Question about Harley Davidson Motorcycles

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Engine knock M brother has a 2010 ultra glide. After fueling up with cheap gas, only station inremote ND, hesays that he began to hear a loud knocking sound at the top end of the engine when he would get the bike up to and over 65 mph or at the higher end of therpm range on the lower gears. Any idea what it could be? The bike has 48k mile and oil last chenged 4000 miles ago, oh and he said that after riding it he checked the oil and it was "Bubbly" Thanks for your time and feedback.

Posted by Anonymous on


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  • Harley Davidson Master
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Hi Anonymous, take a ride or drive over to your local dealers service department, I'm sure they will be happy to take your Harley Davidson for a test ride if necessary and offer professional advice and assistance concerning your issue. Have a nice day.

Posted on Jun 10, 2015


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SOURCE: 2008 1200 rt-p engine rattle during high speed deceleration.

keep on your dealer on your drive there is a spring pressure that holds a coupler together look at pic .
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SOURCE: 2002 kawasaki klx 300 r

If you are not a mechanic, take it to a shop before you completly destroy your cylinder or case. You most likely have a broken ring, bad valve or loose ring clip, but either way, the reason it is worse at the lower end is because that is where you are putting the most stress on the engine. could try using higher octane fuel, OR...your running the engine to lean. In any case, you should seek professional help with the issue, because running it with it knocking WILL end in an expensive repair.

Posted on May 26, 2009

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SOURCE: Engine knock at high revs

Sounds like Pre-ignition, aka Detonation, aka Engine knock. Carbon deposits build up on the head, valves and piston. They can get hot enough to ignite the fuel before the spark plug has a chance to. This is the Pre-ignition noted above. This is VERY hard on the engine. Take the head off the cylinder then beat the valve area with with a hammer followed by aggressively beating the top of the piston. Pre-ignition does the same thing. Not good for the top end, and not good for the crankshaft. Use only good quality premium gas. Change to a spark plug one heat range colder than the stock plug. Seal up any air leaks on the intake system. Running a lean fuel mix means running hot.

A “very helpful” rating for this answer? Thanks!

Posted on Jun 11, 2009

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SOURCE: Ducati 999 died on a ride - electrical problem I think

i have the same problem but what plugs are u talking about and have u been able to fix it. i know for sure my batt is blown it will not hold charge so my first step is to replace it. but i was wondering what other problemPost Solutions i may encounter

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SOURCE: 1998 Honda Shadow VLX chain break

When you say you got a diffrent type of gas ,do you mean make or octain .some engines like a certain type or makes of fuel.diffrent fuels can cause backfiring .or in some cases if the tanks are allowed top get too low watewr can be drawn up from the pump which causes many problems .As for your chain breaking this is down to either a badly worn chain or incorrectly adjusted .Remember a chain is only as strong as its weakest link .Oil or grease regularly .and allow for swinging arm movement and check adjustment by turning the chain and check several places on the chain as stretching can occur and tight spots will be found .

Posted on Mar 12, 2010

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