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Bad Crank Bearings?

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2nd gear at low throttle rolling on SM wheels I can feel a 'slow' spot in the rpms, when wrapped up you cannot feel it, and in 3-5 not noticable, is this a crank bearing starting to go?

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2nd gear at low throttle rolling on SM wheels I can feel a 'slow' spot in the rpms, when wrapped up you cannot feel it, and in 3-5 not noticable, is this a crank bearing starting to go?

Crank bearing wear usually shows up in the oil as brass 'sparklies'.

Don't understand your explanation.

What is 'low throttle'? Low RPM? Partial throttle opening?

What is 'wrapped up'?

You would not feel a crank 'go' by increased friction, as they get loose as they go. Well until they go all the way, that is.

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I'm going to say from what you are saying that you have a flat spot in your jetting.

I agree with Krannie.

You may only need to change or ajust your fuel screw.

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As the others mentioned, it's probably jetting, but I'm gonna say my usual spiel and recommend you try running with the TPS unplugged and see if it changes anything.

I had similar issues with mine, and after talking to JD, he recommended a test run with the TPS unplugged. BAM, all gone. Bad TPS? Perhaps, but my theory is that when we're running in supermoto trim and staying at constant speeds at various throttle angles, we may be hitting some transition points in the ignition map which aren't too smooth. I'd love to test with another TPS, but I'm not going to go out and buy one just for testing.

I've been running with my TPS unplugged for about 4k miles now and it works great.

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TPS, the sensor on the carb w/ the 6mm plastic nut?

Or are you reffering to the pink wire mod? I have pink wire snipped.

I feel like its a jetting issue as well. Chain is smooth and it kicks over fine.

Running 2 1/2 turns, 170 main, 45 pilot, 55 leak w/ a full exhaust + 04' option cam, no port. I just went up to the 170 from a 165 and @ night time temps it really rips, daytime the 165 runs a little better.

I might also put in a 35 leak and new Accelerator pump diaphragm and see how this improves the situation.

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TPS, the sensor on the carb w/ the 6mm plastic nut?

Or are you reffering to the pink wire mod? I have pink wire snipped.

I feel like its a jetting issue as well. Chain is smooth and it kicks over fine.

Running 2 1/2 turns, 170 main, 45 pilot, 55 leak w/ a full exhaust + 04' option cam, no port. I just went up to the 170 from a 165 and @ night time temps it really rips, daytime the 165 runs a little better.

I might also put in a 35 leak and new Accelerator pump diaphragm and see how this improves the situation.

DO NOT dismantle the TPS! Just unplug it. If you dismantle it, it will not go back together in calibration, and it will not work (will work worse).

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FML :thumbsup:

Just striped out 2/4 of those POS phillips head screws on the leak jet cover on the bottom of the FCR carb.

Assuming i can find a dremel tool to cut off the bolt heads and extract the remaining screw, where can I order FCR parts???

Uhg, if I had my way people who use small phillips head screws should be shot in the foot and thrown in the shark tank.

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FML :thumbsup:

Just striped out 2/4 of those POS phillips head screws on the leak jet cover on the bottom of the FCR carb.

Assuming i can find a dremel tool to cut off the bolt heads and extract the remaining screw, where can I order FCR parts???

Uhg, if I had my way people who use small phillips head screws should be shot in the foot and thrown in the shark tank.

http://www.sudco.com/Diagrams323728/expfcrmx.gif Find the screw in question, go to your local hardware store and get you a good hex head screw - or just bring an old one if you can get it all out. Wish I would have replaced all my screws when I had it apart.

Oh, and like Krannie said, just unplug your TPS for the test, don't take it apart!

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I went ahead and ordered a new pump diaphragm off of TT and some new screws...

Yes replacing with hex screws is a great idea! Hopefully I will be able to find an extractor small enough tomorrow and get these bad boys out.

Also, I pulled my exhaust can off and my new header already has a layer of black soot inside...

-Am I running too rich? I feel like im jetted pretty good, maybe a little rich on the fuel screw or pilot?

-Bad seal on exhaust port? I siliconed it and put in a new washer.

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I went ahead and ordered a new pump diaphragm off of TT and some new screws...

Yes replacing with hex screws is a great idea! Hopefully I will be able to find an extractor small enough tomorrow and get these bad boys out.

Also, I pulled my exhaust can off and my new header already has a layer of black soot inside...

-Am I running too rich? I feel like im jetted pretty good, maybe a little rich on the fuel screw or pilot?

-Bad seal on exhaust port? I siliconed it and put in a new washer.

Shouldn't be too much soot in there.

The only way to adjust jetting is by 'seat of the pants' or with a F&A mixture reader. You can't do the plug thing on a four-stroke. You can't do it with a dyno, cause that only does WOT. The best way is to find a gradual hill about 1/8 mile long, and do a 'partial throttle' examination: dividing the throttle into (5) sections, go up that gradual hill using one of the (5) partial openings, and record the results: flat spot, really snappy, gurgle, etc. Then use a FCR MXCR jetting guide to make adjustments.

That, or read the stickies at the top of the forum, and copy jetting specs from a similarly modified bike.

http://www.thumperfaq.com/jetting.htm

http://shop.thumpertalk.com/PhotoGallery.asp?ProductCode=JDGuide

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The 35 leak really runs much better, disconected the TPS and it didnt run so hot, so plugged it back in.

Oh yeah got the screw off with a vice grip, dunno why it took me so long to figure that one out!

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