RVF400 Tyga Twin Stack

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wogstaa
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RVF400 Tyga Twin Stack

Post by wogstaa » Mon May 16, 2016 8:17 am

Hey guys,

I've got the full tyga system with twin stack installed on my bike and there is a massive dip in power as per the dyno chart. Has anyone got any advice on how to sort it out, or at least make it a little better?

My mechanic said that it's a typical issue with the twin exhaust but I thought I'd check here to see if anyone has had any luck.

Not sure on the current jetting but it's got stock needles, RO hrc springs and the intake is stock.

Thanks

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CMSMJ1
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Re: RVF400 Tyga Twin Stack

Post by CMSMJ1 » Mon May 16, 2016 5:38 pm

you need the air/fuel graph too.

There is no reason a twin stack will make any difference to the fuelling - you need to know from each set of stacks what the mixture is like.

if it is lean, sort it - if it is rich, sort it.

Are the slides standard? not drilled?
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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Wed May 18, 2016 4:24 am

Mechanic said it's not lean or rich, which I don't believe.

I'll go past next week when I get a chance and see if he can give me the air/fuel chart.

I think it might be a bit rich since the flat spot is much worse once the engine gets up to operating temp.

I believe the slides are standard, I don't think my mechanic would've drilled them.

I might try switching back to standard springs on Sunday since I need to replace the fuel tap on the tank, I'll do it while I'm there, see if it makes any difference.

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Re: RVF400 Tyga Twin Stack

Post by CMSMJ1 » Wed May 18, 2016 12:43 pm

I don't trust mechanics to know fuck all if they are blatantly blagging that there is no issue with fuelling.

it might have been clutch slipping if there is no indication of anything else?

Slide springs allow it to open faster and it might be choking a bit - you can fiddle a bit with riding it with choke on to see if it is really dying under overfuelling. or you can get yuor needles out, take a washer off them and that will make it leaner
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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Thu May 19, 2016 9:55 am

I got my mate that works at the shop to send me the Dyno sheet with the A/F readings on it

I'll go and get a hard copy of it when I get a chance but here it is for now
I need to do some reading up on A/F ratio etc as I honestly don't have much idea on it yet.

There's definitely no issue with the clutch slipping, you can hear the engine note change in the rev range where the power dip is.

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Re: RVF400 Tyga Twin Stack

Post by CMSMJ1 » Thu May 19, 2016 3:32 pm

Super duper mega rich isn't it? needs smaller jets, needles removing or new air filter...
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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Thu May 19, 2016 9:52 pm

Yeah, are air fuel readings usually that lumpy on these bikes?
My air filter is fairly new but I'll double check it.
I think putting the stock springs back in would be a good start as it runs well on full throttle and I don't know what size jets are in there at the moment but I had 125 jets when I was running a TSR half system and it ran perfect

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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Sun May 22, 2016 5:01 am

Turns out the needles had an extra shim. Im just changing the springs out and ill see how it runs.

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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Sun May 22, 2016 5:41 am

Ok so it's still running 125 mains all round and I finally have learned the art of reinstalling the carbs in under a minute :)

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Re: RVF400 Tyga Twin Stack

Post by wogstaa » Sun May 22, 2016 7:21 am

Can confirm it's running better, still has a little stumble but not as bad.

Current setup: 125 mains, stock springs and needles with 2 shims, stock pilot jets (didn't check settings just screwed them in not even 1/8 of a turn in) , air filter looks ok, I removed the metal mesh from the bottom of it.

I'm not sure if I should remove the 2nd shim from the needles or maybe go down a main jet size.


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