Missfiring

Technical questions and answers

Missfiring

Postby Ells » Wed Jun 01, 2016 3:37 pm

Few issues at Snetterton that need ironing out.
Sunday am the bike would not start. Thanks to Len for sorting flooded carbs and Fish for the push. New plugs went in and off we went. In the race the bike definatelly had a different tone to the engine. The engine seemed to be searching and had a deeper echoy sound. We pulled off in the last lap when the bike really started to misfire.
Sunday afternoon race was worse than the morning. Even in the collecting area the bike felt and sounded different. Once out of the collecting area and up to Richies and that was when the bike really started to misfire.

Apart from the new plugs (one was dropped in the rush) and the awkward starting nothing had changed from Saturday. Watching back on video the temperature stays around the 60 degree mark even though I thought it went higher.

So we will be swapping engines (As the gear shaft that comes out on the stator side it looks a little bent and is causing a few missed gear changes). Additionally we have a new gear rod and roses from SES to replace the current item and improve the gear changes.

Will try to rectify the misfiring by checking the wiring particulalry earths then swapping in order
1.plugs
2.CDI
3.Pick up
4.Stator

could a duff battery be the issue? (running total loss). I am beginning to wonder if the bike was reluctant to start due to electrical issues and then the carbs got flooded rather?

PS Engine Number 2 comes with kick starter :D

Cheers
Mark
#90 Going slower than last year
Ells
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Re: Missfiring

Postby ypm76 » Thu Jun 02, 2016 3:29 pm

Add the coil and HT leads to your list.

At what revs did the misfire occur? or was it all the time, even at tickover?

If you have video footage, post it to youtube so we can see the symptoms
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Re: Missfiring

Postby Ells » Thu Jun 02, 2016 11:02 pm

I have uploaded Saturday first race and Sunday first race
https://www.youtube.com/watch?v=nCDBBFPuOTw
https://www.youtube.com/watch?v=sa3wHhBoFk0

I will get Sundays 2nd race up as that ended at the first corner! Saturdays race was a little slower pace (its more of a refined gentle ride at the back) :D

I did wonder about fuel starvation as I was running less fuel in the tank on Sunday (6 litres) and it started to play up going round Ritchies! However we hardly got out of the collecting area Sunday let alone a few laps before she started to play up.

Oh and yes we are having an issue with changing gear smoothly. There seems a lot of flex in the rod from rear sets to gear arm and also the shaft that goes through the motor looks like it is slightly bent. Thats why spare engine is going in for Oulton.

Cheers
Mark
#90 Going slower than last year
Ells
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Re: Missfiring

Postby ypm76 » Fri Jun 03, 2016 11:06 am

@ 12:30 on Sunday's video...is that what we're talking about? Exiting Ritches and there's no drive with a stutter?

If so my money is on fueling. At a guess I'd say the fuel lines need looking at as I know you've had the carbs apart a lot.

The only reason other than a nip up that can cause an engine noise change is either PV seals, pv end cap, base gaskets or exhaust system (headers, pipes etc)

I don't think that's electrical from what we've seen in the video.

Oh and there's nothing wrong with your pace, you'd put most trackdayers to shame.
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Re: Misfiring

Postby Ells » Fri Jun 03, 2016 1:35 pm

ypm76 wrote:@ 12:30 on Sunday's video...is that what we're talking about? Exiting Ritches and there's no drive with a stutter?

Yep that was the final straw although she had been feeling a little off on Sunday. Will swap the engine over and see what unravells. Will also look at the fueling. She was really hard to start for race 4 which ended one turn into the warm up lap.
Will look at the fuel flow I know what she should flow so should be easy to check.

Crossed fingers for Oulton.
Cheers
Mark
#90 Going slower than last year
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Re: Missfiring

Postby Ells » Fri Jun 03, 2016 9:02 pm

Well,
got in the garage to have a quick look. Left hand exhaust spring had disappeared. Still lock wired on but more movement than if the spring was there.

Left hand spark plug the cap just felt not fully home. When I puled the plugs out(they had only been in for 7 laps - race 3 and 4). The left hand plug the porcelain was white just like when the plug went in. The right hand plug the porcelain part of the plug was black and generally quite wet.

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