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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: notcoffeetable on November 05, 2016, 01:20:59 PM
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So my father-in-law has a '91 K1 which he bought several years ago. He's letting me take it over because, while he loves the bike, it doesn't really fit him (he's more of a cruiser with all the bells and whistles type guy). The bike sat for a year, covered, but not really garaged, before I got it running (new gas, new battery). I know it has had maintenance by a local import bike shop, though I don't know the full service record.
After ~100 mile ride the other day it started bogging down. It would be running well, then suddenly the bike would start dropping RPMs and the throttle's responsive ceiling would get lower and lower. I'd pull over, turn it off and sit for 5-10 minutes. Then I'd start it up and it'd run fine for several miles, before I'd have too do the same process again. If I didn't wait long enough it would be hard to start as if it was very cold without enough choke.
My first thought was overheating as the symptoms were similar to when my Trans Am would overheat. But I was able to get the bike to cool down and the problem persisted. The next time I rode it, everything was fine though I only went ~20 miles. Since getting it running it's probably gone about 300 miles and just ticked over 10k on the odometer. My current hypothesis is junk in the fuel system is causing problems. I'm hoping the gurus here have some advice.
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Since it sat up for awhile, a good first guess would be the fuel system. It needs to be checked and verified clean from end to end, i.e. fuel cap gasket, vent line, tank, pump and pump vibration isolator, filter, lines, rail, injectors, regulator.
i like to drain the tank and catch the contents in clear plastic jugs to inspect for water and debris. If those are present it makes troubleshooting easier.
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+1(I'm no guru)
At 10k there won't be much maintenance history!
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I'll say fuel filter. pretty common issue and cheap and easy to fix. there's threads on compatible ones, basically go to an auto parts store and find an all steel one with 1/4" nipples about the same size as the one in there now.
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5/16" ~= 8mm
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+1 on the fuel system. Fine debris at the bottom of the tank getting stirred up and blocking the screen on the fuel pump. Or blocking the inline fuel filter.
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Remove fuel tank cap and inspect. Check the rubber damper holding pump, check fuel lines, pull pump check screen and for junk in tank. Replace filter, drain tank of water, and replace bad parts. Get no ethanol gas, bottle of Techron added and ride it hard.
Report back if that cured it. If not phase 2
Sent from my iPhone using Tapatalk
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5/16" ~= 8mm
could be, I think I'm succumbing to anhauser's disease :yes
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i know what you're saying, i've got the yinglings...
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Thanks for the advice! I'll report back when I get a spare weekend to checkout the top end of the fuel system.
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If it was a plugged filter the symptoms would be present across the board.
The screen on the bottom of the pump is a possibility.
My K1 had sat for 8 years and the fuel was solid shellac.
It needed a full inside tank rebuild and cleaning.
Once I did that it ran fine but I noticed a small weep on the left side seam. Took the tank off and found several pinholes
on that sides seams.
I used the silver type tank sealer after thoroughly cleaning and etching the inside of the tank.
This is a two week process.
That was 6 months ago and no problems since.
Good Luck
Don