Author Topic: HD 125 tops out at 40mph???  (Read 2041 times)

kk15501

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HD 125 tops out at 40mph???
« on: June 24, 2013, 09:37:43 AM »
Seems I have fixed the fuel backing up into the airbox and oil (thanks oot), now when I take it out for a test drive, wot gets me to just about 40mph. Here is what I have done so far..... taken the carb out, disassembled completely and did an overnight soak in carb cleaning solution, soaked the jets and non rubber/plastic parts, assembled, put pilot back to 2 turns as was before, checked diaphragm for tears. Scoot idles smooth, sounds strong as you rev her up, no misses or sputters during acceleration. I'm pretty sure it has something to do with a carb adjustment, not sure where to look next. Any advice is welcome and appreciated.

Thanks, Karl

ootscoot

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Re: HD 125 tops out at 40mph???
« Reply #1 on: June 24, 2013, 11:21:56 AM »
The pilot jet should be screwed in all the way, the Air/fuel mixture screw should be 1.5 turns out.
Ooty's Scooters - Santa Barbara, CA.
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kk15501

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Re: HD 125 tops out at 40mph???
« Reply #2 on: June 24, 2013, 01:59:14 PM »
Thanks oot, mix at 1 1/2 turns, pilot all the way in. Still barely makes it to 40.

kk15501

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Re: HD 125 tops out at 40mph???
« Reply #3 on: July 02, 2013, 12:54:17 PM »
I finally did a compression test, did not have a 10mm adapter. Max psi is 130, manual states should be 170ish. Bad rings? would this cause lack of top end speed? Thanks Oot for your help

kk15501

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Re: HD 125 tops out at 40mph???
« Reply #4 on: July 02, 2013, 12:58:49 PM »
And I wonder, if this was caused by the gas in the crankcase, will the rings go back to normal?

Miki

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Re: HD 125 tops out at 40mph???
« Reply #5 on: August 02, 2013, 12:43:52 AM »
You should replace the rings and maby the piston and the cylinder, befor that check the rollers.

ootscoot

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Re: HD 125 tops out at 40mph???
« Reply #6 on: August 02, 2013, 09:02:40 AM »
The rings may have been washed by fuel. Are you seeing smoke?
Ooty's Scooters - Santa Barbara, CA.
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kk15501

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Re: HD 125 tops out at 40mph???
« Reply #7 on: August 03, 2013, 12:52:00 PM »
Yes, there was quite a bit of blue smoke

kk15501

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Re: HD 125 tops out at 40mph???
« Reply #8 on: August 06, 2013, 11:11:55 AM »
ootscoot, thanks for all your help so far, really goes beyond and helps with what the manual lacks. Status update, replace the rings, piston and cylinder look great with no scoring. Now here is my issue....

1. After I finally got the timing chain on the mark at TDC on the flywheel, the engine stops at half a turn using the 10 mm on the timing cam bolt. I am thinking cam 180 degrees off? Piston is stopping on valves open when should be closed?

2. As I was trying to rotate the cam 180, the mounting flange for the gear came off the camshaft, there is an index mark on the mounting plate but not on the end of the camshaft. How can I make sure I press it in the right place or does it not matter?