Bike hesitating- I'm about to throw it in the lake. NEED HELP

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HMBAtrail
Posts: 56
Joined: Wed Aug 16, 2017 4:07 am
Location: Indpls, IN

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby HMBAtrail » Mon Aug 19, 2019 10:28 pm

etsjw wrote:Been thinking about your problem and I think Eldert identified what is happening - the float bowl is running out of fuel resulting in a lean condition at
WOT in 4th/5th gears.
You could check by installing a transparent fuel line, put the bike on some type of stand so the rear tire is off the ground, run through the gears and observe the fuel level in the line.
As you have checked tank venting and petcock size, then something most be upsetting the action of the float and inhibiting the fuel flow. This might be related to some vibration issue. Can you insulate the carb from the head to try and lower/change frequency of the vibrations reaching the carb?
These kind of situations can be real tests of character!
Good luck and please let us all know what finally worked.
John


John,
I'm of the same mind as you on this. The motor is sitting on the bench right now about to go back into the bike. I've adjusted the floats and also have a 3.5mm float needle to put in there. If it's a fuel bowl starvation issue then I have to think that it will soon be corrected. If it doesn't then I will be sufficiently convinced the bike is possessed and I will burn it at the stake. Either way I will be sure and report back here.

HMBAtrail
Posts: 56
Joined: Wed Aug 16, 2017 4:07 am
Location: Indpls, IN

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby HMBAtrail » Sun Sep 08, 2019 10:57 pm

A complete success. Went to a bigger float needle, adjusted the floats and re-routed the fuel line. All signs of hesitation are gone. Now I can focus more on proper jetting.

I welded in an O2 sensor bung into the exhaust pipe and hooked up a wideband air/fuel sensor. It still seems I'm running a little rich from mid range to WOT. At idle about about 13.5:1, and at 1/4 throttle about the same to slightly richer at 13:1. At 50% throttle it riches up to about 12:1 and at WOT I'm at about 11.5:1.

I have a 166P8 needle jet in the bike presently and will step down to a P6 or P5 needle jet as soon as the arrive. I also moved from a 240 main to a 220 main, which helped. Removing the screen on the carb helped even more. That got me from 10:1 to 11.5:1

Barber is in a few weeks so work continues.

graeme
Posts: 618
Joined: Sun Mar 25, 2012 12:00 am
Location: Australia

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby graeme » Mon Sep 09, 2019 2:33 am

You probably know already,,,

Do 1 change at a time and record the result
Or you will be chasing your tail

Graeme

blethermaskite
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Location: northern ireland

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby blethermaskite » Mon Sep 09, 2019 7:56 am

Interesting the difference removing the screen from the carb air intake made for you, I would never use a screen on a race bike carb.......they always restrict max air flow even the coarse mesh ones. Glad you have beaten the gremlins.
Cheers
George

HMBAtrail
Posts: 56
Joined: Wed Aug 16, 2017 4:07 am
Location: Indpls, IN

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby HMBAtrail » Mon Sep 09, 2019 12:14 pm

graeme wrote:You probably know already,,,

Do 1 change at a time and record the result
Or you will be chasing your tail

Graeme


I could do one change at a time, yes. Or I could do four changes at a time and be four times as fast. I've done the calculations and if I did six changes at a time the bike would be capable of over 600mph and I'm not sure the chassis can handle those types of speeds. I mean, that's just science. You can't argue science. :)

jbcollier
Posts: 80
Joined: Sun Oct 10, 2010 2:30 am

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby jbcollier » Tue Sep 10, 2019 12:15 am

Screens are very restrictive. Can be useful though if you have unscrupulous fellow competitors. Yes, sadly, I have seen that happen.

LaceyDucati
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Location: Wales UK
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Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby LaceyDucati » Tue Sep 10, 2019 5:31 pm

Screens mounted over bellmouths are very restrictive and are no use on a race bike. However appropriately sized K&N's and some foam filters can sometimes have little or no effect. The problem on a race bike is often accommodating filters, sods law means it's were you want your leg! Like all these things best tested on a dyno to confirm output/effect. I've prefer a large radiused bellmouth. With these I have used larger strainers covering the bellmouth (not interfering with the radius edge of the bellmouth) with no power losses at all, think kitchen sieve :-)

Regards Nigel

HMBAtrail
Posts: 56
Joined: Wed Aug 16, 2017 4:07 am
Location: Indpls, IN

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby HMBAtrail » Wed Sep 11, 2019 1:00 am

IMG_6932.jpg


Nigel, in your opinion is this too restrictive?

themoudie
Posts: 27
Joined: Sat Jun 14, 2014 12:44 am
Location: Scotland

Re: Bike hesitating- I'm about to throw it in the lake. NEED HELP

Postby themoudie » Wed Sep 11, 2019 9:07 am

This is an example of the sort of lateral thinking that may help. I know it is on a TT2 and very different from a single, but Nigel's nod to the kitchen is well illustrated. ;)

The stainless steel mesh is readily available in various sized sheets on eBay and requires tinsnips to cut rather than "heavy scissors" :( that I saw recommended in one advert!

Thanks to Glyn of Sports Motorcycles, NZ, for posting this on his Facebook 19/8/2018.

My regards, Bill
Attachments
Sports_Motorcycle_TT2_airfilter.jpg


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