Need help troubleshooting bike tune 250m drag

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Thu Apr 16, 2015 9:52 am

Throttle is fine. Verified it opens fully.

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Re: Need help troubleshooting bike tune 250m drag

Post by John Wallace » Thu Apr 16, 2015 10:54 am

You haven't checked to see what the actual timing is yet?

Need to know at least what the baseline is before just changing it?

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Thu Apr 16, 2015 5:12 pm

This has a cdi. Electronically controlled timing. We didnt change anything. we just loss 3 seconds on our time which is really big. Problem is at high rpm. It doesnt pull like it should. At first we thought it was the valve springs so we changed it and it didnt help. We also tried to install taller gears and still no improvement

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Re: Need help troubleshooting bike tune 250m drag

Post by BCjohnny » Thu Apr 16, 2015 6:48 pm

bladefrost wrote:....... also there is slight intake valve leak where we did fix also.
What was the problem and how did you 'fix' it?
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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Thu Apr 16, 2015 7:30 pm

BCjohnny wrote:
bladefrost wrote:....... also there is slight intake valve leak where we did fix also.
What was the problem and how did you 'fix' it?
its a slight leak on the intake valves, we just replaced the valves and leak was fixed. after that we can feel the bike accelerates significantly stronger but there is great power loss on the top rpm.

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Re: Need help troubleshooting bike tune 250m drag

Post by BCjohnny » Fri Apr 17, 2015 2:55 am

What did you do with the seats?

How did the installed valve heights compare before and after replacement? A taller installed height could give you the symptoms you have.........
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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Fri Apr 17, 2015 5:31 am

BCjohnny wrote:What did you do with the seats?

How did the installed valve heights compare before and after replacement? A taller installed height could give you the symptoms you have.........

i did nothing with the seats. i just installed new valves and thats it. we already testing replacing the valves springs and shimming it but problem still exist. today we changed the magnetic pickup coil / crank sensor and the bikes sounded different, seem to have more power. but we still have to test it on the tracks. i hope this is it.

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Fri Apr 17, 2015 7:42 am

We tested today. Pulser pickup coil didnt fix the issue. Could this be the ignition coil?

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Fri Apr 17, 2015 8:01 am

https://www.dropbox.com/s/u9fue4awtw01h ... 1.mp4?dl=0

Our test run today. Bike is laboring. Seem like something is dragging. Similar to when you applying the brakes lightly. Please see and listen, the video should help you guys understand what i mean.

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Fri Apr 17, 2015 7:32 pm

I notice also sometimes the bike would die after a full throttle run and sometimes when you are about to stop the idle would be low and it would die. Im not sure if this is a sign that would lead to the problem. Today I will replace the ignition coil and see what happens.

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Sat Apr 18, 2015 6:51 am

tested today with the new ignition coil, still problem exist. i wonder what parts could be at fault which has very big influence on how it runs considering we lost 3 seconds.

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Re: Need help troubleshooting bike tune 250m drag

Post by ijames » Sat Apr 18, 2015 9:27 am

Have you done a compression and/or leakdown test?

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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Sun Apr 19, 2015 1:06 am

James, havent done it. I have limited tools here at home. Here in the philippines not much tools available also money to buy those tools. could it be the valve clearance? I have noticed the clearance varies when on the base circle. It should be uniform right and just changes when your on the ramps already?

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Re: Need help troubleshooting bike tune 250m drag

Post by BCjohnny » Sun Apr 19, 2015 5:06 am

So now it sounds like the cam may be bent, or the bearing clearances are shot and the cam's responding to spring pressure.

I'd suggest if you want constructive help you go back to the beginning, carefully explain what you've 'fixed', why it had to be done, and seriously consider going back over it all again (some of your methods described, to say the least, not 'best practice'). Also the tool situation needs addressing, few us can see in the dark, and I'm sure some of the stuff you need (DTI, small mic, Plastigauge etc) can be picked up at reasonably enough.

This is certainly a better way to proceed than chasing phantoms.
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Re: Need help troubleshooting bike tune 250m drag

Post by bladefrost » Sun Apr 19, 2015 6:21 am

johnny, thanks for the input. i didnt have proper education regarding engines, i only research and thru experience learned about it. anyway this bike just suddenly slowed down after an overhaul and intake valves changed, i wonder if the valve lash was different before and that made it run fast. im not sure what clearances i've used. camshaft bearing clearances are okay. clearances when on the base circle varies lets say i measured exhaust when the intake begins to close and it reads 0.15mm and when i turn the engine over it becomes looser & now reads 0.20mm, this engine uses solid rollers.

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