Help I've ruined my bike.

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Martin83
Posts: 2
Joined: Wed Feb 17, 2016 7:23 pm
My Bike: Speed triple 1050

Help I've ruined my bike.

Post by Martin83 » Sun Jul 22, 2018 11:47 am

Hi guys I'm after some help/advice. I bought my zxr400 L9 18k on the clock a few years ago and have not had a chance to do anything with it since, it's dog eared but it was cheap and I love these little bikes, so this year I decided to get it out and give it some use.
After mot and a couple of rides out I discovered it was a bit asthmatic and had an issue with starting when hot. So I decided to give it a birthday I checked valve clearances and found the cam chain was knackered (tensioner fully extended). So I replaced the cam chain and was a hundred percent happy timing was right before refitting everything. Whilst doing this I found the coils were not original and not correct for the bike so I did a stick coil mod as per the thread on this forum. When putting the bike back together I decided to remove the air box resonator pipe to aid breathing.
I Have just been out on it and it runs great up to 6k then the stutter starts and it bucks like an angry donky and will not get above 10k revs. Revs fine when not under load. Additionally it has a k&n air filter and scorpion end can fitted by PO.
So I know I have made a rod for my own back by changing several things all at once, But is it likely that the issue under load is fuelling due to air filter end can and removal of air resonator (for better airflow to carbs) or is it likely I've messed somthing else up ie cam timing ,stick coils, wiring etc.
Any help greatly appreciated TIA.

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banner001
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Posts: 2280
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Help I've ruined my bike.

Post by banner001 » Sun Jul 22, 2018 4:53 pm

Yeah, it's probably running way too lean...go for a run, and just before it starts to bog give it a load of choke and pin it...if it now pulls and doesn't bog you are way too lean, you will need a few sets of main jets to fully assess it, but you might wanna start with main jets w sizes bigger than what you currently have...then go from there.
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

Martin83
Posts: 2
Joined: Wed Feb 17, 2016 7:23 pm
My Bike: Speed triple 1050

Re: Help I've ruined my bike.

Post by Martin83 » Sun Jul 22, 2018 7:10 pm

Cheers banner, that's what I was thinking too whilst out this morning I did try pulling the choke on before bogging and it did make it less dramatic but it was still noticeable. I'll open up the carbs and see what main jets it's running. Does anyone know what standard jets should be fitted and what sort of sizes are others running with a filter and can but otherwise standard bike?

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banner001
Track day God
Track day God
Posts: 2280
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Help I've ruined my bike.

Post by banner001 » Mon Jul 23, 2018 7:56 am

It's a 95 on the standard bike, yours sounds like mine, I would go with a 105 main, see how that feels and see if you now think it's too rich or too lean

https://www.motorcycleproducts.co.uk/ke ... 8_423.html
UK ZXR 400 L4
UK ZXR 400 L3 track bike
1989 FZR 1000 EXUP-R streetfighter

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