn't account for the haunted speedo which is electronic. Possible they're on the same fuse and it's loose Or bad wiring to the block? That would account for intermittent fuel and tach issues...lemme find a wiring diagram....

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So just got seat off an started bike to run gas out of carbs in case they need cleaning. Noticed back muffler isnt hot like front one.

Sent from my iPhone using Tapatalk

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Is this one of your first rides on it this year, and was the fuel stabilized over the winter?

 

I don't believe anyone has mentioned checking the spark just yet...  I'd recommend it as a way to check if it's electrical vs fuel. I've noticed some motorcycle tachometers run off of the spark signal to the coil also. Use a timing light while it's running and look for the light to cut out indicating the a miss in the spark.

 

An alternative way to test... With the spark plugs, or a tester that can increase the spark gap, look for a miss in the spark while turning it over with the starter. Be sure to turn off the fuel, and disconnect the other spark plugs while testing each cylinder. Otherwise it may fire up & start running... possibly blowing fire into your face. It may or may not show up at cranking RPM's but could help diagnose the root cause without much hassle.

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I loved my Hawk!!  

 

100_3284_zpswdecxzve.jpg

 

I had a similar problem and ended up being a bad Fuel Pump...I replaced it with one from an R6 and all was good.

 

DPG.

Edited by dpgasser
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Ok. chase your plug wire back to the coil and make sure your connection is good. Then inspect the wires that go to the coil, make sure those connections are kosher. If all that checks out then you'll need to check your coil with a VOM and see if it's cooked. Where in ohio are you?

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I'm in massillon, that's between akron and canton sorta. not exactly a short drive. you can swap the small wires between the front and back cyl coil and see if the problem Follows the coil or the wires. from there you can tell if you need a new coil or if you have an issue with the cdi box, the ignitor or the wiring.

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