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Any guesses???

3670 Views 22 Replies 7 Participants Last post by  sfcmcgan
So.. My6 bike has a sever issue... I had to put it in the shop (Hinshaws motorcycle in Auburn).. it has the mech's baffled!!! Here are the symptoms:

1. rear cylinder has very little (i mean very little) exhaust. Kinda like when you breath fog on a window. the little it has gets very hot compared to the front cylinder. make a wierd "Psst, Psst Psst sound at idle.
2. engine light does NOT illuminate. But the fuel meter seems to be stuck at full bars even though I have less than a 1/4 tank fuel... this could be a different issue...not sure.
3. Rear cylinder has good compression... good spark.
4. using the Diagnostic mode... both injectors check out as good.
5. both cylinder run at approx 10 degrees diffrent from eachother... 201 -211.. these flux slightly... but nothing out of the ordinary. ( side note... if you measure either front or rear temps just below the plastic chrome covers... 1 side will be way warmer than the other... just FYI)
6. The bike still produces power and is totally ridable. there is power loss, but I could hit 60 fairly hassle free.
7. Gas is good (someone would ask)... drained all the fuel and replaced with fresh gas.
8. there is no strange internal sounds. Used a stethescope and listened.
9. there is no smoke coming out the oil filler hole... nor is there water in the oil.
10. no backfiring of any kind either thru the exhaust or intake.

Last thing... I completely disconnected the Cobra powerpro tuner and hooked up the stock config (much easier the 3rd time)... same issue...

My diagnoses is a bad fuel injector (I pray that is what it is!!!), but nobody at the shop had ever seen this particular issue.... I will let everyone know when I do... but your opinions are welcome!!!
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Somethings up with that injector. Did you check the wiring from the ecu to the injector? Figger you could rule out the ecu with an oscilloscope and compare it to the front..
Hah. Yeah I don't have one laying around either and I assume they're heinously expensive. But if you did have one I assume both cylinders should be getting a similar signal. Anyhow its pretty easy to take the throttle body and intake manifold apart and make sure everything is clean so I was assuming the mechanic did that
Straightjacket said:
Rear cylinders allways have a higher temp on a v-twinn, they get all the heat from the front cylinder on them. On a carberated version you would jet them different to compensate.
Wouldn't that be less of an issue on a water cooled bike?
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